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About Margaret Lin-Martore, MD

ALiEMU PEM POCUS Series Editor
Assistant Clinical Professor of Emergency Medicine and Pediatrics
University of California, San Francisco
Benioff Children's Hospital San Francisco

PEM POCUS Series: Pediatric First-Trimester Pregnancy

PEM POCUS pediatric cardiac

Read this tutorial on the use of point of care ultrasonography (POCUS) for pediatric first-trimester pregnancy evaluation. Then test your skills on the ALiEMU course page to receive your PEM POCUS badge worth 2 hours of ALiEMU course credit.

Module Goals

  1. List the indications for performing an obstetric point-of-care ultrasound (POCUS)
  2. Identify the characteristic findings of an intrauterine pregnancy in the first-trimester
  3. Describe how to measure fetal heart rate (FHR) and methods of estimating gestational age using POCUS
  4. Identify findings concerning for ectopic pregnancy in the first-trimester of pregnancy

Case Introduction

A 17-year-old female with a past medical history of pelvic inflammatory disease, presents as a walk-in from triage with lower abdominal pain and vaginal bleeding that started this morning. She has soaked through three pads since this morning without the passage of clots. She reports mild nausea, and dizziness. She denies any fevers, chills, chest pain, shortness of breath, vomiting, or decreased appetite. She is currently sexually active with one male partner in a monogamous relationship and does not use protection. Her menstrual periods are irregular and she is unsure of her last menstrual period.

On arrival, her vital signs are:

Vital Sign Finding
Temperature 37 C
Heart rate 94 bpm
Blood pressure 98/62
Respiratory rate 14
Oxygen saturation (room air) 99%

Exam

The patient is in mild distress secondary to pain and is lying supine in the stretcher. She has mild tenderness in lower quadrants with some voluntary guarding. There is no evidence of abdominal distension, rebound, rigidity, or palpable masses. Bowel sounds are present. On the pelvic exam, she has some blood in the vaginal vault, but no clots. No abnormal discharge. There is mild tenderness on the bimanual exam. The cervical os is closed. There is no cervical motion tenderness.

Diagnostics and Management

She is started on IV fluids and is given PO acetaminophen. Vitals improve to HR 85, BP 105/70, RR 12, 99% on RA. Basic labs, PT/PTT/INR, type and screen, and a urine pregnancy test are sent. While waiting for the results, you are concerned about an ectopic pregnancy and decide to perform a point-of-care (POCUS) obstetric ultrasound examination.

An obstetric POCUS can be performed using both the curvilinear (transabdominal approach) and endocavitary probes (transvaginal approach). Certain anatomical structures such as the ovaries and an early pregnancy can be visualized earlier and with greater detail using an endocavitary probe due to its closer proximity to the area of interest. While earlier pregnancies may be identified by the transvaginal approach, we recommend starting with the transabdominal probe because it is less invasive. The transabdominal examination is best performed with a full bladder and the endocavitary examination is best performed with an empty bladder. Longitudinal and transverse views of the uterus should be obtained when using either the transabdominal or endocavitary probe.

ultrasound probes

Figure 1. Different probes used for first-trimester pregnancy ultrasound

transabdominal positioning

Figure 2. Positioning for transabdominal approach

  • Position the ultrasound machine to the patient’s right with the screen facing you (figure 2).

Obtaining the transverse view

  • Place the transabdominal probe with the probe marker toward the patient’s right, just above the pubic bone and identify the bladder and uterus. The fundus of the uterus may be visualized superior to the bladder if the uterus is anteverted and posterior to the bladder if retroverted.
  • Once the uterus is identified, scan through the uterus in its entirety and identify the myometrium, and endometrium.
  • An examination of the adnexa can also be attempted to identify the ovaries, potential masses, or surrounding free fluid. The ovaries typically measure 2-3 cm in diameter and appear less echogenic than the surrounding tissue.
transabdominal view transverse

Figure 3. Normal transverse view of the uterus and bladder using the transabdominal probe. Image courtesy of The Pocus Atlas and Drs. Lindsay Davis and Hannah Koplinski

Obtaining the longitudinal (sagittal) view

  • Rotate the transabdominal probe clockwise 90 degrees so that the probe marker is facing the patient’s head.
  • In this view, you should be able to identify the bladder, uterine fundus, uterine body, cervix, vaginal canal, posterior cul-de-sac, and rectum. The thin, hyperechoic line in the center of the uterus is the endometrial stripe.
  • An examination of the adnexa may also be attempted to identify the ovaries, potential masses, or surrounding free fluid (especially in the retrouterine cul de sac) by fanning slowly left and right.
transabdominal longitudinal view pregnancy

Figure 4. Normal longitudinal (sagittal) view of an anteverted uterus and bladder using the transabdominal probe. Image courtesy of The Pocus Atlas and Drs. Lindsay Davis and Hannah Koplinski

Not all institutions have access to an endocavitary probe. However, if your institution does, the transvaginal ultrasound examination can provide additional views of the uterus and surrounding structures.

  1. Position the ultrasound machine to the patient’s right with the screen facing you, similar to the transabdominal positioning.
  2. Position the patient in the dorsal lithotomy position (similar to a normal pelvic exam), drape the patient, and have a chaperone present in the room
  3. Place gel at the tip of the endocavitary probe and apply a sterile condom or cover over the endocavitary probe. Subsequently apply sterile gel to the tip of the covered probe.

endocavitary positioning

Figure 5a. Positioning of endocavitary probe in transvaginal approach using a simulation model

Endocavitary probe

Figure 5b. Indicator labeled on endocavitary probe

Obtaining the longitudinal view

  • Hold the probe with the indicator at the 12 o’ clock position (figure 5b).
  • Slowly insert the probe until the endometrial stripe is visualized
  • Tilt/fan the probe to the left and right and identify the bladder, uterine fundus, endometrial stripe, myometrium, cervix, posterior cul-de-sac, and rectum

Obtaining the transverse view

  • Rotate the probe counterclockwise so that the indicator is facing the patient’s right (9 o’ clock position).
  • Tilt/fan the probe up and down to visualize the bladder, endometrium and myometrium.
  • Obtain a view of the ovaries by looking at the adnexa (lateral and/or posterior to the uterus).

Key Point: To definitively diagnose an intrauterine pregnancy, either a yolk sac or fetal pole must be visualized within the gestation sac of the uterus.

There are many conflicting opinions about the upper limits of the discriminatory zone (B-hCG level at which an embryo is expected to be seen). In general, for a patient with a positive B-hCG with concern for an ectopic pregnancy, an ultrasound should be performed. Typically, a pregnancy should be visible by transvaginal ultrasound examination with a B-hCG of 1000-2000 mIU/mL and by transabdominal ultrasound examination at 6000-6500 mIU/mL [1, 2].

Figure 6. Double decidual sac sign in a normal intrauterine pregnancy

Figure 7. Fetal pole and yolk sac in a normal intrauterine pregnancy

In these sonographic images, there are several characteristic sonographic features of a normal first-trimester IUP. To definitively diagnose an intrauterine pregnancy, either a yolk sac or fetal pole must be visualized within the gestation sac of the uterus.

  1. Gestational sac – an intrauterine, fluid-filled (anechoic or black) structure surrounding the embryo. This is the first structure seen in pregnancy by ultrasound in the first trimester and is characterized as an anechoic circular cavity
  2. Double decidual sac sign – consists of the decidua parietalis (lining of the uterine cavity) and the decidua capsularis (lining of the gestational sac) which on ultrasound is visualized as two concentric rings surrounding an anechoic gestational sac. The presence of a double decidual sac sign is highly indicative of an early intrauterine pregnancy (figure 6) [3].
  3. Yolk sac – this is the first anatomic structure identified within the gestational sac in the first-trimester and is seen on ultrasound as a circular, thick-walled echogenic structure with an anechoic center within the gestational sac (figure 7).
  4. Fetal pole – the growing embryo appears as an echogenic thickened margin on the edge of the yolk sac (figure 7).
  5. Ensure the gestational sac is well seated within the fundus of the uterus and surrounded by at least 5 mm of myometrium on all sides.

Once the embryo is identified, a fetal heart rate (FHR) can be obtained as early as 6 weeks of gestation. The fetal heart movement may be visualized as a flicker of movement. Visualization can be performed using either the endocavitary or curvilinear probe and the M-mode function. In POCUS, we do not use Doppler as this has a theoretical risk to the fetus.

To calculate the FHR, follow the following steps:

  1. Identify the beating fetal heart.
  2. Enlarge and center: Use the zoom function on the machine to enlarge fetal heart image
  3. M-mode: Align the M-mode line over the fetal heart, record the M-mode, and freeze the image. Find the sine wave and measure either crest to crest, or trough to trough.

A normal FHR usually ranges from 110-160 beats per minute. It begins around 90–110 bpm and increases to 170 bpm by 9 weeks of estimated gestational age.

Figure 8. Fetal heart rate measurement (rate of 148 bpm) using M-mode

The most accurate time to estimate gestational age is during the first trimester. Accurate estimation of gestational age is crucial for guiding prenatal care, decision making in high-risk pregnancies, and establishing a reliable due date. This can be performed by either measuring mean sac diameter (MSD) or crown-rump length (CRL).

Measuring mean sac diameter (MSD)

The MSD is the earliest measurement that can be used to estimate gestational age. This measurement is, however, less accurate than using crown-rump length and is typically performed between 5-8 weeks of gestation using the following steps:

  1. Obtain a longitudinal view of the gestational sac
  2. Measure the height and the length of the gestational sac
  3. Rotate the probe 90 degrees to obtain a transverse view of the gestation sac
  4. Measure the width of the gestational sac
  5. Add the height, length, and width then divide by 3 to obtain the MSD

Most ultrasound machines should help you perform this calculation; however, the gestational age can be calculated manually using the following formula: [4]

Gestational Age (days) = MSD (mm) + 30

Measuring crown-rump length (CRL)

Once an embryo is present in the gestational sac, CRL can be measured. CRL is the most accurate single measurement and is typically used to estimate gestational age between 6-13 weeks of gestation [4]. This measurement can be performed using the following steps:

  1. Obtain a mid-sagittal view of the entire embryo
  2. Measure the cephalic pole to caudal rump

Most ultrasound machines should help you perform this calculation. There are also available calculators (e.g. perinatology.com CRL calculator).

Figure 9. Crown rump length measurement showing an estimated fetal age of 6 weeks and 3 days

An ectopic pregnancy is a pregnancy in which a fertilized egg implants and grows outside the uterine cavity. The most common site for an ectopic pregnancy is the ampulla of the fallopian tube. The primary goal of performing an obstetric ultrasound in a pregnant patient who presents with abdominal pain, pelvic pain, and vaginal bleeding is not to rule in an ectopic pregnancy, but rather to rule in an IUP.

Ruling in an IUP essentially rules out an ectopic pregnancy, given that the incidence of a heterotopic pregnancy – the simultaneous occurrence of an intrauterine and an ectopic pregnancy – is 1 in 30,000. The rate of heterotopic pregnancies, however, rises significantly in patients who have undergone in-vitro fertilization (IVF) to ranges from 1 in 100 to 1 in 500 pregnancies [5]. A history of pelvic inflammatory disease also increases concern for heterotopic and ectopic pregnancy.

Uterus Views

If an empty uterus is visualized on bedside ultrasound in a patient (as shown below) with a B-hCG level greater than the discriminatory zone, the next step is to examine the adnexa for sonographic signs of an ectopic pregnancy. However, the lack of a visualized IUP on POCUS in a pregnant patient is concerning for ectopic pregnancy, and it is not expected to be able to visualize the actual ectopic pregnancy.

Video 1. Coronal (transverse) view of uterus without an intrauterine pregnancy

Video 2. Sagittal (longitudinal) view of uterus without an intrauterine pregnancy

Adnexa Views

To examine the adnexa in the transabdominal view, ensure that the patient has a full bladder and identify the uterus in the sagittal and transverse views. Using the uterus as a landmark, sweep laterally and posteriorly at which point the ovaries may or may not be visualized. Use color Doppler to help distinguish the ovary (which has a vascular hilum) from surrounding structures. Sonographic signs of an ectopic pregnancy include:

1. Tubal ring sign

A thick hyperechoic ring around a hypoechoic tubal mass

Video 3. Coronal (transverse) view of uterus showing tubal ring sign

2. Ring of fire sign

A well-circumscribed hypoechoic structure surrounded by a hypervascular ring seen on color Doppler due to trophoblastic activity and neovascularization. Note that the ring of fire sign is also present in corpus luteum cysts, which are a type of functional ovarian cyst that forms after ovulation to support a possible pregnancy.

Figure 10. Ring of fire of the adnexa

Free Fluid Assessment

If there is high suspicion for an ectopic pregnancy, assess for free fluid in the pelvis and abdomen, especially in the posterior cul-de-sac (pouch of Douglas) and hepatorenal recess (Morison’s pouch). The hepatorenal view is key for detecting hemoperitoneum in the supine patient. Fluid will often collect in Morison’s pouch first. Sweep through the pelvis in both sagittal and transverse planes to look for anechoic or hypoechoic fluid. While trace fluid may be normal in patients, the presence of moderate to large amounts of free fluid, particularly if echogenic (suggesting hemoperitoneum), raises concern for ruptured ectopic pregnancy and warrants immediate intervention. Ultimately, if the bedside ultrasound is inconclusive in a patient with clinical concern for ectopic pregnancy, a radiology performed ultrasound and/or gynecology consult should be ordered urgently.

Figure 11. Free fluid collecting in the right upper quadrant hepatorenal recess (Morison’s pouch)

Uterine fibroids, also known as leiomyomas or myomas, are benign smooth muscle tumors of the uterus. On ultrasound, they typically appear as well-circumscribed, hypoechoic (relative to the myometrium) structures that can arise within the myometrium (intramural), along the outer surface of the uterus (subserosal), project into the endometrial cavity (submucosal), and can be attached by a stalk (pedunculated).

Figure 12. Uterine fibroids

A molar pregnancy, also called a hydatidiform mole, is a type of gestational trophoblastic disease that results from abnormal fertilization, leading to the growth of abnormal trophoblastic tissue rather than a normal embryo.

A complete mole, which occurs due to fertilization of an empty ovum by one (or two) sperm, typically has a “snowstorm” or “cluster of grapes” appearance. On ultrasound, the uterus may appear larger than expected for gestational age and may show a diffusely echogenic intrauterine mass with numerous cystic spaces.

Figure 13. Molar pregnancy

An ovarian cyst is a fluid-filled sac within or on the surface of the ovary. Most are benign and functional, especially in reproductive-age women, and often resolve spontaneously.

On ultrasound, simple ovarian cysts appear as a thin, smooth-walled anechoic structure. A corpus luteum cyst, which may have a “ring of fire” appearance on color Doppler, is more thick-walled in appearance. Hemorrhagic cysts tend to have mixed echogenicity with a lacy, reticular pattern.

Figure 14. Ovarian cysts

Ovarian torsion is often on the differential for female patients presenting with sudden onset lower abdominal pain. It is a gynecologic emergency where the ovary twists on its own vascular pedicle, compromising blood flow. Patients with large ovarian cysts or masses ≥5cm are at increased risk.

On ultrasound, an enlarged, edematous ovary with absent or decreased flow may suggest this diagnosis. The ovary also tends to have peripheralized follicles. A midline ovary can also be a concerning sign. Venous flow is typically lost prior to arterial flow; however, presence of flow does not rule out ovarian torsion. Lastly, a highly specific finding for ovarian torsion may be the presence of a whirlpool sign which is visualized as a targetoid, coiled structure on color Doppler.

Figure 15. Ovarian torsion with midline, edematous ovary

Integration of the obstetric POCUS into early pregnancy assessment can significantly accelerate diagnosis and initiation of treatment, particularly in urgent cases like an ectopic pregnancy. Faster timelines could translate into improved clinical outcomes and more efficient ED workflows.

Studies that helped shape the landscape for the utility of POCUS in early pregnancy in the emergency department setting include:

Study Study Type, Location (Time frame) N, Ages Notes
Doubilet et al., N Engl J Med. 2013 [6] Review Article N/A This review establishes more stringent ultrasound criteria for diagnosing early pregnancy failure to minimize false-positive results:

  • CRL ≥7 mm without heartbeat or MSD ≥25 mm without embryo confirm a nonviable pregnancy.
  • Equivocal findings trigger serial scans and hCG monitoring to safely evaluate uncertain cases.

These guidelines are designed to protect viable pregnancies from premature or inappropriate interventions.
Thamburaj et al. Pediatr Emerg Care. 2013 [7] Retrospective case-cohort review, Single ED at Newark Beth Israel Medical Center (2007) 330 Female patients aged 13-21

Bedside POCUS group (n = 244, ~74%; Radiology group (n = 86)

 Time-to-scan: 82 min vs. 149 min (POCUS vs. radiology), P < 0.001

LOS: 142 min vs. 230 min (P < 0.001)

Despite similar demographics, chief complaints, diagnoses, and dispositions between groups, bedside ultrasound significantly reduced both scan time and overall ED stay.
McRae et al. CJEM. 2009 [8] Systematic review, multiple EDs including international data N/A ED-targeted ultrasound is highly specific and reliably identifies IUP. The specificity for detecting IUP exceeded 98% in most studies, and sensitivity typically above 90%.

Bedside ultrasound reduced missed ectopic diagnosis, decreased time to surgical treatment for ectopic cases, shortened ED lengths of stay in normal pregnancies, and showed greater cost-effectiveness versus formal radiology ultrasound.
Durston et al. Am J Emerg Med. 2000 [9] Retrospective cohort, single-center (1992-1998) 120 patients diagnosed with ectopic pregnancy Compared 3 different ultrasound availability models over sequential time periods:

  1. Radiology-performed ultrasound only
  2. Limited ED physician-performed ultrasound availability
  3. Full ED physician-performed bedside ultrasound availability

Increasing ED ultrasound availability improved the quality of ectopic pregnancy detection.

The combined approach of initial ED physician bedside ultrasound followed by formal imaging when indicated was the most cost-effective and efficient.
Mateer et al. Acad Emerg Med. 1995 [10] Prospective cohort, single-center 148 pregnant women at risk for ectopic pregnancy Emergency physicians trained in bedside transvaginal ultrasound (TVUS) demonstrated a 93% agreement rate with gynecologists in interpreting scans. Most ectopic pregnancies were identified early, allowing prompt management.

Established feasibility and high accuracy of ED physician-performed POCUS for early pregnancy evaluation, promoting wider adoption in emergency care.
Beals et al. Am J Emerg Med. 2019 [11] Systematic review, multi-center 2,350 patients across 6 studies Patients who received POCUS had a mean reduction in ED LOS of 73.8 minutes (95% CI: 49.1–98.6) compared to those who underwent comprehensive ultrasound.

All included studies reported decreased LOS with POCUS.
Table 1. Key published studies on first-trimester obstetric POCUS

Case Resolution

You use a curvilinear abdominal probe (Figure 16) and endocavitary probe (Figure 17) and visualize the following:

ring of fire ultrasound adnexa

Figure 16. Right adnexal view showing a “ring of fire” sign suggestive of an ectopic pregnancy

Figure 17. Sagittal view of uterus showing the absence of an intrauterine pregnancy

Given her initial low blood pressure and an obstetric ultrasound concerning for an ectopic pregnancy, you decide to perform a FAST exam, and you see free fluid in the hepatorenal recess.

Figure 18. Right upper quadrant abdominal view, showing free fluid in Morison’s pouch

ED Course

Serum labs show the following:

  • hCG 8400 mIU/mL
  • WBC 13.3 x 103/uL
  • Hematocrit 25.1%

The obstetrics and gynecology team is consulted for a likely ectopic pregnancy, and the patient is taken to the OR for an emergent laparotomy.

References

  1. Hamza A, Meyberg-Solomayer G, Juhasz-Böss I, et al. Diagnostic Methods of Ectopic Pregnancy and Early Pregnancy Loss: a Review of the Literature. Geburtshilfe Frauenheilkd. 2016;76(4):377-382. doi:10.1055/s-0041-110204
  2. Kadar N, DeVore G, Romero R. Discriminatory hCG zone: its use in the sonographic evaluation for ectopic pregnancy. Obstet Gynecol. 1981;58(2):156-161. PMID: 7254727
  3. Rodgers SK, Chang C, DeBardeleben JT, Horrow MM. Normal and Abnormal US Findings in Early First-Trimester Pregnancy: Review of the Society of Radiologists in Ultrasound 2012 Consensus Panel Recommendations. Radiographics. 2015;35(7):2135-2148. doi:10.1148/rg.2015150092
  4. Weissleder R, Wittenberg J, Harisinghani MG, Chen JW. Primer of Diagnostic Imaging. 5th ed. Mosby/Elsevier; 2011. ISBN: 9780323065382
  5. Habana A, Dokras A, Giraldo JL, Jones EE. Cornual heterotopic pregnancy: contemporary management options. Am J Obstet Gynecol. 2000;182(5):1264-1270. doi:10.1067/mob.2000.103620. PMID: 10819869
  6. Doubilet PM, Benson CB, Bourne T, Blaivas M. Diagnostic Criteria for Nonviable Pregnancy Early in the First Trimester. N Engl J Med. 2013;369(15):1443-1451. doi:10.1056/NEJMra1302417
  7. Thamburaj R, Sivitz A. Does the use of bedside pelvic ultrasound decrease length of stay in the emergency department? Pediatr Emerg Care. 2013;29(1):67-70. doi:10.1097/PEC.0b013e31827b53f9. PMID: 23283267
  8. McRae A, Murray H, Edmonds M. Diagnostic accuracy and clinical utility of emergency department targeted ultrasonography in the evaluation of first-trimester pelvic pain and bleeding: a systematic review. CJEM. 2009;11(4):355-364. doi:10.1017/s1481803500011416. PMID: 19594975
  9. Durston WE, Carl ML, Guerra W, Eaton A, Ackerson LM. Ultrasound availability in the evaluation of ectopic pregnancy in the ED: comparison of quality and cost-effectiveness with different approaches. Am J Emerg Med. 2000;18(4):408-417. doi:10.1053/ajem.2000.7310. PMID: 10919529
  10. Mateer JR, Aiman EJ, Brown MH, Olson DW. Ultrasonographic examination by emergency physicians of patients at risk for ectopic pregnancy. Acad Emerg Med. 1995;2(10):867-873. doi:10.1111/j.1553-2712.1995.tb03099.x. PMID: 8542485
  11. Beals T, Naraghi L, Grossestreuer A, Schafer J, Balk D, Hoffmann B. Point of care ultrasound is associated with decreased ED length of stay for symptomatic early pregnancy. Am J Emerg Med. 2019;37(6):1165-1168. doi:10.1016/j.ajem.2019.03.025. PMID: 30948256
By |2026-05-21T19:26:36-07:00May 22, 2026|Expert Peer Reviewed (Clinical), Ob/Gyn, Pediatrics, PEM POCUS|
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PEM POCUS Series: Pediatric Appendicitis

PEM POCUS pediatric appendicitis

Read this tutorial on the use of point of care ultrasonography (POCUS) for pediatric appendicitis. Then test your skills on the ALiEMU course page to receive your PEM POCUS badge worth 2 hours of ALiEMU course credit.

Module Goals

  1. Describe the indications for performing point-of-care ultrasound (POCUS) for appendicitis
  2. Describe the technique for performing POCUS for appendicitis
  3. Recognize anatomical landmarks for POCUS for appendicitis
  4. Interpret signs of appendicitis on POCUS
  5. List the limitations of POCUS for appendicitis

Case Introduction: Child with thigh pain

Mason is an 8-year-old boy who comes to the emergency department for abdominal pain. The pain has been present for 12 hours, started near his belly button, and now has migrated to the lower right side. He describes it as constant and worsening. His parents are concerned because he had a fever to 101F since 2 hours prior to arrival and had 2 episodes of emesis. They deny diarrhea or bloody stool. They gave acetaminophen for fever 2 hours prior to arrival. He has not wanted to eat anything today.

Vital Sign Finding
Temperature 37.5 C
Heart Rate 120 bpm
Blood Pressure 106/58
Respiratory Rate 18
Oxygen Saturation (room air) 100%

He is uncomfortable appearing, and abdominal examination is soft and tender to palpation periumbilically and in the right lower quadrant. The patient also endorses pain with jumping. Given his history and abdominal pain and tenderness on examination, you are concerned for appendicitis. You place a surgical consult and while waiting, decide to perform a point of care ultrasound (POCUS) examination of the appendix.

Why should I perform the appendix POCUS?

  • Lack of radiation exposure, lower cost, less patient preparation
  • Superior sensitivity and specificity for diagnosing pediatric appendicitis
  • POCUS can save ≥2 hours compared to radiology-performed ultrasound
  • Can help prioritize radiology studies or expedite surgical consult

Limitations of the appendix POCUS

  • Operator dependency and variability in sensitivity
  • Difficult visualization of appendix in retrocecal or aberrant locations
  • Limitation of visualization dependent on patient body habitus
  • Sometimes the appendix cannot be visualized (normal or otherwise)

What are the general principles behind the technique?

  • You are using POCUS to look for an abnormal appendix and/or secondary signs of appendicitis.
  • It is important to recognize anatomical landmarks.
  • The patient should be placed in a supine position.
  • Using the linear transducer is appropriate for most pediatric patients, but if the patient has a larger body habitus, the curvilinear transducer may be used (figure 1).

Figure 1. Linear (left) and curvilinear (right) transducer for ultrasonography

  • Place the probe over the point of maximal tenderness in the abdominal RLQ.
  • Slowly apply increasing gentle pressure (i.e., “graded compression”) to move bowel gas out of the way until able to identify the important landmarks:
    • Iliopsoas muscle
    • Rectus muscle
    • Iliac vessels
  • You can also lightly “jiggle” the probe as shown below to help mitigate bowel gas artifact.
Video 1: External view of the RLQ abdomen with the application of graded compression, such that bowel gas is moved out of the way to obtain a view of the desired anatomical structures
Video 2: POCUS clip of the RLQ abdomen demonstrating the application of graded compression and “jiggling” the probe

1. Start in the RLQ Abdomen

appendicitis pediatric abdomen

Figure 2: Starting in the RLQ abdomen and inferior to the iliac crest, visualize the iliacus muscle and pelvis with no bowel in view. The first bowel you visualize should be the cecum as you scan in a cephalad direction.

Video 3: POCUS clip of the RLQ abdomen showing the cecum coming into view

2. Move the probe more cephalad

Figure 3: Moving the probe in a progressively more cephalad direction, attempt to visualize the iliopsoas, abdominis rectus muscles, and iliac vessels. These anatomic landmarks to help identify the appendix (marked as *) with the CURVILINEAR probe. The appendix may appear in the triangle made by these structures as a blind-ended pouch that does not have peristalsis.[Image courtesy of Dr. Sally Graglia]

Figure 4: Anatomic landmarks to help identify the appendix with the LINEAR probe [image courtesy of Dr. Sally Graglia]

3. Identify the tubular appendix structure

Figure 5: Visualize the appendix in the longitudinal view. In this plane, visualize the end of the pouch to confirm it is a blind-ending tubular structure with no peristalsis that initiates at the cecum. [Image courtesy of Dr. Margaret Martore-Lin]

Figure 6: Visualize the appendix in the transverse view. In this plane, measure the diameter of the appendix from the outer wall to outer wall. An abnormal appendix is >6 mm and non-compressible. [Image courtesy of Dr. Margaret Martore-Lin]

A technique described in Sivitz et al. [1] involves placing the ultrasound probe in a transverse position and starting at the level of the umbilicus. Using compression, move the probe along POCUS-identified anatomical landmarks.

  1. Move laterally to identify the lateral border of the ascending colon.
  2. Move down the lateral border to the end of the cecum.
  3. Move medially across the psoas and iliac vessels.
  4. Move down the border of the cecum.
  5. Move up the border of the cecum.
  6. Rotate the probe into a sagittal position and identify the end of the cecum in the long axis and move medially across the psoas.

Figure 7: The Sivitz et al technique for identifying the appendix on POCUS

Sometimes there is a suboptimal view of the anatomy landmarks on POCUS. The following are troubleshooting tips that may be useful:

  1. Perform graded compression to displace bowel gas that may be obscuring your view.
  2. Apply posterior manual compression to the right lower back in an anteromedial direction of the ultrasound probe. This is usually done with the POCUS operator’s opposite hand (Figure 7).
pediatric appendicitis POCUS posterior compression

Figure 8: Posterior manual compression technique to assist with POCUS visualization of the appendix

  1. Position the patient in the left lateral decubitus position to help visualization of a retrocecal appendix.
  2. Administer analgesia before starting and distraction (videos, smartphone) during the exam to reduce patient movement.
  3. Position the patient with knees flexed, which can relax the abdominal wall musculature.
  4. Use a high-frequency linear probe to improve the resolution of regional structures and anatomy (although a curvilinear probe should be used if increased depth is required for a larger body habitus).

pediatric normal appendix POCUS

Figure 9: Normal appearing appendix on POCUS [Image courtesy of Dr. Will Shyy]

The appendix is a tubular, blind ending structure, which initiates from the cecum and has no peristalsis. A normal appendix is less than 6 mm, is compressible, and has little to no blood flow in the wall of the appendix.

Ultrasonography Signs of Acute Appendicitis

  1. Enlarged appendix >6 mm (Figure 10)
  2. Noncompressible (although can be compressible if perforated appendix)
pediatric appendicitis POCUS

Figure 10: Enlarged appendix measuring 1.36 cm (>6 mm is abnormal) with hyperechoic fat concerning for inflammation [Image courtesy of Dr. Will Shyy]

Secondary Ultrasonographic Signs of Appendicitis

  1. Peri-appendiceal free fluid
  2. Hyperechoic mesenteric fat
  3. Appendicolith
  4. Increased blood flow (“ring of fire”) surrounding the appendix on Doppler color mode
  5. Complex right lower quadrant mass, suggestive of ruptured appendix
Secondary Sign of Appendicitis Ultrasound View
Peri-appendiceal free fluid secondary to inflammatory edema or perforation. You may also see an abscess that appears as a complex mass and is a sign of a ruptured appendicitis.
pediatric appendicitis POCUS

Figure 11. Appendix with peri-appendiceal fluid collection [image by Dr. Will Shyy]
Hyperechoic mesenteric fat as a sign of inflammation visible (also see figure 10)
pediatric appendicitis POCUS

Figure 12: Appendicolith (A) within the lumen of the appendix in addition to hyperechoic fat (arrows) concerning for inflammation [image courtesy of Dr. Will Shyy]

pediatric appendicitis POCUS

Figure 13. Appendicitis with hyperechoic fat suggestive of inflammation

Video 4: POCUS clip of a pediatric patient with appendicitis. Notice the hyperechoic fat surrounding the appendix, visible in transverse as a tubular structure at the bottom of the screen. [Video courtesy of Dr. Ashkon Shaahinfar]
Appendicolith: A hyperechoic structure within the appendiceal lumen has a dark, clean acoustic shadow, similar to the appearance of a gallstone. Figure 12 above
“Ring of Fire”, or increased blood flow surrounding the appendix: Using the color Doppler mode on the ultrasound, the appendix in transverse view will appear hyperemic, suggestive of appendiceal inflammation.
pediatric appendicitis POCUS ring of fire

Figure 14. “Ring of fire” appendiceal hyperemia using the color Doppler mode on ultrasound [image by Dr. Will Shyy]

pediatric appendicitis POCUS

Figure 15. Cross-sectional image of appendicitis with hyperemia
Complex RLQ mass: A ruptured appendicitis may appear as a complex right lower quadrant mass, where the appendix itself may be difficult to visualize. It can be difficult to distinguish this from other pathologies, such as intussusception or ruptured Meckel’s diverticulitis.

Video 5: POCUS clip of ruptured appendicitis, appearing as a complex right lower quadrant mass [Video courtesy of Dr. Ashkon Shaahinfar]​
pediatric appendicitis POCUS

Figure 16. Close-up POCUS view of the appendix from video 5 [image courtesy of Dr. Ashkon Shaahinfar]

Benefits of Appendix POCUS

An appendix POCUS benefits children with suspected appendicitis, as demonstrated in the literature:

  1. Decrease in CT scan utilization [2-4]
  2. Decrease in lengths of Emergency Department stay [3, 4]
    • Tsung et al, Critical Ultrasound J, 2014 [4]: There was a shorter ED length of stay (LOS) with mean LOS reported for the following modalities:
      • POCUS: 154 minutes
      • Radiology US: 288 minutes
      • CT scan: 487 minutes

Equivocal Findings on POCUS

  • Oftentimes an appendix cannot be visualized on both POCUS and radiology-performed ultrasound, especially in patients with higher BMI [5].
  • In situations with an experienced sonographer, where the appendix is not visualized and there are no secondary signs on radiology-performed ultrasound, patients are at low risk for appendicitis with a negative predictive value in the 80’s% [6, 7].
  • Serial ultrasound has been recommended in equivocal ultrasound cases as ultrasound’s sensitivity increases with length of pain [8].
  • For POCUS for appendicitis, non-visualized appendix studies continue to represent a diagnostic dilemma [1, 9]. For more on this topic, read a deeper-dive on this topic in a PEM Pearls post.

The studies below examine the sensitivity and specificity of appendix POCUS for identification of appendicitis in patients of any age with the exception of Sivitz et al., which specifically studied pediatric patients only. (Table 1).

Study N Patient Age Sensitivity Specificity Comments
Sivitz et al., 2014 [1] 264 Pediatric
85%
(95% CI: 75-95%)
93%
(95% CI: 85-100%)
In this study, pediatric emergency medicine ultrasonographers were able to visualize the appendix in 71% of patients. Gold standard was either pathologic review, telephone follow-up to 6 months, or electronic medical records review up to 1 year, if unable to reach the patient.
Fields et al., 2017 [9] 6,636 Pediatric 89%

(95% CI: 47–99%)

 97%

(95% CI: 84–99%)

 These test characteristics were derived from a pediatric-only sub-analysis of a larger systematic review and meta‐analysis study across all ages to identify the test characteristics of the appendix POCUS, performed by emergency physicians. The overall test characteristics across all ages was 91%
(95% CI: 83–96%) sensitivity and 97% (95% CI: 91–99%) specificity.
Chen et al., 2000 [10] 317 Any age 85% 98% After a 5-day intensive training course in abdominal ultrasound, emergency physician-performed POCUS was compared to surgeon’s clinical impression in diagnosing acute appendicitis, as confirmed by pathological reports. Ultrasonography performed better than surgeon clinical impression and resulted in a high sensitivity and specificity.
Fox et al., 2008 [11] 132 Any age 65%

(95% CI: 52-76%)

 90%

(95% CI: 81-95)

 Emergency physicians performed a 5-minute appendix POCUS for patients with a clinical suspicion for acute appendicitis. The gold standard confirmation was either pathology specimens from appendectomy surgery or telephone follow-up.
Table 1. Published studies evaluating the sensitivity and specificity of appendix POCUS

Case Resolution

The patient has a leukocytosis with a WBC 13.3 x 109/L and an absolute neutrophils count (ANC) 10.3 x 109/L but otherwise unremarkable labs. His final Pediatric Appendicitis Score (PAS) is 8. You decide to incorporate appendix POCUS to your evaluation. You place a linear, high-frequency transducer on the patient and visualize his appendix. You observe the following:

Video 6. An appendix POCUS, demonstrating appendicitis.

Figure 17: Enlarged appendix measuring 1.36 cm in diameter (>6 mm is abnormal)

Normal anatomy for comparison:

Video 7: Appendix POCUS clip showing normal anatomy including the psoas muscle, vasculature, and a small, compressible appendix.

ED Course

The patient receives IV morphine and is made NPO. The general surgeon on call is consulted and agrees with the plan for an appendectomy.

Learn More…

References

  1. Sivitz AB, Cohen SG, Tejani C. Evaluation of acute appendicitis by pediatric emergency physician sonography. Ann Emerg Med. 2014;64(4):358-364.e4. doi:10.1016/j.annemergmed.2014.03.028. PMID: 24882665
  2. Doniger SJ, Kornblith A. Point-of-Care Ultrasound Integrated Into a Staged Diagnostic Algorithm for Pediatric Appendicitis. Pediatr Emerg Care. 2018;34(2):109-115. doi:10.1097/PEC.0000000000000773. PMID: 27299296
  3. Elikashvili I, Tay ET, Tsung JW. The effect of point-of-care ultrasonography on emergency department length of stay and computed tomography utilization in children with suspected appendicitis. Acad Emerg Med. 2014;21(2):163-170. doi:10.1111/acem.12319. PMID: 24673672
  4. Tsung JW, Tay ET, Elikashvili I.  The effect of point-of-care ultrasonography on emergency department length of stay and CT utilization in children with suspected appendicitis. rit Ultrasound J 6, A32 (2014). https://doi.org/10.1186/2036-7902-6-S1-A32
  5. Abo A, Shannon M, Taylor G, Bachur R. The influence of body mass index on the accuracy of ultrasound and computed tomography in diagnosing appendicitis in children. Pediatr Emerg Care. 2011;27(8):731-736. doi:10.1097/PEC.0b013e318226c8b0. PMID: 21811194
  6. Cohen B, Bowling J, Midulla P, et al. The non-diagnostic ultrasound in appendicitis: is a non-visualized appendix the same as a negative study?. J Pediatr Surg. 2015;50(6):923-927. doi:10.1016/j.jpedsurg.2015.03.012. PMID: 25841283
  7. Ly DL, Khalili K, Gray S, Atri M, Hanbidge A, Thipphavong S. When the Appendix Is Not Seen on Ultrasound for Right Lower Quadrant Pain: Does the Interpretation of Emergency Department Physicians Correlate With Diagnostic Performance?. Ultrasound Q. 2016;32(3):290-295. doi:10.1097/RUQ.0000000000000214. PMID: 27082937
  8. Bachur RG, Dayan PS, Bajaj L, et al. The effect of abdominal pain duration on the accuracy of diagnostic imaging for pediatric appendicitis. Ann Emerg Med. 2012;60(5):582-590.e3. doi:10.1016/j.annemergmed.2012.05.034. PMID: 22841176
  9. Matthew Fields J, Davis J, Alsup C, et al. Accuracy of Point-of-care Ultrasonography for Diagnosing Acute Appendicitis: A Systematic Review and Meta-analysis. Acad Emerg Med. 2017;24(9):1124-1136. doi:10.1111/acem.13212. PMID: 2846445
  10. Chen SC, Wang HP, Hsu HY, Huang PM, Lin FY. Accuracy of ED sonography in the diagnosis of acute appendicitis. Am J Emerg Med. 2000;18(4):449-452. doi:10.1053/ajem.2000.7343. PMID: 10919537
  11. Fox JC, Solley M, Anderson CL, Zlidenny A, Lahham S, Maasumi K. Prospective evaluation of emergency physician performed bedside ultrasound to detect acute appendicitis. Eur J Emerg Med. 2008;15(2):80-85. doi:10.1097/MEJ.0b013e328270361a. PMID: 18446069

Additional Reading

  1. Benabbas R, Hanna M, Shah J, Sinert R. Diagnostic Accuracy of History, Physical Examination, Laboratory Tests, and Point-of-care Ultrasound for Pediatric Acute Appendicitis in the Emergency Department: A Systematic Review and Meta-analysis. Acad Emerg Med. 2017;24(5):523-551. doi:10.1111/acem.13181. PMID: 28214369
  2. Estey A, Poonai N, Lim R. Appendix not seen: the predictive value of secondary inflammatory sonographic signs. Pediatr Emerg Care. 2013;29(4):435-439. doi:10.1097/PEC.0b013e318289e8d5. PMID: 23528502Lin-Martore M, Kornblith AE. Diagnostic Applications of Point-of-Care Ultrasound in Pediatric Emergency Medicine. Emerg Med Clin North Am. 2021 Aug;39(3):509-527. doi: 10.1016/j.emc.2021.04.005. PMID: 34215400
  3. Vasavada P. Ultrasound evaluation of acute abdominal emergencies in infants and children. Radiol Clin North Am. 2004;42(2):445-456. doi:10.1016/j.rcl.2004.01.003. PMID: 15136027
By |2026-05-21T10:06:51-07:00May 31, 2022|Pediatrics, PEM POCUS, Ultrasound|
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PEM POCUS Series: Pediatric Peripheral IV Access

PEM POCUS peripheral IV ultrasound badge

Read this tutorial on the use of point of care ultrasonography (POCUS) for pediatric peripheral IV placement. Then test your skills on the ALiEMU course page to receive your PEM POCUS badge worth 2 hours of ALiEMU course credit.

Take the ALiEMU PEM POCUS: Peripheral IV Quiz – test your skills

PATIENT CASE: Child with Sickle Cell Pain

Abigail is a 10-year-old girl with known sickle cell disease, who presents with severe atraumatic pain in her hips and back. She is afebrile, but tachycardic and tachypneic with 10/10 pain. Nurses have made several attempts but have been unsuccessful in establishing a peripheral IV(PIV) for giving IV fluids and medications. They now ask you to obtain access. You decide to perform an ultrasound-guided PIV placement. 

Exam

Vital SignFinding
Temperature37.6C
Heart rate135 bpm
Blood pressure135/90
Respiratory rate23
Oxygen saturation (room air)99%
  • General: Well-developed, appears in significant distress due to pain.
  • Cardiovascular: Tachycardic with regular rhythm, good distal pulses, and capillary refill
  • Pulmonary: Tachypneic without retractions; good aeration without wheezes, rales, crackles.
  • Abdomen: Soft, normal bowel sounds
  • Neurologic: Alert and oriented x3 with GCS 15; no focal deficits on cranial and sensorimotor exam

What are some potential challenges in peripheral IV placement?

  • Dehydration: Veins may collapse as a result of dehydration, making them harder to identify and cannulate.
  • Vein mobility: Veins are more mobile than arteries. Particularly mobile veins can “roll” or move during cannulation attempts.
  • Overlying soft tissue: Large body habitus can interfere with visualization of veins.
  • Vein size: Some patients, especially infants, have small veins.
  • Repeated venipuncture: Some patients with chronic conditions, such as sickle cell disease, often require frequent venipuncture. Repeated venipuncture can cause veins to change morphologically over time, making them difficult to identify and cannulate.

How can POCUS be helpful in obtaining IV access?

  • Direct visualization and guidance: Real-time visualization of IV catheter/needle in real-time as it approaches and cannulates the vessel.
  • Surrounding anatomy: Visualization of surrounding structures (e.g., nerves, arteries, other veins) which may not be apparent on visual examination.
  • Differentiating vein from artery: Distinguishing between different types of vessels.

Ultrasound-Guided Peripheral IV Access: Normal Findings

1. Differentiating Veins from Arteries

Veins and arteries can be difficult to distinguish. Below is a table to help differentiate using ultrasonography. 

CharacteristicVeinsArteries
DiameterTypically larger than arteries (is dependent on fluid status)Relatively fixed in size, round in shape
Wall ThicknessThinThick
CompressibilityEasyMore difficult
Color Doppler FlowNon-pulsatilePulsatile
Vessel ValvesPresent (but not always visible)Absent
Table 1. Anatomical and ultrasonography differences between veins and arteries
  • Compressibility: Typically, veins are easily compressed, while arteries with their thick walls are more difficult to compress.  
Video 1: Ultrasound clip of a vein being compressed
  • Color Doppler Flow: Color Doppler can be used to differentiate pulsatile from non-pulsatile flow. Red and blue colors do NOT correlate with venous or arterial blood flow. Instead, the colors represent the direction of flow. A helpful acronym is BART – “Blue Away, Red Towards.”
Video 2: Ultrasound clip of a vein (red) with non-pulsatile flow and artery (blue) with pulsatile flow

2. Identifying Nerves

Nerves can be confused with blood vessels when looking on ultrasound. The following are ways to identify a nerve.

  • Honeycomb appearance: Classically nerves appear in cross-section with small hypoechoic (dark) areas separated by hyperechoic (bright) septae.
Video 3: Ultrasound clip of nerve (left) and artery (right). The nerve has a honeycomb appearance with several hypoechoic (dark) areas separated by hyperechoic (bright) septae whereas the artery is more uniformly hypoechoic. There is also a needle entering from the left of the screen. See below labeled still image of same anatomical structures below.
peripheral IV ultrasound nerve artery
Figure 1: Ultrasound still image with labeled nerve and artery. See Videos 3 and 4 for ultrasound videos of same structures with and without doppler flow. 
  •  No Color Doppler flow: While Color Doppler can be used to assess for pulsatile and non-pulsatile flow of arteries and nerves, respectively, nerves should not demonstrate any flow. 
Video 4: Ultrasound clip of nerve (left) and artery (right) with color Doppler. This is a clip of the same location on the same patient in Video 3 and Figure 1. The nerve (center of yellow box) shows no flow under color Doppler. In contrast, the artery (partially captured at right of yellow box) demonstrates pulsatile flow. 
  • Anisotropy: This ultrasound artifact is exhibited by nerves (as well as tendons and ligaments), whereby the nerve changes brightness depending on the angle of ultrasound beam.
Video 5: Ultrasound clip of nerve exhibiting anisotropy. The brightness of the nerve (in center, labeled in Figure 2 below) changes with the angle of the probe.

PEM POCUS peripheral IV anisotropy ultrasound
Figure 2: Still image from Video 5 above with nerve highlighted in yellow. 

Fun fact: Certain gemstones like tiger’s eye and figured woods like flamed maple exhibit chatoyance which is analogous to anisotropy, but occurs under visible light, rather than ultrasound beams like anisotropy.

gemstone anisotropy
Figure 3: Image of Tiger’s eye gemstone. These gemstones exhibit chatoyance, a characteristic of light reflection which is analogous to “anisotropy” under ultrasound. (Image: Benjamint444 [CC BY-SA])

3. Needle Artifact

Needles exhibit ultrasound artifacts which can help with identification.

  • Ring down artifact:  This resonance artifact describes when ultrasound beams encounter trapped gas and create a spotlight effect.  See additional information on Radiopaedia.org.
  • Reverberation artifact:  This artifact describes when ultrasound beams reflect back and forth between two strong parallel reflectors and the machine interprets additional objects deeper than the actual object.  See additional information on Radiopaedia.org.
Video 6: Ultrasound clip of needle in water bath with both ring down and reverberation artifacts. The tip of the needle appears to have a spotlight beam shining down,  this is an example of ring down artifact from trapped air at the needle tip. This video also demonstrates reverberation artifact where there appears to be a deeper hyperechoic (bright) needle at the bottom left of the video seen best at the beginning of the clip.

TECHNIQUE

Vein Selection: Upper Extremity

Typically, pediatric patients receive a peripheral IV in the upper extremity in one of 2 locations: 

  1. Antecubital fossa (Figure 4):
    • Access superficial veins, which includes the basilic, cephalic, and median cubital veins. 
    • Tip: Beware of tortuously curved paths of veins, branch points, and nearby nerves.
arm anatomy vein
Figure 4: Diagram of venous anatomy of the arm focused on antecubital fossa. The antecubital fossa area (the inside of the elbow) is shown in the blue box. Adapted from image By OpenStax College – Anatomy & Physiology, Connexions Web site. Jun 19, 2013. [CC BY 3.0]
  1. Upper arm near medial bicipital groove (Figure 5):
    • Access the deep brachial vein or more proximal aspect of the basilic vein.
upper arm vein anatomy
Figure 5: Diagram of venous anatomy of the upper extremity. By OpenStax College – Anatomy & Physiology, Connexions Web site. Jun 19, 2013. [CC BY 3.0]

Vein Selection: Lower Extremity

If unable obtain upper extremity access, the lower extremity can also be accessed. This is more typically performed in infants and young children. 

  • Lower medial leg (Figures 6, 7): This site allows for access to thegreat saphenous vein. 
leg vascular anatomy
Figure 6: Diagram of veins of the leg. Blausen.com staff (2014). “Medical gallery of Blausen Medical 2014“. WikiJournal of Medicine 1 (2). [CC BY 3.0]
Figure 7: Diagram of veins of the lower leg. Adapted from image by Blausen.com staff (2014). “Medical gallery of Blausen Medical 2014”. WikiJournal of Medicine 1 (2). [CC BY 3.0]

Set up for success

  • Prior to starting the procedure, set up the room for optimal visualization. 
  • Place ultrasound system monitor in direct line of site with the angiocatheter.
ultrasound set up position peripheral IV
Figure 8: Ultrasound machine positioning such that the probe, patient, and screen are in one line of sight.
  • Apply tourniquet around the extremity.
  • Use the high-frequency linear transducer (Figure 9) to identify potential veins before the procedure to map out the course, depth, and size of veins. Initial scanning can be done without sterile precautions. 
    • The best vein: The ideal vein is large, superficial, not near other anatomic structures, and relatively straight.
    • Depth: Set an appropriate depth on the ultrasound monitor such that the target vein is centered on the screen.
ultrasound linear probe
Figure 9: A high-frequency linear probe
  • Tip: Pre-scan multiple areas on both arms (or legs) to find the optimal site for ultrasound-guided peripheral IV placement. 
  • Cleaning and probe covers
    • Clean off any non-sterile gel from the patient’s skin.
    • Prepare the skin with chlorhexidine or an alcohol swab.
    • Use a single-use probe cover.
      • Consider a Tegaderm patch, sterile glove, condom, or sterile probe cover.
      • For further discussion of the relevant literature around probe covers, see this ALiEM post.
    • Use sterile ultrasound gel between the skin and the covered probe.
linear ultrasound probe cover glove
Figure 10: Sterile glove as a makeshift probe cover. Here the entire probe fits into a single finger of a sterile glove. For another method of using a sterile glove as a probe cover see this Trick of the Trade.

Probe Positioning

  • Proper orientation and terminology
    • In this procedure, there are 3 objects to coordinate in space. All of these relationships should be in a perpendicular or parallel orientation (not oblique). 
      • The vein
      • The probe
      • The needle 
    • The needle should always be parallel with (i.e., directly overlying) the vein. This leaves two other positional relationships: probe/vein and probe/needle. 
      • Probe/vein: The probe is either transverse or longitudinal relative to the vein (Figure 11).
      • Probe/needle:The needle is either out of plane (i.e., perpendicular) or in plane (i.e., parallel) relative to the length of probe. When using the transverse orientation, the needle is typically also perpendicular, or out of plane, with the length of the probe. Conversely, when using longitudinal orientation, the needle will be parallel, or in plane, with the probe.
ultrasound short and long axis linear probe
Figure 11: Labeled axes of linear ultrasound probe

POCUS-Guided IV Cannulation Technique

There are 2 approaches in using POCUS for cannulating peripheral veins based on if the operator is using the transverse or longitudinal orientation.

  1. Transverse orientation: This view is particularly helpful for keeping adjacent structures in view and requires less precision to keep the vein in view. It is important to keep in mind the distance the needle must travel to successfully enter the vein, which will depend on the angle of the needle and the depth of the vein. Videos 7 and 8 show the transverse orientation ultrasound views. Note that in this view, once the needle passes into the plane of the ultrasound beam,  it can be difficult to distinguish the tip of the needle from the shaft. 
Video 7: Ultrasound clip of a phantom model vein in transverse orientation with vein cannulation at end of clip. The needle can be identified based on the ring down artifact as it passes into the plane of the ultrasound beam.

Video 8: Ultrasound clip of a patient’s vein in transverse orientation with vein cannulation. The vessel is in the top center of the screen. The needle is the bright white (hyperechoic) dot entering it, seen out of plane.
  • Transverse technique (out of plane) with dynamic needle tip visualization: The shaft of the needle can appear indistinguishable from the tip of needle in the transverse or out-of-plane approach. The dynamic needle tip visualization technique allows the operator to continuously identify the location of the tip of the needle. 
    • As soon as the skin is entered, slide the probe closer towards the tip of the needle. 
    • Advance the probe just beyond the tip of the needle. As soon as the needle is no longer in view (i.e., just beyond the tip), it is clear where tip of the needle is. 
    • Hold the probe steady just beyond the needle tip, and advance the needle forward, returning it into the field of view. 
    • Advanced the probe just beyond the tip of the needle again.
    • Repeat the previous steps until the needle is visualized entering the vein.
      • Tip: Make small movements and attempt to keep the vein in the center of the screen. For beginners with this technique, it is recommended to alternate moving either the probe or the needle, one at a time.
Video 9: Ultrasound clip of a phantom model in transverse orientation with vein cannulation using dynamic needle tip visualization. The operator alternates moving the probe just beyond the tip of the needle and advancing the needle toward the vessel until cannulation. 

Video 10: Demonstration of the dynamic needle tip visualization technique, showing alternating movements of the probe and needle
  1. Longitudinal orientation: Conceptually, this orientation is more straightforward (probe, vein and needle are all parallel), but the precision involved requires a steady hand and a stationary patient. The needle must stay parallel to the probe within the slice thickness of the ultrasound beam. This value will vary depending on the machine and the probe, but is on the order of millimeters. Video 12 demonstrates the importance of maintaining the vein and needle parallel to the ultrasound beam or else the vein and/or needle disappears from view.
Video 11: Ultrasound clip with needle in and out of view using the longitudinal orientation technique. Being slightly out-of-plane makes it difficult to visualize the needle and needle tip. Of note, this needle has a guidewire extended past the needle tip which is curved slightly upward from the length of the needle.
  • Longitudinal (in plane) technique
    • Align the probe parallel to the vein. Ideally, the vein should be the same depth and thickness across the screen. 
    • Introduce the needle in-plane (parallel) to the probe marker at a shallow angle. Depending on the depth and size of the vein, this may be close to parallel with the skin.
    • Maintain visualization of the needle tip as it enters the vessel.
    • Tip: If it is unclear where the needle tip is, first stop moving the needle and assess if the probe has drifted or rotated. While keeping the needle still, make corrections with the probe until the needle and needle tip is once again visualized in plane. 

Video 12: Ultrasound clip of needle cannulating vessel in longitudinal view using in-plane technique

After Cannulation

After the needle tip is visualized entering the vein and a flash of blood appears in the hub of the needle, advance the needle forward an additional 1-2 mm before threading the catheter. Why? The catheter does not extend fully to the tip of the needle. Thus the needle must be advanced past the initial flash of blood to ensure that the catheter has also penetrated the vein. If there is resistance when threading the angiocatheter into the vein, reassess the needle tip position using the ultrasound and confirm the needle is still positioned intravascularly. 

Peripheral IV catheter with needle
Figure 12: Typical angiocatheter for peripheral IV access. The first few millimeters of the needle tip extend beyond the catheter.

After successful threading, retract the needle, attach pre-primed IV tubing, and flush and lock the tubing. Secure the catheter in place.

LITERATURE REVIEW

There have been many studies evaluating ultrasound-guided peripheral IVs in patients, and below are several key articles involving pediatric patients. Overall, ultrasound-guidance appears to be helpful in pediatric patients with difficult access, but the exact technique involved and the experience of the operator likely have an effect. 

YearAuthorsTitleMajor Findings
2009Doniger et al. [1]Randomized controlled trial of ultrasound-guided peripheral intravenous catheter placement versus traditional techniques in difficult-access pediatric patientsUltrasound-guided peripheral IV placement in difficult-access patients took less time, was more often successful, and required fewer needle re-directions.
2010Oakley and Wong [2]Ultrasound-assisted peripheral vascular access in a paediatric EDUltrasound-guidance was associated with slightly increased success rates in peripheral IV placement. This effect was more pronounced in cases with difficult-access patient.
2018Otani et al. [3]Ultrasound-guided peripheral intravenous access placement for children in the emergency department In contrast to many other publications on ultrasound-guided peripheral IV procedures, the authors report a LOWER success rate for patients that had one failed IV attempt, as compared to the conventional method. An important potential confounder was that this study used a “dual-operator” method, in which one clinician operates the ultrasound, and the other places the IV. 
2018Desai et al. [4]Longevity and complication rates of ultrasound guided versus traditional peripheral intravenous catheters in a pediatric emergency departmentUltrasound-guided peripheral IVs had a longer catheter survival time compared with traditionally-placed peripheral IVs. Complications from the peripheral IVs were similar between the two groups. 
Table: Key literature on pediatric cases studying ultrasound-guided peripheral IV access

References [click to expand] +

  1. Doniger SJ, Ishimine P, Fox JC, Kanegaye JT. Randomized Controlled Trial of Ultrasound-Guided Peripheral Intravenous Catheter Placement Versus Traditional Techniques in Difficult-Access Pediatric Patients. Pediatr Emerg Care. 2009;25(3):154-9. doi:10.1097/pec.0b013e31819a8946.
  2. Oakley E, Wong A-M. Ultrasound-assisted peripheral vascular access in a paediatric ED. Emerg Med Australas. 2010;22(2):166-70. doi:10.1111/j.1742-6723.2010.01281.x.
  3. Otani T, Morikawa Y, Hayakawa I, et al. Ultrasound-guided peripheral intravenous access placement for children in the emergency department. Eur JPediatr. 2018;177(10):1443-49. doi:10.1007/s00431-018-3201-3.
  4. Desai K, Vinograd AM, Abbadessa MKF, Chen AE. Longevity and Complication Rates of Ultrasound Guided Versus Traditional Peripheral Intravenous Catheters in a Pediatric Emergency Department. J Assoc Vascular Access. 2018;23(3):149-54. doi:10.1016/j.java.2018.06.002.

CASE RESOLUTION

Using POCUS, you begin by visualizing Abigail’s veins at the antecubital fossa and are able to identify the basilic and cephalic veins. Tracing the basilic vein proximally, you note that it is relatively large and straight; however, you see a honeycomb-like structure nearby it, which displays anisotropy and appears to be a nerve. You opt instead to follow the cephalic vein. There do not appear to be any nerves or other vessels nearby. You clean her skin appropriately and apply a sterile glove over the probe, and apply sterile gel. After these preparations, you re-identify the vessel in the transverse plane, use dynamic needle tip visualization with an out-of-plane approach, and successfully guide the tip of the needle into the vein. 

Video 13: Ultrasound clip of a vein in transverse orientation being successfully cannulated.

After visualizing the tip of the needle in the vein, you slightly advance the needle another 2 mm and then thread the catheter. You are able to obtain bloodwork. After flushing the catheter and cleaning the surrounding skin, you secure the catheter. Abigail is now able to get pain medications and fluids.

She soon feels much improved after 3 hours. Her laboratory results are similar to her baseline values. She is able to return home with ongoing management as an outpatient basis with close follow-up. 

Take the ALiEMU PEM POCUS: Peripheral IV Quiz – test your skills

The PEM POCUS series was created by the UCSF Division of Pediatric Emergency Medicine to help advance pediatric care by the thoughtful use of bedside ultrasonography.

Read other PEM POCUS tutorials. Learn more about bedside ultrasonography on the ALiEM Ultrasound for the Win series.

By |2026-05-21T10:09:19-07:00May 24, 2021|PEM POCUS, Ultrasound|
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PEM POCUS Series: Hip Effusion

Read this tutorial on the use of point of care ultrasonography (POCUS) for pediatric hip effusion. Then test your skills on the ALiEMU course page to receive your PEM POCUS badge worth 2 hours of ALiEMU course credit.

Take the ALiEMU PEM POCUS: Hip Effusion Quiz – test your skills

PATIENT CASE: Child with a Limp

Sarah is a 4-year-old girl who comes into the emergency department complaining of a limp for the last day. She had an upper respiratory infection which started a week ago for which she had been taking acetaminophen and ibuprofen with her last dose of either being 2 days ago. Those symptoms have improved. Yesterday, she started complaining of diffuse right leg pain primarily at her hip, thigh, and knee. Today, her parents noted she was walking with a limp.

On arrival, her vital signs are:

Vital SignFinding
Temperature100.1F
Heart rate100 bpm
Blood pressure97/50
Respiratory rate19
Oxygen saturation (room air)100%

She is well appearing and walks with an antalgic gait favoring the left leg. She has a normal HEENT, neck, cardiac, respiratory, abdominal, and back examination. She points to her right anterior thigh when you ask her where her pain is. She has limited range of motion with internal and external rotation of her right hip and complains of pain. She cries when you palpate any part of her leg, but is able to range her knee, ankle, and foot fully. She has 2+ dorsalis pedis and posterior tibialis pulses and intact sensation to light touch throughout. 

Given her pain with range of motion at her hip, you order a hip radiograph, but while waiting for it, decide to perform a hip point of care ultrasound (POCUS) examination.

PEDIATRIC HIP EFFUSION: Ultrasound Technique

It can be difficult for children to locate the exact area of pain and often hip pain can present with referred knee and thigh pain. A thorough physical examination along with hip POCUS can help localize the area of discomfort. When we use POCUS to evaluate the hip, we are primarily looking for a joint effusion in the synovial space. This is best visualized anterior to the femoral neck.  

hip anatomy hip effusion
Figure 2. Hip anatomy with target landmark being the femoral neck (red arrow) 

Technique

  1. The patient should be positioned supine.
    • Depending on the age of the child, the child can be positioned supine in the guardian’s lap while undergoing the examination. 
    • Offering the child a toy, book, or phone/tablet for distraction during the examination can also help ease anxiety.
  2. Use a linear high frequency transducer with a wide footprint.
  3. Place the transducer along the anterior hip.
    • Use the greater trochanter as a lateral landmark and place the probe on top of the femoral head and neck (Figure 3)
  4. Aim the probe marker towards the patient’s umbilicus.
hip effusion ultrasound
Figure 3. Linear transducer at the hip with probe marker (red dot) aimed towards the patient’s umbilicus
  1. Identify the anatomical landmarks on ultrasound (figure 4) 
    • Hip muscles: Sartorius, quadriceps, and iliopsoas
    • Bones: Femoral head, femoral neck
  2. The area of interest in looking for a hip effusion is the synovial space anterior to the femoral neck and NOT anterior to the femoral head. This area is also referred to as the anterior synovial recess.
Figure 4. Ultrasound image showing the normal landmarks for a pediatric hip without an effusion and the location of the femoral head (X) and synovial space (circle) with the linear transducer positioned overlying and longitudinal to the femoral neck
  • Tips:
    • It is often helpful to ultrasound the unaffected side as a comparison.
    • Be aware of the patient’s comfort throughout the examination.

ABNORMAL ULTRASOUND FINDINGS

A hip effusion will appear anechoic (black) in the synovial space anterior to the femoral neck (anterior synovial recess). Measure the distance between the anterior surface of the femoral neck and the posterior surface of the iliopsoas muscle. Examples are illustrated in figures 5 and 6.

hip effusion PEM POCUS ultrasound

There have been different methods used to assess if an effusion is present including:​1,2​

  • Measured effusion is >0.5 cm 
  • Measured effusion with >0.2 cm difference compared to the contralateral hip
  • Gestalt view with the anterior synovial recess areas appearing asymmetric compared to the other hip

Limitations of the Hip POCUS

Note that hip POCUS does not tell you the cause of an effusion but rather only whether an effusion is present or not. Effusions can result from infectious, inflammatory, and traumatic etiologies, and thus it is important to take into account the context of the patient’s presentation. 

References

  1. Vieira R, Levy J. Bedside ultrasonography to identify hip effusions in pediatric patients. Ann Emerg Med. 2010;55(3):284-289. PMID 19695738
  2. Cruz C, Vieira R, Mannix R, Monuteaux M, Levy J. Point-of-care hip ultrasound in a pediatric emergency department. Am J Emerg Med. 2018;36(7):1174-7. PMID 29223689 

FACTS and LITERATURE REVIEW

There have been multiple case reports of hip POCUS identifying hip effusions in children with fractures, septic joints, and in the work up of children with limps.​1–3​ There are limited studies examining the accuracy of hip POCUS compared to radiology-performed ultrasound in children (table 1).

StudyNSensitivitySpecificityComments
Vieira et al., Ann Emerg Med, 2010​4​2885%93%If the pediatric emergency physician had a high confidence in ultrasound accuracy, the sensitivity increased to 90% and specificity to 100%
Cruz et al., Am J Emerg Med, 2018​5​51685%98%For each additional hip POCUS performed, the odds of an accurate scan increased by 2.4%. 
Table 1. Published studies comparing pediatric hip POCUS to radiology-performed ultrasound

 

References [click to expand] +

  1. Deanehan J, Gallagher R, Vieira R, Levy J. Bedside hip ultrasonography in the pediatric emergency department: a tool to guide management in patients presenting with limp. Pediatr Emerg Care. 2014;30(4):285-287. PMID 24694889
  2. Garrison J, Nguyen M, Marin J. Emergency Department Point-of-Care Hip Ultrasound and Its Role in the Diagnosis of Septic Hip Arthritis: A Case Report. Pediatr Emerg Care. 2016;32(8):555-557. PMID 27490732
  3. Tsung J, Blaivas M. Emergency department diagnosis of pediatric hip effusion and guided arthrocentesis using point-of-care ultrasound. J Emerg Med. 2008;35(4):393-399. PMID 18403170 
  4. Vieira R, Levy J. Bedside ultrasonography to identify hip effusions in pediatric patients. Ann Emerg Med. 2010;55(3):284-289. PMID 19695738
  5. Cruz C, Vieira R, Mannix R, Monuteaux M, Levy J. Point-of-care hip ultrasound in a pediatric emergency department. Am J Emerg Med. 2018;36(7):1174-1177. PMID 29223689 

CASE RESOLUTION

The patient’s hip plain film radiographs are unremarkable. You decide to incorporate hip POCUS to your evaluation. You place a linear, high-frequency transducer and visualize the patient’s bilateral hips. You observe the following:

Right Hip (Affected Side) POCUS Video and Key View

Though the child complained of hip, knee, and thigh pain, your POCUS evaluation identifies a right hip effusion which helps you narrow the location of her pain.

Video 1. A hip POCUS of the case patient’s right hip (affected side)

 

PEM POCUS hip effusion
Figure 7. Right (affected side) hip POCUS with a hip effusion measuring 0.77 cm

Left Hip (Normal Side) POCUS Video and Key View

Video 2. A hip POCUS of the case patient’s left hip (unaffected side) for comparison

 

PEM POCUS hip no effusion normal
Figure 8. Left (unaffected side) hip POCUS with no effusion

ED Course

The patient’s labs result, and she has reassuring labs, which include a serum WBC 8.3 x109/L and ESR 34 mm/hr. The patient receives ibuprofen during her visit and within 1 hour is able to walk without a significant limp and states she feels better. The patient’s family notes they have spent the last few weeks of summer in a Lyme-endemic region, and so you send off Lyme titers.

Given the resolution of limp, lack of fever, and reassuring lab values, you do not believe the patient has a septic joint. Her effusion is more likely the result of a transient tenosynovitis. You recommend close pediatrician follow-up.

Pediatrician Clinic Follow-Up

At her pediatrician clinic visit 1 week later, her Lyme titers return negative, and the patient continues to be limp-free.  

 

Take the ALiEMU PEM POCUS: Hip Effusion Quiz – test your skills

The PEM POCUS series was created by the UCSF Division of Pediatric Emergency Medicine to help advance pediatric care by the thoughtful use of bedside ultrasonography.

Read other PEM POCUS tutorials. Learn more about bedside ultrasonography on the ALiEM Ultrasound for the Win series.

By |2026-05-21T10:09:22-07:00May 17, 2021|Orthopedic, PEM POCUS, Ultrasound|
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PEM POCUS Series: Intussusception

Read this tutorial on the use of point of care ultrasonography (POCUS) for pediatric intussusception. Then test your skills on the ALiEMU course page to receive your PEM POCUS badge worth 2 hours of ALiEMU course credit.

 

Take the ALiEMU PEM POCUS: Intussusception Quiz – test your skills

PATIENT CASE

Johnny is a 2-year-old boy who comes into the emergency department for abdominal pain for the last day. His parents are concerned that he has been having intermittent abdominal pain and has seemed very tired all day. Parents deny bloody stool.

On arrival, his vital signs are:

Vital Sign Finding
Temperature 36.9C
Heart rate 110 bpm
Blood pressure 97/50
Respiratory rate 22
Oxygen saturation (room air) 99%

He is tired appearing, and his abdominal exam is soft but diffusely tender. Given his intermittent abdominal pain, you decide to perform an intussusception point of care ultrasound (POCUS) exam.

ULTRASOUND TECHNIQUE

Intussusception is when one part of the bowel telescopes, or gets stuck, in another part of the bowel. Typically intussusception refers to ileocolic intussusception where the ileum becomes stuck in the colon. To perform the ultrasound, start in the right lower quadrant and trace the colon. See below for a step-by-step technique.

intussusception
Overview of sequential ultrasound transducer positioning on the anterior abdomen to assess for intussusception

Technique

  • The patient should be positioned supine.
  • To aid in comforting the child, the child can be positioned supine in the parent’s lap while undergoing the scan. Having the parent or another provider offer a toy, book, or phone/tablet to distract the child during the scan can also help ease anxiety.
  • Begin in the right lower quadrant (RLQ), using a high frequency linear probe with the probe marker to patient’s right.
  • First, identify the anatomical landmarks in the RLQ (see ultrasound images below):
    • Psoas muscle (green) laterally
    • Right iliac vessels (blue)
    • Abdominal muscles (red)
    • Bladder (yellow) medially

Ultrasound image: Anterior Abdomen (RLQ) View

intussusception RLQ ultrasound

Ultrasound Image: Anterior Abdomen RLQ (More Medial) View

PEM POCUS intussusception RLQ More Medial
  • Perform graded compression, with slow steady pressure to displace bowel gas
  • Follow the colon from the RLQ to right upper quadrant (RUQ) until the liver (purple) and gallbladder are identified

Ultrasound Image: Anterior Abdomen (RUQ) View

PEM POCUS intussusception RUQ
  • Rotate the probe marker to patient’s head and scan the entire length of the transverse colon.
  • Rotate the probe marker back to patient’s right and scan the entire length of the descending colon, making sure to scan all four quadrants.
  • Save representative video clips and still images of each quadrant.
  • If an intussusception is found, measure its diameter in transverse view and note in which quadrant(s) it is found.
  • At the end of scan, if you have found an intussusception, re-image the abdomen to make sure it was not transient.
  • The provider should maintain awareness of the patient’s comfort throughout the scan.

INTUSSUSCEPTION CLASSIC FINDINGS

Normal (no intussusception)

Normal: There is no target or sandwich sign, but rather just folded normal bowel. (To replay, press circular arrow in bottom left corner)

Abnormal findings

  • Look for findings of a sandwich sign (or pseudo-kidney sign) in the longitudinal view and target sign (or donut sign) in the transverse view.
  • If visualized, measure the diameter of the intussusception in short axis (transverse) and note which in which quadrant(s) it is located.

Sandwich

Anterior abdomen ultrasound: Intussusception – Presence of a sandwich sign (long axis view) and target sign (short axis view)

Target Sign

Intussusception diameter ultrasound
Measurement: The diameter of an intussusception (i.e., target sign) in transverse view involves measuring the distance from outer wall to outer wall.

Additional Anterior Abdominal Ultrasound Videos

Pro Tip
It can be difficult to distinguish intussusception of the small bowel-small bowel (i.e., when the ileum or part of the small bowel telescopes into itself) versus ileocolic (i.e., when the ileum becomes telescopes into the colon). The former often does not require a procedure for reduction, while the latter typically does. If the target sign diameter is <2 cm and transient, a small bowel-small bowel intussusception should be suspected. The length of the intussusception, or how many quadrants are involved, can also be measured for an idea of how much bowel is involved.

Small bowel-small bowel intussusception

Small bowel-small bowel intussusception – Note the small size of the target lesion. Because the ultrasound video scans to a depth of 3.3 cm (see bottom right side of the screen), the target sign appears to be approximately only 1 cm in diameter.

 

Small bowel-small bowel intussusception – There is a target sign, but it is small (<2 cm) with a small fat (white) core.

 

Ileo-colic intussusception

Ileo-colic intussusception with classic target sign – Note the lymph nodes (black) inside the mesenteric fat (white) in the center of the target.

FACTS and LITERATURE REVIEW

Mimickers of Intussusception

There are additional pathologies that can be mistaken for intussusception such as an intussuscepted appendix, appendicitis surrounded by abscess, and Meckel’s diverticulum, which are beyond the scope of this course. Any concerning finding for intussusception should be followed by a confirmatory study by the radiology department.

Benefits of intussusception POCUS scans

Although few studies have looked at point of care ultrasonography (POCUS) for intussusception, the existing studies have shown excellent test characteristics and a decreased length of stay with using POCUS.

Two studies assessed the test characteristics of the intussusception POCUS.

Publication Study Methodology Sensitivity Specificity
Riera et al. (2012)​1​ This journal publication was a prospective study of 82 patients who underwent POCUS by pediatric emergency medicine (PEM) providers. The gold standard was a comprehensive radiology ultrasound. 85% 97%
Trigylidas et al. (2017) ​2​ This abstract reported a retrospective study of 105 intussusception POCUS scans by PEM providers. The gold standard was either a direct radiology over-read of the POCUS scans or a radiology department ultrasound. 96.2% 92.6%
Lin-Martore et al. (2020)6 This systematic review and meta analysis included 1,303 patients and 6 studies. 94.9% 99.1%
Bergmann et al. (2021)7 This prospective study of 256 children across 17 sites (35 sonologists) compared POCUS and radiology performed ultrasound using a gold standard of clinically important intussusception which was defined as an intussusception that required radiographic or surgical reduction during or within 7 days of the incident ED visit. 96.6% 98%

In terms of ED length of stay (LOS), Kim et al. (2017) reported that after the introduction of an intussusception POCUS scanning protocol, the LOS decreased by >200 minutes.​3​

Differentiating small bowel-small bowel from ileocolic intussusception

In general, true ileocolic intussusceptions are:

  • Found on the right side of the abdomen
  • >2 cm in diameter
  • Have mesenteric fat (which is white) and lymph nodes in the center
  • Do not self resolve

There have been studies looking at distinguishing small bowel-small bowel from ileocolic intussusception. These, however, have been radiology-based and not POCUS studies, making generalizability to the ED setting challenging. Thus, if there is a concern for an intussusception, a radiology ultrasound should be ordered.

One small study with 27 patients by Wiersma et al. (2006) found that small bowel-small bowel intussusceptions had a smaller mean diameter and length compared to ileocolic intussusceptions.​4​

Type of intussusception # of patients and scans Mean diameter (range) Mean length (range) Location
Small bowel-small bowel 10 patients, 11 scans 1.5 cm (1.1-2.5 cm) 2.5 cm (1.5-6 cm) Distributed throughout the abdomen (6 paraumbilical, 2 RUQ, 2 RLQ, 1 LLQ)
Ileocolic 14 patients, 16 scans 3.7 cm (3-5.5 cm) 8.2 cm (5-12.5 cm) All on right side of abdomen

Lioubashevsky et al 2013​5​ had a larger sample size (174 patients) with similar findings. The authors also measured the ratio of the inner fat core to the intussusception outer wall and identified the presence or absence of lymph nodes within the lesion.

Type of Intussusception # of patients Mean diameter (range) Mean length (range) Ratio of fat core to the intussusception outer wall % of patients with lymph nodes in the lesion
Small bowel-small bowel 57 patients 1.4 cm 
(1.1-2.5 cm)		 2.5 cm 
(1.5-6 cm)		 <1 14%
Ileocolic 143 patients 2.6 cm 
(1.3-4 cm)		 8.2 cm 
(5-12.5 cm)		 >1 89.5%

References [click to expand] +

  1. Riera A, Hsiao A, Langhan M, Goodman T, Chen L. Diagnosis of intussusception by physician novice sonographers in the emergency department. Ann Emerg Med. 2012;60(3):264-268. PMID 22424652
  2. Trigylidas TE, Kelly JC, Hegenbarth MA, Kennedy C, Patel L, O’Rourke K. 395 Pediatric Emergency Medicine-Performed Point-of-Care Ultrasound (POCUS) for the Diagnosis of Intussusception. Annals of Emergency Medicine. October 2017:S155. DOI
  3. Kim J, Lee J, Kwon J, Cho H, Lee J, Ryu J. Point-of-Care Ultrasound Could Streamline the Emergency Department Workflow of Clinically Nonspecific Intussusception. Pediatr Emerg Care. September 2017. PMID 28926507
  4. Wiersma F, Allema J, Holscher H. Ileoileal intussusception in children: ultrasonographic differentiation from ileocolic intussusception. Pediatr Radiol. 2006;36(11):1177-1181. PMID 17019589
  5. Lioubashevsky N, Hiller N, Rozovsky K, Segev L, Simanovsky N. Ileocolic versus small-bowel intussusception in children: can US enable reliable differentiation? Radiology. 2013;269(1):266-271. PMID 23801771
  6. Lin-Martore M, Kornblith AE, Kohn MA, Gottlieb M. Diagnostic Accuracy of Point-of-Care Ultrasound for Intussusception in Children Presenting to the Emergency Department: A Systematic Review and Meta-analysis. West J Emerg Med. 2020 Jul 2;21(4):1008-1016. doi: 10.5811/westjem.2020.4.46241. PMID: 32726276.
  7. Bergmann KR, Arroyo AC, Tessaro MO, et al; P2Network. Diagnostic Accuracy of Point-of-Care Ultrasound for Intussusception: A Multicenter, Noninferiority Study of Paired Diagnostic Tests. Ann Emerg Med. 2021 Jul 2:S0196-0644(21)00340-1. doi: 10.1016/j.annemergmed.2021.04.033. Epub ahead of print. PMID: 34226072.

Case Resolution

You place a linear, high-frequency probe on the right side of the patient’s abdomen. You perform a bedside ultrasound scan, viewing transversely and longitudinally through the upper and lower abdomen. You observe the following:

What is the diagnosis?

This is an intussusception!

The intussusceptum (red) is the part of the bowel that has telescoped into the intussuscipiens (blue). When ileum becomes trapped in the colon, this can lead to ischemia and necrosis over time. This is what causes the classic “currant jelly stools”, which are bloody stools.

Tip: The classic triad of colicky abdominal pain, palpable mass and bloody stool are present in less than 50% of patients, and intussusception should be suspected for patients with vomiting, abdominal pain, and/or lethargy.​1​

Hospital course

Johnny underwent an air enema reduction in the Radiology department, which successfully reduced the ileocolic intussusception.

Reference

  1. Daneman A, Alton D. Intussusception. Issues and controversies related to diagnosis and reduction. Radiol Clin North Am. 1996;34(4):743-756. PMID 8677307.
Take the ALiEMU PEM POCUS: Intussusception Quiz – test your skills

The PEM POCUS series was created by the UCSF Division of Pediatric Emergency Medicine to help advance pediatric care by the thoughtful use of bedside ultrasonography.

Learn more about bedside ultrasonography on the ALiEM Ultrasound for the Win series

By |2026-05-21T10:08:50-07:00May 10, 2021|Gastrointestinal, PEM POCUS, Ultrasound|
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Case of a Lethargic Child: Developing a Differential Diagnosis

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