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 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 SignFinding
Temperature37.5 C
Heart Rate120 bpm
Blood Pressure106/58
Respiratory Rate18
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 AppendicitisUltrasound 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.
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
pediatric appendicitis POCUS

Figure 16. Close-up POCUS view of the appendix from video 5

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).

StudyNPatient AgeSensitivitySpecificityComments
Sivitz et al., 2014 [1]264Pediatric
(95% CI: 75-95%)
(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]6,636Pediatric89%

(95% CI: 47–99%)


(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]317Any age85%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]132Any age65%

(95% CI: 52-76%)


(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…


  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 |2022-06-01T10:15:33-07:00May 31, 2022|Pediatrics, PEM POCUS, Ultrasound|

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.

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. 


Vital SignFinding
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. 

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. 
  • AnisotropyThis 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.


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.


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.


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. 

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 |2021-05-27T10:14:48-07:00May 24, 2021|PEM POCUS, Ultrasound|

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.

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
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) 


  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.


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. 


  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 


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).

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 


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.  


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 |2021-07-21T18:55:01-07:00May 17, 2021|Orthopedic, PEM POCUS, Ultrasound|

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.



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 SignFinding
Heart rate110 bpm
Blood pressure97/50
Respiratory rate22
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.


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.

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


  • 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.


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.


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.


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.

PublicationStudy MethodologySensitivitySpecificity
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)6This systematic review and meta analysis included 1,303 patients and 6 studies.94.9%99.1%
Bergmann et al. (2021)7This 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 scansMean diameter (range)Mean length (range)Location
Small bowel-small bowel10 patients, 11 scans1.5 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)
Ileocolic14 patients, 16 scans3.7 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 patientsMean 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 bowel57 patients1.4 cm 
(1.1-2.5 cm)
2.5 cm 
(1.5-6 cm)
Ileocolic143 patients2.6 cm 
(1.3-4 cm)
8.2 cm 
(5-12.5 cm)

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.


  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.

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 |2021-10-21T16:59:09-07:00May 10, 2021|Gastrointestinal, PEM POCUS, Ultrasound|

Case of a Lethargic Child: Developing a Differential Diagnosis

lethargic childA 2-year-old previously healthy boy presents to the emergency department (ED) acting sleepier than usual. Yesterday, he was in his usual state of health, but this morning he didn’t wake up at his usual time of 6 am. When his father went to his room at 7 am, the child was lying in bed. He opened his eyes to look at his father, but did not get out of bed. The mother and father deny any trauma, fever, or seizure activity.


By |2018-11-22T15:23:48-08:00Nov 28, 2018|Pediatrics, Tox & Medications|

PEM Pearls: Pediatric Lung Ultrasound for Diagnosing Pneumonia | The Wave of the Future

pediatric lung ultrasound for diagnosing pneumoniaThe standard for diagnosing pneumonia is a combination of the clinical history, physical examination, and chest x-ray (CXR) findings. However, lung ultrasound (US) has been shown to be a reasonable alternative to CXR in children, and may be an appropriate alternative diagnostic imaging modality in the Emergency Department (ED).


By |2017-12-30T10:55:04-08:00Dec 30, 2017|PEM Pearls, Ultrasound|
Go to Top