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SAEM Clinical Images Series: When it is Not Just a Knot

knot

A 12-year-old male with a history of hydrocephalus status post ventriculoperitoneal (VP) shunt placement presented with an abdominal “knot.” The patient’s mother noticed the knot two days ago, on the right anterolateral thorax, which has steadily been increasing in size. The patient had no known trauma to the area or had been bitten or stung by any insect. He has otherwise been complaining of a headache, generalized, without positional changes, improved with home acetaminophen, ice pack, and rest. There were otherwise no associated vision changes, nausea, vomiting, mental status changes, or fever.

Vitals: T-36.2°C; HR 74 bpm; BP 144/75 mm Hg; RR 20; O2 Sat 96% RA

General: Well-appearing teenager in NAD.

HEENT: NC/AT. PERRL approximately 2-3 mm bilaterally. EOMI.

Neck: Supple, no meningismus.

Chest Wall: Induration to the right anterolateral thorax 5 cm x 4 cm without erythema, fluctuance, or drainage, non-tender to palpation.

Neurological: Alert. No focal neurological deficit observed.

Normal

The cause of the knot is subcutaneous cerebrospinal fluid from a shunt malfunction. The ultrasound images show characteristic “cobblestoning,” indicating fluid in the subcutaneous tissue, around a linear hyperechoic object, the catheter of the VP shunt. On the plain film imaging, a disconnect was found between the thoracic and abdominal portions of the VP shunt. Up to 80% of patients with VP shunts will have experienced a shunt malfunction after 12 years, according to one study, with fractured tubing causing shunt failure in around 15% of all cases (1).

Nausea, vomiting, headache, irritability, or decreased mental status are common but nonspecific findings in shunt malfunction. Pediatric patients may present with other signs such as bulging fontanelles, increasing head circumference, or feeding and behavioral changes. An increase in the interval ventricular size can be seen in neuroimaging but can be absent in as many as 20% of patients (2). If there is a high degree of clinical suspicion for shunt malfunction, normal or unchanged neuroimaging should not preclude neurosurgical consultation.

Take-Home Points

  • In the United States, mechanical causes of VP shunt malfunction are the most common presentation, such as catheter obstruction, fracture along the clavicle or ribs, degradation of tubing, and migration of the distal catheter due to changes in height or weight.
  • Rarely, patients can develop an accumulation of CSF at the distal catheter of the VP shunt due to migration into the abdominal wall forming an abdominal pseudocyst.
  • In patients with VP shunts, abdominal complications should be considered as a sign of shunt malfunction.
  • Consider pertinent physical exam findings and POCUS to confirm the diagnosis of shunt malfunction at the distal catheter.

  • Sainte-Rose C, Piatt JH, Renier D, Pierre-Kahn A, Hirsch JF, Hoffman HJ, Humphreys RP, Hendrick EB. Mechanical complications in shunts. Pediatr Neurosurg. 1991-1992;17(1):2-9. doi: 10.1159/000120557. PMID: 1811706.

  • Reynolds RA, Ahluwalia R, Krishnan V, Kelly KA, Lee J, Waldrop RP, Guidry B, Hengartner AC, McCroskey J, Arynchyna A, Staulcup S, Chen H, Hankinson TC, Rocque BG, Shannon CN, Naftel R. Risk factors for unchanged ventricles during pediatric shunt malfunction. J Neurosurg Pediatr. 2021 Sep 24;28(6):703-709. doi: 10.3171/2021.6.PEDS2125. PMID: 34560626.

Copyright

Images and cases from the Society of Academic Emergency Medicine (SAEM) Clinical Images Exhibit at the 2023 SAEM Annual Meeting | Copyrighted by SAEM 2023 – all rights reserved. View other cases from this Clinical Image Series on ALiEM.

By |2025-02-19T12:57:12-08:00Feb 21, 2025|Neurology, Pediatrics, SAEM Clinical Images, Ultrasound|
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SAEM Clinical Images Series: Rectal Bulge

rectal bulge

A 13-month-old, full-term male presented due to intermittent emesis over a 3-week period. He and his parents had COVID one week prior to presentation. He had multiple episodes of non-bloody, non-bilious vomit the day before and the day of presentation. Parents noted he had been listless and unable to tolerate food. The mother was also concerned that he was straining to have bowel movements and that a mass was coming out of his bottom on the ride to the hospital. Parents reported decreased activity, decreased appetite, and decreased urine output. He was born via cesarean section due to breech presentation but had an otherwise uncomplicated prenatal history.

 

Constitutional: Fatigued.

Gastrointestinal: Diffuse abdominal tenderness. Reducible rectal bulge.

Skin: Pale.

Anion Gap: 19

COVID-19: Positive

WBC: 11.9

Limited Abdominal Ultrasound: A large intussusception is noted, which appears to extend at least to the descending/sigmoid colon.

XR Abdomen: Few prominent, featureless bowel loops with air-fluid levels. No gastric distention.

Air or hydrostatic enemas have a 70-85% success rate in current literature. These are often done under either fluoroscopic or ultrasound guidance. A delayed repeat enema can be done in cases where the initial enema resolved some of the intussusception. If the initial measures are unsuccessful, the patient is unstable, or the patient is exhibiting signs of peritonitis or bowel perforation, surgical management is the next step. This can either be done laparoscopically or open. In this patient’s case, an air enema was attempted but he ultimately required surgery. The surgery was laparoscopic, and he was discharged the same day.

Take-Home Points

  • Consider intussusception in any child with a URI (including COVID-19) and a rectal bulge.
  • Although this patient had a formal ultrasound, POCUS can be a useful tool in the ED to identify and expedite intussusception treatment. The classic “bullseye sign” was seen on this patient’s ultrasound.

  • Mandeville K, Chien M, Willyerd FA, Mandell G, Hostetler MA, Bulloch B. Intussusception: clinical presentations and imaging characteristics. Pediatr Emerg Care. 2012 Sep;28(9):842-4. doi: 10.1097/PEC.0b013e318267a75e. PMID: 22929138.
  • Siafakas C, Vottler TP, Andersen JM. Rectal prolapse in pediatrics. Clin Pediatr (Phila). 1999 Feb;38(2):63-72. doi: 10.1177/000992289903800201. PMID: 10047938.

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Images and cases from the Society of Academic Emergency Medicine (SAEM) Clinical Images Exhibit at the 2023 SAEM Annual Meeting | Copyrighted by SAEM 2023 – all rights reserved. View other cases from this Clinical Image Series on ALiEM.

By |2024-11-13T09:52:52-08:00Nov 22, 2024|Pediatrics, SAEM Clinical Images, Ultrasound|
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SAEM Clinical Images Series: Clot in Transit

clot

A 67-year-old male with a past medical history of CHF, MI, hypertension, and diabetes presented to the ED with complaints of headache, chest pain, and dyspnea for the past four days. He stated that he has been without his medications for the past few months due to cost. He denied any past surgical history. He stated that he primarily presented because he felt like “my blood pressure is high”.

 

Cardiovascular: Tachycardic, 2+ pedal edema bilaterally

Respiratory: Tachypneic, decreased breath sounds bilaterally, ronchi/wheezes bilaterally

Skin: Diaphoretic

Troponin I: 0.13 (elevated)

BNP: 1,504

The findings in this picture are of a phenomenon called clot in transit. Via point-of-care ultrasound we were able to visualize part of a thrombus as it journeyed from the right side of the heart to the lungs, becoming a pulmonary embolism. In studies regarding the subject, clot in transit has been found in 3-18% of patients with acute PE. Unfortunately, clot in transit is associated with higher mortality in patients with acute PE. While not fully understood, part of the reason for this may be related to the fact that the patient population that this finding is found in tends to be sicker with higher rates of CHF, cancer, and immobilization. Additionally, increased mortality may be related to PE size given that the clot must be large enough to be seen by ultrasound. Studies have recorded clot in the 30-day mortality rates for patients with acute PE and visualized clot in transit to be 9-45%.

Take-Home Points

  • Point of care US is an essential tool for quickly assessing and appropriately treating patients. This patient’s story was very consistent with a CHF exacerbation but POCUS allowed us to quickly identify a PE and get the patient on track to definitive management.
  • Clot in transit once identified requires immediate action because it is associated with such high mortality in patients.
  • There remains more research to be done on the matter but it appears that clot in transit signifies a need for advanced forms of PE management (thrombolysis or thrombectomy ) to improve mortality in comparison to normal systemic anticoagulation.

  • Athappan G, Sengodan P, Chacko P, Gandhi S. Comparative efficacy of different modalities for treatment of right heart thrombi in transit: a pooled analysis. Vasc Med. 2015 Apr;20(2):131-8. doi: 10.1177/1358863X15569009. PMID: 25832601.
  • Barrios D, Rosa-Salazar V, Jiménez D, Morillo R, Muriel A, Del Toro J, López-Jiménez L, Farge-Bancel D, Yusen R, Monreal M; RIETE investigators. Right heart thrombi in pulmonary embolism. Eur Respir J. 2016 Nov;48(5):1377-1385. doi: 10.1183/13993003.01044-2016. Epub 2016 Oct 6. PMID: 27799388.
  • FREY J, BROWNBACK K. Clot in transit: A dilema of medical or surgical management. Chest. 2021;160(4):A2190. doi: 10.1016/j.chest.2021.07.1932.
  • Garvey S, Dudzinski DM, Giordano N, Torrey J, Zheng H, Kabrhel C. Pulmonary embolism with clot in transit: An analysis of risk factors and outcomes. Thromb Res. 2020;187:139-147. doi: 10.1016/ j.thromres.2020.01.006.

Copyright

Images and cases from the Society of Academic Emergency Medicine (SAEM) Clinical Images Exhibit at the 2023 SAEM Annual Meeting | Copyrighted by SAEM 2023 – all rights reserved. View other cases from this Clinical Image Series on ALiEM.

By |2024-10-28T09:54:15-07:00Nov 1, 2024|SAEM Clinical Images, Ultrasound, Ultrasound for the Win|
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Trick of the Trade: Cut IV extension tubing for 2-person ultrasound guided nerve block

illustration nerve block ultrasound guided needle

Ultrasound-guided procedures are difficult enough just identifying the anatomy. Performing a nerve block with the ultrasound in one hand and the needle in the other hand adds extra challenges. The simplest 1-person approach involves attaching a syringe with local anesthetic directly to the end of the procedural needle. A 2-person approach involves attach the syringe to a custom tubing-needle setup such as below. However, this custom setup may not be readily available.

IV and extension tubing attached to needle

Trick of Trade: Cut Standard IV Extension Tubing

Required equipment:

  • Ultrasound linear probe
  • 10 cc syringe
  • IV tubing
  • Procedural needle
  • Shears

IV extension injection port

Almost all standard IV extension tubing that connects IV fluid bags to a peripheral IV have an injection port near the downstream end.

  1. Clamp the IV tubing just upstream from the injection port and cut off all the unused upstream IV tubing.
  2. Attach a 10 cc syringe with local anesthetic to the injection port.
  3. Attach the other end of this IV tubing (Luer lock attachment) to the procedural needle.
  4. Prime the IV line with the anesthetic.
  5. Perform the nerve block with one person advancing the needle under ultrasound guidance, while the other person aspirates and injects the anesthetic when needed.

Video: 2-person ultrasound-guided nerve block with cut IV tubing

Bonus Tip: This approach is applicable to many procedures requiring aspiration or instillation of anesthetic, such as peritonsillar abscess aspiration.

Read more from the Tricks of the Trade series.

By |2024-10-23T07:23:46-07:00Oct 23, 2024|Neurology, Tricks of the Trade, Ultrasound|
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SAEM Clinical Images Series: Unidentified Intrauterine Object

IUP

A 31-year-old female G3P2 presented to the emergency department with vaginal spotting for one week and worsening lower abdominal cramping. She tested positive on a home pregnancy test one day prior to presentation. On the day of presentation, she passed a small blood clot and bled through one pad. She had not yet seen an OB for this pregnancy. Her last menstrual period was one month and three days prior. The current pregnancy is undesired. She denied fevers, chills, urinary symptoms, lightheadedness, palpitations, shortness of breath, nausea, or vomiting.

 

gestational sac

Vitals: BP 95/55; HR 75; Temp 98.4°F; Resp 16; SpO2 100% on room air

Abdomen: Soft; tender to palpation in the suprapubic region, no guarding or rebound tenderness

GU: Scant blood in the vaginal canal, no clots or tissue; os closed, no adnexal tenderness, no cervical motion tenderness

bHCG: 36,966

Rh Factor: Positive

Hgb: 9.2

Ectopic pregnancy needs to be ruled out. This patient has vaginal bleeding, a positive pregnancy test, and abdominal pain. She has not established care with an OB provider and has not had a confirmed intrauterine pregnancy. Specific ultrasound findings for an ectopic pregnancy include a gestational sac with a yolk sac outside of the uterus. Findings suggestive of an ectopic pregnancy include complex adnexal masses, free fluid with debris (suggestive of rupture), and an empty gestational sac within an adnexal mass.

Yes, this is a viable intrauterine pregnancy (IUP). Confirmation can be done with transabdominal ultrasound but in very early pregnancy may require a transvaginal ultrasound. Findings needed to confirm an IUP include a gestational sac containing a yolk sac within a thickened myometrium. The hyperechoic structure seen on transabdominal and transvaginal ultrasounds for this patient is an intra-uterine device (IUD) that is in place. The risk of pregnancy with an IUD in place is <1%; according to a database of 18 million hospital deliveries, the reports of retained IUD at birth was 12 per 100,000 births. For pregnancies with an IUD in place, the rate of ectopic pregnancy is higher. There is also a higher risk of maternal infection, miscarriage, preterm premature rupture of membranes, preterm birth, and intrauterine fetal demise. For desired pregnancies, if the strings are visible, the IUD is removed as soon as possible and a single dose of azithromycin is given due to increased risk of infection during pregnancy. There is limited evidence to guide management for desired pregnancies when strings are not visible. One option is hysteroscopic removal, although this increases the risk of pregnancy loss. More than 50% of pregnancies with in situ IUDs were found to end in spontaneous abortion.

Take-Home Points

  • A definite IUP requires an intrauterine gestational sac with yolk sac and/or embryo (with or without cardiac activity).
  • Pregnancy with an IUD is extremely rare and increases the risk of ectopic pregnancy, maternal infection, miscarriage, PPROM, preterm birth, and fetal demise.
  • Management for desired pregnancies with IUDs in place when IUD strings are visible consists of early IUD removal with a single dose of prophylactic antibiotics.

  • ACOG Practice Bulletin No. 121: Long-acting reversible contraception: Implants and intrauterine devices. Obstet Gynecol. 2011 Jul;118(1):184-196. doi: 10.1097/ AOG.0b013e318227f05e. PMID: 21691183.
  • Ganer H, Levy A, Ohel I, Sheiner E. Pregnancy outcome in women with an intrauterine contraceptive device. Am J Obstet Gynecol. 2009 Oct;201(4):381.e1-5. doi: 10.1016/j.ajog.2009.06.031. Epub 2009 Aug 29. PMID: 19716537.
  • Roline, C.E., Heegaard, W.G. & Anderson, K.S. Early pregnancy with an intrauterine device in place. Crit Ultrasound J 3, 91–92 (2011). https://doi.org/10.1007/s13089-011-0068-1

Copyright

Images and cases from the Society of Academic Emergency Medicine (SAEM) Clinical Images Exhibit at the 2023 SAEM Annual Meeting | Copyrighted by SAEM 2023 – all rights reserved. View other cases from this Clinical Image Series on ALiEM.

By |2024-09-28T21:27:46-07:00Oct 4, 2024|Ob/Gyn, SAEM Clinical Images, Ultrasound|
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PEM POCUS Series: Soft Tissue Ultrasound

PEM POCUS fascia iliaca block

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

Case Goals

  1. List the indications of performing a pediatric soft tissue point-of-care ultrasound (POCUS).
  2. Describe the technique for performing soft tissue POCUS.
  3. Interpret signs of cellulitis, abscess, and soft tissue foreign body on POCUS.
  4. Describe the limitations of soft tissue POCUS.
  5. Differentiate abscess from other soft tissue pathologies such as cysts and lymph nodes.

Case Introduction: Child with abdominal pain

Wendy is a 7-year-old girl who comes into the emergency department with redness, swelling, and pain on her left calf. Her symptoms started 1 week ago as a scratch which progressively got more red and painful. There has been no drainage from the lesion. She has had no fevers, but endorses elevated temperatures of 99 F.

On arrival, her vital signs are:

Vital SignFinding
Temperature100.1 F
Heart Rate95 bpm
Blood Pressure105/68
Respiratory Rate20
Oxygen Saturation (room air)100%

On her exam, you notice a 3 x 3 cm area of erythema and induration on her right calf with questionable fluctuance. The area is tender to palpation. She has no other skin findings noted, and she is able to bear weight. Given your concern for an abscess which may require drainage, a POCUS is performed.

Pediatric Soft Tissue POCUS

Figure 1. Linear ultrasound transducer

Probe

  • Use a linear, high-frequency transducer.

Technique

  • Hold the probe perpendicular to the skin.
  • Scan the area of interest in 2 orthogonal (perpendicular) planes.
  • If there is an abscess:
    • Measure the abscess in 3 dimensions.
    • Use color Doppler to ensure the structure is not vascular.

Pro Tips

  • It is often helpful to ultrasound the unaffected side as a comparison.
  • You cannot see what you didn’t scan. Scan the entirety of the affected area in 2 planes.
  • Be aware of the patient’s comfort throughout the examination.
  • A water bath may be helpful to visualize lesions in extremities such as the hands or feet.
    • The probe sits just below the water’s surface and does not need to contact the skin.
    • The benefits of using a water bath include better visualization of superficial structures and alleviates the need for direct skin contact.
waterbath technique with ultrasound image

Figure 2. Left: Water bath technique; Right: Ultrasound of a toe using a water bath (image courtesy of The Pocus Atlas and Moudi Hubeishy, MD)

soft tissue layers ultrasound

Figure 3. Normal soft tissue layers on ultrasound (image courtesy of The Pocus Atlas)

Normally on a soft tissue ultrasound, you will see layers of defined structures separated by fascial planes.

  1. Epidermis/dermis: This is the topmost layer and has an hyperechoic appearance on ultrasound.
  2. Subcutaneous tissue: This deeper layer will appear slightly more hypoechoic.
  3. Muscular layer: This even deeper layer classically appears striated in the long axis view, while in the short axis view, it will have a speckled appearance.
  4. Bone: This layer appears hyperechoic cortex with posterior shadowing.

Cellulitis has a spectrum of appearances on ultrasound. Early cellulitis may present as skin thickening (Figure 4).

pem pocus cellulitis hazy thickening

Figure 4. Cellulitis with skin thickening

 

As cellulitis progresses, there is effacement of the clearly differentiated structures seen above, and the tissue layers may appear hazy and hyperechoic. More advanced cellulitis may have “cobblestoning” which is the result of edematous fluid separating fat globules in the subcutaneous tissue.

pem pocus cellulitis cobblestoning

Figure 5. Cellulitis with cobblestoning

 

Video 1. Ultrasound showing cellulitis with cobblestoning

Abscesses can have varied appearances. They can be anechoic (black) or filled with debris leading to a heterogeneous appearance of contents. The rim may be echogenic or blend in with surrounding tissue. They may be well-circumscribed or may have irregular borders.

A. Abscess with irregular borders and heterogeneous appearance

B. Well-circumscribed abscess with heterogeneous debris

C. Larger abscess with well-circumscribed borders

D. Abscess with irregular borders and surrounding cellulitis

E. Abscess with irregular borders and more homogenous appearance

F. Superficial abscess with well-circumscribed borders

Table 1. Examples of different appearances of abscesses on ultrasound
Video 2. Ultrasound of a cutaneous abscess

Color Doppler Flow

Placing color Doppler flow on a suspected abscess is helpful to differentiate it from a lymph node or blood vessel (see “Abscess Mimickers” section for lymph node examples). It may also aid in identifying nearby vasculature.

Figure 6. Abscess with color Doppler flow

Video 3. Ultrasound of cutaneous abscess with color Doppler flow

Posterior Acoustic Enhancement

Abscesses may exhibit posterior acoustic enhancement, which results in an enhanced transmission of ultrasound waves through a fluid-filled structure. Sometimes the abscess may not be as obvious and appear less anechoic due to debris. A squish (or swirl) sign may be elicited by putting pressure on the region, which will cause movement of the abscess contents. This finding has also been called “pus-talsis”.

Figure 7. Abscess with posterior acoustic enhancement

Video 4. Ultrasound of cutaneous abscess with squish sign

Size Measurement

Abscesses should be measured in 2 planes. Measure depth in 1 plane and length in 2. An easy way to remember this is to measure a plus sign (+) in one view, and a minus sign (-) in the other.

Figure 8. Measurement of abscess in two planes (images courtesy of Dr. Munaza Rizvi)

Lymph Nodes

Lymph nodes appear as ovid and well-circumscribed structures on ultrasound and may be confused for abscesses. They may be differentiated by their homogenous echotexture, central echogenic hilum. When inflamed, they may exhibit internal vascularity which should not be seen in an abscess.

Figure 9. A lymph node with a hilum (left) and a reactive inguinal lymph node with central vascularity (right)

Cysts

Cysts are fluid-filled, well-circumscribed structures which may be similar to abscesses. A common soft tissue cyst is an epidermoid cyst, which is a subepidermoid nodule filled with keratin. In addition to physical exam clues which may help distinguish cysts from abscess, cysts are typically very well-circumscribed and more homogenous in appearance.

Figure 10. Epidermoid cyst (image courtesy of The Pocus Atlas and Dr. Robert Jones)

Soft tissue foreign bodies are a common pediatric presentation and can be easily identified on ultrasound. X-rays can be used to identify foreign bodies; however, their use is limited to radiopaque objects. On ultrasound, foreign bodies often appear as a hyperechoic defect.

Figure 11. Hyperechoic foreign body (glass) embedded in the soft tissue of a foot with posterior shadowing

Video 5. Ultrasound of soft tissue foreign body

Foreign bodies embedded for a prolonged time may have signs of infection, such as cellulitis or abscess (Figure 12).

Figure 12. Wooden splinter embedded in a patient’s plantar foot with surrounding fluid collection consistent with abscess

A foreign body’s composition can affect how it appears on ultrasound. Different materials can produce characteristic ultrasound artifacts.

Foreign BodyUltrasound FindingsUltrasound Image
WoodHyperechoic with posterior shadowing
GlassHyperechoic with posterior shadowing
May have comet tail artifact

Images courtesy of Dr. Ashkon Shaahinfar

MetalVery hyperechoic
Often has a comet tail or reverberation artifact
Table 2. Foreign body characteristics on ultrasound

Foreign Body Removal

Ultrasound assistance in foreign body removal may be static (used to locate the foreign body’s position) or dynamic (using ultrasound to guide foreign body removal in real-time). Measuring the foreign body and assessing the object’s depth on ultrasound may assist in determining if bedside removal versus surgical removal is indicated.

Limited evidence suggests that there may be some sonographic differences between the papular urticaria of a “skeeter syndrome” and local cellulitis. On ultrasound, both findings will have thickening of dermal and subcutaneous tissues. Angioedema characteristically includes more linear, horizontal, striated bands — in comparison to cobblestoning found in cellulitis [1]. However, additional studies are needed to confirm this.

Figure 13. Ultrasound of angioedema (left) and cellulitis with cobblestoning (right). Angioedema image courtesy of Dr. Laura Malia.

Necrotizing fasciitis is a rare pediatric diagnosis but a rapidly progressive and life-threatening condition if not identified quickly. While necrotizing fasciitis is primarily a clinical diagnosis, imaging may be helpful when the diagnosis is uncertain. Computed tomography (CT) and magnetic resonance imaging (MRI) have good test characteristics; however, these tests are time-consuming and may not be available in all centers. CT also involves ionizing radiation. Point-of-care ultrasound has the benefit of rapid bedside use and lack of ionizing radiation.

On ultrasound, early necrotizing fasciitis presents with thickening of the subcutaneous tissue, similar to cellulitis. Fluid in the fascial layers may also be present, and a thick layer of pre-fascial fluid >4 mm has been associated with necrotizing fasciitis [2]. Subcutaneous air with dirty shadowing (Figure 14) is a characteristic but late finding in necrotizing fasciitis. These findings may be recalled using the “STAFF” mnemonic [3]:

  • Subcutaneous Thickening
  • Air
  • Fascial Fluid

Note: It may be difficult to distinguish early cases of necrotizing fasciitis from cellulitis. Therefore ultrasound should not be used to exclude necrotizing fasciitis. Patients with findings concerning for necrotizing fasciitis require additional work-up and surgical consultation.

Figure 14. Necrotizing fasciitis on POCUS exam showing the presence of air with dirty shadowing within soft tissue (image courtesy of Dr. Di Coneybeare)

For additional reading on ultrasounding necrotizing fasciitis, see these ALiEM articles:

  • As with all ultrasound applications, soft tissue POCUS is operator dependent.
  • The ultrasound can only see what is scanned. You must make sure the lesion is fully imaged.
  • It is difficult to differentiate between various types of fluid on ultrasound. For example, hematomas may resemble abscesses. Therefore clinical context is important.

There have been multiple studies (Table 3) that support the use of soft tissue POCUS for identification of cellulitis or abscess. Soft tissue POCUS has been shown to have good sensitivity and specificity. It has also been shown to be superior to clinical assessment in several pediatric studies.

POCUS can also reduce the length of stay (LOS) for our patients. In one pediatric study including 3,094 children suspected of a soft tissue infection who underwent either POCUS or radiology department ultrasound, POCUS was shown to have a shorter median LOS by 73 minutes (95% CI 52.4-93.6 min) [4].

StudyNMethodsPOCUS Sensitivity (95% CI)POCUS Specificity (95% CI)Conclusions
Gottleib et al., Ann Emerg Med 2020 [5]2,656Systematic review of adult and pediatric studies94.6%

(89.4-97.4%)

85.4%

(78.9-90.2%)

POCUS has good diagnostic accuracy. Led to correct change in management in 10% of cases.
Lam et al., J Emerg Med 2018 [6]327Prospective cohort study of children 6mo-18yrs comparing clinical assessment to POCUS90.3%

(83.4-94.7%)

80%

(70.0-87.4%)

POCUS changed management in 22.9% of cases*
Subramaniam et al., Acad Emerg Med 2016 [7]800Systematic review of adult and pediatric (patients from birth – 21yrs) studies97%

(94-98%)

83%

(75-88%)

POCUS may assist physicians in distinguishing cellulitis versus abscess.
Adams et al., J Pediatr 2015 [8]151Prospective cohort study of patients 3mo-21yrs comparing clinical assessment to POCUS96%

(90-99%)

87%

(74-95%)

POCUS changed management in 27% of cases.** For every 4 ultrasounds performed, 1 correct change in management.
Sivitz et al., J Emerg Med 2009 [9]50Prospective cohort study of children <18yrs comparing clinical assessment to POCUS90%

(77-100%)

83%

(70-97%)

POCUS changed management in 22% of cases.
Table 3. Studies comparing soft tissue POCUS to clinical assessment in the management of soft tissue infections.
* Change in management after POCUS defined by the following:
  • Changed incision location/size
  • Added packing
  • Medical to surgical management
  • Surgical to medical management
  • Consultation of specialist
  • Other
** Change in management defined as when the ultrasound diagnosis was discordant from the physical exam and matched the ultimate lesion classification.

Case Resolution

After reviewing the literature, you decide to perform a POCUS to evaluate for skin abscess. You place a linear, high-frequency transducer over the patient’s affected area and you observe the following:

Video 6. Soft tissue ultrasound showing an abscess with heterogeneous appearance and irregular borders with posterior acoustic enhancement, surrounding soft tissue haziness, cobblestoning

ED Course

The patient underwent successful incision and drainage of the abscess, and she was discharged home with antibiotics.

 

Learn More…

References

  1. Tay ET, Ngai KM, Tsung JW, Sanders JE. Point-of-Care Ultrasound on Management of Cellulitis Versus Local Angioedema in the Pediatric Emergency Department. Pediatr Emerg Care. 2022 Feb 1;38(2):e674-e677. doi: 10.1097/PEC.0000000000002416. PMID: 34398861.
  2. Yen ZS, Wang HP, Ma HM, et al. Ultrasonographic screening of clinically-suspected necrotizing fasciitis. Acad Emerg Med. 2002;9:1448–1451. PMID 12460854.
  3. Castleberg E, Jenson N, Dinh VA. Diagnosis of necrotizing faciitis with bedside ultrasound: the STAFF Exam. West J Emerg Med. 2014 Feb;15(1):111-3. doi: 10.5811/westjem.2013.8.18303. PMID: 24578776; PMCID: PMC3935782.
  4. Lin MJ, Neuman M, Rempell R, Monuteaux M, Levy J. Point-of-Care Ultrasound is Associated With Decreased Length of Stay in Children Presenting to the Emergency Department With Soft Tissue Infection. J Emerg Med. 2018 Jan;54(1):96-101. doi: 10.1016/j.jemermed.2017.09.017. Epub 2017 Oct 27. PMID: 29110982.
  5. Gottlieb M, Avila J, Chottiner M, Peksa GD. Point-of-Care Ultrasonography for the Diagnosis of Skin and Soft Tissue Abscesses: A Systematic Review and Meta-analysis. Ann Emerg Med. 2020 Jul;76(1):67-77. doi: 10.1016/j.annemergmed.2020.01.004. Epub 2020 Feb 17. Erratum in: Ann Emerg Med. 2022 Jan;79(1):90. PMID: 32081383.
  6. Lam SHF, Sivitz A, Alade K, Doniger SJ, Tessaro MO, Rabiner JE, Arroyo A, Castillo EM, Thompson CA, Yang M, Mistry RD. Comparison of Ultrasound Guidance vs. Clinical Assessment Alone for Management of Pediatric Skin and Soft Tissue Infections. J Emerg Med. 2018 Nov;55(5):693-701. doi: 10.1016/j.jemermed.2018.07.010. Epub 2018 Aug 28. PMID: 30170835; PMCID: PMC6369916.
  7. Subramaniam S, Bober J, Chao J, Zehtabchi S. Point-of-care Ultrasound for Diagnosis of Abscess in Skin and Soft Tissue Infections. Acad Emerg Med. 2016 Nov;23(11):1298-1306. doi: 10.1111/acem.13049. Epub 2016 Nov 1. PMID: 27770490.
  8. Adams CM, Neuman MI, Levy JA. Point-of-Care Ultrasonography for the Diagnosis of Pediatric Soft Tissue Infection. J Pediatr. 2016 Feb;169:122-7.e1. doi: 10.1016/j.jpeds.2015.10.026. Epub 2015 Nov 10. PMID: 26563535.
  9. Sivitz AB, Lam SH, Ramirez-Schrempp D, Valente JH, Nagdev AD. Effect of bedside ultrasound on management of pediatric soft-tissue infection. J Emerg Med. 2010 Nov;39(5):637-43. doi: 10.1016/j.jemermed.2009.05.013. Epub 2009 Aug 8. PMID: 19665335.
By |2024-05-12T22:03:30-07:00May 13, 2024|Expert Peer Reviewed (Clinical), Infectious Disease, Pediatrics, PEM POCUS, Ultrasound|
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SAEM Clinical Images Series: An Ultrasonographic Rabbit Hole

hole

An 86-year-old man with a past medical history of coronary artery disease, hypertension, hyperlipidemia, chronic kidney disease, COPD, choledocholithiasis requiring ERCP and sphincterotomy 2 years ago presented with five days of feeling unwell. History was limited due to cognitive impairment. His daughter had reported to staff he had been feeling unwell for five days, intermittently having nausea and generalized abdominal pain, subjective fevers, chest pain, and shortness of breath. His daughter also reported a history of intermittent lower abdominal cramping which was chronic for him. He denied changes to urination or bowel movements.

 

Vitals: BP 106/67, Temp 36.2°C, Pulse 115, Resp 20, SpO2 95%

General: Nontoxic appearing, no distress

Heart: Regular, no murmurs

Lungs: Clear bilaterally, normal work of breathing

Abdomen: Diffusely tender, greatest in left upper quadrant

CBC with differential: WBC 14.1, Neutrophil 12% (high)

Comprehensive metabolic panel (CMP): Total bilirubin 2.7 (high), AlkP 328 (high), AST/ALT normal

Lipase: Normal

Troponin x2: Negative

Chest x-ray: No acute abnormality

This patient has sonographic evidence of perforated gangrenous cholecystitis which was confirmed on subsequent CT scan. Gallbladder perforation is a complication of cholecystitis and has a reported incidence of 5-10%. It has been reported as early as two days after the onset of symptoms to as late as several weeks afterward. The most common site of perforation is the fundus due to relatively poor blood supply. In this case, the culprit perforation was in the proximal body adjacent to the stone which is suspected to have eroded through the wall.

Figure 1 depicts a minimally thickened gallbladder wall measured at 3.5 mm with a large shadowing stone-in-neck and associated perihepatic fluid collection (arrow) with a subtle intraluminal membrane and wall irregularity consistent with gangrenous cholecystitis. Figure 2 doppler images show no flow within the fluid collection and a suspiciously thin gallbladder wall (arrow). Figure 3 again highlights an irregular wall with small “hole sign” (arrow) signifying perforation of the gallbladder into the adjacent fluid collection. This patient was admitted to the hospital’s general surgical service and treated with IV broad-spectrum antibiotics and a percutaneous cholecystostomy tube placed by interventional radiology.

Take-Home Points

  • Look out for “hole signs” with adjacent fluid collection on your gallbladder ultrasounds which would suggest perforation.
  • Intraluminal membranes or wall irregularities suggest gangrenous cholecystitis.
  • Initial treatment includes broad-spectrum antibiotics and cholecystostomy tube decompression.

  • Indiran, V., Prabakaran, N. & Kannan, K. “Hole sign” of the gallbladder. Indian J Gastroenterol 36, 66–67 (2017). https://doi.org/10.1007/s12664-016-0723-3
  • Jeffrey RB, Laing FC, Wong W, Callen PW. Gangrenous cholecystitis: diagnosis by ultrasound. Radiology. 1983 Jul;148(1):219-21. doi: 10.1148/radiology.148.1.6856839. PMID: 6856839.
  • Sood, B.P., Kalra, N., Gupta, S., Sidhu, R., Gulati, M., Khandelwal, N. and Suri, S. (2002), Role of sonography in the diagnosis of gallbladder perforation. J. Clin. Ultrasound, 30: 270-274.

Copyright

Images and cases from the Society of Academic Emergency Medicine (SAEM) Clinical Images Exhibit at the 2023 SAEM Annual Meeting | Copyrighted by SAEM 2023 – all rights reserved. View other cases from this Clinical Image Series on ALiEM.

By |2024-04-01T09:12:28-07:00Feb 16, 2024|Gastrointestinal, SAEM Clinical Images, Ultrasound|
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