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Emergency Ultrasound

Pediatric Emergency Ultrasound: Deep Dive on POCUS for Intussusception

By Lilly A. Bellman, MD (@LillyBellman) & Manpreet Singh, MD (@MPrizzleER)

Case

Your nurse is about to fill three rooms with vomiting children – must be another AGE virus going around! Two of the kids have classic vomiting with diarrhea and had a sick contact, and look very well. They’ll be easy Zo-Po-Go (ie Zofran, PO challenge, Go Home)!

The third one, however, is a 2-year-old now on his second day of vomiting (non-bilious, non-bloody), has no diarrhea, no fever, and the parent tells you they’ve been very “irritable.” It’s hard to examine his belly as he starts crying the minute you get close (even with all your great pediatric flair). His vitals are “OK” – somewhat tachycardic but probably was crying, normal BP, RR, SpO2, and temperature.

So you’re thinking differential: Could still be AGE? However, you’re also worried about other pathologies, such as appendicitis, intussusception, or testicular torsion (though normal GU exam).

You want some more information…

Let’s Review

Intussusception happens when the bowel telescopes in on itself and gets stuck. The stuck section in the middle drags along with it some mesentery with its blood supply, which can be compromised. This dying bowel becomes edematous and can eventually become necrotic. With peristaltic waves of the surrounding gut come the episodes of pain classically described in its clinical presentation. Pain, along with vomiting, and bloody stool (also often described with right sided sausage shaped mass) make up the triad often seen in test questions. Only 21-65% of children present classically, so you must have a high index of suspicion to make this diagnosis.1-2

What do we know about ultrasound for intussusception?

Radiology performed ultrasound for intussusception has excellent test performance.

A 6 year validation study reviewing 814 ultrasound exams over 7 years found sensitivity of 97.9% and specificity of 97.8%, PPV of 86.6%, and NPV of 99.7%.3 In this study positive exams were confirmed via radiographic reduction procedure or surgery. Many of the reads were from radiology residents suggesting that relatively inexperienced radiologists perform very well in interpreting this study.

So, if you’re lucky to have radiology available 24/7, you can just send the kid for rule-out intussusception ultrasound, right? What if you’d have to call in the tech from home? Or what if you just want to try your hand at this yourself?

The literature supports you! After some case reports of EM physicians including young trainees picking up intussusceptions on bedside ultrasounds,4,5 Riera et al. conducted the first prospective study of point of care ultrasound by emergency physicians which enrolled 82 patients. They found that after a brief didactic and hands on session, pediatric emergency attendings and fellows performed remarkably well with sensitivity of 85% and specificity of 97%.6

Now, more recently, a retrospective cohort study by Kim et al. compared records of children with “clinically nonspecific intussusception” (those presenting with only one symptom of the triad) before and after an educational intervention teaching POCUS to ED attending physicians.7 They found improved resource utilization (higher rates of positive studies in radiology performed ultrasounds), increased use of POCUS, and reduced ED length of stay. This study could not characterize test performance as patients were not followed up and could also have potentially been confounded by significant change in ED staffing in the pre- and post-intervention group. Still, it is the only study to date of this type and provides evidence to support that use of POCUS could streamline ED visits. 

Let’s do an ultrasound!

Prepare your patient

As these are not the happiest of young children in your department, scanning them can be a challenge. Some ways to help make this scan easier for everyone are:

-       Enlist the parents to help you. They can hold their child lying in their lap and comfort them.

-       Control pain before you start.

-       Use warm gel (you can use a warmer or rub some gel between your hands before applying it to your little patient’s abdomen).

Probe Choice

The linear probe will have enough depth to see intussusception in most children (most of these children will be under 36 months of age2). I like to use linear probes with larger footprints if available. If you need more depth, an abdominal curvilinear probe will work as well in larger kiddos.

Scanning technique

 

Most intussusceptions will be on the right side as the vast majority are ileocolic. Scanning over the full path of the colon will help find less common colicocolic intussusceptions or cases where the cecum isn’t exactly where expected. The most comprehensive technique is the lawn-mower method which is discussed here in the emDOCs post about small bowel obstruction. Use graded compression along your scanning path to push bowel gas that might be obscuring your view out of the way as well as assess the compressibility of the bowel.

US Findings

This schematic nicely shows the intussusception process and its cross-sectional anatomy that we then see in the ultrasound images and clips below.8

 

 

 

 

 

 

 

 

 

 

 

Source: Ongom et al.8 (Open Access Emergency Medicine Journal)

 

The Doughnut or Target Sign in the transverse or short axis of the intussusception process. Note the multiple layers of bowel wall

Source: The POCUS Atlas (Open Access). Target or Doughnut sign in transverse view of intussusception

Source: The POCUS Atlas (Open Access). Target or Doughnut sign in transverse view of intussusception.

 

Hayfork or Sandwich Sign in the long axis

Source: The POCUS Atlas (Open Access).

 

Pseudokidney sign is sometimes seen in an oblique or long axis view.

Case courtesy of Dr T Menezes, Radiopaedia.org, rID: 33056 Radiopedia.org9

Associated Findings

Along with the intussusception itself, you may also see the following:

-       Mesenteric lymph nodes

-       Fluid trapped inside the intussusception

-       Fluid around the intussusception

-       Fluid filled bowel from obstruction

-       Poor blood flow to the intussuscipiens (the inside part) on color Doppler

Some of these findings (namely multiple lymph nodes >1cm,10 fluid trapped inside or around,11 outer wall thickness >1cm,12 and left sided intussusceptions11) may be predictive of failed radiologic reduction.

Potential False Positives

Other processes associated with bowel wall thickening including infectious or inflammatory colitis can look almost like the doughnut but will be missing the multiple layers of bowel wall in intussusception.

A mass or hematoma in the bowel wall, or solid stool can also be mistaken for intussusception. These will also lack the layering.

Finally, an intermittent intussusception that self reduces before radiology’s scan can be a false positive.

Any concerning or unexplained finding should be referred to radiology for formal study.

Potential False Negatives

False negatives tend to be operator dependent and often are due to not visualizing the area where the intussusception is or not visualizing the entire structure in question.13 Make sure to use adequate depth in your scanning and to systematically scan the abdomen. Of course, an intermittent intussusception could also be a false negative study.

Awareness of the lower sensitivity (85%) of EM doc performed POCUS for intussusception is key! This means that if your scan is negative, but your clinical suspicion is still high, send your patient for confirmatory scan by radiology!

Documenting your scan

A guideline for documenting this and many other pediatric specific ultrasounds can be found in the Pediatric Emergency Medicine Point-of-Care Ultrasound: Summary of the Evidence.14 Properly documenting scans helps better communicate with colleagues as well as help collect data for internal quality assurance and improvement, and of course ensure reimbursement where applicable.

Back to our case

You put the probe down on that kid and find the tell-tale doughnut! You send him to radiology for reduction which is successful, observe him about 6 hours after (he’s feeling much better), and send him home with good return precautions for recurrence if his symptoms should return.15

A Summary “Recipe Card”

Adapted from Pediatric Emergency and Critical Care Ultrasound.13

References

1.      Bruce J, Huh YS, Cooney DR, et al. Intussusception: Evolution of current management. J Pediatr Gastroenterol Nutr. 1987;6(5):663-674.

2.      Mandeville K, Chien M, Willyerd FA, et al. Intussusception: Clinical presentations and imaging characteristics. Pediatr Emerg Care. 2012;28(9):842-844.

3.      Hryhorczuk AL, Strouse PJ. Validation of US as a first-line diagnostic test for assessment of pediatric ileocolic intussusception. Pediatr Radiol. 2009;39(10):1075-1079.

4.      Kairam N, Kaiafis C, Shih R. Diagnosis of pediatric intussusception by an emergency physician-performed bedside ultrasound. Pediatr Emerg Care. 2009;25(3):177-180.

5.      Doniger SJ, Salmon M, Lewiss RE. Point-of-care ultrasonography for the rapid diagnosis of intussusception: A case series. Pediatr Emerg Care. 2016;32(5):340-342.

6.      Riera A, Hsiao AL, Langhan ML, et al. Diagnosis of intussusception by physician novice sonographers in the emergency department. Ann Emerg Med. 2012;60(3):264-268.

7.      Kim JH, Lee JY, Kwon JH, et al. Point-of-care ultrasound could streamline the emergency department workflow of clinically nonspecific intussusception. Pediatr Emerg Care. 2017;0(0):1-6.

8.      Ongom P, Kijjambu S. Adult intussusception: a continuously unveiling clinical complex illustrating both acute (emergency) and chronic disease management. OA Emergency Medicine 2013 Aug 01;1(1):3. http://www.oapublishinglondon.com/images/article/pdf/1379671793.pdf. Accessed January 23, 2018.

9.      Menezes T. Ileocolic Intussusception. Radiopedia.org. 2014. https://radiopaedia.org/cases/ileocolic-intussusception-4.

10.    Koumanidou C, Vakaki M, Pitsoulakis G, et al. Sonographic detection of lymph nodes in the intussusception of infants and young children: clinical evaluation and hydrostatic reduction. AJR Am J Roentgenol. 2002;178(2):445-450. doi:10.2214/ajr.178.2.1780445.

11.    He N, Zhang S, Ye X, et al. Risk factors associated with failed sonographically guided saline hydrostatic intussusception reduction in children. J Ultrasound Med. 2014;33(9):1669-1675. doi:10.7863/ultra.33.9.1669.

12.    Mirilas P, Koumanidou C, Vakaki M, et al. Sonographic features indicative of hydrostatic reducibility of intestinal intussusception in infancy and early childhood. Eur Radiol. 2001;11(12):2576-2580. doi:10.1007/s003300100883.

13.    Sivitz AB. The Pediatric Abdomen. In: Doniger SJ, ed. Pediatric Emergency and Critical Care Ultrasound. Vol Cambridge, UK: Cambridge University Press; 2013:134-159.

14.    Marin JR, Abo AM, Arroyo AC, et al. Pediatric emergency medicine point-of-care ultrasound: summary of the evidence. Crit Ultrasound J. 2016;8. doi:10.1186/s13089-016-0049-5.

15.    Bajaj L, Roback MG, Viboud C, et al. Postreduction management of intussusception in a children’s hospital emergency department. Pediatrics. 2003;112(6):1302-1307. doi:10.1542/peds.112.6.1302.

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