These ultrasounds, performed by EM residents at HUM, nicely demonstrate the classic sonographic finding consistent with intussusception: the target sign, or layers of invaginated bowel seen in cross section.
How to perform this exam using the linear or abdominal probe:
- Place the probe over the bladder
- Move probe to patient’s right and find the illiac vessels
- Move probe further to the patient’s right until the illiac crest is visualized, the iliocecum usually lies just cephalad to the iliac crest
- Follow the entire colon in a “U” shape pattern looking for a target sign
- If you see a target sign, try to confirm the intussusception by obtaining a transverse view of the stacked bowel layers, which will have the appearance of a pancake stack
So how good is ultrasound in diagnosing intussusception? In a study published in Annals of Emergency Medicine in 2012, 6 pediatric emergency physicians were given a 1 hour training on diagnosing intussusception in children and were able to achieve a sensitivity of 85% and a specitivity of 97%. Evaluating for an intussusception with bedside ultrasound is similar to evaluating for appendicitis: if you see that target sign, the intussusception is most likely there, but if you don’t see it, always consider that you might have missed it while you continue your workup for other conditions.
Why is this so important to the Emergency Physician? We see it often and if treated, kids do well, and if not treated, they don’t (an untreated intussusception is usually fatal). While it is the most common cause of bowel obstruction in young children, remember that it can present in many ways. A child with intussusception may present with only crying or vomiting or lethargy or bloody stools or they may have all of them together.
So keep on looking (or probing) out for it because if you do, it’s a target you’re sure to find!
More information:
Pediatric Ultrasound Tricks of the Trade – Abdominal Ultrasound – Emergency Ultrasound
Ultrasound Podcast – Intussusception
