Intussusception

This week's image of the week comes to us from Dr. Stephanie Cohen, a pediatric emergency medicine attending at CHOA. She used bedside ultrasound to make the diagnosis of intussusception.  

Those of you studying for the in-service exam will recall that the classic presentation of intussusception is crampy abdominal pain, currant jelly stools, and a sausage-like right upper quadrant mass in a toddler aged child. This case emphasizes that classic presentations are not always common. This patient was a 7-year-old who presented with colicky abdominal pain.  She was found to have a Meckel's diverticulum as the lead point for her intussusception.

The "bulls eye" or "target sign" is the most commonly described ultrasound appearance of an intussusception.

This is an axial cross-section of the affected bowel.  There is a thickened hypoechoic rim representing the edematous outer bowel, and there is a hyperechoic center secondary to the compressed telescoping inner segment. 

The image below shows the intussusception in sagittal cross-section.

To obtain these images, the curvilinear probe was used.  In a small child, the high frequency linear probe could also be used.  If a mass is palpated, this area should be scanned first.  If there is no mass, the entire abdomen can be scanned in two planes in a systematic fashion to find the classic target sign.