Clinical Presentation

A toddler with episodic abdominal pain and “currant jelly” stools.

Further Work-up

(A) A transverse sonographic image of the left lower quadrant demonstrates a mass with concentric rings of hyperechogenicity and hypoechogenicity, the so-called target sign (arrow). (B–E) Four fluoroscopic images obtained during an air reduction enema (with the patient in the prone position in C and D) demonstrate a sausage-like soft-tissue mass in the descending colon (arrows) that is progressively reduced proximally through the colon and end with disappearance of the soft-tissue mass and free reflux of air through the small bowel.

Differential Diagnosis

• Intussusception: The target sign is essentially diagnostic of intussusception, and in this case, the intussusception is not located in the right side of the abdomen because it has progressed distally into the descending colon.

• Appendicitis: May also be associated with a soft-tissue mass, but this is typically located in the right lower quadrant and does not demonstrate the target sign.