Retrograde intussusception: a lead-point for prograde intussusception.

Retrograde intussusception is an extremely rare entity. The authors report a case of retrograde jejuno-jejunal intussusception in a 12 year old. The features of interest are (1) the retrograde intussusception mass acting as a lead-point for a second prograde jejuno-jejunal intussusception, (2) the anastomotic suture line of a previous resection-anastomosis acting as the lead-point for the retrograde intussusception, and (3) the presence of a "reverse claw sign" (on a barium meal study) caused by the intussusceptum of the retrograde intussusception.