Distal intussusception of processus vaginalis: a cause of acute hydrocele.

Acute obstruction of a patent processus vaginalis occurred in two boys, mimicking incarceration of an inguinal hernia. In fact, obstruction was caused by an intussusception of the processus vaginalis forming an intussuscipiens that occluded the hernia sac. This lesion, described previously in 1896 and in 1974, is one of the mechanisms by which an asymptomatic hernia or hydrocele becomes acutely symptomatic.