The clinical implications of non-idiopathic intussusception.

A pathological lesion can be identified at the leadpoint of intussusception in about 6% of episodes. Occasionally, general manifestations of an underlying disease indicate the specific cause of an intussusception (e.g., perioral pigmentation in Peutz-Jeghers syndrome), but usually the clinical features provide no clues as to the aetiology. Neonatal intussusception may be caused by a duplication cyst or Meckel's diverticulum. Beyond 12 months, the proportion of intussusceptions due to a pathological lesion at the leadpoint increases with age. There is an identifiable lesion in the majority of children over 5 years of age. Postoperative intussusception accounts for between 0.5% and 16% of intussusceptions, although it has a variety of causes; it typically follows retroperitoneal dissection. It is unusual for an intussusception due to a pathological lesion at the leadpoint to be reduced by enema. If it is reduced, the lesion may be seen at the time of reduction or fluoroscopy, or subsequently on ultrasonography.