Pathological lead points (PLP) have been reported in 1.5 - 12% of intussusceptions occurring in childhood. PLP may be due to focal abnormalities of the bowel or more generalized diseases. The most common focal lesion to act as a PLP is Meckels diverticulum. This may invert itself into the ileum which may then progress to an ileoileal
intussusception and eventually an ileocolic intussusception. Other common focal lesions include polyps and gastrointestinal duplication cysts. Lymphoma may also act as a PLP but this is less common. Some focal PLP are easily depicted by sonography such as duplication cysts and lymphoma but others may be more difficult such as Meckels diverticulum and polyps. Generlised diseases that may cause intussusception include Henoch-Schonlein purpura, polyposis syndromes, cystic fibrosis and celiac disease. However, these may account for only 30% of intussusceptions due to PLP and therefore sonography is extremely important to determine which of those children with intussusception and no known generalized disease may have a focal PLP
which may require surgery.