Intussusseption is caused by part of the gut being pulled inward. This can obstruct the passage of digestive contents through the intestine. Strangulation, in which the blood supply is cut off, can occur in the segment of intestine that has been pulled inside. This can cause the tissue to die.

The pressure created by the two walls of the intestine pressing together causes irritation, swelling, and decreased blood flow. Tissue death can occur, with significant bleeding, perforation, and infection. Shock and dehydration can occur very rapidly.

The cause of intussusception is not known, although viral infections may be responsible in some cases. Sometimes a mass like a lymph node, a polyp, or a tumor can serve as a lead point triggering the telescoping of the gut. The older the child, the more likely a lead point will be found.

Intussusception can affect both children and adults, although most cases occur in children between 6 months and 1 year of age. It affects males twice as often as females.

The first sign of intussusception is usually sudden, loud, and pained crying caused by abdominal pain. The pain is colicky and intermittent (not continuous), but recurs frequently, increasing in both intensity and duration.

As the condition progresses the infant may become weak and may go into shock. Vomiting and fever are common, and about half of the infants will pass bloody, mucuslike stool sometimes referred to as a "currant jelly" stool.

Prompt diagnosis results in the most favorable prognosis.

• Abdominal pain alternating with some pain-free periods
• Vomiting
• Stool mixed with blood and mucus
• Shock (pale color, lethargy, sweating)
• Fever

An infant with severe abdominal pain may draw his or her knees to the chest while crying.

• An abdominal X-ray may suggest obstruction.
• A barium enema may show telescoping bowel.

Initial efforts will be directed at stabilizing the child. A tube will be passed into the stomach through the nose (nasogastic tube) to allow decompression of the bowels. An intravenous (IV) line will be placed, and fluids will be given.

In some cases, the bowel obstruction can be treated with a barium enema performed by a skilled radiologist. There is a risk of bowel perforation with this procedure, and it is not used if a bowel perforation is already present.

If nonoperative treatment is unsuccessful, surgery will be performed. Usually the bowel tissue can be saved, but if not, any dead tissue will be removed.

Intravenous feeding and fluid will be continued until a normal bowel movement has passed.

The probable outcome is good with early treatment. In older children, intussusception may develop because of the presence of polyps or tumor.

There is a risk of recurrence.

Perforation with infection is a complication.