Intussusseption is caused by part of the gut (intestine) being pulled inward into itself in a telescoping fashion. 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 boys twice as often as girls. 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 best outcomes.
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