Pathophysiology
Clinical meaning
Intussusception is a condition in which one segment of the intestine telescopes (invaginates) into an adjacent distal segment, creating a bowel-within-bowel configuration that obstructs the intestinal lumen and compromises mesenteric blood flow. It is the most common cause of intestinal obstruction in children between 3 months and 6 years of age, with peak incidence occurring between 5 and 10 months. The ileocolic type is the most common form, in which the terminal ileum invaginates into the cecum and ascending colon through the ileocecal valve. The telescoping bowel drags its mesentery along with it, compressing mesenteric blood vessels between the layers of invaginated tissue. Venous congestion develops first because veins are thin-walled and compress easily, leading to edema, mucosal hemorrhage, and the production of mucus mixed with blood -- this produces the classic currant jelly stool that contains blood and mucus resembling red currant jelly. If the intussusception is not reduced, arterial supply is eventually compromised, leading to ischemia, necrosis, perforation, and peritonitis. The pathological cascade proceeds from edema to hemorrhage to ischemia to necrosis within hours if untreated, making early...