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Intussusception is the invagination (telescoping) of a proximal segment of intestine (intussusceptum) into the lumen of an adjacent distal segment (intussuscipiens), carrying along its mesentery → obstruction + vascular compromise.

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https://www.youtube.com/watch?v=5KvJ3iJnCQk

https://www.youtube.com/watch?v=waFrk7jQtJA

https://www.youtube.com/watch?v=f0rAmgZuLSg

Epidemiology

• Children: Commonest cause of intestinal obstruction between 6 months – 3 years; usually idiopathic.
• Adults: Rare; usually secondary to a pathological lead point (e.g., tumor).

Etiopathogenesis

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Mechanism: Abnormal peristalsis pulls a segment of bowel into the next, dragging mesentery and vessels.

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Lead points (esp. in adults):

• Benign tumors: Lipoma, adenoma, leiomyoma, Meckel’s diverticulum, polyp.
• Malignant tumors: Adenocarcinoma, lymphoma, GIST.
• Post-op adhesions, foreign bodies.
• Children: ~90% idiopathic (likely hypertrophied Peyer’s patches from viral infection).

Types (based on location)

• Enteroenteric: Small bowel into small bowel.
• Ileocecal / Ileocolic: Ileum into cecum/colon (commonest in children).