Intussusception is the telescoping of one segment of bowel into the adjacent distal segment, creating obstruction and potential ischemia. Symptoms differ between infants and adults but share a core pattern:

1. Paroxysmal abdominal pain
   Sudden, severe colic lasting 15–20 minutes recurs with increasing frequency; the infant screams, draws up the knees, or an adult doubles over in pain .
2. Vomiting
   Initially gastric fluid, later bilious, as small-bowel obstruction develops .
3. “Currant-jelly” stool
   Blood mixed with mucus appears after venous congestion of the intussusceptum; it is more common in infants but can occur in adults .
4. Palpable sausage-shaped mass
   The intussuscepted segment may be felt in the right upper or mid-abdomen, especially between spasms in infants .
5. Lethargy or shock-like state
   Infants may become pale, floppy, and apathetic between attacks; adults report fatigue when pain persists for days .
6. Abdominal distension and guarding
   Progressive bloating, hyper-resonance, and localized rebound indicate developing obstruction or peritonitis.
7. Fever and systemic toxicity
   Temperature remains normal early on; high fever, tachycardia, and hypotension suggest bowel necrosis or perforation .

Any infant with intermittent screaming attacks and any adult with unexplained intermittent colic plus vomiting should be imaged urgently with ultrasound or CT to confirm the diagnosis and guide reduction or surgery.