Intussusception
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Direct answer
Between six months and two years of age, intussusception outruns every other cause of intestinal obstruction. An infant draws up the legs in colicky pain every fifteen to twenty minutes, vomits, passes red-currant-jelly stool late in the illness, and shows a sausage-shaped mass in the right upper abdomen with emptiness in the right iliac fossa. In about nine of ten cases the ileum telescopes into the caecum with no anatomical reason beyond Peyer-patch hypertrophy after a viral illness; a lead point — Meckel's diverticulum, a polyp, lymphoma — should be suspected outside the classic age window. Ultrasound, with its target or doughnut sign, confirms the diagnosis, and pneumatic or hydrostatic reduction succeeds in 70-90%; peritonitis or perforation sends the child straight to theatre, as does intussusception in adults, where a malignant lead point is common enough to mandate resection.
What you must remember
- Epidemiology: the peak is five to nine months with a male predominance; ileocolic idiopathic intussusception accounts for about 90-95%, attributed to hypertrophied Peyer patches after viral illness or around weaning.
- Lead points to name: Meckel's diverticulum, juvenile polyp, duplication cyst and lymphoma in older children; in adults, malignant tumours dominate — so adult intussusception is resected rather than reduced.
- Clinical picture: paroxysmal pain with legs drawn up, vomiting that becomes bilious, a sausage-shaped right upper quadrant mass that may shift, Dance sign (emptiness in the right iliac fossa), late red-currant-jelly stool, and a curiously lethargic child between spasms.
- Ultrasound first: the transverse target (doughnut) sign of telescoped bowel with its echogenic mesenteric fat, and the pseudokidney sign longitudinally; the same machine can guide hydrostatic saline reduction.
- Reduction rules: pneumatic (air, fluoroscopic) or hydrostatic (saline, ultrasonic) enema succeeds in 70-90%; recurrence runs about 10% and re-reduction is acceptable; contraindications are perforation, peritonitis and established sepsis or shock.
- Surgery: resuscitate first; at laparotomy milk the intussusception out by compression from the apex distally — never pull it — resect non-viable bowel or a lead point, with appendicectomy traditionally added.
- Indian reality: late presentation after native remedies is routine, so obstruction and the currant-jelly stage are commoner than in Western descriptions — fluid resuscitation and decompression precede any reduction attempt.
A currant-jelly infant, worked through
An eight-month-old boy is brought with six hours of screaming episodes, each lasting minutes, with limp exhausted intervals. He vomits twice; the abdomen is soft between spasms with a fullness under the right costal margin, and the right iliac fossa feels oddly empty. The junior worry is colic; the examining registrar's is intussusception. Pathway: intravenous access, fluid bolus, nasogastric tube, bloods and crossmatch, then ultrasound — the transverse scan shows a 3.5 cm target sign in the right upper quadrant. Ileocolic intussusception, no free fluid, child haemodynamically acceptable: pneumatic reduction under fluoroscopy, with the paediatric surgeon standing by. Reflux of air into the terminal ileum and disappearance of the mass, plus a rested, feeding child, mark success. Admission for 24 hours of observation covers the one-in-ten recurrence.
Change one detail and the pathway forks: the child is grossly distended, tachycardic and poorly perfused with a rigid abdomen — theatre, antibiotics, and laparotomy with resection of gangrenous bowel; or the patient is a 45-year-old with a week of colicky pain and a mass — adult intussusception goes to resection, because the lead point is malignant until proven otherwise.
How the exam frames it
NBE has quietly updated its own question bank here: older MCQs name barium enema as the investigation of choice, but the current answer is ultrasound — and knowing why the change happened (barium peritonitis after iatrogenic perforation) marks a prepared candidate. The other tested pairs are the age window (six months to two years), the Dance sign, the target sign, and the adult rule of resection. Expect one stem describing a two-year-old with a recurrent episode asking the next step — repeat enema reduction is acceptable — and one describing a lethargic child with a soft abdomen asking the diagnosis; the lethargy between spasms is the discriminator students miss.
Frequently asked questions
What is the classic age and type of idiopathic intussusception?
Six months to two years, ileocolic, following Peyer-patch hypertrophy after a viral illness.
Which investigation confirms intussusception first?
Ultrasound, showing the transverse target or doughnut sign and the longitudinal pseudokidney sign.
What is Dance sign?
Emptiness in the right iliac fossa because the caecum has been drawn into the intussusception, alongside a sausage-shaped mass in the right upper abdomen.
Why is adult intussusception treated by resection?
Because an adult lead point is commonly a malignant tumour, so reducing it risks spilling tumour and leaves the pathology in situ.
What are the contraindications to enema reduction?
Bowel perforation, peritonitis, and the septic or shocked child — each demands immediate surgery after resuscitation.