What is intususseption
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Intussusception
Definition
Intussusception is the telescoping of a proximal segment of bowel (the intussusceptum) into the lumen of a more distal, adjacent segment (the intussuscipiens). This creates a "bowel within bowel" configuration that obstructs the intestinal lumen and compresses the mesenteric blood supply, risking ischemia, gangrene, and perforation.
- Grainger & Allison's Diagnostic Radiology, p. 1805
- Bailey and Love's Short Practice of Surgery, 28th ed.
Epidemiology
- The second most common cause of acute abdomen in children after appendicitis.
- Most cases occur between 2 months and 2 years of age, with peak incidence at 5-9 months.
- Can occur up to school age; cases beyond 6-7 years are more likely to have a pathological lead point.
- In adults, intussusception is uncommon and frequently associated with neoplasm or malignancy.
Types (by location)
| Type | Frequency |
|---|---|
| Ileocolic (ileum telescopes into colon) | Most common, >80% |
| Ileoileocolic | Less common |
| Ileo-ileal (small bowel only) | Less common; often reduces spontaneously |
| Colocolic | Rare |
Causes and Lead Points
In children (>90% have NO lead point):
The most common cause is lymphoid hypertrophy (enlarged Peyer's patches), typically following a viral infection.
Pathological lead points (5-10%):
- Meckel's diverticulum
- Intestinal polyp
- Duplication cyst
- Small bowel lymphoma
- Nasojejunal tubes
Pathological lead points are more common in children >2 years, in recurrences, and in adults.
Clinical Presentation
The classic triad in infants:
- Colicky abdominal pain - the infant draws up their legs during spasms
- Vomiting
- "Redcurrant jelly" stools - blood-stained mucus passed rectally (a late sign)
Other features:
- Between pain episodes, infant initially appears well
- Dehydration and abdominal distension develop over time
- Palpable right upper quadrant mass - present in less than 50% of patients
- Can rapidly deteriorate to hypovolemia, shock, and become life-threatening
Diagnosis
Ultrasound (first-line, gold standard)
- Sensitivity and specificity approaching 100%
- Characteristic signs:
- "Target" or "doughnut" sign - concentric rings in the transverse plane
- "Sandwich" appearance - in the longitudinal plane
- "Crescent in doughnut" sign - hyperechoic semilunar structure from mesenteric fat pulled into the intussusceptum
- Helpful to identify lead points and assess bowel viability
Plain radiograph
- Small bowel obstruction pattern (dilated loops, fluid levels)
- Paucity of gas in the right iliac fossa
- "Meniscus sign" - soft-tissue mass contrasting an air-filled bowel loop
CT scan
- Reserved for adults, complex cases, or when ultrasound is insufficient
Intraoperative Appearance
Below is a surgical photo showing intussusception - the proximal bowel (intussusceptum) has telescoped into the distal segment (intussuscipiens), creating the classic "bowel within bowel" appearance:
Bailey and Love's Short Practice of Surgery, 28th ed.
Treatment
Resuscitation first:
- IV fluids
- Nasogastric drainage
- Broad-spectrum antibiotics
Non-operative reduction (first-line):
- Pneumatic (air) enema or hydrostatic enema - successful in >70% of cases
- Success confirmed by air flowing into the small bowel and resolution of symptoms
- Contraindications: peritonitis, bowel perforation, shock, or free intraperitoneal air
Surgical reduction:
Indicated when:
- Enema reduction fails
- Peritonitis or perforation present
- Strangulation suspected
- Pathological lead point identified
- Can be open or laparoscopic
Bowel resection required when:
- Irreducible intussusception
- Infarction/gangrene
- Pathological lead point requiring excision
Recurrence
- Occurs in approximately 5% after non-operative reduction
- Recurrences are more likely to have a pathological lead point
Adults vs. Children
| Feature | Children | Adults |
|---|---|---|
| Lead point | Usually absent (viral/idiopathic) | Usually present (neoplasm) |
| Most common type | Ileocolic | Variable |
| Treatment | Enema reduction first | Typically surgical |
| Malignancy association | Rare | Common |
Recent systematic reviews (2024-2025) confirm that adult intussusception requires careful evaluation for underlying malignancy, and surgical resection is the standard management in most adult cases - PMID 39085533, PMID 40831154.
Sources: Grainger & Allison's Diagnostic Radiology; Bailey and Love's Short Practice of Surgery, 28th ed.; Rosen's Emergency Medicine; Goldman-Cecil Medicine.
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