Makindo Medical Notes

Masses in the bowel or lumen act as an irritant and provoke abnormal peristaltic movement, potentially leading to the telescoping of one bowel segment over the adjacent segment.

About

• Intussusception in adults is the invagination of a proximal segment of bowel into a distal segment.
• The term originates from Latin: intus (within) and suscipere (to receive).

Epidemiology

• Intussusception in adults is rare.
• Accounts for approximately 5% of all intussusceptions.
• Causes around 1% of all bowel obstructions in adults.

Aetiology

• May be caused by polyps, tumours, or Meckel's diverticulum at the apex.
• Telescoping of the bowel leads to edema, vascular insufficiency, and may cause gut necrosis, peritonitis, and, if untreated, death.

Causes

• Polyp, tumour, or gastrointestinal stromal tumour (GIST).
• Small bowel intussusception often secondary to benign lesions.
• Scar tissue (adhesions) within the intestine.
• Weight-loss surgery (e.g., gastric bypass) or other bowel surgeries.
• Inflammation due to conditions such as Crohn’s disease.

Site

• Approximately 52% occur in the small intestine:
  • 39% enteroenteric (small intestine to small intestine)
  • 13% ileocolic (small intestine to large intestine)
• 38% in the large intestine:
  • 17% ileocecal (junction of small and large intestine)
  • 17% colocolic (large intestine to large intestine)
  • 4% appendiceal

Clinical Presentation

• General symptoms include malaise and fever.
• Colicky abdominal pain that comes and goes, nausea, and vomiting.
• Patients may hold their knees drawn up to the chest.
• Additional symptoms may include melaena, weight loss, fever, and constipation.
• Symptoms are often of long duration (weeks to months), but some patients may present with an acute abdomen.

Investigations

• Blood tests: FBC may show raised WCC; U&Es indicate dehydration.
• Abdominal X-ray: May reveal dilated, gas-filled proximal bowel, paucity of gas distally, and multiple fluid levels; however, early stages may appear normal.
• Ultrasound: Can identify the "doughnut" or "target" sign or detect a mass.
• CT Scan: Intussusception appears as a sausage-shaped mass when parallel to the CT beam's longitudinal axis or as a target-like mass when perpendicular.
• Barium Enema: Previously the gold standard, showing a crescent sign or filling defect, although now air and water-soluble double-contrast methods are preferred.

Management

• Intussusception in adults commonly presents as acute or partial bowel obstruction.
• Timely diagnosis is crucial to prevent complications like bowel infarction, perforation, and to resect any underlying lesion.
• Exploratory Laparotomy: Entire bowel is inspected from the ligament of Treitz to the terminal ileum, especially if malignancy is suspected as the lead point.
• Acute Abdomen: Initial management includes resuscitation with IV fluids, a nasogastric tube, and an air enema if appropriate. If enema is unsuccessful or peritonitis is suspected, laparotomy with operative reduction is performed.

Prognosis

• Prognosis depends on the underlying aetiology. Early diagnosis and management generally lead to favourable outcomes.

References

• Intussusception (Adults) - AJR