Small Bowel Obstruction

About Small Bowel Obstruction

Small bowel obstruction (SBO) is a mechanical or functional blockage of the small intestine that prevents normal passage of intestinal contents. It represents one of the most common surgical emergencies, with adhesions from prior abdominal surgery being the leading cause in developed countries, followed by hernias, tumors, and inflammatory conditions.

Pathophysiology

Mechanical obstruction causes proximal bowel distension as fluid and gas accumulate above the blockage, leading to increased intraluminal pressure and compromised bowel wall perfusion. Progressive distension stimulates secretion of additional fluid into the bowel lumen, creating a cycle of worsening obstruction and potential ischemia. If left untreated, continued distension can lead to bowel wall necrosis, perforation, and sepsis.

Clinical Reasoning

Diagnosis relies on the classic triad of abdominal pain, vomiting, and obstipation, though complete symptom presentation occurs in only 60-70% of cases. CT imaging with oral contrast is the gold standard for diagnosis, showing dilated small bowel loops with a transition point and collapsed distal bowel. Management involves fluid resuscitation, nasogastric decompression, and determining the need for surgical intervention based on signs of strangulation, complete obstruction, or failure of conservative management.