Small Bowel Obstruction: Diagnosis and Management
Written by Dr. Muhammad Salar Raza · Manually reviewed by Dr. Muhammad Salar Raza · Content updated
Clinical Pathway
Suspect mechanical obstruction with colicky central abdominal pain, distension, vomiting, and absolute constipation, especially with previous abdominal surgery. Examine for distension, high-pitched or absent bowel sounds, hernias, and signs of strangulation such as peritonism or shock. Erect abdominal X-ray shows dilated small bowel loops with air-fluid levels, while CT with contrast defines the level, cause, and complications. Initial management is nil by mouth, nasogastric decompression, intravenous fluids, electrolyte correction, and catheterization with monitoring. Adhesive partial obstruction without danger signs may settle conservatively with a defined trial period, but complete obstruction, strangulation, closed-loop obstruction, or failure to improve requires urgent laparotomy.
Clinical Reasoning
Adhesions from prior surgery cause the majority of small bowel obstructions, followed by hernias and malignancy; always check the groins, because an irreducible femoral hernia in an elderly woman is a classic hidden cause. Strangulation is the killer and is flagged by constant rather than colicky pain, fever, tachycardia, leukocytosis, lactic acidosis, and peritonism; these signs end any conservative trial. Large bowel obstruction presents with less vomiting and more distension, and volvulus or cancer dominate its causes. Never give prokinetics or laxatives in mechanical obstruction. Absent bowel sounds with a silent distended abdomen late in the course suggests ischemia or perforation, not resolution.
Sample MCQ
A 60-year-old man with a previous open appendectomy has 2 days of colicky abdominal pain, vomiting, distension, and no flatus. Bowel sounds are high-pitched, he is afebrile with normal vital signs, and X-ray shows dilated small bowel loops with air-fluid levels. What is the most appropriate initial management?
- ANil by mouth, intravenous fluids, and nasogastric decompression
- BImmediate laparotomy in all such patients
- COral stimulant laxatives
- DUrgent outpatient colonoscopy
Correct Answer: Nil by mouth, intravenous fluids, and nasogastric decompression
Adhesive small bowel obstruction without strangulation signs is managed initially with bowel rest, fluid and electrolyte resuscitation, and nasogastric decompression; many partial obstructions resolve with this approach under close monitoring. Laparotomy is mandatory for complete obstruction, strangulation, peritonitis, or failed conservative management, but not automatically for every stable adhesive obstruction. Stimulant laxatives are dangerous in mechanical obstruction because they increase intraluminal pressure against a blockage and risk perforation. Colonoscopy does not diagnose or treat small bowel obstruction and delays decompression.
Guidelines and further reading
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