Summary

Small Bowel Obstruction (SBO) is a mechanical blockage of the small intestine preventing the normal passage of intestinal contents. It is a common surgical emergency, with adhesions from previous abdominal surgery being the most common cause (~60%), followed by hernias (~20%). Clinical features include colicky abdominal pain, vomiting, abdominal distension, and constipation. Diagnosis is primarily clinical and radiological (Abdominal X-ray shows dilated small bowel loops). CT Abdomen is the gold standard for assessing cause and identifying complications. Management involves resuscitation ("Drip and Suck"), with conservative management (NG tube, IV fluids, Gastrografin challenge) often successful for adhesive SBO. Surgery is indicated for signs of strangulation, closed loop obstruction, hernias, failure of conservative management, or complete obstruction. [1,2]

Clinical Pearls

"Never Let the Sun Set on a Bowel Obstruction": This old adage reminds clinicians that delayed treatment of SBO, especially with strangulation, leads to bowel necrosis and significantly increased mortality.

Adhesions = Most Common Cause: 60% of SBO is due to adhesions from previous surgery. No hernia? Ask about abdominal operations.

Vomiting is Early, Constipation is Late: Unlike large bowel obstruction. In proximal SBO, vomiting is profuse and early. Distension may be minor.

Gastrografin Challenge: Diagnostic and potentially therapeutic. Passage of contrast to colon within 24 hours predicts resolution; can accelerate resolution.

• Adhesive SBO: ~70-80% resolve with conservative management.
• Mortality: Low for simple obstruction (less than 5%). Higher for strangulated/perforated bowel (15-25%).
• Recurrence: ~20-30% for adhesive SBO.

Key Guidelines

Landmark Trials

• Gastrografin Studies: Demonstrated faster resolution of partial adhesive SBO with water-soluble contrast.

What is Small Bowel Obstruction?

It is a blockage in the small intestine (the long, thin tube that carries food from the stomach to the large bowel). Food and liquid cannot pass through, causing pain, vomiting, and swelling of the tummy.

What causes it?

The most common cause is scar tissue (adhesions) from previous surgery. Hernias are the second most common cause.

How is it treated?

We put you on a drip for fluids and place a tube through your nose into your stomach to drain the backed-up fluid. This lets the bowel rest and often allows the blockage to settle. Sometimes a special dye drink (Gastrografin) can help the bowel unblock.

Will I need surgery?

Not always. Many blockages resolve with rest and fluids. But if the blockage doesn't clear, or if the blood supply to the bowel is at risk (strangulation), you will need an operation to fix it.

Common Exam Questions

1. Most Common Cause: "Most common cause of SBO in adults?"
   • Answer: Adhesions (from previous surgery).
2. X-ray Findings: "Describe AXR findings in SBO."
   • Answer: Centrally located dilated small bowel loops (>3cm). Valvulae conniventes (lines across full width of bowel). Air-fluid levels (on erect film).
3. Strangulation Signs: "Signs of strangulation on CT?"
   • Answer: Thickened bowel wall, Mesenteric haziness, Reduced bowel wall enhancement, Pneumatosis intestinalis, Portal venous gas.
4. Gastrografin: "Role of Gastrografin in adhesive SBO?"
   • Answer: Diagnostic (if reaches colon = likely resolution) and potentially therapeutic (osmotic effect).

Viva Points

• Bologna Guidelines: Know indications for surgery vs conservative management.
• Closed Loop Obstruction: Explain high risk of ischaemia and need for urgent surgery.

Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.