Adhesive small bowel obstruction: CT before conservative management
The case
A 68-year-old woman presents with 24 hours of colicky periumbilical abdominal pain, progressive distension and repeated bilious vomiting. She has passed no flatus since yesterday. She had an open total abdominal hysterectomy 15 years ago and has no inflammatory bowel disease. She is afebrile with a heart rate of 98/min and blood pressure 115/70 mmHg. The abdomen is distended and tympanitic with central tenderness but no rebound or guarding. White cell count is 12.2 × 10^9/L (4.0–11.0), CRP 18 mg/L (below 5) and lactate 1.3 mmol/L (0.5–2.0). Plain abdominal X-ray shows multiple dilated small bowel loops with air-fluid levels and no free gas under the diaphragm. She is haemodynamically stable. What is the next best step in management?
Options
- AContrast-enhanced CT to find the transition point
- BOral osmotic laxative and fluids
- CGastrografin challenge and watch for passage
- DConservative management with nasogastric tube and IV fluids alone
- EImmediate laparotomy without imaging
Think it through before you read on. Which single option is best, and why are the other four wrong?
Show the answer and explanation
Answer
A. Contrast-enhanced CT to find the transition point
Why this is the right answer
The clinical picture is a mechanical small bowel obstruction: colicky central pain, bilious vomiting, distension, absolute constipation and dilated loops with air-fluid levels on X-ray. Previous open abdominal surgery makes adhesions the most likely cause, which is true in about three-quarters of cases in Australia.
She has no signs of strangulation: no fever, no peritonism, normal lactate and only a mildly raised white cell count. That makes her a candidate for non-operative management. But before committing to that path, current guidance (Bologna guidelines on adhesive small bowel obstruction, endorsed in Australian surgical practice) recommends contrast-enhanced CT of the abdomen [VERIFY].
CT does several things a plain film cannot. It confirms the diagnosis, shows the transition point, distinguishes partial from complete obstruction, and identifies signs of ischaemia such as bowel wall thickening, reduced enhancement, mesenteric oedema or a closed loop. It also excludes other causes such as a hernia or tumour.
In parallel, she should be kept nil by mouth, have a nasogastric tube inserted for decompression, receive intravenous fluids with electrolyte correction, and have a urinary catheter for fluid balance.
If CT shows an uncomplicated adhesive obstruction, a water-soluble contrast (Gastrografin) challenge can follow. Passage of contrast into the colon within 8 to 24 hours predicts successful conservative management; failure, or any sign of deterioration, means surgery.
Why the other options are wrong
- B
Laxatives and oral fluids in a complete obstruction increase vomiting, aspiration and perforation risk.
- C
The Gastrografin challenge is useful, but only after CT has excluded strangulation.
- D
Conservative treatment is likely to be right, but a plain film alone cannot safely exclude ischaemia; CT is needed first.
- E
Surgery without imaging is for peritonitis or strangulation, which she does not have.
High-yield takeaway
Suspected adhesive small bowel obstruction without peritonism: nil by mouth, nasogastric tube, fluids, and contrast CT before deciding on conservative treatment.
Reference: Bologna Guidelines for Diagnosis and Management of Adhesive Small Bowel Obstruction (WSES update) (2018)
Common questions
What does CT add to a plain abdominal X-ray?
It confirms the diagnosis, finds the transition point, separates partial from complete obstruction and shows signs of ischaemia that a plain film cannot.
What is a Gastrografin challenge?
Water-soluble contrast given by nasogastric tube. If it reaches the colon within 8 to 24 hours, conservative treatment is likely to succeed.
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