Adhesive small bowel obstruction: drip and suck, or straight to theatre?
A 74-year-old man presents with two days of colicky central abdominal pain, vomiting and distension. He had an open appendicectomy at 20 and a sigmoid colectomy for diverticular disease six years ago, and has not passed flatus for 24 hours. Temperature 37.9 °C, HR 104, BP 132/78, RR 20, SpO2 96% on air. The abdomen is distended and tympanic with mild diffuse tenderness and no guarding or rebound; both groins and the umbilicus are clear and there is a midline laparotomy scar. Rectal examination is empty. Bloods: white cell count 13.2, haemoglobin 13.4, creatinine 1.35 mg/dL against a baseline of 0.9, potassium 3.2 mmol/L, lactate 1.9 mmol/L, CRP 78. CT abdomen with intravenous contrast shows dilated small bowel to 4 cm with a transition point in the mid-jejunum, a collapsed distal ileum and colon, no free air, no pneumatosis, no closed loop and no mass. The registrar plans to admit for "drip and suck" and review in the morning.
1. Justify a trial of non-operative management and specify the criteria that would end it.
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Why a trial is reasonable. The CT shows a simple, single-level adhesive obstruction with no ischaemic or strangulation signs: no closed loop, no free air, no pneumatosis or portal venous gas, no reduced bowel wall enhancement, no mesenteric oedema or whirl sign. The patient is haemodynamically stable and has no peritonitis. In that setting, 70–80% of adhesive small bowel obstructions resolve with nasogastric decompression and fluid resuscitation, and avoiding an operation in a hostile abdomen is a real gain.
Why the registrar's plan is not sufficient. "Review in the morning" is not monitoring. He needs a nasogastric tube on free drainage, a urinary catheter with hourly output, intravenous crystalloid, correction of potassium 3.2 and the acute kidney injury, analgesia, antiemetics, and a thromboprophylaxis decision that balances bleeding against immobility. Crucially, he needs serial abdominal examination by the same surgical team every four to six hours plus a water-soluble contrast challenge.
Criteria to stop the trial and operate:
- Localised or rebound tenderness, involuntary guarding, or worsening pain.
- Temperature above 38.5 °C, tachycardia persisting after fluid resuscitation, or rising white cell count or CRP.
- Rising lactate or metabolic acidosis.
- Increasing rather than decreasing nasogastric aspirate, or no flatus and no contrast reaching the colon by 24 hours.
- Any CT sign of closed loop or ischaemia at any stage.
Absence of fever and peritonitis on admission does not exclude ischaemic bowel - deterioration is the signal, which is why the serial examination matters more than the initial numbers.
2. Describe the water-soluble contrast study protocol, how you interpret it, and why it is safe in this patient.
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Protocol. Give 50–100 mL of water-soluble contrast (for example sodium diatrizoate) down the nasogastric tube, clamp the tube for about an hour, then take a plain abdominal radiograph at 4–6 hours; a further film at 24 hours is taken if the first does not show colonic contrast.
Interpretation.
- Contrast visible in the colon or rectum: partial obstruction, resolution very likely. Remove the tube, start sips of fluid and advance diet; discharge with safety-netting.
- Contrast failing to reach the colon at 24 hours: high likelihood of needing surgery, and a strong indication to operate rather than wait further.
The test has high sensitivity for predicting failure of non-operative management and a modest therapeutic effect - the hyperosmolar load draws fluid into the lumen and may reduce wall oedema.
Why it is safe here. There is no perforation, no peritonitis, no clinical suspicion of ischaemia, no haemodynamic instability and no severe dehydration; these are the contraindications, because in those situations oral contrast is unnecessary, may worsen matters and delays theatre. The contrast is water-soluble, so if there were an unrecognised perforation it is absorbed rather than causing the peritonitis seen with barium. A documented contrast allergy is the other reason to avoid it.
3. At 20 hours he has passed no flatus, the nasogastric aspirate is 2.5 L, HR is 118, temperature 38.4 °C, there is new right iliac fossa tenderness with guarding, and lactate is 3.4 mmol/L. What happens next, and what are the operative principles?
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Decision. This is failure of non-operative management with peritonitis and evolving sepsis - likely a strangulated or ischaemic segment at the transition point. Stop the trial and proceed to urgent laparotomy; do not order further imaging that will not change the decision.
Before theatre. Resuscitate with balanced crystalloid, cross-match blood, correct potassium, start broad-spectrum antibiotics covering enteric Gram-negatives and anaerobes (for example co-amoxiclav, or cefuroxime plus metronidazole), insert a urinary catheter, obtain informed consent including the possibility of a stoma, and involve critical care for postoperative planning.
Operative principles.
- Midline laparotomy through or around the previous scar; enter with care given the underlying adhesions.
- Divide adhesions systematically and identify the transition point; handle the dilated, oedematous bowel gently.
- Assess viability at the transition point using colour, warmth, peristalsis and Doppler flow; resect frankly necrotic bowel.
- Primary anastomosis if the ends are healthy and the patient is stable; consider a stoma if there is gross contamination, faecal peritonitis, haemodynamic instability or doubtful viability.
- Avoid unnecessary adhesiolysis of uninvolved bowel, and consider damage-control laparotomy in a physiologically unstable patient.
- Lavage, close, and plan a critical care bed.
Reflection. The initial examination and lactate were reassuring, and that is precisely the trap: ischaemic bowel in the elderly can present with mild findings until it perforates. The rising lactate, fever and focal guarding are the redeeming signals, and acting on them promptly is what determines survival.