Small Bowel Necrosis

Small bowel necrosis is irreversible full thickness death of jejunum or ileum caused by prolonged ischaemia, strangulation, volvulus, vascular occlusion, severe inflammatory injury or overwhelming infection.

It is not reversible with antibiotics or observation. Necrotic bowel must be removed.

The surgical priority is to remove dead bowel while preserving every viable segment possible because excessive resection may produce short bowel syndrome and permanent intestinal failure.

Continuous severe abdominal pain, peritonism, ileus and systemic toxicity are typical once necrosis is advanced.

Late manifestations include:

• Hypotension
• Metabolic acidosis
• Rising lactate
• Hyperkalaemia
• Oliguria
• Septic shock

The absence of dramatic examination findings early does not exclude evolving necrosis in mesenteric vascular disease.

CT angiography or contrast CT: identify the underlying vascular or mechanical cause and determine whether bowel perfusion is severely compromised.

Peritonitis in a patient with suspected bowel ischaemia is sufficient reason for emergency exploration and should not be delayed for repeated imaging.

Begin resuscitation, broad spectrum antibiotics and immediate operative preparation.

A practical regimen is:

Piperacillin tazobactam 4.5 g IV every 8 hours by extended infusion, with renal adjustment.

At operation:

• Correct the cause where possible
• Detorse volvulus or divide strangulating bands
• Restore mesenteric perfusion when feasible
• Resect clearly necrotic bowel
• Preserve marginal bowel until viability can be reassessed

Primary anastomosis is appropriate when both ends are well perfused, contamination is controlled and physiology is stable.

Shock, vasopressor dependence, major bowel oedema, severe acidosis or uncertain viability should favour bowel discontinuity, temporary abdominal closure and planned second look surgery.

Record the length and anatomy of remaining bowel, including residual ileum, ileocaecal valve and colon, because these predict subsequent intestinal function.