Small Bowel Ischaemia

Bowel perforation is full thickness disruption of the gastrointestinal wall allowing enteric contents, bacteria and gas to escape into the peritoneal cavity or adjacent tissues.

It may result from peptic ulcer disease, appendicitis, diverticulitis, colorectal malignancy, bowel ischaemia, obstruction, inflammatory bowel disease, trauma, foreign body, iatrogenic injury or anastomotic failure.

Perforation may be free, producing diffuse contamination and peritonitis, or contained by adjacent bowel, mesentery or omentum, producing local inflammation or abscess.

The management question is not simply whether a perforation exists. It is whether contamination is controlled and whether the underlying defect requires immediate source control.

Free perforation commonly produces sudden severe pain followed by rapidly progressive peritonism. Tachycardia, fever, ileus and abdominal distension follow.

With severe contamination, patients develop hypotension, oliguria, altered mentation, metabolic acidosis and septic shock.

Contained perforation may produce localised pain, fever and tenderness without diffuse rigidity.

Steroids, immunosuppression and advanced age can blunt peritoneal findings despite major contamination.

Obtain full blood count, renal function, electrolytes, blood gas, lactate, coagulation and crossmatch according to severity.

CT abdomen and pelvis with IV contrast: preferred in a stable patient; identifies the perforation source and whether contamination is free or contained.

Do not delay surgery for repeated imaging in an unstable patient with convincing generalised peritonitis.

Keep fasting, establish large bore IV access and resuscitate with balanced crystalloid according to perfusion response. Insert a urinary catheter in significant sepsis or shock and a nasogastric tube when vomiting, ileus or major distension is present.

Start antibiotics promptly.

For a stable community acquired perforation:

Ceftriaxone 2 g IV every 24 hours plus metronidazole 500 mg IV every 12 hours.

For severe sepsis, extensive contamination, healthcare associated infection or substantial resistant organism risk:

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

Source control depends on location and pathology and may consist of primary repair, resection with primary anastomosis, resection with diversion, exteriorisation, drainage or definitive treatment of the diseased organ.

Free perforation with generalised peritonitis, uncontrolled sepsis, bowel ischaemia or haemodynamic deterioration requires urgent surgery.

A small contained perforation may occasionally be managed with antibiotics, bowel rest and selective percutaneous drainage when the patient is stable and there is no diffuse contamination. This strategy requires reliable serial assessment.

The choice between anastomosis and stoma is physiological, not ideological. Shock, vasopressor dependence, gross faecal contamination, severe bowel oedema, poor perfusion and major comorbidity increase anastomotic risk and may favour diversion or damage control surgery.

During source control, obtain intra abdominal cultures in complicated infection where results may change antimicrobial therapy.

After adequate source control, limit antibiotic treatment to approximately 4 days. Persistent fever, ileus, pain or organ dysfunction should trigger investigation for ongoing leakage, abscess or failed source control rather than automatic extension of therapy.