Stercoral Perforation

Stercoral perforation is full-thickness rupture of the colon or rectum caused by pressure necrosis from a fecaloma, causing fecal peritonitis. It accounts for about 3% of colonic perforations, and affects the rectosigmoid in most cases, usually on the antimesenteric border where the blood supply is poorest. It is the most dangerous consequence of fecal impaction.

It affects older adults (mean age 60 to 80 years) with chronic constipation, and bedridden or institutionalized patients are at highest risk. Contributing factors: opioids, anticholinergics, psychotropic drugs, spinal cord injury, dementia, hypothyroidism and previous colonic surgery. The pathological hallmark is a stercoral ulcer: a round or oval ulcer on the antimesenteric wall, typically 1 to 2 cm in size, opposite the fecaloma, with surrounding ischemic necrosis, inflammatory infiltrate and fecal material through the defect.

Mortality is 30 to 60%, higher than for diverticular perforation, because of delayed diagnosis, frailty and feculent contamination. Complications: septic shock, multiple organ failure, abscess, wound infection and stoma problems.

• Acute onset of severe abdominal pain, often left-sided, with distension, vomiting and a history of long constipation
• Generalized peritonitis, rigidity and absent bowel sounds in most patients
• Fever, tachycardia, hypotension and altered mental state
• Atypical or silent presentation in frail or demented patients, with only confusion
• Red flags: hypotension, rising lactate, free air and altered consciousness

1. Resuscitation first. Do not delay surgery for investigations in a patient in shock.
2. CT of the abdomen and pelvis with intravenous contrast: free intraperitoneal gas and fluid, a fecaloma in a dilated rectosigmoid, a focal wall defect or extraluminal fecal material, and pericolic stranding.
3. Erect chest radiograph: free gas under the diaphragm.
4. Laboratory tests: full blood count, C-reactive protein, creatinine, lactate, blood gases, coagulation, blood cultures and group and screen.

Differentials: perforated diverticulitis, perforated colon cancer, perforated peptic ulcer, ischemic colitis with perforation, toxic megacolon, mesenteric ischemia.

1. Sepsis management within the first hour: IV crystalloid 30 mL/kg, blood cultures, norepinephrine infusion at 0.05 to 0.5 micrograms/kg/min to maintain a mean arterial pressure of 65 mmHg or higher, and a urinary catheter.
2. Antibiotics: piperacillin-tazobactam 4.5 g IV every 6 hours (with a dose adjusted for renal function), continued for 4 to 7 days after source control. Add vancomycin 15 to 20 mg/kg IV every 8 to 12 hours if there is risk of resistant organisms.
3. Emergency laparotomy:
   • Hartmann procedure (resection of the perforated segment with end colostomy) is the standard operation in unstable or contaminated patients.
   • Remove the fecaloma and the necrotic bowel, wash out the peritoneum with at least 6 to 10 litres of warm saline, and drain the pelvis.
   • Primary anastomosis with a defunctioning ileostomy only in stable patients with limited contamination.
   • Primary repair or simple closure carries a high leak rate and is avoided.
4. Prophylaxis: enoxaparin 40 mg SC once daily for 7 days after operation (adjust in renal impairment).
5. Postoperative care: intensive care, early enteral nutrition, stoma care and nutritional support. Reversal of the Hartmann procedure after 3 to 6 months, after a contrast enema and colonoscopy of the remnant.
6. Prevention of recurrence: macrogol 3350 17 g orally once to twice daily, review of constipating drugs, fluid and fiber intake, and a bowel routine.
7. Complications: wound infection (30%), stoma complications, intra-abdominal abscess, pneumonia and delirium.

Follow-up at 2 weeks and 6 weeks, then before reversal. Counsel relatives about prognosis, and the need for a bowel regimen.