Stercoral Colitis

Stercoral colitis is inflammation of the colonic wall caused by pressure from impacted feces, which leads to ischemic necrosis and ulceration of the mucosa. It affects the rectosigmoid in over 90% of cases, because the stool is firmest there, the lumen is narrowest and the blood supply is relatively poor. The term covers a spectrum from simple inflammation to ulceration and, eventually, perforation.

It affects older adults (mean age about 70 years) and is more common in people who are bedridden, institutionalized, demented or have neurological or psychiatric disease.

Risk factors

• Chronic constipation
• Opioids, anticholinergics, calcium channel blockers, iron, antipsychotics and aluminum-containing antacids
• Hypothyroidism, diabetes, hypercalcemia, hypokalemia, spinal cord injury, Parkinson disease and Hirschsprung disease
• Dehydration and immobility

Mechanisms: raised intraluminal pressure compresses the wall and reduces capillary flow, a fecaloma causes pressure necrosis at the antimesenteric border, and bacteria invade the damaged mucosa. Overall mortality is about 10 to 35%, and the lethal complications are perforation, hemorrhage and sepsis. Early recognition prevents progression.

• Abdominal pain, distension, nausea and vomiting, with a history of chronic constipation and then overflow diarrhea
• Rectal bleeding in some patients
• Left lower quadrant tenderness, a hard fecal mass on rectal examination, and reduced bowel sounds
• Fever, tachycardia, leukocytosis and a raised lactate in complicated cases
• Atypical presentation in frail or demented patients, with confusion or reduced intake
• Red flags: peritonitis, hypotension, free air, rising lactate and rectal bleeding with anemia

1. CT of the abdomen and pelvis with intravenous contrast is the investigation of choice: a dilated, stool-filled rectosigmoid (fecaloma), colonic wall thickening over 3 mm, pericolic fat stranding, mucosal hyperenhancement, and possible extraluminal gas or fluid that points to perforation. A focal discontinuity of the wall means impending or actual perforation.
2. Abdominal radiograph: dilated colon filled with stool, and free gas under the diaphragm on an erect chest film if perforated.
3. Laboratory tests: full blood count, C-reactive protein, urea and electrolytes, calcium, thyroid stimulating hormone, glucose, lactate and blood cultures in sepsis.
4. Flexible sigmoidoscopy after disimpaction (with minimal insufflation) when the diagnosis is unclear, showing circumferential or solitary ulcers.

Differentials: ischemic colitis, diverticulitis, infectious colitis, colon cancer with obstruction, inflammatory bowel disease, sigmoid volvulus, toxic megacolon.

1. Resuscitation: nil by mouth, IV crystalloid 20 mL/kg initially then by response, and correction of potassium, calcium and magnesium.
2. Disimpaction:
   • Manual disimpaction under analgesia, repeated as required.
   • Enemas: warm water or saline 500 to 1000 mL PR, or mineral oil 120 mL PR once to soften stool, repeated every 12 hours as needed for up to 3 doses. Avoid sodium phosphate enemas in renal impairment and in the elderly.
   • Bisacodyl 10 mg PR once daily as a suppository, once the fecaloma is softened.
3. Antibiotics when there is inflammation with systemic signs: ceftriaxone 2 g IV once daily with metronidazole 500 mg IV every 8 hours for 5 to 7 days.
4. Surgery: laparotomy and Hartmann procedure (resection of the affected segment with end colostomy) for perforation, ischemia or failed medical therapy.
5. Prevention of recurrence: stop or reduce constipating drugs, polyethylene glycol (macrogol) 3350 17 g orally once to twice daily, lactulose 15 to 30 mL orally twice daily, fluid intake over 1.5 litres a day, dietary fiber over 25 g a day, mobilization and a scheduled toileting routine. Treat hypothyroidism.
6. Complications: perforation (up to 10 to 15% of cases), hemorrhage, sepsis and recurrence.

Follow-up at 1 to 2 weeks. Colonoscopy at 6 to 8 weeks if there is a doubt about an underlying mass. Counsel the patient and carers on bowel regimens.