Stercoral perforation is defined as a bowel perforation due to pressure necrosis from a faecal mass (faecaloma). It is an uncommon, but life-threatening, complication of unresolved faecal impaction and can be a cause of acute abdomen secondary to faecal peritonitis.
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Epidemiology
It may represent 3.2% of all colonic perforations and 2.2% of randomly-selected autopsy examinations 2. It generally occurs in older individuals 8.
Associations
Conditions causing chronic constipation, see article on faecaloma for list of associations and aetiologies.
Pathology
The postulated pathogenesis is from a rise in intraluminal pressure which becomes greater than the capillary perfusion pressure within the bowel. This then results in focal ischaemia, necrosis, ulceration, and ultimately perforation 1,2.
Location
It typically involves the rectosigmoid colon on the antimesenteric side in ~90% of cases 7.
Radiographic features
CT
A universal component in a stercoral perforation is the formation of a faecaloma which is a localised hard, inspissated, or calcified faecal mass, usually of a diameter equal to or greater than the colonic lumen (due to the lowest blood supply and narrowest diameter).
Hyperdense mucosa may be seen on non-contrast CT scans.
There is evidence of extraluminal gas +/- extruding faecal content. The site of perforation usually involves the antimesenteric border of the colon.
Treatment and prognosis
They can be life-threatening with mortality rates ranging between 30-55% 8.
Stercoral perforations are almost always free and open, although to some extent plugged by a faecaloma, hence unlikely to resolve spontaneously with conservative management.