Amit Narang

Rectal perforation by impacted fecaloma—a new mechanism proposed

Editor: A fecaloma is a mass of accumulated feces that is much harder in consistency than a fecal impaction. The rectosigmoid area is the common site for fecalomas [1]. Fecal impaction, defined as a “compacted, immovable mass of feces filling the rectum,” is commonly seen in chronic constipated patients. It can result in obstipation, the inability to pass stool or gas, but can also present with diarrhea, because liquid stool can pass around the impaction. If untreated, fecal impaction may result in a variety of complications, including stercoral perforation [2]. We describe a patient with stercoral perforation with an atypical location. A 65-year-old female presented with nonpassage of flatus and stool for 8 days, abdominal distention for 5 days, vomiting and fever for 1 day, and a history of constipation for the last 5 years. On examination the pulse rate was 104/min and BP, 104/76 mmHg. The abdomen was distended, and generalized guarding was present. Per rectal examination revealed hard fecoliths. Plain X-ray of the abdomen (Fig. 1) showed radiopaque masses all over the colonic area. Ultrasonography of the abdomen showed content-filled gut loops with free fluid. Contrast-enhanced computed tomography of the abdomen revealed free air and fluid in the peritoneal cavity with prominent small and large bowel, suggestive of bowel perforation. The patient was explored urgently. On exploration about 1 L of foul-smelling blackish fluid was aspirated from the peritoneal cavity. A large gangrenous patch of size 5 cm × 5 cm was present in the upper rectum on the posterior wall with a stony hard fecolith protruding through the necrosed central part (Fig. 2). The entire colon was loaded with hard fecoliths which were extracted (Fig. 3). A segment of gangrenous rectosigmoid was resected, the rectal stump closed, and the distal cut end of the sigmoid colon brought out as an end colostomy. Fecal impaction causes the intraluminal pressure within the colon to increase and exceed the capillary perfusion pressure in the bowel wall, resulting in pressure necrosis of the wall and eventually ulceration and perforation. The most common sites of fecal impaction are the sigmoid and rectosigmoid colon, because here much of the water has already been reabsorbed from the feces, which can then develop into hardened masses or scybala [2]. In addition, the distal colon, particularly along the antimesenteric border, has a relatively poor blood supply, making it more susceptible to pressure necrosis from scybala. Finally, because these areas of the colon have the narrowest diameter, they allow the formation of higher intraluminal pressure in the event of fecal impaction which can lead to perforation [2]. Mauer et al. proposed four diagnostic criteria of stercoral perforation [3].