Black colon.

Early diagnostic endoscopic evaluation is useful in evaluation of mucosal viability and possible endoscopic reduction in patients with sigmoid volvulus. Black-brown mucosa is consistent with gangrene, a life-threatening complication requiring surgery.

A 70‐year‐old female patient presented with worsening abdominal pain and distention, constipation for a week, associated with multiple episodes of non‐bloody vomiting. Physical examination revealed a distended and mildly tender abdomen without any peritoneal signs or hemodynamic instability. Blood tests were remarkable for lactate of 6.4 mmol/L, leukocytosis (15 K/MCL), and elevated creatinine of 2 mg/dl. CT abdomen pelvis without contrast confirmed sigmoid volvulus. An emergent sigmoidoscopy with CO2 showed massively dilated sigmoid colon with a continuous area of black discoloration of the mucosa (Figures 1,2), with sparing of the rectum. What is the etiology and treatment of this clinical scenario?

FIGURE 1

Sigmoidoscopy showing black discoloration of the sigmoid mucosa with minimal mucosal sparing

FIGURE 2

Sigmoidoscopy showing dilated sigmoid colon with complete black discoloration of mucosa

Sigmoid volvulus is the wrapping of the sigmoid colon around its mesentery causing an acute close looped intestinal obstruction. With prolonged obstruction, patient may develop sigmoid gangrene, which in association with sigmoid volvulus is seen in 6.1%‐30.2% of all patients and in 10.7 ‐ 93.4% of surgically treated cases. Factors involved in development of bowel gangrene include comorbidities such as cardio‐vascular disease, shock, over‐rotation of the bowel, ileosigmoid knotting, and delayed hospitalization. Endoscopy can be used to assess for viable mucosa and endoscopic reduction in an attempt to avoid surgery. In our patient, an emergent sigmoidoscopy confirmed a frankly necrotic sigmoid colon, which was resected during exploratory surgery (Figure 3), followed by end colostomy and creation of a Hartmann's pouch. The patient had an uneventful postoperative course and was discharged home.

FIGURE 3

Gross surgical specimen of necrotic sigmoid colon

CONFLICTS OF INTEREST

The authors declare that there is no conflict of interest regarding the publication of this paper.

AUTHOR CONTRIBUTION

NS: involved in manuscript preparation. MA: served as endoscopist, and involved in image collection and editing, and manuscript preparation. RB: served as endoscopist, and involved in manuscript editing and final approval.