Unusual Reasons for Incomplete Colonoscopy

Abstract

Purpose: A 50 year old woman had h/o chronic constipation for 15 years. She could not have any bowel movement without the use of laxatives. She has been using laxatives daily for 15 years but she assured us that she only used a”safe, natural, herbal” laxative. Therewas no h/o hematemesis, melena or hematochezia. There were no constitutional symptoms. There were no other GI complaints, there was no F/H of colon cancer. The review of systems was unremarkablePhysical Examination was normal. CBC & Chemistry panel was normal. A screening colonoscopy was per formed after usual PEG preparation. The rectum and the sigmoid colon were very dark due to severe melanosis coli. As the scope entered the descending colon, the view became pitch dark; the endoscopist felt he was in a jungle at night without a flash light. Manually increasing the brightness to the maximum on the light source did not help. The procedure was abandoned. Biopsies were obtained in the sigmoid colon. Later on an elective BE ruled out any masses or polyps in the rest of the colon. The histologic examination of the biopsy showed extensive infiltration of the cells in the lamina propria & submucosa with pigment. On further questioning, the patient informed us that she has been using Nature's Secret—Super Cleanse laxative which she said had natural herbs. An evaluation of the composition of Super- Cleanse showed it contained Cascara sagrada bark which is rich in anthraquinones & anthracene which are known to cause melanosis coli. Methods: This is an unusual case in that SEVERE melanosis coli prevented completion of screening colonoscopy. The exact composition of so called”narural, herbal, safe” laxatives should be ascertained: besides cascara sagrada other herbs such as Aloe vera and Senna (Swiss Kriss) may contain chemicals which can cause melanosis coli & other serious side effects. The pigment in melanosis coli is not melanin so it should be called pseudo -melanosis coli. Melanosis coli involving pericolonic lymph nodes associated with the herbal laxative Swiss Kriss has been reported in a patient with colonic adenocarcinoma (Arch Path lab Med128:565–567, 2004). Rarely melanosis may involve other parts of the GI tract such as the ileum, esophagus & stomach. It may also involve the Vagina & Prostate. Anthraquinone-induced apoptosis of colonic epithelial cells may be important in pathogenesis.(Am J Path, 131:465–476, 1988).