Sigmoidouterine Fistula: Anal Menstruation as a Rare Presentation

Background: Anal menstruation due to sigmoidouterine fistula in the anterior wall of the uterus has not been reported so far. Case: A thirty year old female presented to us with periodical anal bleeding without natural menstrual loss one year after dilatation and curettage for 10 weeks’ gestation. Hysterosalpingography raised the doubt of a fistulous tract between the uterus and the bowel with the dye present in the bowel.MRI revealed thinning of the anterior wall of the retroverted uterus with colon adherent to its anterior surface. Excision of the fistula along with a segment of sigmoid colon was done in a single stage. Conclusion: High degree of suspicion and planned investigations are required to reach at the diagnosis of such a bizarre condition.