129 Uterus Septus Subtotalis Bicollis: A Rare Müllerian Duct Abnormality

Abstract Background Müllerian duct anomalies (MDAs) are congenital defects of the female genital system that arise from abnormal embryological development of the Müllerian ducts. The incidence of MDAs varies, with reports ranging from 0.16% to 10.00%. In patients with an adverse reproductive history the prevalence is 8%-10%. Septate uterus is the most common of all MDAs, resulting from incomplete resorption of the medial septum after fusion of the Müllerian ducts has occurred. There are many types of septal variations, including septa extending from the uterine fundus to the internal cervical os (complete septum), as well as septa that do not fully extend to the os (partial septum). The combination of a complete uterine septum with a double cervix, and complete vaginal septum has been reported in a few case reports; however, in the majority of these reports, the uterine septum was a complete septum. We present the case of a patient with a partial uterine septum, as well as a double cervix and complete vaginal septum. Case The patient was a 23-year-old G0, with a history of dysmenorrhea and dysfunctional uterine bleeding. An exploratory laparoscopy showed severe endometriosis and peritoneal adhesions. MRI findings were interpreted as bicornuate bicollis uterus. Given the extreme pelvic pain, the patient underwent an elective TAH and BSO. Pathologic examination showed a uterine septum that extended to above the lower uterine segment. The endometrium thus had two cavities communicating through the partial septum. Furthermore, two fused cervices were present. Our findings highlight an extremely rare type of MDA: a partially septate uterus with two cervices, which we refer to as uterus septus subtotalis bicollis. This case highlights a rare MDA that is not widely described in the literature. Recognition of the various types of MDAs is important as it informs and challenges our understanding of Müllerian development.