A Case of Normal Uterus With Bicollis and Vaginal Septum: A Challenge to the Classical Theory of Mullerian Duct Fusion

Mullerian duct abnormalities (MDAs) are common, known to occur in 5% of women and can be categorized using a number of different classification systems, including those from the American Society for Reproductive Medicine (ASRM) or the European Society of Human Reproduction and Embryology (ESHRE). The most popular developmental theories assume that Mullerian duct fusion begins caudally then extends cranially. However, these theories cannot explain isolated cervical or vaginal MDA. Our case of a 20-year-old with isolated cervical duplication and longitudinal vaginal septum but normal uterus, diagnosed at the time of hysteroscopy, calls into question this hypothesis, instead supporting the theory of segmental or bidirectional fusion of the Mullerian ducts.