What are the more common congenital uterine anomalies and their clinical significance?
Müllerian duct anomalies can cause abnormalities in uterine development that may be associated with infertility, miscarriage, and endometriosis. Accurate classification of müllerian duct anomalies is critical because treatment options vary depending on the type of underlying abnormality. MRI is the study of choice for delineation of uterine anomalies, while US and hysterosalpingography are often used for initial evaluation.
The classification of anomalies relates to the embryology of uterine development. Two paired müllerian ducts develop into the anatomic structures of the female reproductive tract including the fallopian tubes, uterus, cervix, and upper two thirds of the vagina. The ovaries and lower third of the vagina are derived from different origins.
There are three phases of development, and disruption of these processes can lead to anatomic variation and uterine anomalies. Failure of development during the organogenesis phase where one or both müllerian ducts do not fully develop can result in uterine agenesis, uterine hypoplasia, or a unicornuate uterus. The fusion phase refers to both lateral and vertical fusion of the paired müllerian ducts. Failure of lateral fusion can lead to bicornuate or didelphys uterus, and vertical fusion failure can result in incomplete development of the vagina. When the müllerian ducts fuse, a central septum is created which subsequently must then be resorbed to form a single uterine cavity. If not, this can lead to a septate uterus. Septate uterus is the most common type of congenital uterine anomaly and is associated with the highest risk of complications such as recurrent spontaneous abortions and premature delivery.