A bicornuate uterus is a Y-shaped uterus resulting from incomplete fusion of the paramesonephric ducts during formation of the uterovaginal canal. The uterus and the superior end of the vagina form as the paramesonephric ducts fuse near their attachments to the posterior wall of the primitive urogenital sinus. The ducts then zipper together in a superior direction between the 3rd and 5th months.

Many anatomic anomalies of the female reproductive system arise from defects in this fusion. A bicornuate uterus results when lack of fusion is limited to the superior portion of the uterine body. The resulting constricted environment is associated with limb anomalies, both as a direct consequence of compression of the fetus by the uterine wall and as an indirect effect of compression resulting in vascular disruption. As with other Mullerian duct anomalies, it can result in infertility, preterm labor, and first trimester abortion. The current treatment strategy is metroplasty.

Ultrasound techniques have long been employed in imaging of the female reproductive tract. Hysterosalpingography (HSG)is commonly used in the assessment of infertility and demonstrates congenital malformations of the uterus. MR is currently considered the optimal modality for evaluation of uterine morphology because, unlike ultrasound, it is multiplanar, permitting coronal imaging of the uterus, and, unlike HSG, permits evaluation of the GU tract beyond its lumen. In a recent publication, 3D-sonography demonstrated Mullerian duct anomalies with a sensitivity and specificity of 100%, but it is not widely available.