Only the upper part of that part of the Müllerian system that forms the uterus fails to fuse, thus the caudal part of the uterus is normal, the cranial part is bifurcated. The uterus is "heart-shaped". This condition can be complete or partial.
The two Müllerian ducts have fused, but the partition between them is still present, splitting the system into two parts. With a complete septum the vagina, cervix and the uterus can be partitioned. Usually the septum affects only the cranial part of the uterus. A uterine septum is the most common uterine malformation and a cause for miscarriages. It is diagnosed by medical image techniques, i.e. ultrasound or an MRI. MRI is considered the preferred modality due to its multiplanar capabilities as well as its ability to evaluate the uterine contour, junctional zone, and other pelvic anatomy. A hysterosalpingogram is not considered as useful due to the inability of the technique to evaluate the exterior contour of the uterus and distinguish between a bicornuate and septate uterus. This condition can be complete or partial
An additional variation is the arcuate uterus where there is a concave dimple in the uterine fundus within the cavity. The distinction between an arcuate uterus and a septate uterus is not standardized.
A rudimentary uterus is a uterine remnant not connected to cervix and vagina and may be found on the other side of a unicornuate uterus.
Patients with uterine abnormalities may have associated renal abnormalities including unilateral renal agenesis.[1]
"Double vagina"
As the vagina is largely derived from the Müllerian ducts, lack of fusion of the two ducts can lead to the formation of a vaginal duplication and lack of absorption of the wall between the two ducts will leave a residual septum, leading to a "double vagina". This condition may be associated with a uterus didelphys or a uterine septum.[2][3][4]
