There are many uterine (womb) abnormalities. Bicornuate uterus literally means "two horns," and refers to a congenital uterine formation problem.
Embryologically, the uterus is formed beginning at five weeks of gestation. It starts out near the kidney as two separate structures called horns, then migrates down into the pelvis as the two horns fuse into one. The area of fusion is a septum dividing the two, and is reabsorbed to make a normal intrauterine cavity. Sometimes, however, this normal progressions does not occur.
A true bicornuate uterus is one in which the two horns migrate down but do not completely fuse to make a normal uterus. A more common abnormality is a septate uterus. This is an abnormality in which the uterine horns fuse completely, but the intervening septum is not completely absorbed. The uterus then appears as two horns internally, but externally looks to be unified.
A septate uterus may be associated with miscarriages, while a true bicornuate uterus is generally associated not with miscarriages, but a higher risk of preterm laborand birth. A noninvasive procedure called a pelvic MRI can differentiate these two conditions and other uterine congenital abnormalities.
Both abnormalities can be approached surgically. A septate uterus can be repaired with a day surgical procedure called an operative hysteroscopy with septum resection. A true bicornuate uterus can only be approached through a more major surgery called a Strassman procedure, which requires an abdominal incision.