Some women have an odd shaped uterus
If the two uteri only fuse at the very bottom leaving a large unreabsorbed vertical wall between the two cavities, a bicornuate (Latin for “2 horns”) uterus results. In this condition, the patient has two small uterine cavities and a single cervix. These cavities each have an attached Fallopian tube, so pregnancy is possible, although the chance of pregnancy in these patients is significantly reduced. In addition, when pregnancy does result, the risk of premature labor is very great as the uterus cannot grow as large as it normally would in a term pregnancy.
Sometimes only one of the two uteri forms during embryologic development.
This uterus has only one fallopian tube and it is called a unicornuate (Latin for “1 horn”) uterus. Both ovaries will still be present, as they come from different embryologic tissue. The chance for pregnancy in these patients is about 60% of that in a patient with a normal uterus. In addition, pregnancy can only occur during months in which the woman ovulates from the ovary on the same side as the fallopian tube (remember there is only one tube present in this condition).
On very rare occasions, both uteri are present but they fail to fuse at all. This condition, called a uterine didelphys, results in two separate uteri – each with its own fallopian tube and cervix. This condition is easily recognized by the general gynecologist; as such patients have two cervices (plural of cervix) on pelvic examination.
With the exception of the uterine septum, these abnormalities are not repaired because the chance of improving pregnancy outcome is typically worse following surgical repair than it is without repair. The situation is vastly different for the septate uterus, however, as multiple large studies have shown that surgical repair dramatically improves pregnancy outcome.