A couple of weeks ago, I discussed the septate uterus. Today, I would like to continue the discussion about abnormal shaped uteri. Remember, a uterus can be misshaped due to 2 reasons: congenital (born with it) or acquired (born with a normal shape but developed an abnormality or had uterine surgery that changed the conformation of the uterus). Today, I discuss the bicornuate uterus.
The uterus is basically formed by fusing 2 ducts together to create one larger chamber. This is usually accomplished by the 10th week of gestation. It is thought that the 2 ducts begin fusing together from the bottom up (i.e. starting from the cervix and ending at the fundus/top of the uterus).
Sometimes the uterus does not complete the fusion process. This results in a fused lower portion of the uterus but an unfused top portion of the uterus (think of the shape of a letter “Y”). Partial lack of fusion produces a single cervix with a varying degree of separation in the top portion of the uterus. Thus, some women have a minor degree of lack of fusion whereas other women may have a severe degree of lack of fusion.
The two separate chambers that remain after partial fusion are called uterine horns. As there are 2 uterine horns produced, this type of abnormal uterine configuration is termed bicornuate uterus (cornua means horn shaped).
Theories abound as to why a uterus does not form correctly. But, currently, the reason why a uterus does not complete fusion is unknown
Bicornuate uteri are relatively common in women. Luckily, pregnancy outcome is nearly like any pregnancy with a normal shaped uterus. However, some women with a bicornuate uterus may experience a higher rate of early miscarriage, preterm labor, preterm delivery, and breech presentations.
As the pregnancy outcomes are nearly identical to those with normal shaped uteri, the bicornuate uterus does not require surgical correction.
If you have been found to have a bicornuate uterus, ask your doctor about the treatments, if any, you may require.
Source: Speroff L, Glass R, Kase N, Clinical Gynecologic Endocrinology and Infertility , 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2005: 123-153.
Dr. Lowell Ku, M.D. is an award winning and leading Reproductive Endocrinology and Infertility specialist at Dallas IVF, one the nation’s premiere infertility centers. Dr. Ku clarifies the many confusing terms used in the world of Infertility using straightforward explanations.
