Overview of Bicornuate Uterus

A bicornuate uterus is a type of congenital uterine malformation or müllerian duct anomalies in which the uterus appears to be heart-shaped. Bicornuate uteri have two conjoined cavities whereas a typical uterus has only one cavity.

Müllerian duct anomalies, including bicornuate uteri, develop early during prenatal development. While in utero, the reproductive system of a female fetus forms. At first, fetuses have two müllerian ducts which merge to form one uterus. In the case of a bicornuate uterus, these ducts do not fully merge. This can happen to women whose mothers took a medication called diethylstilbestrol (DES) while pregnant or for other, unknown reasons.

A bicornuate uterus is one of the several types of müllerian duct anomalies. Other types include uterus didelphys, two separate uteri; unicornuate uterus—where only one duct is present—resulting in a smaller-than-average uterus; and septate uterus, which occurs the uterus is divided by a wall or septum. Bicornuate uteri are the most common müllerian duct anomaly.

Doctors can get an idea of whether a woman has a bicornuate uterus through a standard ultrasound or by using a hysterosalpingogram (HSG) or a hysteroscopy. In some cases, a diagnosis may need to be confirmed using a three-dimensional ultrasound or laparoscopy.

Most women do not know they have a bicornuate uterus until they are pregnant or trying to get pregnant. Menstruation, in most cases, is normal.

The primary risks associated with a bicornuate uterus are preterm labor and possible cervical insufficiency. Having a bicornuate uterus does not cause first-trimester miscarriages. Cervical insufficiency and preterm delivery could potentially cause a second-trimester miscarriage or pregnancy loss at birth if the baby is born too prematurely––before 24 or 25 weeks of pregnancy, the point at which a premature baby can potentially survive. Because of the indentation on the top of the uterus, a developing fetus may not have enough room to grow, which can result in preterm labor.

While these complications can occur, many women with bicornuate uteri carry their pregnancies without any problems. If you are concerned that your bicornuate uterus may cause pregnancy complications, speak with a high-risk obstetrician or fertility specialist who can evaluate your medical history and personal risk. 

In most cases, doctors do not suggest surgical treatment, although some may recommend reconstructive laparoscopic surgery. If you are pregnant, you may need a cervical cerclage––a stitch placed in the cervix to stop premature dilation. This procedure prevents premature delivery and possible late-term pregnancy loss. Your treatment will depend on your physician and the circumstances surrounding your pregnancy.

If you are experiencing recurrent miscarriages, you may have septate uteri as opposed to bicornuate uteri. The two congenital uterine malformations can look similar to imaging studies, such as HSG or ultrasound. A septate uterus is round on the top with a single cavity and a bicornuate uterus dips on the top, forming a heart shape with two cavities.

A bicornuate uterus might not be treated, except to watch for signs of cervical dilation. If it is treated surgically, a reconstruction will be done via laparoscopic surgery. A septate uterus is usually treated through a hysteroscopic surgery. While a bicornuate uterus is not usually considered a factor in recurrent miscarriages, a septate uterus is known to increase miscarriage risks.

If you are having recurrent miscarriages and your doctor has determined you have a bicornuate uterus, consider seeing a specialist for a second opinion to confirm your diagnosis and discuss treatment plans.