What Is a Bicornuate Uterus?

What Is Bicornuate Uterus?

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

Although bicornuate uterus is not that common in the general population occurring only 0.4% of the time, it is slightly more common among people who have had more than one miscarriage. In fact, 2.1% of people with multiple miscarriages have a bicornuate uterus. Of all uterine abnormalities that exist, bicornuate uterus is the most common and represents 26% of those abnormalities.

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 before which a premature baby can potentially survive.

Because of the indentation on the top of the uterus, a developing fetus also may not have enough room to grow, which also can result in preterm labor or a low birth weight baby. Birth defects are also possible due to limited space in the uterus. According to one older study, the risk for congenital defects is four times higher than it is for infants born to women with a normal uterus.

Symptoms

Because women with a bicornuate uterus are born with the condition, most of them have no idea their uterus is shaped differently than most unless they have had an ultrasound or other imaging test. Overall, there are no noticeable symptoms when it comes to a bicornuate uterus.

In fact, most women have no idea they have a bicornuate uterus until they are pregnant. Other women may learn about the anomaly if they have had recurrent miscarriages, as this uterine abnormality increases the risk of miscarriage.

Sometimes in adolescence, young women with a bicornuate uterus will experience menstrual pain (dysmenorrhea) and heavy bleeding (menorrhagia). But these symptoms do not occur in every person and are not necessarily symptoms of bicornuate uterus.

Identifying a Bicornuate Uterus

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 (3D) ultrasound or laparoscopy.

Using HSG alone, doctors are able to correctly diagose 55% of cases of bicornuate uteri but when combined with ultrasonography, that result improves to 90%. What's more, studies have shown that 3D ultrasonography has a sensitivity of 99% and a specificity of 100% when helping doctors distinguish between a bicornuate and septate uterus.

Some doctors may even use an MRI to identify a bicornuate uterus. This procedure provides a number of pictures and can give a doctor information on the uterine structure and its fundal surface. It also provides data on the anatomy of the vagina and pelvis area.

Causes

Müllerian duct anomalies, including bicornuate uteri, develop early during prenatal development. At first, female 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 people whose mothers took a medication called diethylstilbestrol (DES) while pregnant, or for other, unknown reasons.

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

Sometimes a septate uterus is confused for a bicornuate uterus. The two congenital uterine malformations can look similar on imaging studies, such as HSG or ultrasound.

A septate uterus is round on the top with two cavities. A bicornuate uterus dips on the top, forming a heart shape with one cavity. A septate uterus is usually treated with hysteroscopic surgery.

Treatment

If you're pregnant and have a bicornuate uterus, your pregnancy will likely be treated as high risk. Not only will your medical team perform frequent ultrasounds, but they also will monitor the position of the baby.

If 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. Here are some of the things that you may need to discuss.

Surgery

In most cases, doctors do not routinely suggest surgical treatment of a bicornuate uterus, although some may recommend laparoscopic surgery if you have recurrent miscarriages. Known as laparoscopic Strassman's metroplasty, this procedure is less invasive than abdominal Strassman's metroplasty that was orginally used.

Despite the invasiveness of the abdominal metroplasty, Strassman's metroplasty was a helpful procedure that improved the chances of giving birth. For instance, one study found that live birth rates improved from 3.7% to 80% with abdominal metroplasty. Another study found that 88% of women who received Strassman metroplasty abdominally went on to give birth to healthy infants via c-section.

Cervical Cerclage

If you are pregnant, your doctor may recommend a cervical cerclage—a stitch placed in the cervix to stop premature dilation. This procedure can help prevent premature delivery and possible late-term pregnancy loss. In fact, one study found that in women with cervical cerclage, 76.2% experienced term delivery and only 23.8% experienced preterm delivery.

C-Section

A bicornuate uterus often creates a tight fit for most babies and may result in your baby being breech or being born pre-term. If you're able to carry your baby to term, your physician may recommend a scheduled c-section as it gets closer to your delivery date, especially if there is little room for your baby to get in the correct position for birth.

A Word From Verywell

Learning that you have a bicornuate uterus may feel overwhelming at first. While feeling uncertain is normal, it's also important to recognize that many women with bicornuate uterus go on to 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. Together, you can determine what is right for you.