A bicornuate uterus is a uterus that has two separate upper chambers instead of one unified cavity, giving it a heart-like shape when viewed on imaging. It’s a congenital variation, meaning you’re born with it, and it affects roughly 1 in 200 women. Many people live their entire lives without knowing they have one, while others discover it during a pregnancy ultrasound or when investigating symptoms like recurrent miscarriages.
How a Bicornuate Uterus Forms
During fetal development, the uterus forms from two tube-like structures that normally fuse together into a single pear-shaped organ. In a bicornuate uterus, that fusion is incomplete at the top, leaving two distinct “horns” that branch outward while sharing a single cervix and lower uterine segment. The degree of separation varies. Some women have a shallow dip at the top of the uterus, while others have two almost completely separate chambers.
The defining feature on imaging is an external fundal cleft (an indentation on the outer surface of the uterus) that measures at least 1 cm deep. This is the key measurement that distinguishes a bicornuate uterus from a septate uterus, which looks similar from the inside but has a flat or convex outer surface. On certain imaging studies, the two horns of a bicornuate uterus typically separate at a wide angle of 105 degrees or more, compared to 75 degrees or less in a septate uterus. The distinction matters because the two conditions carry different risks and require different treatments.
Symptoms You Might Notice
Most women with a bicornuate uterus have no symptoms at all. Because the condition has been present since birth, any differences in your periods or pelvic sensations may just feel normal to you. That said, some women do experience painful periods, irregular vaginal bleeding, abdominal discomfort, or pain during intercourse. These symptoms overlap with many other conditions, so they rarely point to a bicornuate uterus on their own.
The most common way the condition is discovered is incidentally, during an ultrasound performed for another reason, often a routine pregnancy scan. Some women learn about it only after experiencing repeated miscarriages or preterm births, which prompts more detailed imaging.
How It’s Diagnosed
A standard two-dimensional ultrasound can raise suspicion, but confirming a bicornuate uterus usually requires imaging that shows both the inside cavity and the outer surface of the uterus at the same time. Three-dimensional ultrasound and MRI are the most reliable tools for this. The 2021 classification from the American Society for Reproductive Medicine defines a bicornuate uterus as having an external fundal indentation greater than 1 cm, and it specifies that any imaging technique capable of measuring that indentation can be used for diagnosis.
Getting the diagnosis right is particularly important because a septate uterus (which has a wall of tissue dividing the cavity from the inside, without a deep external cleft) can be corrected with a relatively simple procedure through the cervix. A bicornuate uterus cannot be fixed that way, so misidentifying one as the other leads to the wrong treatment plan.
Effects on Fertility and Conception
If you’ve just been told you have a bicornuate uterus and you’re worried about getting pregnant, the reassuring news is that the condition does not appear to reduce your chances of conceiving. A study published in the European Journal of Obstetrics and Gynecology compared IVF outcomes in women with bicornuate uteri to those with normal uteri and found no significant differences. Cumulative pregnancy rates after one IVF cycle were 59.6% versus 71.0%, and cumulative live birth rates were 58.2% versus 64.8%, with neither difference reaching statistical significance. Ovarian responses were also similar between the two groups.
The real concern with a bicornuate uterus isn’t getting pregnant. It’s staying pregnant and carrying to term. Each horn of the uterus has less space than a full-sized cavity, which can restrict fetal growth and increase the risk of preterm labor, breech presentation, and miscarriage. The cervix may also be weaker in some cases, a condition called cervical insufficiency, where the cervix opens too early under the weight of a growing pregnancy.
Pregnancy Monitoring and Management
A pregnancy in a bicornuate uterus is generally considered higher risk, but many women carry successfully to term with appropriate monitoring. Your provider will likely track cervical length more closely throughout the second trimester, watching for signs that the cervix is shortening or opening prematurely. If cervical insufficiency is identified or suspected based on your history, a cervical cerclage (a stitch placed around the cervix to keep it closed) may be recommended. Prophylactic cerclage, placed between 12 and 18 weeks of pregnancy, has been proposed as a way to improve live birth rates in women with this anatomy.
In some cases, a cerclage can be placed before pregnancy through an abdominal approach, which may be preferred for women who have had a failed vaginal cerclage or whose cervical anatomy makes the standard approach difficult. The timing depends on your history and the specifics of your anatomy.
Because babies in a bicornuate uterus are more likely to settle into a breech or transverse position due to the unusual shape of the cavity, cesarean delivery is more common. Your care team will typically assess fetal position in the third trimester to plan accordingly.
When Surgery Is Considered
Most women with a bicornuate uterus never need surgery. The primary indication for surgical correction is a history of recurrent pregnancy loss or preterm delivery that can be attributed to the uterine shape rather than other causes. The procedure, called a Strassman metroplasty, involves opening the abdomen, removing a wedge of tissue from the inner wall of each horn, and stitching the two cavities together into a single, more spacious chamber. Unlike a septate uterus, which can be corrected through the cervix using a hysteroscope, a bicornuate uterus requires this open or sometimes robotic abdominal approach.
The outcomes for women who do undergo metroplasty are striking. In one study, the fetal survival rate increased from 0% before surgery to 80% after the operation. A larger review reported fetal survival improving from 3% to 86% after abdominal metroplasty, and another found that the pregnancy loss rate dropped from 87.9% before surgery to 9.1% afterward. Among women who had the procedure, 88% went on to achieve pregnancies resulting in a viable infant. These numbers come from women with the worst reproductive histories, so they represent the group most likely to benefit, not the average experience of someone with a bicornuate uterus.
Surgery also carries its own risks, including the need for cesarean delivery in all future pregnancies (because the uterine scar creates a risk of rupture during labor) and a recovery period of several months before attempting conception. For these reasons, it’s reserved for women whose pregnancy losses are clearly linked to the uterine anatomy and who have not responded to less invasive management like cerclage.
Living With a Bicornuate Uterus
Outside of pregnancy, a bicornuate uterus rarely requires any treatment or lifestyle changes. If you experience significant period pain or heavy bleeding, those symptoms can be managed with the same approaches used for anyone with painful periods. The condition doesn’t increase your risk of uterine cancer or other gynecological diseases.
If you’re planning a pregnancy, the most useful step is making sure your diagnosis is accurate. Confirm whether you truly have a bicornuate uterus (external cleft) rather than a septate uterus (internal wall), since the management and surgical options differ significantly. A three-dimensional ultrasound or MRI can settle the question. From there, your care team can tailor a monitoring plan based on your specific anatomy and reproductive history.