A bicornuate uterus is when the uterus is sectioned into two chambers, or horns, instead of one. Also referred to as a “heart-shaped” uterus, this organ shape forms during the embryonic stage of development. The Mullerian ducts, which become the ovaries and fallopian tubes, don’t fuse properly causing the bottom part of the uterus to appear normal while the upper part folds inward causing a malformed uterus shaped like a heart.
There are different severities of a bicornuate uterus from a partial bicornuate, where only part of the upper portion dips into the chamber, to a full bicornuate, where the entire upper portion folds down, creating two chambers.
Many women don’t even realize they have a bicornuate uterus until they try to get pregnant. Although not related definitely to infertility, this uterus shape can make getting pregnant challenging and put a women into a high-risk category if she does conceive. These women are often told they will have difficulty conceiving, if at all, and are at high risk for miscarriage (63%) as well as pre-term delivery (15-25%). Because a uterus with a two chambers has less room than a normally shaped uterus, the possibility a baby will be born breech increases in a partial bicornuate to 40 – 50%.
A bicornuate uterus is usually detected during an initial ultrasound during pregnancy, if it hadn’t been detected earlier. It can also be detected through an MRI.
Having a bicornuate uterus is estimated to occur in approximately in 0.1 – 05.% of women living in the United States. It should be noted this is likely an underestimate, as many cases go undetected.
Some symptoms experienced by women who have this type of uterus include abdominal pain, heavy or irregular menstrual periods, and painful ovulation. Women with these symptoms should advise their doctors and ask for an ultrasound to rule out the possibility of bicornuate uterus.