How a Septate Uterus Increases Miscarriage Risk

A septate uterus is a congenital malformation in which a thin membrane called the septum divides the uterus either partially or completely. It is a genetic abnormality a woman is born with but one that can be treated surgically, if needed, to improve the chances of successful pregnancy.

A septate uterus significantly increases the risk of miscarriage and may be a key factor in recurrent miscarriages. While statistics vary, the rate of miscarriage in women with septate uteri is believed run anywhere from 25 percent to 47 percent. By contrast, the rate of miscarriage in the general population is only between 10 percent and 25 percent.

Moreover, the rate of recurrent miscarriage in women with uterine malformation is between eight percent and 23 percent. Roughly a third of these will have a septate uterus.

While a septate uterus does not affect a woman’s ability to conceive, it can complicate her pregnancy. The septum itself is a fibrous tissue that doesn’t have much of a blood supply. So if a fertilized egg is implanted on the septum, it has less chance of developing normally since the nutritional source will be largely cut off.

The one unusual aspect of a septate uterus is that miscarriage can often happen well into the second trimester. By contrast, the vast majority of miscarriages occur during the first trimester and often without a woman even knowing it.

Women with septate uteri who do not miscarry are also believed to be an increased risk of preterm labor.

A septate uterus often remains undiagnosed until a woman experiences repeated miscarriage. At other times, the doctor may stumble upon it during a routine physical exam. This is because is a septate uterus is often accompanied by similar malformations of the cervix and vagina. Typically referred to as a "double cervix" and "double vagina," these are often the first clues of a similar abnormality in the uterus.

Doctors will begin the investigation with either an ultrasound or magnetic resonance imaging (MRI) scan. A definitive diagnosis may require on a hysterosalpingogram (an X-ray procedure highlighting the uterus) and/or hysteroscopy (a visual examination using a lighted scope).

Even with these examinations, a septate uterus can sometimes be misdiagnosed as a bicornuate uterus, also known as a “heart-shaped uterus." While the malformation is by no means considered normal, it does not typically increase the risk of miscarriage.

A septate uterus is treated with surgery, most commonly by removing the septum during a hysteroscopy. This is a fairly minor procedure usually performed on an outpatient basis.

The technique, called metroplasty, is minimally invasive and involves the insertion of a medical device through the cervix and into the uterus to cut away excess tissue. This can be usually be performed in between 30 and 60 minutes. Antibiotics and estrogen may be prescribed afterward to prevent infection and aid in the healing. 

Hysteroscopic metroplasty can improve chances of a successful pregnancy in women with recurrent pregnancy by 53.5 percent, according to a comprehensive analysis of 29 studies conducted from 1986 to 2011.

It is unnecessary to women with septate uteri who have no intention of getting pregnant. On its own, a septate uterus poses no risk for cancer.