What Is Septate Uterus and How Does It Affect Pregnancy?

Key Points

• A septate uterus is when a wall of tissue divides a uterus into two cavities that vary in size.
• It essentially forces a baby to develop in a "townhouse" rather than a "big house."
• A septate uterus can cause pregnancy complications, including recurrent miscarriages, but surgery to remove that wall can help.

At my routine 13-week ultrasound, the maternal and fetal radiologist, a woman with the smallest pinky nails I'd ever seen, bounced into the exam room after looking at the sonogram images.

"Baby looks great," she said. "But you know you have a septate uterus, right?"

You don't know what a septate uterus is? Neither did I. In the simplest terms, it's when a wall of tissue divides the uterus into two cavities of varying sizes depending on the length and width of the tissue wall (also called a septum).

"Most fetuses live in a big house," the radiologist said. "But your baby lives in a townhouse."

A wall down the middle of my uterus separated the two identical "houses" from each other, but at the bottom of the uterus was "one shared yard," she said.

Great. I couldn't even give my unborn baby an open floor plan like all the other babies got.

What is a septate uterus?

If a townhouse analogy isn't enough, a septate uterus is a type of congenital uterine anomaly, so it's something you're born with. It occurs when the reproductive organs don't form properly, resulting in the presence of a band of fibrous tissue or muscle down the center of the uterus.

In a female embryo, the Müllerian ducts eventually develop into the reproductive tract that includes the uterus, fallopian tubes, cervix and the upper part of the vagina. Sometimes, congenital anomalies are called Müllerian anomalies.

Uterine anomalies in addition to a septate uterus include the following:

• Bicornuate. The uterus is heart-shaped.
• Didelphys. The uterus splits into two fully separate halves.
• Unicornuate. Only half of the uterus is present.

One of the confusing things is that most of the anomalies cause a septum—that's the wall of tissue—but only one is called a septate uterus.

Recommended

• What Does It Mean to Have a Heart-Shaped Uterus?: An arcuate or heart-shaped uterus is a common abnormality.
• Life After a Miscarriage: Following a pregnancy loss, having sex and trying again should happen at your own pace.
• The Grief and Joy of Pregnancy After a Miscarriage: Losing a pregnancy doesn't have to mean the end of your parenthood journey.

Can a septate uterus cause miscarriage?

When I received this news, I was pregnant for the second time. A year earlier, before I knew I had a septum, my pregnancy ended in miscarriage. While chromosomal abnormalities cause most miscarriages, they may occur in someone with a septate uterus if the fetus implants on the wall of tissue where it does not receive the blood flow it needs to survive.

If you have one miscarriage, you will not be checked for uterine anomalies unless you ask. You'll likely pay out of pocket since insurance is unlikely to cover the tests required after a single miscarriage. It's generally assumed that the fetal loss was due to chromosomal abnormalities.

"The most common cause of miscarriage is chromosomal. After a pregnancy loss, we see if it's something that's going to recur. And when we've worked up individuals with recurrent pregnancy loss, that's when the prevalence of congenital uterine or Müllerian anomalies increases by 10 percent to 18 percent," said Natasha Spencer, M.D., an OB-GYN with Orlando Health Physician Associates.

Miscarriage is often traumatic. I fainted during mine and needed stitches in my head from where I fell into the shower. I ended up in EMDR therapy to process the experience. I was extremely lucky not to have a second miscarriage.

In cases in which a septate uterus is thought to be causing recurrent pregnancy losses, surgery can be performed to remove the septum.

Can you see a septate uterus on an ultrasound?

I was surprised I hadn't heard about my septate uterus sooner, given the number of ultrasounds I'd undergone at that point—at least four between the two pregnancies—but a septate uterus is not always easy to detect. Sometimes it won't be discovered until pregnancy or even after birth.

"[A septate uterus] is not always seen on a simple, routine ultrasound, which is a 2D image of the uterus, which is a 3D structure. Also, it can be hard to appreciate anything abnormal in the cavity of the uterus without distending it with fluid/contrast and then doing imaging to visualize it," said Lucky Sekhon, M.D., an OB-GYN and board-certified reproductive endocrinologist and infertility specialist with RMA of New York.

As an example of how difficult uterine abnormalities can be to detect, Spencer once didn't discover a uterine didelphys (that's when a person has two uteruses) until her patient's postpartum appointment.

It was likely only because my radiologist was specially trained in maternal-fetal medicine that she even saw it. In the sonogram images, the septum looked like a slight color variation. A longer or thicker septum may be easier to see.

Suppose your doctor is specifically looking for a uterine abnormality. In that case, they will likely perform either an MRI or a saline infusion sonogram (SIS). An SIS, according to Spencer, is an ultrasound but with a little catheter inserted up into the cervix to fill the uterus with saline. Then they inflate a balloon to hold the fluid in.

A 3D ultrasound can help provide a clearer picture of the reproductive organs.

Can a septate uterus cause other pregnancy complications?

In addition to first-trimester losses, a septate uterus is associated with later losses because the fetus may run out of space to develop properly.

"[Septate uterus] can be associated with preterm delivery," Sekhon said.

The main manifestations, though, are early recurrent first-trimester miscarriages and fetal malpresentation (breech babies). Breech babies are more common because the baby may turn into a feet-down position and not be able to flip back over due to the space constraints caused by the septum.

However, a septate uterus does not always cause pregnancy complications. The radiologist told me there was no way I'd carry my baby to full-term, something that turned out to be untrue. I made it more than 40 weeks before I delivered him, and in subsequent ultrasounds—I went in every six weeks since the septate uterus put me in the high-risk category—the septum was not even visible.

I am both so grateful I carried to term and regretful that I spent my pregnancy worrying about something out of my control.

The bottom line

If you learn you have a septate uterus or another anomaly and you don't plan to have kids, it doesn't typically cause issues.

"There are people who walk around in this world today; some may have had babies who don't know they have this," Spencer said.

If you find out you have a septate uterus, your doctor will probably recommend you get your kidneys checked, because the reproductive organs form close to and on a similar timeline as the kidneys and urinary tract.

"Sometimes, septums can be found in association with renal anomalies or other reproductive tract anomalies (double cervix, etcetera)," Sekhon said.

Speak with your doctor if you have any questions about how your septate uterus can potentially affect your pregnancy.