Septate Uterus, Bicornuate Uterus and Other Uterine Anomalies: Fertility and Pregnancy

A septate uterus is a womb that has a wall of tissue, called a septum, running down from the top and dividing the inside into two parts. It forms before birth, usually causes no symptoms, and many women only find out during a scan for miscarriage or difficulty conceiving. It is the uterine anomaly most linked to miscarriage, and it is also the one that can usually be corrected with a short hysteroscopy, without any cuts on the tummy. At Yaal Fertility Centre in Chennai, Dr. Rukkayal Fathima and our team help women understand what their womb shape means and whether anything needs to be done.

What Are Uterine Anomalies?

Uterine anomalies (also called congenital uterine or Müllerian anomalies) are differences in the shape of the womb that a woman is born with. They are not caused by anything you did, by past pregnancies, by infections or by diet.

How the Womb Forms Before Birth

In a baby girl, the womb starts as two separate tubes called the Müllerian ducts. Over the first few months of pregnancy, these tubes move together, join in the middle, and the wall between them dissolves to leave one open cavity. A difference can arise at any step:

• One tube does not develop → a unicornuate (one-sided) womb
• The tubes do not join fully → a bicornuate (heart-shaped) womb, or two separate wombs (didelphys)
• The tubes join but the middle wall does not dissolve → a septate womb
• The wall almost fully dissolves → an arcuate womb, with only a slight dip at the top

How Common Are They?

Uterine anomalies are found in a small minority of women in general, but they are more common among women who have had repeated miscarriages. The septate uterus is the most common of the significant anomalies. Many women with a mild anomaly have normal pregnancies and never know they have one. Shape is also different from position: an anteverted or retroverted womb is a normal tilt, explained in our guide to uterus size and position.

Because the kidneys develop at the same time as the womb, some anomalies, especially a unicornuate uterus or uterus didelphys, come with a kidney difference on the same side. A kidney scan is often advised when one of these is found.

Septate, Bicornuate, Arcuate and Unicornuate Uterus Compared

The table below compares the main types. Exact definitions vary slightly between medical societies, so your doctor will explain where your scan fits.

Septate vs Bicornuate Uterus: Why the Outside Shape Matters

On the inside, a septate and a bicornuate womb can look almost the same, because both seem to have two compartments. The difference is on the outside. A septate womb has a normal, smooth top with the wall only inside. A bicornuate womb has a clear dip on the outside, because the two halves never joined fully.

This matters because the treatments are different. A septum can be cut through from inside the womb. A bicornuate womb is made of normal muscle, and cutting it would weaken it, so it is usually left alone. Getting the diagnosis right is the most important step.

Partial vs Complete Septum

A partial septum divides the upper part of the cavity and stops before the cervix. A complete septum runs all the way down to the cervix, and sometimes there is a second wall in the upper vagina as well. Both can be treated, and the plan depends on the length and thickness of the wall.

Arcuate Uterus: Usually a Normal Variation

An arcuate uterus has only a gentle dip at the top of the cavity. Most specialists regard it as a variation of normal, and it is not usually linked with fertility problems or miscarriage. It rarely needs treatment.

Unicornuate Uterus and the Rudimentary Horn

In a unicornuate womb, only one side has formed. The womb is smaller and connected to only one fallopian tube, though both ovaries are usually normal. Some women also have a small undeveloped horn on the other side. If that horn has its own lining but no opening, it can cause painful periods, and a pregnancy in it would be dangerous, so removal by keyhole surgery is usually advised.

Symptoms of a Septate Uterus and Other Anomalies

Most Women Have No Symptoms

Periods and hormones are usually completely normal, because the ovaries work as usual. That is why most anomalies are found only when a woman has a scan for another reason: a fertility work-up, a pregnancy scan, or tests after miscarriage.

Signs That Can Point to an Anomaly

• Repeated miscarriages, especially in the first trimester or early second trimester
• A baby lying breech or sideways in more than one pregnancy
• Preterm birth without another clear reason
• Severe period pain from the first periods onwards, which can happen when menstrual blood is trapped in a blocked horn
• Difficulty using tampons or pain during sex, sometimes linked to a vaginal septum

None of these proves an anomaly is present, but they are reasons to look at the shape of the womb carefully.

How Uterine Anomalies Are Diagnosed

3D Ultrasound

A 3D transvaginal ultrasound is now the first-choice test. It shows the inside of the cavity and the outside of the womb at the same time, which is exactly what is needed to tell a septate womb from a bicornuate one. It is quick, painless for most women and uses no radiation. A standard 2D scan can raise the suspicion, but it often cannot make the final call.

The scan is best done in the second half of the cycle, when the thicker lining outlines the cavity more clearly.

HSG (Hysterosalpingography)

An HSG is an X-ray test where dye is passed into the womb to check the tubes. It also shows the outline of the cavity, so it may be the first test to show a "two-part" cavity. But because it shows only the inside, it cannot tell a septum from a bicornuate womb. Our guide to the HSG test explains what the procedure involves and what the images show.

Hysteroscopy and Laparoscopy

A hysteroscopy passes a thin camera through the cervix to look directly inside the womb. It confirms a septum and lets the doctor see the openings to the tubes. A laparoscopy (keyhole camera through the navel) looks at the outside of the womb, tubes and ovaries. In the past the two were often done together to confirm the diagnosis. Today, 3D ultrasound or MRI usually answers the question beforehand, and laparoscopy is used mainly when another problem such as endometriosis also needs checking. See our article on laparoscopy for fertility for what it involves.

MRI

An MRI of the pelvis gives a detailed picture of the womb, cervix and vagina. It is useful for complex or unclear anomalies, rudimentary horns, or when a vaginal septum or blocked horn is suspected. It does not use radiation.

Comparing the Tests

Uterine Anomalies and Pregnancy

Can You Get Pregnant With a Septate Uterus?

Yes. Most women with a septate womb conceive normally, because the anomaly does not stop ovulation or block sperm. The concern is mainly what happens after conception. Whether a septum on its own reduces the chance of conceiving is still debated, and it is usually considered only after other causes of subfertility have been checked.

Why a Septum Can Lead to Miscarriage

The septum is made of tissue with a poorer blood supply than the normal womb wall. If an embryo implants on the septum, the placenta may not develop well, and the pregnancy is more likely to end in miscarriage. This is why a septate uterus is one of the causes we look for in women who have had repeated losses. Our guide to recurrent pregnancy loss covers the full set of tests, from blood clotting to chromosomes, and our recurrent pregnancy loss treatment page explains how we plan care.

Preterm Birth, Breech and Growth

As the baby grows, a womb with less space or an unusual shape can lead to:

• Preterm labour or waters breaking early
• Breech or transverse position, which more often means a caesarean birth
• Slower growth of the baby, especially with a unicornuate womb
• Cervical weakness in some women, where the cervix shortens early

These risks are highest with unicornuate, bicornuate and unrepaired septate wombs, and low with an arcuate womb. Many women with each type still go on to have healthy babies with good monitoring.

Hysteroscopic Septum Resection

Who Is It For?

Removing the septum is usually advised for women who:

• Have had two or more miscarriages, with the septum the likely cause
• Have had a preterm birth or late loss linked to the septum
• Are about to start IVF, so that precious embryos are not transferred into a divided cavity
• Have a long or thick septum found during a fertility work-up, after a discussion of the evidence

For a woman who has never tried to conceive and has had no losses, the decision is less clear-cut, as explained below.

What Happens During the Procedure

A hysteroscope is passed through the vagina and cervix into the womb. The doctor cuts through the septum along the middle until the cavity looks like a single, normal space. Because the septum has little blood supply, bleeding is usually minimal. There are no cuts on the tummy, and it is usually a day-care procedure under anaesthesia.

For a fuller explanation of the procedure, preparation and recovery, see our article on hysteroscopy for fertility and our hysteroscopy service page.

Recovery and When to Try

• Most women go home the same day and return to normal activity within a day or two
• Light bleeding or cramping for a few days is common
• Some doctors prescribe a short course of hormone treatment to help the lining heal; your doctor will advise you
• A follow-up scan or hysteroscopy is often done after one to two cycles to check the cavity
• Many women are advised to wait one to three cycles before trying to conceive or having an embryo transfer

Risks

Septum resection is generally safe. Uncommon risks include infection, bleeding, fluid overload, a small tear in the womb wall, and scarring inside the cavity. Scarring can lead to Asherman syndrome, which is one reason a follow-up check of the cavity is worthwhile.

Is Surgery Always Needed? The Evidence Debate

For women with repeated miscarriages and a septum, many specialists and guidelines support resection. For women who have never miscarried, recent studies have not clearly shown that removing the septum improves the chance of a live birth, and some experts now advise against routine surgery in that group. Medical societies differ in their guidance.

In practice, the decision depends on the size of the septum, your history, your age, and whether you are about to have IVF. We discuss the pros and cons openly so that you make the choice that fits your situation.

Pregnancy Care With a Uterine Anomaly

Early Planning

If you know you have an anomaly, it helps to see a specialist before or early in pregnancy. An early scan confirms where the pregnancy has implanted, which is especially important in a womb with a horn or two cavities.

Monitoring During Pregnancy

Women with a bicornuate, unicornuate, didelphys or unrepaired septate womb are usually looked after as a higher-risk pregnancy. Care may include:

• Cervical length scans in the second trimester, to spot early shortening
• Growth scans to check the baby is growing well
• Checking the baby's position in the third trimester to plan the birth
• Clear advice on the warning signs of preterm labour: regular tightenings, low back ache, pressure or a fluid leak

If the cervix shortens, treatments such as a cervical stitch (cerclage) or medication may be discussed. Our high-risk pregnancy team provides this kind of closer monitoring.

Planning the Birth

Many women with uterine anomalies have a normal vaginal birth. A caesarean is more likely if the baby is breech or sideways, and your team will plan the birth with you as the due date approaches.

IVF Considerations With Uterine Anomalies

Checking the Womb Before Transfer

Before IVF, the cavity is assessed with a scan, and sometimes a hysteroscopy. If a septum is found, many specialists suggest removing it before the embryo transfer, so the embryo has a healthy, well-supplied surface to implant on. In some cases, eggs are collected and embryos frozen first, and the transfer is done after the womb has healed.

Single Embryo Transfer

For women with any uterine anomaly, transferring one embryo at a time is strongly preferred. A twin pregnancy in a smaller or divided womb raises the risk of preterm birth considerably. A single, well-chosen embryo gives a safer pregnancy.

Where the Embryo Is Placed

In a bicornuate or didelphys womb, the doctor uses ultrasound guidance to place the embryo in the cavity that looks more suitable on the scan.

When the Womb Cannot Carry a Pregnancy

Very rarely, a womb cannot safely carry a pregnancy at all, for example when it is absent or very underdeveloped. Options in that situation, including surrogacy within Indian law, are discussed with the couple individually.

Other Womb Problems to Rule Out

Not every abnormal cavity is a birth anomaly. Scarring after surgery or infection, polyps, fibroids and adenomyosis can also change the shape of the womb. If your report says the womb is enlarged rather than misshapen, our article on a bulky uterus explains the usual causes.