Congenital Uterine Anomalies

Congenital uterine anomalies are irregularities of the uterus (womb), the reproductive organ where a baby is carried during pregnancy.

Roughly 5% of people with female reproductive systems are born with some sort of uterine difference. While they're not dangerous, they can cause complications during pregnancy.

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On this page:  

• What Are Congenital Uterine Anomalies?  
• What Are the Symptoms of Congenital Uterine Anomalies?  
• How Do You Diagnose Congenital Uterine Anomalies? 
• How Do You Treat Congenital Uterine Anomalies?  

What Are Congenital Uterine Anomalies?  

Congenital uterine anomalies are irregularities of the uterus (womb) that are present at birth. The uterus is the reproductive organ where a baby is carried during pregnancy.

Congenital uterine anomalies can cause complications with pregnancies. People with uterine abnormalities may have problems with recurrent miscarriages and preterm deliveries.

About 25% of the time, the kidneys and genitourinary system are also affected.

Congenital uterine anomalies also may be referred to as Müllerian duct anomalies because the uterine abnormalities result from problems with the Müllerian ducts as the fetus grew in the womb.

How common congenital uterine anomalies?

About 5% of people with female reproductive systems have some sort of congenital uterine anomaly.

What are the types of congenital uterine anomalies? 

The most common anomalies and their frequencies include:

• Septate uterus (35%) — Is normal on the outside surface but has two endometrial cavities inside.
• Bicornuate uterus (26%) — Has an abnormal indented outside surface and two endometrial cavities inside.  
• Arcuate uterus (18%) — Is normal on the outside surface, but there’s less than 1 centimeter indentation into the endometrial cavity.
• Didelphic uterus (8%) — Two separate uteruses.
• Unicornuate uterus (8%) — Only one half of the uterus has developed.
• Hypoplastic/aplastic uterus (4%) — The uterus is underdeveloped or absent altogether.

What causes congenital uterine anomalies? 

Inborn uterine anomalies seem to stem from the lack of complete fusion of the two uterine horns (cornua of uterus) at the time a person is developing in their mother’s uterus.

When an embryo is in the early stages of development, a pair of tubes called the Müllerian ducts grows to form the female reproductive organs. This forms the cervix, fallopian tubes, and upper vagina. (The ovaries are formed by a different embryonic source.)

As the Mullerian duct develops, it depends on three phases to reach completion.

They are:

• Organogenesis — The first phase of development, organogenesis is the formation of both Müllerian ducts. If failure occurs during this developmental phase, the result is uterine hypoplasia/aplasia or a unicornuate uterus.
• Fusion — The second phase, fusion, involves the ducts coming together to form the uterus. If the ducts fail to fuse, the result is bicornuate or didelphys uterus.
• Septal resorption — The final phase, septal resorption, involves the central septum being reabsorbed by the body once the ducts have fused. If the septum isn't reabsorbed, the result is septate or arcuate uterus.

Müllerian duct development occurs independently of sex determination.

People with Müllerian anomalies typically have normal ovaries and ovarian function. However, Müllerian development is closely aligned with urinary tract development, so renal anomalies often are diagnosed at the same time as Müllerian anomalies. For this reason, doctors will image both the genital and urinary systems when they suspect Müllerian anomalies because they're affected in 25% of cases.

What is Müllerian agenesis?

Also referred to as Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome, vaginal agenesis, or Müllerian aplasia, Müllerian agenesis is caused by the embryonic underdevelopment of the Müllerian duct.

As a result, the vagina, uterus, or both fail to develop completely or at all. This condition is often identified when a person goes to their provider because haven’t gotten their period within the expected age range or haven’t met other growth and puberty milestones.  

What are the risk factors and complications of congenital uterine anomalies?  

Congenital uterine anomaly risk factors

Doctors haven't identified any risk factors for congenital uterine anomalies.

Complications of congenital uterine anomalies

People who have congenital uterine anomalies are known to have a higher incidence of infertility.

For those who can conceive, other adverse pregnancy outcomes are associated with uterine anomalies including:

• Cervical insufficiency.
• Fetal growth restrictions.
• Malpresentation at birth.
• Preterm labor and birth.
• Postpartum bleeding.
• Recurrent miscarriage.

People with Müllerian duct anomalies (MDA) have the same complications, as well as:

• Repeated first-trimester miscarriage.
• Retained placenta.

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What Are the Signs and Symptoms of Congenital Uterine Anomalies? 

Many people don’t even realize they have a uterine abnormality until they undergo infertility testing. That’s because some people don’t have symptoms.

When symptoms do occur, they include:

• Absence of periods — Intrauterine scarring can cause lesions that make the walls of the uterus stick to one another, which thins the endometrial lining. This can prevent an embryo from attaching to the uterus and may even stop menstrual bleeding altogether.  
• Abnormal baby positioning — During pregnancy, a malformed uterus may cause a baby to go into the breech position where their head is up and their feet or bottom are down.
• Pain during sex or while inserting a tampon — Uterine anomalies may make it uncomfortable to insert a tampon. In the same way, vaginal intercourse may hurt.
• Preterm labor and delivery — Anomalies can result in preterm labor and delivery, which increases the risk of developmental issues.
• Painful menstruation — The abnormal or incomplete development of the uterus or vagina can create a blockage for menstrual bleeding. This can cause cramps and belly pain.
• Recurrent miscarriages — Some uterine anomalies don’t interfere with fertilization, but an abnormal uterus can make it hard to keep a pregnancy and often leads to recurrent miscarriage.

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How Do You Diagnose Congenital Uterine Anomalies?  

To diagnose congenital uterine anomalies, doctors take a medical history and do a pelvic exam.

Your doctor will ask about your menstrual history, reproductive health, past pregnancies, and any symptoms you're experiencing. This information can provide important clues.

A pelvic exam allows your doctor to assess the size, shape, and position of your uterus and the surrounding structures. Certain anomalies, such as a septate or bicornuate uterus, may be detected during a pelvic exam.

They may also evaluate the kidneys and genitourinary system, since they're also affected a quarter of the time.

Your doctor will likely also order imaging tests.

Tests to diagnose congenital uterine anomalies

Imaging techniques

• Transabdominal or transvaginal ultrasound — Provide detailed images of the uterus and help identify abnormalities such as septate, bicornuate, unicornuate, or didelphic uterus.
• MRI — Used when ultrasound findings are inconclusive or further detail is needed.

Hysterosalpingography

This procedure involves injecting a contrast dye into the uterus and fallopian tubes, followed by x-ray imaging. It can help identify abnormalities such as uterine septum or other structural defects.

Sonohysterography

This test involves injecting saline solution into the uterus followed by ultrasound imaging. It can help provide detailed images of the uterine cavity and detect abnormalities such as septate or subseptate uterus.

Genetic testing

If your doctor suspects a genetic syndrome associated with uterine anomalies, they may recommend genetic testing.

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How Do You Treat Congenital Uterine Anomalies?  

Uterine anomalies don’t always need to be treated, but for those that do, surgery is often the best treatment.

Medicine to treat uterine anomalies

Medication and hormone therapy are usually the first courses of treatment.

Surgery for uterine anomalies

Depending on the type of anomaly, surgical correction may be the best treatment.

Anomalies and their recommended surgeries:

• Unicornate — Surgery is recommended when the person has a cavitary horn. With a noncavitary horn or no horn, no treatment is recommended.
• Didelphate — Surgical reconstruction called metroplasty often is recommended. However, full-term pregnancies have occurred when the condition was left untreated.
• Bicornate — Surgery is rarely needed, but metroplasty may be considered.
• Septate — Minimally invasive treatment with transvaginal hysteroscopic resection of the septum is recommended. Conception is possible two months after surgery.

How effective is treatment?

Depending on the uterine anomaly, some people are able to get pregnant and carry a pregnancy to term with or without surgery.

But hypoplasia/agenesis has no reproductive potential. In vitro fertilization (IVF) of a donor egg and implantation in a surrogate uterus is needed.

By UPMC Editorial Staff. Last reviewed on 2024-09-05.