4 types of Mullerian anomalies of the uterus, explained by a doctor

If you have encountered the term Mullerian anomaly online, or even if you’ve been told you have one yourself, you might have more questions than answers. And, treatment options for pregnancy success, there are a few information there.

However, it tends to be aimed at healthcare professionals rather than patients and, as more research into these rare diseases is still needed, what is available can be somewhat fragmented and, well, a little confusing.

This type of specific advice always comes best from the experts, which is why, to start the year, we’re launching a three-part mini-series with Samantha M. Pfeifer, MD, specialist in reproductive endocrinology and fertility at Weill Cornel in New Yorkand a leading expert in Mullerian anomalies, to answer some of the most frequently asked queries.

Here in the first partwe ask Dr. Pfeifer what a Mullerian anomaly of the uterus actually is, as well as the main types to be aware of and their main differences.

In the second and third partswe will provide more detailed advice on how certain individual abnormalities may specifically affect fertility and pregnancy.

But first: the basics.

What is a Mullerian anomaly?

“A Mullerian anomaly is a rare variation in uterine developmentand there’s a spectrum of these abnormalities from no uterus to what appears to be two uteruses and cervixes and vaginas and everything in between,” says Dr. Pfeifer.

These variations occur before birth, when the mullerian ducts (which form the uterus, cervix, fallopian tubes, and upper vagina) do not develop or fuse in the usual way.

This results in different uterine shapes and structures, and are currently grouped under the name Classification of Mullerian Anomalies ASRM 2021.

Mullerian abnormalities can manifest in adolescence as primary amenorrhea – absence of first periods, or intermittent lower abdominal pain associated with absence of first periods, or intense pain during menstruation. But many Müllerian anomalies have no symptoms and are first discovered during imaging, fertility investigations, or pregnancy care.

What is a double uterus and is it the same as a Müllerian anomaly?

One of the most searched questions is what is a double uterus?

This may give a pretty clear picture for many of us, but in medical terms it’s not actually a single diagnosis.

“A double uterus is absolutely real and can refer to many different forms of uterine abnormalities, including a septate uterus, a bicornuate uterus, and a didelphys uterus. Each is very separate and distinct, and the term ‘double uterus’ doesn’t really explain the exact variation and therefore shouldn’t really be used,” says Dr. Pfeifer.

Basically, accurate diagnosis and categorization is very important, because different abnormalities not only look different, but also have different implications on the pregnancy and are managed in very different ways.

Types of Mullerian anomalies of the uterus, visualized

Learn more: Having a successful pregnancy with a bicornuate uterus – what is possible?

3. Unicornuate uterus

A unicornuate uterus has a simple, one-sided banana shapeand is formed when only one of the two Mullerian canals develops.

“The unicornuate uterus is usually found on one side of the pelvis and is connected to a fallopian tube on the same side. On the other side, there may be a small, non-functional, underdeveloped uterine remnant and a fallopian tube. Sometimes this remnant can contain endometrial tissue and cause pain,” says Dr. Pfeifer.

The uterus is smaller than average, which can affect how the pregnancy progresses.

Fertility is often possible, but pregnancies are usually monitored by a high-risk obstetrician.

4. Uterus didelphys

A didelphysis of the uterus is the abnormality that most people imagine when they think about what a uterus didelphysis is. double uterus it seems.

“Here we will usually have two distinct outer bodies that look like two separated half-uteri with two endometrial cavities, two cervixes and two vaginal canals,” explains Dr. Pfeifer.

Each uterus functions independently and pregnancy can occur in either one. Fertility is generally not affected, but pregnancy care should be completely individualized.

Other Mullerian anomalies

The ASRM guidelines have other categories and treatment pathways for abnormalities that do not fit the above, including:

• Mullerian agenesis – Also known as Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome, this is a complete absence of the uterus. In this case there are great consequences for fertility, since it is not possible to carry a pregnancy, but biological children are possible through other means.
• Other complex anomalies – A category for cases that involve combinations of anomalies, or those that simply do not fit into the other specific categories.

Learn more: These are the main reasons why someone might opt ​​for surrogacy (and they are all very valid)

Are you looking for support?

If you have been diagnosed with a Mullerian anomaly, it may be helpful to connect with reliable resources for advice and support. Here are some options to explore:

• Browse our own library of stories shared on TRB – of a MRKH Surrogacy Journey to IVF with IVF with Uterine Didelphysit’s here
• RESOLVED: The National Infertility Association – offers support groups, educational resources, and advice for anyone navigating reproductive health
• American Society for Reproductive Medicine (ASRM) – provides patient-friendly information about Mullerian anomalies, fertility and treatment options
• MRKH Connect – peer support and education for women with MRKH or related uterine anomalies
• Society for Women’s Health Research (SWHR) – resources on reproductive health and conditions affecting women’s fertility

Connecting to these resources can help you better understand your diagnosis, explore treatment options, and find support from others who have had similar experiences.

Do you have any other questions? You can also contact Dr. Pfeifer here – she is currently accepting new patients at Weill Cornell in New York.