Uterine Malformations: Congenital Abnormalities of the Uterus and Their Treatment

To understand uterine malformations, it is helpful to look at embryology. The uterus, the fallopian tubes, and the upper part of the vagina develop from the two Müllerian ducts. Normally, these ducts fuse to form a single hollow organ. If this fusion does not occur or occurs only partially, uterine malformations result. The medical literature (e.g., *Obstetrics & Gynecology*) often refers to these as “anomalies associated with Müllerian duct defects.” Vaginal malformations may also occur concurrently.

The categorization and classification of these anomalies are crucial for treatment. International societies such as the ESHRE (European Society of Human Reproduction and Embryology) and the ASRM have developed guidelines for the classification of uterine anomalies. The VCUAM system (Vagina Cervix Uterus Adnex – associated Malformation) is also used.

Here are the most important uterine anomalies in women:

1. Uterus septus and subseptus

A septate uterus is the most common uterine malformation. In this condition, the Müllerian ducts have fused, but the dividing wall (septum) has not resolved.

• Subseptate uterus: The septum extends only partially into the uterine cavity.
• Complete septate uterus: The septum completely divides the uterine cavity and extends into the cervix.
• Clinical significance: Since the endometrium (mucous membrane) on the septum is often poorly perfused, the risk of miscarriage is increased. A septate uterus is considered a common cause of infertility.

2. Bicornuate uterus

In a bicornuate uterus, the Müllerian ducts failed to fuse in the upper portion. The uterus has two “horns.” A distinction is often made between a partial bicornuate uterus and a unicollis bicornuate uterus (two horns, one cervix). A bicornuate uterus often poses less of a problem for conception but increases the risk of preterm birth due to lack of space.

3. Uterus didelphys

In a uterus didelphys (double uterus), no fusion has occurred at all. There are two separate uterine cavities, two cervixes, and often a double vagina as well.

4. Unicornuate uterus

In this case, only one Müllerian duct has developed. The result is a unicornuate uterus, often with only one fallopian tube. Sometimes a rudimentary horn exists on the opposite side, which can cause problems if a pregnancy implants there (ectopic pregnancy).

5. Arcuate Uterus

The arcuate uterus is the mildest form. The fundus (top of the uterus) is slightly indented. It is often considered a normal variant and usually has no negative effects on pregnancy.

From a septate uterus to a bicornuate uterus—congenital uterine anomalies can take many forms and require precise diagnosis via ultrasound or MRI.

If a uterine malformation is suspected in a patient—for example, following miscarriages—precise diagnosis is essential.

• Ultrasound: 3D ultrasound is now the gold standard for assessing, for example, a septate uterus and its extent.
• Hysteroscopy & Laparoscopy: Hysteroscopy and laparoscopy provide a direct view of the anomalies.
• MRI: Helps diagnose complex malformations of the female genital tract.

Medical reference works such as the DocCheck Flexikon or specialized journals (Obstet Gynecol) emphasize that the kidneys should also be examined, as renal malformations are frequently associated with Müllerian anomalies.

Not every malformation requires treatment. However, in patients with recurrent miscarriages and a confirmed uterine septum, hysteroscopic septum dissection (removal of the septum) is the standard of care.

• Preoperative planning is essential.
• The goal is to create a normal uterine cavity to facilitate implantation.
• Postoperatively, hormone therapy may be administered to build up the endometrium and prevent intrauterine adhesions.

In cases of a unicornuate uterus or didelphys uterus, surgical correction to unite the uteri is often not possible or is too risky. In such cases, close monitoring of the pregnancy is the priority.

Uterine malformations are complex but can be easily diagnosed thanks to modern medicine. A congenital uterine malformation is not an absolute barrier to pregnancy, but it does require specialized care. Whether it is a septate uterus, bicornuate uterus, or arcuate uterus: Individualized counseling by specialists in gynecology and reproductive medicine is the key to having the child you desire.