Can You Get Pregnant with a Unicornuate Uterus? Fertility & IVF Explained

What Is a Unicornuate Uterus?

A unicornuate uterus develops when one Müllerian duct develops incompletely, resulting in a uterus with a single functional horn. Normally, in the developing female fetus, two non-fused ducts, called Müllerian ducts, come together to form a complete and symmetric uterus and two fallopian tubes. This results in a uterus with one main uterine horn and a smaller, underdeveloped structure that may represent a rudimentary horn.

It is a structural change that occurs in approximately 0.1% to 0.4% of the general female population. A secondary, undeveloped side will often exist. This secondary structure is called a rudimentary horn by medical professionals.

A horn may connect to the uterus, be present but not connected to the uterine cavity, or exist with no functional endometrial lining. Since this condition is present at birth, it isn't caused by lifestyle or personal habits.

Can You Get Pregnant with a Unicornuate Uterus?

The answer is yes. A unicornuate uterus can be associated with reduced fertility in some women, although the impact varies and many women can conceive naturally. However, some women might face unicornuate uterus fertility challenges and carry a higher risk of certain pregnancy complications.

There are, however, additional preparations and medical care needed to ensure that a pregnancy successfully occurs and is maintained. The most important problem is not always the failure to conceive, but the inability to stay pregnant.

How Does a Unicornuate Uterus Affect Fertility?

A unicornuate uterus is one of those congenital uterine anomalies that can affect fertility in several specific ways:

• Limited Physical Space: The single-horned uterus has a significantly smaller total capacity than a normal uterus, which may limit early embryonic development and growth space.
• Reduced Blood Supply: There are two major uterine arteries to a normal uterus. The anatomy of a unicornuate uterus typically involves a single large artery, which can limit the blood supply to your uterus, affecting nutrient and oxygen exchange.
• Single Fallopian Tube Access: Most individuals with this anomaly have only one fully functional fallopian tube, which limits the mechanical pathways available for egg transport each month.
• Cervical Incompetence: Some women may have cervical shortening or cervical insufficiency, which can contribute to pregnancy loss or preterm birth. Cervical length may therefore be monitored during pregnancy when clinically indicated.

Pregnancy Risks with a Unicornuate Uterus

Medical risks are increased when a child is carried in a unicornuate uterus pregnancy. Close collaboration with a high-risk maternal-fetal medicine specialist helps manage these potential complications.

• Increased Risk of Miscarriage

The rate of spontaneous pregnancy loss is higher for individuals with a single uterine horn. Fetal loss is frequently associated with inadequate blood flow in the shrinking tissue mass in the first trimester. Second-trimester loss often occurs due to physical space limitations and/or early cervical weakness.

• Preterm Birth

The altered shape and smaller uterine cavity may contribute to an increased risk of preterm birth. Regular obstetric monitoring can help identify signs of cervical shortening, foetal growth problems or other complications.

• Ectopic Pregnancy

Pregnancy can seldom develop within a rudimentary horn, especially if functional endometrial tissue is present. Primitive horn pregnancy is serious because the poorly developed horn may rupture as it enlarges, resulting in major internal bleeding. This increases the importance of early diagnosis and treatment.

• Foetal Growth Restriction

The smaller uterine cavity and altered uterine anatomy may increase the risk of foetal growth restriction (FGR). Regular ultrasound scans may be recommended to monitor foetal growth and blood flow when clinically indicated.

• Breech Presentation and Delivery Considerations

During the last (third) trimester, when the size of the baby increases, it may not be possible to turn the baby back into a head-down position for vaginal delivery because of restricted space. Breech or transverse positions occur frequently. The mode of delivery depends on the baby's position, maternal and fetal condition, and other obstetric factors. A caesarean section may be recommended when clinically appropriate.

How Is a Unicornuate Uterus Diagnosed?

Structural uterine abnormalities are rarely found in a routine pelvic exam, because the outside structures look normal. Doctors may use imaging tests to assess the shape and structure of the uterus to help confirm their diagnosis.

• Pelvic Ultrasound

Transvaginal pelvic ultrasound is typically used as a first-line screening tool, which is a 2D scan. It may reveal an irregular uterine shape, but sometimes, even on 2D ultrasound, smaller rudimentary components are not identified.

• 3D Ultrasound

Three-dimensional ultrasound technology creates a clear 3D image of the uterus's outer contour and the uterine cavity's shape. It enables specialists to accurately measure the internal dimensions and distinguish a unicornuate uterus from other malformations, such as a bicornuate or septate uterus.

• MRI

MRIs provide detailed images of soft tissues from multiple angles. MRI can provide detailed images of the uterus and surrounding pelvic structures and may be recommended when ultrasound findings are unclear or when a complex uterine anomaly needs further evaluation.

• Hysterosalpingography (HSG)

HSG works by introducing an opaque contrast dye into the cervix, and then X-rays are taken to view the uterus, while checking to see if the fallopian tube has opened properly.

• Hysteroscopy and Laparoscopy

Minimally invasive surgical procedures offer definitive visualisation when non-invasive imaging leaves room for doubt. A hysteroscope is used to view the inside of the womb, and a laparoscope enables the doctor to view the outside of the womb and other pelvic organs.

Can IVF Help Women with a Unicornuate Uterus?

IVF could be used if a female fertility problem that prevents conception, like blocked fallopian tubes, a lack of ovulation, or sperm count issues, is present along with a unicornuate uterus. If IVF for unicornuate uterus were used, it would avoid the fallopian tubes since an embryo can be transferred into the uterine cavity; however, the uterine abnormalities and pregnancy risks with a unicornuate uterus would not be resolved.

Specialists often use certain protocols to maximise the chances of IVF success in the case of a “Single horn” uterus:

1. Elective Single Embryo Transfer (eSET): Multiple gestation pregnancies carry high risks in a standard uterus, but in a unicornuate uterus, carrying twins or triplets presents complications. The transfer of just one good embryo prevents overcrowding of the limited uterine capacity.
2. Progesterone Support: Progesterone may be prescribed as part of some IVF protocols to support the uterine lining after embryo transfer, depending on the individual's treatment plan.
3. Preimplantation Genetic Testing (PGT): Preimplantation genetic testing (PGT) may be considered in selected IVF cases to identify certain genetic or chromosomal abnormalities before embryo transfer. Its suitability depends on individual circumstances and should be discussed with a fertility specialist.

Pregnancy Care with a Unicornuate Uterus

After confirmation of pregnancy, clinical care continues within a framework designed to reduce complications and monitor fetal growth and development.

• Frequent Ultrasound Monitoring: During the first and second trimesters, women undergo serial ultrasounds to assess placental growth & location.
• Cervical Length Monitoring: Cervical length may be monitored during pregnancy. If significant cervical shortening or cervical insufficiency is identified, the obstetrician may consider interventions such as cervical cerclage based on the individual situation.
• Growth Tracking Scans: Third-trimester scans for growth tracking to monitor fetal weight and blood flow through the umbilical artery in order to identify key signs of growth restriction.
• Planned C-Section Preparation: Given the incidence of breech presentation, obstetrician teams plan deliveries to avoid emergency surgical complications.

Can a Unicornuate Uterus Be Treated?

No surgical method is available to restore a missing half of a uterus or enlarge a single horn into a normal banana-shaped uterus. Surgical treatment is directed towards controlling complications from secondary structures and preserving the functional uterine horn.

If a rudimentary horn contains functional endometrial tissue but does not communicate with the main uterine cavity, menstrual blood may accumulate within it. This can cause severe pelvic pain and may contribute to endometriosis. In selected cases, laparoscopic removal of the rudimentary horn may be recommended. This method can help alleviate symptoms and avoid complications, and leave the healthy uterine structure intact.

Conclusion

Being diagnosed with a unicornuate uterus speaks to medical considerations, but not to the possibility of building a family. The use of advanced imaging techniques, reproductive treatments, and high-risk obstetric monitoring has made it possible for many women with this condition to have successful pregnancies. The collaboration with well-qualified fertility and maternal-fetal medicine experts allows individuals to navigate treatment options safely and effectively advocate for their reproductive health.