A bicornuate uterus is a congenital uterine anomaly where the uterus is shaped distinctly like a heart, rather than its typical pear-like form. The top of the uterus is partially divided, creating two distinct horns or cavities.
Understanding a Bicornuate Uterus
A typical uterus is a single, hollow, pear-shaped organ designed to expand and accommodate a developing pregnancy. In contrast, a bicornuate uterus has a deep indentation at its top, giving it a characteristic heart-shaped appearance. This results in two separate cavities or “horns” at the upper part of the uterus, while the lower part, including the cervix, usually remains fused. The degree of this division can vary from a slight dip (partial bicornuate) to a more pronounced separation (complete bicornuate). This anatomical difference sets it apart from other uterine variations, such as a septate uterus, where a wall of tissue divides the internal cavity but the external shape remains normal.
Prevalence and Incidence
A bicornuate uterus is considered one of the more common congenital uterine anomalies, yet it remains relatively rare within the general female population. Its prevalence is estimated to be less than 0.5% of females. The exact numbers can vary across studies due to differing diagnostic methods and populations examined.
While infrequent in the general population, the incidence of a bicornuate uterus is notably higher among women experiencing reproductive challenges. Among women with infertility, the prevalence can range from approximately 1.1% to 7.3%. For those with a history of recurrent miscarriages, the figures are higher, reported between 2.1% and 20%.
Causes and Formation
A bicornuate uterus is a congenital anomaly that arises during fetal development, specifically between 10 and 20 weeks of pregnancy, when the female reproductive system is forming. The uterus develops from two structures known as Müllerian ducts. Normally, these two ducts completely fuse to form a single, unified uterine cavity.
In a bicornuate uterus, this fusion process is incomplete. The Müllerian ducts do not fully merge, leading to the characteristic heart shape with two distinct upper sections. This developmental variation is not caused by anything the mother did or did not do during pregnancy. It is not hereditary and cannot be prevented. Sometimes, a bicornuate uterus may occur alongside other congenital issues, such as kidney abnormalities.
Implications and Management
While many women with a bicornuate uterus experience successful pregnancies, the condition can be associated with an increased risk of certain complications. These potential issues include a higher likelihood of miscarriage, preterm labor, and early delivery. The unique shape of the uterus can affect the baby’s position, leading to a higher incidence of breech or transverse presentations, which often necessitates a cesarean section delivery. Other reported complications include low birth weight, preeclampsia, and issues with the placenta.
A bicornuate uterus is diagnosed through imaging techniques. Ultrasound is often the initial diagnostic tool, providing clear images of the uterine shape. Magnetic Resonance Imaging (MRI) offers more detailed views, helping to distinguish a bicornuate uterus from other anomalies. Hysterosalpingography (HSG), which involves an X-ray after a special dye is injected, can also aid in diagnosis.
Management often involves increased monitoring during pregnancy to observe the uterus and baby’s development. Surgical correction, known as metroplasty, may be considered in specific circumstances, such as a history of recurrent miscarriages, to unify the uterine cavities. However, this procedure is not always necessary, as many women with a bicornuate uterus carry their pregnancies to term without intervention.