Bicornuate uterus results from incomplete fusion of two uterine horns (Müllerian tubes) leading to varying degrees of separation between the cavities (Pic. 1.). As a result, the lower part of the uterus is unitary while the upper part is bifurcated. The condition is also called a heart-shaped uterus (Pic. 2). There are many degrees of a bicornuate uterus. There is a continuous range of the degree and location of the fusion of the paramesonephric ducts, and existence of a spectrum, rather than a fixed number of types corresponding to strict medical definitions. This degree of fusion and reabsorption can determine the likeliness of a pregnancy reaching full term.
A bicornuate uterus is estimated to occur in 0.1-0.5% of women in the U.S. It is possible that this figure is an underestimate, since subtle abnormalities often go undetected. Some intersex individuals whose external genitalia are perceived as being male may nonetheless have a variably shaped uterus.

Associated disease

Associated defects may affect the renal system, and less common, the skeleton or so called cloacal disease.

Complications

  • fetal growth restriction
  • premature fetal membranes breach

Risk factors

Uterine malformations are associated with genetic and teratogenic factors. Seen as problematic can be contact with any substance with teratogenic potential during pregnancy. Fetus is the most vulnerable in the period of 2 to 12 weeks.

Previously, a bicornuate uterus was thought to be associated with infertility, but recent studies have not confirmed such an association. Pregnancies in a bicornuate uterus are usually considered high risk and require extra monitoring because of association with poor reproduction potential.

A bicornuate uterus is associated with increased adverse reproductive outcomes, such as: 
  • Recurrent pregnancy loss
  • Preterm birth: the rate of preterm delivery is 15 to 25%. A pregnancy may not reach full term in a bicornuate uterus when the baby begins to grow in either of the uterine horns. A short cervical length seems to be a good predictor of preterm delivery in women with a bicornuate uterus.
  • Malpresentation (breech birth or transverse presentation): a breech presentation occurs in 40-50% of pregnancies with a partial bicornuate uterus and not at all (0%) in a complete bicornuate uterus.
  • Deformity: Offspring of mothers with a bicornuate uterus are at high risk for deformities and disruptions and malformations.

None recognized, except for avoiding contact with teratogenic factors.

None possible.

Pharmacotherapy

Pharmacological treatment is mostly additional to deal with conception issues. Hormonal treatment is used for ovarian stimulation and ovulation induction. It is commonly combined with assisted reproduction techniques.
To prolong pregnancy time, to prevent preterm birth, maintaining uterine quiescence in the latter half of pregnancy is important. Limiting the production of stimulatory prostaglandins and inhibiting the expression of contraction-associated protein genes (ion channels, oxytocin and prostaglandin receptors, and gap junctions) within the myometrium seems to be helpful.

Surgical therapy

Usually, women with bicornuate uterus have relatively good reproductive outcomes. Therefore, the pure type rarely require treatment. In case of hybrid types hysteroscopic metroplasty is needed.

The most often method is IVF-ICSI in combination with surgical solution and pharmacotherapy. Own oocytes or donated ones may be used, depending on woman' age and quality of her eggs. Multiple pregnancies may have a negative impact on the likelihood of a full term pregnancy; therefore, a singleton pregnancy should be ensured by eSET (elective single embryo transfer) in these patients.
If all efforts to prevent pregnancy loss fail repeatedly, surrogate mother is needed to carry a baby.

Find more about related issues

Sources

Uterine malformation ―sourced from Wikipedia licensed under CC BY-SA 3.0
Bicornuate uterus ―sourced from Wikipedia licensed under CC BY-SA 3.0
In vitro fertilisation ―sourced from Wikipedia licensed under CC BY-SA 3.0
Bicornuate uterus - diagram ―by Rosenkranzova, created for Fertilitypedia.org licensed under CC BY-SA 4.0
Bicornuate uterus ―by Uthman licensed under CC0 1.0
Uterus bicornis ―by Bayraktar
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