It results from an abnormal development of the paramesonephric ducts that results in a uterus divided into two horns from a partial failure of fusion.
- an associated longitudinal vaginal septum may be present in ~ 25 % of cases
- as with other Mullerian duct anomalies, abnormalities of the renal tract may also be present.
Bicornuate uterus is divided according to the involvement of the cervical canal. It can thus be divided into:
- bicornuate bicollis - two cervical canals - central myometrium extends to external cervical os
- bicornuate unicollis - one cervical canal - central myometrium extends to internal cervical os
In most cases, a bicornuate uterus is incidentally discovered when the pelvis is imaged. The most common symptomatic presentation is with early pregnancy loss and cervical incompetence 6 . Infertility is not usually a problem with this type of malformation because implantation of the embryo is not impaired.
The preferred methods of imaging uterine anomalies are ultrasound, hysterosalpingogram or MRI. The external uterine contour is concave or heart shaped, and the uterine horns are widely divergent. The fundal cleft is typically more than 1cm deep and the inter-cornual distance is widened.
The uterus is seen as comprising of caudally fused symmetric uterine cavities with some degree of communication between the two cavities (usually at the uterine isthmus). Although not a specific finding, the angle between the horns of the bicornuate uterus is usually more than 105° 3.
Fluoroscopy - hysterosalpinogram (HSG)
Difficult to differentiate between septate and bicornuate anomalies due to the outer uterine contour not being visible 5.
May help confirm anatomy by showing a deep (> 1cm) fundal cleft in the outer uterine contour and an inter-cornual distance of more than 4cm. The uterus demonstrates normal uterine zonal anatomy.
Treatment and prognosis
Surgical intervention is usually not indicated is absence of reproductive difficulties.
In women with a history of recurrent pregnancy loss and in whom no other infertility issues have been identified and Strassman metroplasty can be considered.
In patients with cervical incompetence placement of a cervical cerclage may increase fetal survival rates 9. Indeed the association between cervical incompetence and bicornuate uterus is so high, that prophylactic cerclage may be appropriate in some instances.
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