Uterus bicornuate

Definition Bicornuate uterus is the result of incomplete fusion of the cranial parts of the miillerian ducts [21,28] (Fig. 4.5). 

Two uterine cavities with normal zonal anatomy can be depicted. The leading imaging feature is a fundal cleft greater than 1 cm of the external uterine contour that helps to distinguish bicornuate uterus from septate uterus. 

Bicornuate uterus occurs with wide variability. Extension of the intervening fundal cleft to the internal cervical os characterizes the complete bicornuate uterus with a single cervix (bicornuate, unicollis uterus), whereas variants of partial bicornuate uterus exist if the cleft is of variable length. Bicornuate uterus maybe associated with a duplicated cervix (bicornuate bicollis uterus), as well as with a longitudinal... 

Differentiation from bicornuate uterus is based on the complete fundal unification however, a broad-based septate uterus is difficult to distinguish from an arcuate uterus. There is much controversy as to whether an arcuate uterus should be considered a real anomaly or an anatomic variant. Fact is that MRI may detect this abnormality but, typically, it is not clinically significant because arcuate uterus has no significant negative effects on pregnancy outcome. 

Congenital abnormalities of the fallopian tubes are also extremely rare. As in the ovaries, they present more likely a sequelae of torsion or an inflammatory process. Tubes may be partially atretic or hypoplastic and associated with uterine abnormalities such as rudimentary uterine horn or bicornuate uterus. In infertility patients exposed to diethylstilbestrol, short sacciflated or dilated fallopian tubes have been reported [21]. 

A longitudinal vaginal septum (Fig. 12.9) occurs as a consequence of incomplete fusion of the miille-rian ducts or resorption failure of the vaginal septum. This anomaly is also typically associated with other malformations of the mullerian ducts [septate uterus, bicornuate uterus, uterus didelphys (Fig. 12.9), cervical duplication] [2j. 

HSG of a bicornuate uterus will demonstrate separate uterine cavities with an intercornual angle that usually exceeds 105X With this imaging modality, however, the outer uterine contour cannot be evaluated, and overlap with the appearance of a septate uterus can occur. 

Sonographic diagnosis of a bicornuate uterus is made by analysis of both the outer fundal contour as well as visualization of a separate endometrial stripe in each horn. However, sonographic differentiation of a bicornuate uterus from a septate uterus may be difficult. 

Sonography and MRI are each superior to HSG. The external uterine contour is normally convex, flat, or minimally indented by less than 1 cm [14], in contrast to that of a bicornuate uterus. Coronal MRI allows the characteristic fundal changes of a septate uterus to be identified. 

Fig. 7.4a-f. Schematic presentation of classes 111, IV, and V. a Uterus didelphys (class 111) b-d bicornuate uterus (class IV) b complete, c partial, d arcuate e,f septate uterus (class V) e complete, f partial... 

An uterus didelphys or bicornuate uterus can, therefore, readily be demonstrated. The prepubertal uterus is smaller, has a tube shape, and a non-appar-ent endometrium, making it almost impossible to evaluate uterine anomalies (Fig. 7.10). 

Formerly this MDA was classified as the mildest form of either a bicornuate or septate uterus. In 1988, the American Fertility Society issued a separate classification of arcuate uterus. Arcuate uterus should be considered a normal variant and it has no effect on fertility. 

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