136 Bicornuate Uterus

Clinical Presentation

A 26-year-old woman presents with vaginal bleeding. She has a history of multiple miscarriages.

Fig. 136.1 (A) Axial MR T2-weighted image demonstrates two uterine horns with a single cervix. Uterine zonal anatomy appears otherwise normal. A rounded T2 hyperintense focus is visualized within the cervix consistent with a nabothian cyst.(B) Axial MR T1-weighted fat-suppressed image obtained after the administration of intravenous gadolinium shows normal enhancement of the uterus.

Radiologic Findings

An axial magnetic resonance (MR) T2-weighted image (Fig. 136.1) demonstrates two uterine horns with a single cervix. The uterine zonal anatomy appears otherwise normal. A rounded T2 hyperintense focus is visualized within the cervix consistent with a nabothian cyst. An axial MR T1-weighted fat-suppressed image obtained after the administration of intravenous gadolinium shows normal enhancement of the uterus.

Diagnosis

Bicornuate uterus

Differential Diagnosis

Arcuate uterus
Septate uterus
Uterus didelphys

Discussion

Background

Uterovaginal (müllerian) anomalies result from alterations in the development or fusion of müllerian ducts and are associated with a high incidence of infertility, spontaneous abortion, fetal intrauterine growth retardation, preterm labor, and retained placenta; for this reason, most of these abnormalities are discovered in young adulthood or during pregnancy. The incidence is roughly estimated to range between 0.1 and 0.5% in the female population.

Müllerian duct anomalies are commonly categorized into four classes according to embryology:

Class I: dysgenesis—agenesis or hypoplasia of müllerian duct derivatives (uterus, cervix, and upper part of the vagina), as in Mayer-Rokitansky-Kuster-Hauser syndrome (agenesis of the uterus and proximal part of the vagina)
Class II: disorders of vertical fusion—failure of fusion of the descending müllerian duct with the ascending sinovaginal bulb (this group includes cervical agenesis/dysgenesis and obstructive or nonobstructive transverse vaginal septa)
Class III: disorders of lateral fusion—failure of fusion of the paired müllerian ducts (uterus didelphys and bicornuate uterus) and failure of resorption of the midline septum (septate uterus); a subclassification differentiates asymmetric obstructive forms (unicornuate uterus with obstructed horn, unilaterally obstructed double uterus, and unilateral vaginal obstruction) from symmetric nonobstructive forms (unicornuate, bicornuate, septate, didelphys, and diethylstilbestrol [DES]– related uteri)
Class IV: unusual configurations and combined anomalies

Prompt identification of these anomalies is mandatory for the appropriate treatment of infertility and related symptoms.