Unilateral aplasia of the Müllerian ducts

Unilateral aplasia of the Müllerian ducts, also known as unicornuate uterus, is a congenital anomaly of the female reproductive tract in which one of the two Müllerian (paramesonephric) ducts fails to develop properly during embryonic life. This results in a uterus that is formed from only one Müllerian duct, giving it a characteristic banana-shaped or asymmetric appearance. The condition is classified under Müllerian duct anomalies and corresponds to a Class II anomaly in the American Fertility Society classification system. The affected side may have a completely absent duct or may have a rudimentary horn that can be communicating or non-communicating with the main uterine cavity. The condition primarily affects the reproductive system, including the uterus, and may also be associated with ipsilateral renal anomalies (such as renal agenesis on the affected side), as the Müllerian and mesonephric duct systems develop in close embryologic proximity. Key clinical features include an increased risk of adverse obstetric outcomes such as recurrent pregnancy loss, preterm labor, malpresentation, and ectopic pregnancy (particularly in a rudimentary horn). Some patients may experience dysmenorrhea or pelvic pain, especially if a non-communicating rudimentary horn with functional endometrium is present, leading to hematometra. Many women, however, remain asymptomatic and the condition may be discovered incidentally during imaging for other reasons or during evaluation for infertility or recurrent miscarriage. Diagnosis is typically made through imaging modalities such as pelvic ultrasound, hysterosalpingography, or magnetic resonance imaging (MRI), which is considered the gold standard for characterizing Müllerian anomalies. Treatment depends on the clinical presentation. Surgical excision of a symptomatic non-communicating rudimentary horn may be indicated to relieve pain or prevent complications such as ectopic pregnancy. For women with fertility concerns, close obstetric monitoring is recommended. Cervical cerclage may be considered in cases of cervical insufficiency. There is no cure for the underlying structural anomaly, and management is primarily supportive and symptom-directed.

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