Term Pregnancy with a Live Fetus in Non-communicating Rudimentary Horn with Placenta Percreta.

Abstract

Abnormalities of embryogenesis of mullerian duct system resulting in congenital anomalies of female genital tract are relatively common [1]. The prevalence of congenital uterine anomalies in the general population is 6.7 % [2]. In women with a history of repeated pregnancy loss, the rate of mullerian anomalies increases to 3–25 % [2, 3]. Unicornuate uterus accounts for 5 % of all mullerian anomalies. Unicornuate uterus is thought to occur in general population at a rate of 1:4,020 [1]. Unicornuate uterus is a type II mullerian anomaly according to the American Fertility Society classification system [1, 4] that occurs due to a complete or partial failure of development of one mullerian duct and incomplete fusion with contralateral side [1]. The failed mullerian duct fusion leads to the formation of an isolated hemiuterus without a contralateral structure (in complete failure) to various degrees of a rudimentary horn (in partial failure) [1]. This rudimentary horn is subclassified into communicating or non-communicating with uterine cavity and a horn with no cavity [1]. In about 84 % of these cases, a contralateral rudimentary horn exists, almost always of a non-communicating type [1, 5]. The attachment of the rudimentary horn may vary from a fibromuscular band (separated variety) to an extensive fusion between the two horns where there is no external separation between them [4, 6]. This was a case with an extensive fusion between the two horns. Pregnancy in such a rudimentary horn is extremely rare, tenfold less common than an abdominal pregnancy [1, 2, 4]. The natural course of a rudimentary horn pregnancy is rupture during the first or mid-second trimester with potentially life-threatening bleeding [1, 5]. In the majority of cases, horn rupture occurs before 20 weeks of gestation [7]; reports of rupture varying from 5 to 37 weeks are described [1, 7]. The uterine wall being thicker and more vascular, bleeding is more severe in rudimentary horn pregnancy rupture, therefore it commonly manifests with acute abdominal pain and intraperitoneal hemorrage [1, 7].