Management of bicornuate uterus non-communicating rudimentary uterine horn: A case report

Uterus bicornuate non-communicant rudimentary horn (UBNCRH) is a rare malformation of the uterus (Muellerian duct abnormality type IIB of the American Fertility Society classification) [1]. These anomalies are most typically described as de novo congenital occurrences and are often asymptomatic. A pregnancy in the UBNCRH corresponds to the clinical picture of an ectopic pregnancy. Thus, many complications that may affect the woman and the fetus are an indication of the importance of an early diagnosis of Muellerian anomalies. Often the endometrium in the rudimentary horn is not mature for pregnancy. The decidua is described as thinner, which means that the villi often penetrate the myometrium and erode the wall. A pregnancy in the UBNCRH is a rare form of gestation that occurs due to the transperitoneal migration of the sperm or the zygote during the implantation period. Its incidence is of approximately 1/100,000 to 1/140,000 pregnancies [2]. 75–80% of pregnancies occur in the non-communicant rudimentary horn and is often associated with ectopic pregnancies [3]. The risk of uterine rupture is up to 90% and occur by the end of the second trimester [4]. The maternal and fetal prognosis in unrecognized rudimentary horn ectopic pregnancies is poor, with an average neonatal survival rate of 6% and the rate of uterine rupture close to 80% [5]. Due to the difficult diagnosis of an UBNCRH, it often only shows up with a rupture of the rudimentary horn.

A 28-year-old woman, gravida 2, para 1 conceived a twin dichorionic diamniotic pregnancy and presented in the 16th week of gestation with an imminent aborting (IUFD) after a spontaneous partus 2014. There were no previous illnesses or previous operations. The patient had spotting for several days, as well as recurrent pain with vaginal bleeding. Ultrasound showed negative heartbeat for both fetuses. On admission, the abdomen was soft, without any defensive tension. The transvaginal sonography showed an intrauterine twin pregnancy without recognizing the uterine abnormality (Figure 1).

A crest length of 74 and 52 mm was measured. No heart action was found in either of the fetuses. The Douglas space was free of fluid. After informed consent the patient opted for termination of pregnancy by Cytotec (off-label use) and Nadalor. (Misoprostol 50 μg every 6 hours a maximum of 6 dose. One ampoule of Nalador 50 μg/hour, maximum dose 8.3 μg/min). After four days of unsuccessful induction of labor, we opted for operative termination by curettage and hereby, a uterus bicornus with cornus rudimentarius was suspected. Vaginal access to the right uterine horn could not be achieved. The dilation using Hegar pencils under sonography control was only possible in the left empty uterine horn. The access to the right horn, in which the pregnancy was located, could not be found with a uterine probe. After unsuccessful attempt at uterine dilation, a cesarean section parva was indicated. The situs presented a uterus with two separate parts of the body, which connected into a common cervix (Figure 2). The tubes each separated into a horn. The left uterus was small and inconspicuous, the right uterus distended up to the tube outlet with a conspicuous vascular pattern of the serosa. An incision was made on the front wall and both fetuses and placenta parts were removed. No internal cervix or access to the cervix could be visualized or palpated. Overall, a bicornuate uterus with unilateral right horn atresia was assumed, in which the pregnancy was caused by sperm migration through the abdominal cavity through the contralateral tube. Resection of the obliterated horn, or at least the right tube, was recommended to avoid recurrence.

Muellerian duct anomalies are generally rare and often associated with increase perinatal morbidity and mortality. These abnormalities occur in 0.1–3% of women and are often associated with reproductive problems such as miscarriages, premature labor, premature diaphragm rupture, or misrepresentation [6],[7],[8]. Early diagnosis is difficult, which is why pregnancy in a rudimentary horn is often only revealed by rupture of the rudimentary horn [2]. The time of rupture varies between the 5th and 35th week of gestation, depending on the strength of the myometrium. Pregnancy in a rudimentary horn has a poor reproductive potential and requires close monitoring. In asymptomatic women, the presence of bicornuate uterus may not be detected until during pregnancy or delivery [8],[9]. The sensitivity of sonography reaches approximately up to 26%. Obstetrical outcomes are generally reported to be better in cases of bicornuate uterus in comparison to unicornuate uterus [6]. Ultrasound in early pregnancy has a major rule in the early diagnosis. Magnetic resonance imaging (MRI) can be a useful noninvasive diagnostic tool [10]. The wide reported range of the incidence of rudimentary horn pregnancies lects the rarity of the condition [11],[12],[13]. Only 14% of cases are diagnosed prior to clinical manifestation, usually in the second trimester [14],[15] because rudimentary horns are frequently not diagnosed prior to pregnancy [15]. The low diagnostic suspicion may be attributed to the absence of clinical symptoms in pregnancy. When symptoms such as retrograde menstruation, abdominal pain, dysmenorrhea and fertility are present, a non-rudimentary horn can be suspect. Transvaginal sonography, although the method to investigate adnexal pathology, has a low sensitivity (26–33%) for the diagnosis of a rudimentary horn even before pregnancy. Three-dimensional ultrasound and pelvic MRI scan have become standard imaging modalities for the characterization of Muellerian anomalies. The standard treatment consists of immediate excision of the pregnant rudimentary horn due to the high risk of rupture [11],[14],[15].

The presence of uterus bicornuate non-communicant rudimentary horn poses a great challenge for a gynecologist because that occurs due to the transperitoneal migration of the sperm or the zygote during the implantation period and the Muellerian anomalies are often asymptomatic.