Spontaneous successful term delivery in a unicornuate uterus: A case report and literature review.

We hereby present the case of a 24-year-old primiparous Moroccan woman, with no notable medical history who presented to our facility with pelvic pain in the form of uterine contractions at 39 weeks of gestation. The prenatal follow-up of the pregnancy had been uneventful according to the prenatal consultation records. An ultrasound performed at 36 weeks of gestation revealed a progressing singleton pregnancy in oblique presentation with an estimated fetal weight of 3100 g. Following the clinical examination, the patient exhibited regular uterine contractions, and the fetus was found to be in a breech presentation with a significant and prolonged decrease in the fetal heart rate variability detected during monitoring. This alarming condition necessitated an emergency cesarean section due to acute fetal distress. Consequently, a healthy male newborn weighing 3 kg, with a satisfactory APGAR score, was successfully delivered. Upon further examination, the presence of a lateral entanglement of the umbilical cord was observed. During the examination, it was noted that the uterus had a cylindrical shape with a flattened left wall . Fig. 1 shows the absence of the left tubal ostium, left fallopian tube, and left ovary. No other abnormalities were detected during the exploration of the abdominal cavity. It is a UU classified IId according to the American Fertility Society classification (AFS). Hemostasis was ensured with an estimated blood loss of 400 ml. The postoperative course was uneventful. Thus, an ultrasound scan of the kidneys and urinary tract was performed, which did not reveal any abnormalities of the urinary tract. Fig. 1 Intraoperative images of the uterus objectify right unicornuate uterus: (a): The right fallopian tube and the right ovary. (b) and (c): The uterus is cylindrical with a flattened left wall. Fig. 1 Intraoperative images of the uterus objectify right unicornuate uterus: (a): The right fallopian tube and the right ovary. (b) and (c): The uterus is cylindrical with a flattened left wall.

The work has been reported in line with the SCARE criteria.

Abdelhamid Benlghazi, Moad Belouad, Hamza Messaoudi and Saad Benali were responsible for the patient's diagnosis and clinical management. Abdelhamid Benlghazi wrote the manuscript. Benali Saad contributed to the analysis, supervision, writing, reviewing, and editing of the manuscript for intellectual content. All authors have read and approved the final manuscript.

Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.

Ethics approval has been obtained to proceed with the current study.

None.

The corresponding author is the guarantor of submission.

Women with a UU are known to be at increased risk of obstetrical complications, such as spontaneous abortion, premature delivery, post-partum hemorrhage, abnormal fetal presentation and cesarean delivery. It is important to consider women with this anomaly as being at high obstetrical risk. In case of clinical suspicion, advanced imaging examinations are necessary to establish a precise diagnosis. This will enable timely obstetric management and prevention of complications.

The UU can arise from two embryological causes: incomplete development of the para-mesonephric canal or anomalies in the urogenital crest. These causes can also result in variations in renal and ovarian structures. When the development of the mesonephric duct is disrupted, it can lead to abnormalities not only in the mullerian structures but also in renal anatomy [ 5 ].In a study focused on urinary tract anomalies in individuals with a UU, Fedele et al. found that 40.5 % of the 37 patients with a UU had coinciding renal anomalies. The most common anomaly was contralateral renal agenesis to the UU, occurring in 16 % of cases. Other less frequent anomalies associated with the UU included ectopic kidney and horseshoe kidney [ 6 ]. As a result, it is recommended to evaluate the renal system using imaging techniques such as CT, MRI, pelvic ultrasound, or intravenous pyelography whenever a UU is detected [ 7 ]. Although the UU frequently goes unnoticed in many women, based on available incidence data in the literature, the occurrence of a UU is estimated to be approximately one in 4020 women in the general population [ 5 ]. However, this anomaly is notably more prevalent among women experiencing fertility issues, as well as those who have faced repeated pregnancy failures. While the genetic underpinnings of uterine development remain incompletely understood, the UU demonstrates a multifactorial inheritance pattern, although a definitive genetic connection has not been established [ 8 ]. Several theories have been proposed to account for the adverse outcomes associated with the UU, with the most prevalent ones including reduced muscle mass, abnormalities in uterine blood flow, and cervical incompetence [ 9 ]. The AFS classification is commonly employed for Müllerian anomalies due to its simplicity and clinical relevance. However, it has been criticized for excluding vaginal and cervical anomalies ( Fig. 2 ). The American Society for Reproductive Medicine (ASRM) recent classification categorizes Müllerian anomalies into nine groups,while alternative systems like European Society of Human Reproduction and Embryology (ESHRE), and European Society for Gynaecological Endoscopy (ESGE) classification also exist ( Fig. 3 ). Nonetheless, the comprehensive understanding of the diverse range of Müllerian anomalies remains limited, leading to ongoing confusion in the field [ 10 , 11 ]. Fig. 2 Classification of congenital uterine anomalies by American Fertility Society. Fig. 2 Fig. 3 Classification of congenital uterine anomalies by the European Society of Human Reproduction and Embryology, and the European Society for Gynaecological Endoscopy. Fig. 3 Classification of congenital uterine anomalies by American Fertility Society. Classification of congenital uterine anomalies by the European Society of Human Reproduction and Embryology, and the European Society for Gynaecological Endoscopy. Besides a history of premature delivery, there are other clinical indicators that may necessitate the use of imaging for a pre-delivery diagnosis. These signs encompass abnormal fetal presentation, such as breech or transverse positioning, a history of recurrent miscarriage, preterm labor, atypical pelvic examination findings, asymmetrical growth restriction, or a history of infertility. Thoroughly investigating these clinical manifestations and employing advanced imaging techniques enables obstetricians to establish a precise diagnosis and employ suitable management approaches for pregnant women displaying signs that suggest a unicornuate uterus UU [ 7 ]. The UU displays diminished uterine volume and an asymmetrical ellipsoidal shape, detectable through ultrasound and MRI imaging. While it may resemble a normal uterus on ultrasound, MRI definitively identifies a uterine horn without expansion of the endometrial canal towards the fundus.The Hysterosalpingography shows a solitary fusiform uterine cavity with a lateral deviation in the pelvis, ending in a single Fallopian tube.It is worth noting that the diagnosis of a UU can often go undetected during pregnancy, even with the most skilled ultrasound examinations. Despite the expertise of the healthcare provider, there are instances where the diagnosis remains elusive [ 10 ]. Historically, the focus for patients with a UU has been on their ability to sustain pregnancy rather than on fertility issues. It has been observed that these patients have a higher incidence of spontaneous miscarriages in the first and second trimesters, as well as an increased risk of preterm labor and abnormal fetal presentations [ 12 ]. In their study, Raga et al. reported an infertility rate of 23.7 % among patients with a UU [ 15 ]. The reduced fertility in these cases could be attributed to reduced uterine muscle mass or the absence of uterine vascularization [ 12 ]. Regarding the impact of a UU on pregnancy outcomes, a study conducted by Reichman et al. examined 290 women with a reported UU in the literature. Among these women, 175 successfully conceived, resulting in a total of 468 pregnancies. The findings showed that 2.7 % of the pregnancies were ectopic, 24.3 % ended in first-trimester miscarriages, and 9.7 % ended in second-trimester miscarriages. Additionally, 20.1 % of the pregnancies resulted in preterm delivery, while 44.0 % reached full term. Furthermore, 10.5 % of the pregnancies resulted in intrauterine fetal death in the third trimester. Overall, the rate of live births was 49.9 % [ 5 ]. One of the well-documented characteristics of the UU, which gives rise to gynaecological and obstetrical complications, is the existence of a rudimentary uterine horn in cases classified as A1a and A1b. This horn typically encompasses a small cavity housing a functional endometrium. Commonly observed gynaecological issues associated with this condition include endometriosis, hematometra, hematosalpinx, and pelvic pain [ 13 ]. It is also well established that the rudimentary uterine horn is a predisposing factor for ectopic pregnancies. This additional uterine structure can serve as an implantation site, leading to gestation at the level of the horn itself. This situation is particularly common in patients with A1a malformations, where the horn cavities are directly connected to the main uterine cavity [ 5 ]. Removal of the rudimentary uterine horn is now considered the preferred surgical approach for treating dysmenorrhea, ectopic pregnancy and retrograde menstruation in affected patients. The removal of asymptomatic rudimentary horns containing endometrium is recommended. There have been several successful case reports describing the use of laparoscopic techniques for the treatment of a rudimentary uterine horn [ 14 , 15 ]. Furthermore, there is emerging evidence on the application of laparoscopic surgery not only during the first trimester of pregnancy, but also during the second trimester [ 16 ]. Studies have shown that the use of cervical cerclage can prevent premature delivery in patients with a UU. Cervical cerclage may also be beneficial in cases of recurrent miscarriage [ 16 ]. The limitations of this case report include a small sample size, the absence of a control group, a retrospective design, and a case-specific focus. These factors may restrict the generalizability of the findings and the ability to draw definitive conclusions. Future research should involve larger-scale studies with prospective designs to provide more robust evidence and minimize biases. Long-term follow-up studies are also needed to assess reproductive outcomes, and interventional studies can explore the effectiveness of different management strategies.

The faulty fusion of one of the Müllerian ducts gives rise to various uterine anomalies [ 1 ]. According to the literature, the unicornuate uterus (UU) accounts for 2.4 % to 13 % of all Müllerian anomalies [ 2 ]. The prevalence of a UU is 0.1 % [ 3 ]. The UU is classified as type II in the American Fertility Society (AFS) classification of uterine anomalies. There is an additional classification into three categories: with communication, without cavity, and without horn. As these pregnancies are prone to early miscarriages and premature birth, pregnancy in a UU is generally quite rare and can be life-threatening. According to the literature, only 30 % of these pregnancies reach full term [ 4 ].This report presents a rare case of a full-term pregnancy in a unicornuate uterus without an accessory horn, which was incidentally discovered during an emergency cesarean section in our gynecology and obstetrics department. This case report is reported following the SCARE-2020 criteria [ 17 ].

UU Unicornuate uterus AFS American Fertility Society ASRM American Society for Reproductive Medicine ESHRE European Society of Human Reproduction and Embryology ESGE European Society for Gynaecological Endoscopy MRI Magnetic Resonance Imaging CT Computed Tomography Unicornuate uterus American Fertility Society American Society for Reproductive Medicine European Society of Human Reproduction and Embryology European Society for Gynaecological Endoscopy Magnetic Resonance Imaging Computed Tomography

The authors declare no conflict of interest.