Torsion in a Pregnant Noncommunicating Uterine Horn - Journey from Misdiagnosis to Laparoscopic Management: A Case Report.

An 18-year-old primigravida, conceived by self-administered insemination, presented to the emergency department at 17 weeks’ gestation with right-sided abdominal pain. There was no medical or surgical history of note. Her observations were normal. There was some tenderness on palpation of the right lower abdomen with no signs of peritonism. Routine blood and urine analysis were normal. An ultrasound examination confirmed fetal demise on the background of a dating scan which suggested a bicornuate uterus with the pregnancy in the right horn. Medical management with mifepristone/misoprostol was commenced in line with the national guidance for second-trimester miscarriages. During treatment, she experienced variable abdominal pain with episodes of pyrexia, accompanied by a rising C-reactive protein but a normal white cell count. Despite two full cycles of medical management, no cervical change was observed. In view of the ongoing pyrexia and suspicion of sepsis, surgical management under ultrasound guidance was recommended, and the patient was fully counseled regarding all potential risks including hysterotomy. Intraoperative ultrasound revealed that the pregnancy was completely separate from the uterus, rather than within a bicornuate uterus as was previously described, thereby raising the suspicion of a NCUH pregnancy. Laparoscopy then confirmed a torted right NCUH pregnancy [ Figure 1 ], which was totally distinct from the unicornuate uterus and the normal left tube/ovary [ Figure 2 ]. Laparoscopic excision of the gravid horn and right adnexa was performed with minimal blood loss, and the patient was discharged the following day. Histology confirmed a pregnancy sac with an endometrial and myometrial component, thereby clinching the diagnosis of a NCUH pregnancy. Torted right noncommunicating uterine horn pregnancy Pregnancy sac completely separate from the unicornuate uterus and a normal left tube/ovary

Congenital uterine anomalies (CUAs) are due to the abnormal development of Mullerian ducts in fetal life. A meta-analysis estimated the prevalence of CUAs to be 5.5% in general, 8.0% in infertile women, 13.3% in those with a previous miscarriage, and 24.5% in those with miscarriage and infertility.[ 1 ] Unicornuate uterus is a type of CUA that results from abnormal or failed development of one Müllerian duct and is divided into two subclasses depending on the presence or absence of a functional rudimentary cavity. It accounts for 2.4%–13% of all Mullerian anomalies.[ 2 ] 72%–85% of the rudimentary horns are noncommunicating with the cavity[ 3 ] and can be associated with ectopic pregnancies. Pregnancy in a noncommunicating uterine horn (NCUH) is extremely rare with an incidence of 1:100,000–1:140,000.[ 4 ] Diagnosis can be challenging, and ultrasound imaging has limited accuracy, often leading to missed diagnosis and delay in appropriate treatment. Torsion of the noncommunicating horn is even rarer, and there are only a handful of such cases reported in the wider literature. We present one such case, detailing the journey from initial misdiagnosis as a mid-trimester miscarriage to definitive diagnosis as a torted NCUH pregnancy and its successful laparoscopic management.

Our case highlights the importance of an early ultrasound for localizing pregnancy in known uterine anomalies and a high index of clinical suspicion of ectopic pregnancy in such cases. Alternate diagnosis and additional imaging such as MRI should be considered early, especially if there is an unexpected response to standard medical management. The potential of torsion in cases where there is fetal demise and/or worsening pain must also be considered. Misdiagnosis can have catastrophic results in such cases resulting in rupture and significant hemorrhage and the subsequent need for laparotomy and blood transfusions. Hence, an early accurate diagnosis and surgical intervention are key to minimize maternal morbidity and avoid mortality. Excision of rudimentary horn with ipsilateral salpingectomy is the recommended surgical treatment and can be successfully carried out laparoscopically even in more advanced gestations. This study was conducted in accordance with the ethical principles outlined in the Declaration of Helsinki and its amendments. The authors certify that they have obtained all appropriate patient consent form. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed. MD, RM and SS were all involved in the development, writing and review of the manuscript. All authors have read and agreed to the final version of the manuscript. Data sharing is not applicable to this article as no datasets were generated or analyzed during the current study. There are no conflicts of interest.

CUAs arise from nonfusion of the Müllerian ducts or failed resorption of the uterine septum. The European Society of Human Reproduction and Embryology and the European Society for Gynaecological Endoscopy classification system for female genital malformations organizes uterine anomalies into six main classes, of which class U4 includes all cases of unicornuate uterus. This is further divided into two subclasses: class U4a or hemiuterus with a rudimentary cavity characterized by the presence of a communicating or noncommunicating functional contralateral horn and class U4b or hemiuterus without a rudimentary cavity characterized either by the presence of a nonfunctional contralateral uterine horn or by aplasia of the contralateral part.[ 2 ] Clinically, noncommunicating rudimentary horns with a functional endometrium are the most significant subtype as they are likely to be associated with dysmenorrhea and pelvic pain from hematometra or from endometriosis due to retrograde menstruation. Rarely, the rudimentary horn can also be the site of a pregnancy as was first noted by Mauriceau and Vassal in 1669.[ 5 ] The reported incidence is 1 in 100,000–140,000 pregnancies, and the most accepted explanation is the transperitoneal migration of the sperm or fertilized ovum.[ 4 ] This explains the visualization of the corpus luteum in the contralateral ovary. Most cases of pregnancy in the rudimentary horn result in rupture of the horn in the second or third trimester. This is usually observed between the 10 th and 20 th week of gestation; however, a rupture as late as 34 weeks has been reported in the literature.[ 5 ] Rupture usually occurs secondary to an underdeveloped myometrium, a dysfunctional endometrium, and the relatively small cavity size. Furthermore, there is a higher predilection to placenta percreta with a reported incidence of 11.9%.[ 4 ] It is rare for such cases to result in a viable baby. Nanda et al . have reported a case of a twin pregnancy in a unicornuate uterus with a noncommunicating rudimentary horn, in which two siblings, each in separate horns, were delivered successfully by cesarean section.[ 6 ] Nahum analyzed 588 cases to assess the clinical outcomes of rudimentary horn pregnancies. Rupture occurred in 50% of cases and 80% of these occurred before the third trimester. There was no clear trend in either the incidence or timing of rupture over time; however, the overall rates of newborn survival did appear to improve with time and ranged between 0% and 13%.[ 7 ] Another exceptionally rare outcome of NCUH pregnancy is torsion of the gravid horn. Kumar et al . have reported one such case where the uterine axis had twisted 90° bringing the pregnant rudimentary horn anterior to the small unicornuate uterus lying posteriorly and have also noted a case presented by Singh et al . of torsion of a gravid rudimentary horn and ipsilateral ovary.[ 8 ] Imaging plays an essential role in the diagnosis and planning of treatment; however, ultrasound sensitivity is only 26%.[ 4 ] The diagnosis becomes even more challenging with advancing pregnancy as the enlarging horn obscures adjacent anatomical structures, and the sensitivity of ultrasound declines further.[ 4 ] Magnetic resonance imaging (MRI) is associated with a higher diagnostic sensitivity and may provide more useful data regarding the exact uterine anomaly and subtype even at more advanced gestations. It also allows detailed assessment of the renal tract to exclude concurrent renal anomalies. However, selection of the initial imaging modality is often guided by the presenting clinical scenario. In younger patients or acute cases, ultrasound is the preferred method because it is readily available and relatively inexpensive. Three-dimensional ultrasound techniques in skilled hands may also be beneficial and aid diagnosis.[ 9 ] Tsafrir et al . suggested the following criteria for diagnosing a pregnancy in the rudimentary horn: (1) a pseudo pattern of asymmetrical bicornuate uterus; (2) absent visual continuity between the cervical canal and the lumen of the pregnant horn, and (3) the presence of myometrial tissue surrounding the gestational sac.[ 10 ] The differential diagnosis includes a tubal pregnancy, interstitial pregnancy, or an intrauterine pregnancy in a bicornuate uterus. A tubal pregnancy will not show a ring of myometrium surrounding the gestational sac. A variation in the thickness of the myometrium in two horns and a marked distance between them favors the diagnosis of a rudimentary horn pregnancy. The continuity between the endometrium lining the gestational sac and the other uterine horn is typical for a pregnancy in a bicornuate uterus.[ 10 ] Surgery is generally recommended whenever a diagnosis of rudimentary horn pregnancy is made; however, conservative management and close monitoring with early delivery may be an option in advanced pregnancies. However, this needs careful and detailed patient counseling. The traditional treatment was laparotomy and surgical removal of the gravid horn to prevent rupture and recurrent rudimentary horn pregnancies. Recently, however, several cases have been treated successfully by laparoscopies using various techniques.[ 5 ] A safe laparoscopic procedure is associated with rapid favorable outcomes, and immediate surgery also avoids hemorrhagic injuries requiring emergency laparotomy. Excision of the ipsilateral fallopian tube is recommended to prevent a further ectopic tubal gestation. Some authors have described alternatives or adjuncts to surgery in early gestation in the form of systemic methotrexate administration or feticide with intracardiac potassium chloride.[ 5 ] Medical treatment with methotrexate and its resection by elective laparoscopy later is also reported in cases diagnosed during pregnancy. The use of labor induction agents for the termination of pregnancy in a rudimentary horn is unsuccessful and can lead to rupture of the horn. Samuels and Awonuga reported rupture after the use of misoprostol due to misdiagnosis.