Ruptured bicornuate uterus mimicking ectopic pregnancy: A case report

Abstract

Ruptured uterus presenting in first trimester of pregnancy is extremely uncommon and should raise the suspicion of uterine malformations. We report a case of a 24-year-old primigravida with 10 weeks of gestation presenting with acute abdomen and hemoperitoneum. Laparotomy revealed bicornuate uterus with ruptured rudimentary horn. The incidence, diagnosis and management of such cases is discussed.

Introduction

Uterine rupture is an obstetric catastrophe. It is more common in multigravida or scarred uterus and usually occurs in labor. Uterine rupture in early gestation, that is, the first and second trimester, is less common and mostly associated with uterine anomalies. Uterine anomalies are rare, affecting only 0.1–3.0% of all women^1,2 and up to 10% of women who have lost three or more consecutive pregnancies.^3,4 Of all the Mullerian duct anomalies the incidence of bicornuate uterus is 25%.⁵ Bicornuate uterus is caused by incomplete fusion of bilateral Mullerian system during embryogenesis.⁶ It is commonly associated with pregnancy complications, such as mid-trimester loss and preterm labor, but uterine rupture is a rare event. We report a case of bicornuate uterus with rupture at 10 weeks of gestation.

Case Report

A 24-year-old primigravida in the first trimester (10 weeks) presented to our hospital with acute-onset moderate-to-severe continuous pain in the abdomen for 1 day. Pain was predominantly in the lower half of the abdomen. There was no history of bleeding per vagina, fever, vomiting or abdominal distension. On examination the patient had marked pallor. Her pulse rate was 130/min regular, blood pressure was 100/70 mmHg and respiratory rate was 22/min. She was afebrile. The abdomen was distended with guarding and rigidity on palpation. No lump was felt and bowel sounds were absent. On per vaginal examination cervical motion tenderness was present. Exact uterine size could not be made out and all fornices were full. The patient's chest was clear and cardiac examination was also normal. Her urine pregnancy test was positive. An emergency abdominal ultrasound was done which was suggestive of blood in the peritoneal cavity. The uterus appeared slightly enlarged (10 × 8 × 7 cm) with empty uterine cavity. Just adjacent to the left uterine wall, a mass of approximately 6 × 5 cm, with gestational sac and fetus inside, was seen with crown–rump length corresponding to 10 weeks. Under ultrasonographic guidance, blood was aspirated from the peritoneal cavity and it failed to clot. As these findings were suggestive of ruptured ectopic pregnancy, laparotomy was done. Approximately 2.5 L of hemorrhagic fluid was removed from the peritoneal cavity. The uterus was found to be bicornuate with pregnancy in the left rudimentary horn measuring 5 × 6 cm, which had ruptured at its fundus through a 4 × 2-cm rent (Fig. 1). The fetus ensac was lying in the peritoneal cavity. The left horn of the bicornuate uterus was excised and was sent for histopathological examination. Three units of blood were transfused preoperatively. The postoperative period was uneventful. The patient was advised to use contraception for at least 1 year and was discharged.

Figure 1. Photograph of bicornuate uterus with ruptured rudimentary horn.

Discussion

Pregnancy in a bicornuate uterus is usually considered high-risk and requires extra monitoring because of association with poor reproductive potential. Bicornuate uterus may have full-term deliveries. Even the successful delivery of a twin pregnancy in a bicornuate uterus has been documented, although it is unclear whether vaginal or cesarean section has to be chosen.⁷ In the bicornuate uterus, if pregnancy occurs in the well-developed horn, it continues normally and only in cases where conception occurs in the rudimentary horn does danger need to be anticipated.⁸ The common complications and adverse reproductive outcomes associated with bicornuate uterus are recurrent pregnancy loss (25%),⁹ preterm birth (15–25%)¹⁰ and cervical insufficiency (38%)¹¹ pregnancies. Pregnancy in a rudimentary horn is rare, although it is reported in both communicating and non-communicating horns and treated promptly. Incidence of pregnancy in rudimentary horn of bicornuate uterus is about 1/400 000.¹ When a primigravida presents with ruptured uterus in the first or second trimester, then a congenital malformation of the uterus should be suspected. This could be in unicornuate or bicornuate uterus with or without rudimentary communicating or non-communicating horn. In the present case, it was bicornuate uterus, with pregnancy in the non-communicating left horn. It is possible to diagnose a bicornuate uterus using gynecologic sonography, specifically sonohysterography and magnetic resonance imaging. However, as there is no indication to do such procedures on asymptomatic women, the presence of a bicornuate uterus may not be detected until during pregnancy or delivery. In a cesarean section (usually done due to malpresentation) the irregular shape of the uterus can be noticed. Most reliable methods for diagnosis may be combination of hysteroscopy and laparoscopy. These procedures are typically done during the course of an infertility investigation. Preconception transabdominal metroplasty (Strassmann procedure) gives an increased fetal survival rate from 0% to 80%¹² in rudimentary horn pregnancies. Rupture in rudimentary horn pregnancy occurs because of inability of the malformed uterus to expand with increasing gestational age. Rupture in the rudimentary horn is likely to occur late first and early second trimester. Few cases of pregnancy may reach late second trimester. Hemorrhage occurring because of rupture is massive and can be life-threatening unless diagnosed and treated vigorously. Rarely, pregnancy can go on till late second trimester before uterine rupture. Chang et al.¹³ reported rupture of the rudimentary horn as late as 25 weeks of gestation. A mid-trimester rupture generally occurs at the fundus (as in present case) as opposed to lower-segment rupture during labor. The hemorrhage occurring because of rupture is massive and can be life-threatening, unless diagnosed and treated promptly. Treatment is excision of the ruptured horn in order to prevent risk of uterine rupture in case of subsequent pregnancy in the same horn.¹⁴ Due to the presence of a scar in the upper part of the uterus, pregnancy should be avoided for at least 1 year.

This case highlights the fact that uterine rupture can occur as early as 10 weeks when associated with malformed uterus. Presentation mimics ruptured ectopic pregnancy. Therefore, differential diagnosis of the acute abdomen in the first trimester should include uterine malformation with complication.

Acknowledgment

The authors are deeply grateful to the patient and her relatives who gave their consent to reproduce this clinical data. None of the authors has a conflict of interest. None of the authors has a relationship with any company with a financial interest.

Disclosure

None.