Introduction: Uterine rupture is tearing of uterine wall during pregnancy or labor. It can be a catastrophic obstetrical emergency. Various risk factors associated with uterine rupture are well established such as previous uterine surgery, uterine anomaly, inappropriate fundal pressure and placental percreta. Spontaneous rupture of unscarred uterus is very rare, the incidence reported as 1 in 8000-15000. We here report a case of primigravida, double uterus pregnancy encounters spontaneous rupture during late second trimester.

Case Report: A 28-year-old woman, gravid 1 para 0, presents to our emergency room with sudden onset of epigastralgia and cold sweating at 26 weeks of gestation. Her reproductive history is insignificant except double uterus with right side pregnancy is diagnosed during first time prenatal check-up. She has no vaginal bleeding and fetal movement is normal. Fetal nonstress test shows changes of fetal heart rate accompanied with uterine contraction. Physical examination reveals muscle guarding and rebound tenderness over right abdomen. Sonography found no placental hemorrhage except moderate amount of ascites over Morrison's pouch. MRI is performed, clearly shows massive amount of bloody ascites in abdomen and pelvis without other apparent pathologic findings [ figure 1]. Under impression of hemoperitoneum with undetermined cause and fetal distress in second trimester, explore laparotomy is arranged immediately. At surgical entry into abdominal cavity, about 2000cc internal bleeding is initially found, a 1160gm male fetus is delivered with breech presentation with Apgar score: 2'->3'->4'. After removal of placenta, a 1x2cm with 3.5cm depth hole-like defect is seen over fundus of right side uterus [figure 2]. Left side uterus and bilateral adnexa are all in normal figures. Fundal defect is repaired with double layer. The patient has uneventful postoperative course after transfusion with two units of packed RBC.

Conclusion: Uerine rupture can be a fatal event for both fetus and mother. Nearly one fifth of all uterine ruptures occur in women without previous cesarean section. Preterm spontaneous rupture in a non-labouring unscarred uterus is extremely rare, which becomes difficult to diagnose. Congenital uterine anomaly which had been documented as most common risk factor is bicornuate uterus with rudimentary horn pregnancy. To our best knowledge, this is the first report of spontaneous rupture of double uterus in second trimester pregnancy.