Primary Posterior Uterine Rupture in Labor: Case Report and Literature Review

Abstract

Purpose: To report a rare case of primary posterior uterine rupture in a healthy term multigravida. Methods: Case report. Results: We present the case of an otherwise healthy 35-year-old gravida 4 para 3 with no reported medical or surgical history and three prior uncomplicated term vaginal deliveries who presented in labor at 39 weeks gestation. After four hours of oxytocin augmentation, the fetus was noted to have recurrent late decelerations and then became bradycardic with a baseline of 60 bpm. The patient’s cervix was found to be 7 cm dilated, 90% effaced, and -1 station. Standard resuscitative measures were undertaken at which point the patient’s cervix was rechecked and found to be 9 cm dilated, 90% effaced, and -1 station. Attempts at manually reducing the cervix while the patient pushed were unsuccessful. With the fetus still bradycardic with a baseline of 60 bpm, the patient was taken for an emergency Cesarean delivery. Within seven minutes of calling the emergency Cesarean delivery, surgery had started. However, there was difficulty with delivering the fetus, who had flipped to transverse back down. The fetus was rotated to breech before being delivered through a “T” incision made on the uterus to facilitate delivery of the head. Three tight nuchal cords were reduced at time of delivery. Examination of the uterus after delivery of the fetus revealed a full thickness, cruciate-shaped laceration in the posterior lower uterine segment extending ~9 cm in the vertical plane, involving the vagina, and ~5 cm in the transverse plane. The rupture was repaired, and the remainder of the surgery proceeded without further complication. Blood loss was estimated at 2500 mL, and she required transfusion of 4 units of packed red cells, 2 units cryoprecipitate, 1 unit fresh frozen plasma, and 1 unit of platelets. The infant was atonic upon delivery with a weight of 3785g and APGARs of 1/5/7. Umbilical artery blood gas analysis was normal with a pH of 7.19 and a base deficit of 7.9 mmol/L. The infant initially required intubation, but quickly improved and was extubated to room air at 1 hour of life. Imaging and neurological exams indicated possible moderate encephalopathy, and the infant underwent therapeutic hypothermia for four days at which point cooling was discontinued after improvement was noted. The remainder of his NICU stay was unremarkable and he was discharged on day nine of life. The mother required 2 additional units of packed red cells during the remainder of her postpartum course, but otherwise did well and she was discharged on post-op day five. Conclusion(s): Uterine rupture is the complete separation of all three layers of the uterus. It is a life-threatening event for both the fetus and the mother. Most uterine ruptures occur in a previously scarred uterus. Uterine rupture in a previously unscarred uterus (primary uterine rupture) is rare and estimated to occur in ~1:20,000 pregnancies. Over 90% of primary uterine ruptures occur in the anterior lower uterine segment. Although this patient did not have any reported medical or surgical history, her status as a multipara and being of advanced maternal age did pose a higher risk of primary rupture. This patient also underwent 3 ½ hours of oxytocin infusion at the time the Cesarean was called. Although she was not on oxytocin for long, its use is associated with primary uterine rupture more so than secondary rupture. Normal indicators of uterine rupture include non-reassuring fetal heart rate tracing, sudden unexplained abdominal pain, unexplained vaginal bleeding, and loss of fetal station. In this patient, fetal bradycardia was the only sign that her uterus was compromised. Although the uterine arteries were not involved in this patient’s rupture, blood loss was still profound due to the extensive uterine defect. This case highlights that, while rare, uterine rupture can occur in any patient, regardless of uterine surgical history and physicians must be prepared to intervene quickly.