Discussion
Uterine rupture is an obstetrical complication that is associated with maternal and fetal morbidity and mortality, with an incidence of approximately 0.05% of all deliveries.1 The risk factors for uterine rupture include previous uterine surgery, such as cesarean section and myomectomy, induced labor and multiparity.3 The incidence of uterine rupture after cesarean section is 0.3%.7 In women who have had a cesarean section, uterine rupture can suddenly occur even in the absence of labor, although induced labor has been known to be a leading cause of uterine rupture.8 The typical signs of uterine rupture include abdominal pain, bleeding, shock and fetal distress.9 Thus, uterine rupture should be considered in the differential diagnosis of severe abdominal pain, especially for patients with risk factors for uterine rupture.
Cesarean section is commonly performed by a low transverse uterine incision. It has been reported that pregnant women with previous cesarean section by vertical uterine incision have an increased risk of uterine rupture and preterm birth compared to pregnant women with cesarean section by transverse uterine incision.10 In the current case, prior cesarean section was performed by transverse uterine fundal incision, which is one of the procedures for reducing blood loss during cesarean section in cases of placenta previa in which the placenta covers the anterior uterine wall.4
There are limited reports of uterine rupture due to prior transverse uterine fundal incision.5,6 The previous case reports and the current case are summarized in Table 1. Two patients, including the current patient, underwent MRI at 12 months postpartum, which revealed cesarean section scar thinness and a defect at the uterine fundus. The diagnoses of uterine rupture were made at 21, 30 and 33 weeks of gestation. Only one patient without symptoms was diagnosed with uterine rupture by MRI and delivered a live neonate. In this case, the diameter of the ruptured site was 5 to 7 mm. In the other two patients, the ruptured sites were large enough to expel their fetuses outside the uterus, so they were considered to have complained of severe abdominal pain. It is more difficult to evaluate the thickness of the uterine wall at the fundus by ultrasonography as the gravid uterus is enlarged. MRI is an effective method of determining the thickness of the uterine wall during pregnancy.11 However, it is uncertain when or how many times MRI should be performed during pregnancy and when admission should be recommended during pregnancy in pregnant patients with previous cesarean section by transverse fundal incision. Thus, it is considered that the safety and strategies of perinatal management have not been established for subsequent pregnancy following transverse uterine fundal incision.
PMCD is performed in patients with imminent cardiac arrest or active cardiac arrest, with the ultimate goal of successfully resuscitating the mother and improving fetal survivability. The American Heart Association recommends that PMCD should be initiated after four minutes of failure of resuscitative efforts with a goal of delivery within five minutes (the four- to five-minute rule).2 Cardiac arrest in pregnancy is rare, with an incidence of 2.76 to 7.6 per 10,000 pregnancies.12,13 Thus, when performing PMCD, the decision, timing and place could be challenging. In the UK, a prospective, descriptive study of cardiac arrest in pregnant women revealed that maternal survival rates depended on the time from cardiac arrest to PMCD and that cardiac arrest occurred in the hospital, not outside of the hospital.12 This study also showed that the time from cardiac arrest to PMCD in all survivors who received CPR was within 12 min. It is not necessarily easy to perform PMCD while achieving ‘the four- to five-minute rule’, especially for cases of cardiac arrest that occur outside of the hospital.
In the current case, cardiac arrest occurred outside of the hospital. Upon arrival, the patient had not recovered from arrest despite undergoing CPR for 10 minutes. It had been considered to be quite difficult for the current patient to survive, considering the asystole at arrival and the time for performing CPR after arrival at our hospital. The decision was made to perform PMCD based on the timing of her recovery from arrest by 6 cycles of CPR. It would have been possible to initiate PMCD earlier after the decision if our hospital had a well-established system for performing PMCD in the ED. The patient also developed peripartum hemorrhage caused by uterine rupture. DIC is a leading cause of maternal mortality.14 The patient survived by multidisciplinary management of CPR, PMCD, surgical repair of the ruptured site, blood product transfusion, IVR and intensive care; however, impairment of consciousness persisted.
In conclusion, it is known that the safety for future fertility, pregnancy and delivery in cases of previous cesarean section by uterine transverse incision has not been established, although the procedure is useful to reduce blood loss in cases of placenta previa. It is essential to be prepared to perform multidisciplinary management of cardiac arrest in pregnancy.