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.