Emergency delivery in pregnancies at high probability of placenta accreta spectrum on prenatal imaging: a systematic review and meta-analysis.

Background: Placenta accreta spectrum disorders are associated with a high risk of maternal morbidity, particularly when surgery is performed under emergency conditions. This study aimed to investigate the incidence of emergency cesarean delivery in patients with a high probability of placenta accreta spectrum disorders on prenatal imaging and to compare the maternal and neonatal outcomes between patients requiring emergency cesarean delivery and those not requiring emergency cesarean delivery.

Data Sources: MEDLINE, Embase, Cochrane, and ClinicalTrials.gov databases were searched.

Study Eligibility Criteria: This study included case-control studies reporting the outcomes of pregnancies with a high probability of placenta accreta spectrum on prenatal imaging confirmed at birth delivered via unplanned emergency cesarean delivery vs those delivered via planned elective cesarean delivery for maternal or fetal indications. The outcomes observed were the occurrence of emergency cesarean delivery; incidence of placenta accreta and placenta increta/placenta percreta; preterm birth at <34 weeks of gestation; and indications for emergency delivery. This study analyzed and compared the outcomes between patients who underwent emergency cesarean delivery and those who underwent elective cesarean delivery, including estimated blood loss; number of packed red blood cell units transfused and blood products transfused; transfusion of more than 4 units of packed red blood cell; ureteral, bladder, or bowel injury; disseminated intravascular coagulation; relaparotomy after the primary surgery; maternal infection or fever; wound infection; vesicouterine or vesicovaginal fistula; admission to the neonatal intensive care unit; maternal death; composite neonatal morbidity; fetal or neonatal loss; Apgar score of <7 at 5 minutes; and neonatal birthweight.

Methods: Quality assessment of the included studies was performed using the Newcastle-Ottawa Scale for case-control and cohort studies. Random-effect meta-analyses of proportions, risks, and mean differences were used to combine the data.

Results: A total of 11 studies with 1290 pregnancies complicated by placenta accreta spectrum were included in the systematic review. Emergency cesarean delivery was reported in 36.2% of pregnancies (95% confidence interval, 28.1-44.9) with placenta accreta spectrum at birth, of which 80.3% of cases (95% confidence interval, 36.5-100.0) occurred before 34 weeks of gestation. The main indication for emergency cesarean delivery was antepartum bleeding, which complicated 61.8% of the cases (95% confidence interval, 32.1-87.4). Patients who underwent emergent cesarean delivery had higher estimated blood loss during surgery (pooled mean difference, 595 mL; 95% confidence interval, 116.10-1073.90; P<.001), higher number of packed red blood cells transfused (pooled mean difference, 2.3 units; 95% confidence interval, 0.99-3.60; P<.001), and higher number of blood products transfused (pooled mean difference, 3.0; 95% confidence interval, 1.10-4.90; P=.002) than patients who underwent scheduled cesarean delivery. Patients who underwent emergency cesarean delivery had a higher risk of requiring transfusion of more than 4 units of packed red blood cell (odds ratio, 3.8; 95% confidence interval, 1.7-4.9; P=.002), bladder injury (odds ratio, 2.1; 95% confidence interval, 1.1-4.0; P=.003), disseminated intravascular coagulation (odds ratio, 6.1; 95% confidence interval, 3.1-13.1; P<.001), and admission to the intensive care unit (odds ratio, 2.1; 95% confidence interval, 1.4-3.3; P<.001). Newborns delivered via emergency cesarean delivery had a higher risk of adverse composite neonatal outcomes (odds ratio, 2.6; 95% confidence interval, 1.4-4.7; P=.019), admission to the neonatal intensive care unit (odds ratio, 2.5; 95% confidence interval, 1.1-5.6; P=.029), Apgar score of <7 at 5 minutes (odds ratio, 2.7; 95% confidence interval, 1.5-4.9; P=.002), and fetal or neonatal loss (odds ratio, 8.2; 95% confidence interval, 2.5-27.4; P<.001).

Conclusion: Emergency cesarean delivery complicates approximately 35% of pregnancies affected by placenta accreta spectrum disorders and is associated with a higher risk of adverse maternal and neonatal outcomes. Large prospective studies are needed to evaluate the clinical and imaging signs that can identify patients with a high probability of placenta accreta spectrum at birth, patients at risk of requiring emergency cesarean delivery or peripartum hysterectomy, and patients at high risk of experiencing intrapartum hemorrhage.