Placenta Accreta Spectrum Without Placenta Previa

Objective: To evaluate placenta accreta spectrum with and without placenta previa with regard to risk factors, antepartum diagnosis, and maternal morbidity.

Methods: We conducted a retrospective cohort study of pathology-confirmed placenta accreta spectrum deliveries with hysterectomy from two U.S. referral centers from January 2010-June 2019. Maternal, pregnancy, and delivery characteristics were compared among placenta accreta spectrum cases with (previa PAS group) and without (nonprevia PAS group) placenta previa. Surgical outcomes and a composite of severe maternal morbidities were evaluated, including eight or more blood cell units transfused, reoperation, pulmonary edema, acute kidney injury, thromboembolism, or death. Logistic regression was used with all analyses controlled for delivery location.

Results: Of 351 deliveries, 106 (30%) had no placenta previa at delivery. When compared with the previa group, nonprevia placenta accreta spectrum was less likely to be identified antepartum (38%, 95% CI 28-48% vs 87%, 82-91%), less likely to receive care from a multidisciplinary team (41%, 31-51% vs 86%, 81-90%), and less likely to have invasive placenta increta or percreta (51% 41-61% vs 80%, 74-84%). The nonprevia group had more operative hysteroscopy (24%, 16-33% vs 6%, 3-9%) or in vitro fertilization (31%, 22-41% vs 9%, 6-13%) and was less likely to have had a prior cesarean delivery (64%, 54-73% vs 93%, 89-96%) compared with the previa group, though the majority in each group had a prior cesarean delivery. Rates of severe maternal morbidity were similar in the two groups, at 19% (nonprevia) and 20% (previa), even after controlling for confounders (adjusted odds ratio for the nonprevia group 0.59, 95% CI 0.30-1.17).

Conclusion: Placenta accreta spectrum without previa is less likely to be diagnosed antepartum, potentially missing the opportunity for multidisciplinary team management. Despite the absence of placenta previa and less placental invasion, severe maternal morbidity at delivery was not lower. Broader recognition of patients at risk for placenta accreta spectrum may improve early clinical diagnosis and patient outcomes.