Although an infrequent occurrence, the placenta can adhere abnormally to the gravid uterus leading to significantly high maternal morbidity and mortality during cesarean section (CS). Contemporary national statistics related to a morbidly adherent placenta, referred to as placenta accreta spectrum (PAS), are needed.
To examine national trends, characteristics, and perioperative outcomes of women who underwent CS for PAS in the United States.
This is a population-based retrospective, observational study querying the National Inpatient Sample. The study cohort included women who underwent CS from 10/2015-12/2017 and had a diagnosis of PAS. The main outcome measures were patient characteristics and surgical outcomes related to PAS assessed by the generalized estimating equation on multivariable analysis. Temporal trend of PAS was also assessed by linear segmented regression with log transformation.
Of 2,727,477 cases that underwent CS during the study period, 8,030 (0.29%) had the diagnosis of PAS. Placenta accreta was the most common diagnosis (n=6,205, 0.23%), followed by percreta (n=1,060, 0.04%) and increta (n=765, 0.03%). The number of PAS cases increased by 2.1% every quarter-year from 0.27% to 0.32% (P=0.004). On multivariable analysis, (i) patient demographics: older age, tobacco use, recent diagnosis, higher comorbidity, and use of assisted reproductive technology, (ii) pregnancy characteristics: placenta previa, prior CS, breech presentation, and grand multiparity, and (iii) hospital factors: urban-teaching center and large bed capacity hospital, represented the independent characteristics related to PAS (all, P<0.05). The median gestational age at CS was 36 weeks for placenta accreta, and 34 weeks for both placenta increta and percreta versus 39 weeks for non-PAS cases (P<0.001). On multivariable analysis, CS complicated by PAS was associated with increased risk of: any surgical morbidities (78.3% versus 10.6%), CDC-defined severe maternal morbidity (60.3% versus 3.1%), hemorrhage (54.1% versus 3.9%), coagulopathy (5.3% versus 0.3%), shock (5.0% versus 0.1%), urinary tract injury (8.3% versus 0.2%), and death (0.25% versus 0.01%) compared to CS without PAS. When further analyzed by subtype, CS for placenta increta and percreta was associated with higher likelihood of hysterectomy (0.4% for non-PAS, 45.8% for accreta, 82.4% for increta, 78.3% for percreta, P<0.001) and urinary tract injury (0.2% for non-PAS, 5.2% for accreta, 11.8% for increta, 24.5% for percreta, P<0.001). Moreover, women in the placenta increta and percreta groups had markedly increased risks of surgical mortality compared to those without PAS (increta, odds ratio 19.9; and percreta, odds ratio 32.1).
Patient characteristics and outcomes differ across the PAS subtypes and women with placenta increta and percreta have considerably high surgical morbidity and mortality risks. One in 313 women undergoing CS had a diagnosis of PAS by the end of 2017 and the incidence appears to be higher than reported in previous studies.

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