(586) False positive prenatal diagnosis of placenta accreta spectrum: factors associated with overdiagnosis and perinatal outcomes.

Accurate prenatal prediction of placenta accreta spectrum (PAS) is known to improve maternal and neonatal outcomes. However, when striving to increase sensitivity of prenatal sonographic identification of PAS, the risk of overdiagnosis also increases.  We aim to identify factors associated with false positive prenatal diagnosis of PAS and the impact on perinatal outcomes.

Study Design:

All delivery encounters at a single academic institution from 2013-2023 were queried for ICD-10 codes for PAS. Cases (n=775) were then manually reviewed and those with any degree of prenatal suspicion for PAS but no evidence of PAS at the time of delivery were included (n=181). For each case, two variables were created by a consensus of 4 clinical experts: prenatal suspicion (low - true negative; or high - false positive diagnosis), determined by prenatal ultrasound reports and documentation of delivery planning, and a priori risk for PAS (low or high) based on clinical risk factors (i.e prior uterine surgeries and placenta previa). Other patient attributes and perinatal outcomes were identified through the EMR. Bivariate analyses comparing low vs high prenatal suspicion and patient attributes were conducted. Multivariate logistic regression was performed on significantly different outcome measure - preterm birth (PTB) - adjusting for covariates significant at p< 0.05.

Results:

Of the 181cases, 73 (40.3%) were coded as high prenatal suspicion. Advanced maternal age, race, multiparity, higher gestational age at initial prenatal visit and ultrasound, high a priori risk and placenta previa were associated with high prenatal suspicion for PAS. High prenatal suspicion was an independent risk factor for PTB after adjusting for a priori risk and placenta previa (aOR 4.6, 95% 2.1-10.2, p< 0.0001).

Conclusion:

False positive PAS diagnosis (prenatal high suspicion) results in 4.6 times increased risk of iatrogenic preterm birth compared to those with low suspicion. New tools are urgently needed to accurately prenatally rule out PAS to decrease the risk of iatrogenic adverse neonatal outcomes.