Clinical-sonographic scores for the screening of placenta accreta spectrum: A systematic review and meta-analysis.

OBJECTIVE: Clinical-sonographic scoring systems, combining clinical features and ultrasound imaging markers have been proposed for the screening of placenta accreta spectrum (PAS) but their usefulness in different set-ups remains limited. The aim of this study was to assess and compare different clinical-sonographic score systems performed from the midst of pregnancy for the prenatal evaluation of patients at risk of PAS at birth. DATA SOURCES: PubMed/MEDLINE, Google Scholar, and Embase were searched between October 1982 and October 2022 to identify eligible studies. STUDY ELIGIBILITY CRITERIA: Observational studies providing data on the use of a combined clinical-ultrasound score systems performed from the midst of pregnancy for the prenatal evaluation of PAS. METHODS: Study characteristics were evaluated by two independent reviewers using a predesigned protocol PROSPERO (CRD CRD42022332486). Heterogeneity between studies was analysed with Cochran's Q-test and the I2 statistics. Statistical heterogeneity was quantified by estimating the variance between the studies using I2 statistics. The area under the receiver operating characteristic curve AUC of ROC of each score and their summary (SROC) was calculated with sensitivity and specificity, and the integrated score of the SROC of all sonographic markers was calculated. Forest Plots were used to develop the meta-analysis of each sonographic marker and for the integrated sonographic score. RESULTS: Of 1028 articles reviewed, 12 cohorts and two case-control studies including 1630 patients screening for PAS by clinical-ultrasound scores met the eligibility criteria. A diagnosis of PAS was reported in 602 (36.9%) cases for which 547 (90.9%) intraoperative findings and/or histopathologic data were described. A wide variation in reported sensitivities and specificities was observed between studies and in thresholds used for the identification of patients with a high probability of PAS at birth. The SAUCs of the individual sonographic scores ranged between 0.85 (the lowest) for sub-placental hypervascularity to 0.91 for placental location in the lower uterine segment (LUS), myometrial thinning, and placental lacunae and 0.95 for the loss of clear zone. Only four studies included placental bulging in their sonographic score system and therefore no meta-analysis for this score was performed. The integrated SAUC was 0.83 [95% Confidence Interval (95% CI) 79 to 0.86). Forest Plot analysis revealed an integrated sensitivities and specificities of 0.68 [95% CI 0.53-0.80], and 0.88 [95% CI 0.68 to 0.96]), respectively. CONCLUSIONS: Clinical-sonographic score systems can contribute to the prenatal screening of patients at risk of PAS at birth. While we included multiple sonographic studies from the midst of pregnancy, standardized evaluation should be performed not only with strict ultrasound criteria for the placental position, mid third trimester gestational age at examination, and sonographic markers associated with PAS. Numeric sensitivities, specificities, NPVs, PPV, LR-, and LR+ should be recorded prospectively to assess their accuracy in different set-ups and PTP should be verified at delivery. The variables recommended for most predictive screening are: loss of clear zone underneath the placental bed, placentation in the LUS, and placenta lacunae.