Efficacy of shear wave elastography in measuring placental stiffness for pre-eclampsia screening and diagnosis: A systematic review and meta-analysis.

BACKGROUND: Shear wave elastography (SWE) is a non-invasive imaging technique that measures tissue stiffness to assess mechanical properties. In pre-eclampsia (PE), the placenta often stiffens due to abnormal vascular development, inflammation, and fibrosis. Various studies have explored SWE's potential for PE screening and diagnosis but have been limited by diverse patient populations, small sample sizes, and different cut-off values. To evaluate SWE's accuracy for diagnosing and predicting PE across pregnancy trimesters, we conducted this systematic review and meta-analysis, focusing on its pooled sensitivity, specificity, positive predictive value, and negative predictive value.

OBJECTIVES: To find the efficacy of SWE for screening and diagnosing PE in pregnancy.

SEARCH STRATEGY: We systematically searched PubMed, Embase, Scopus, Cochrane Library, Web of Science, and Google Scholar for studies using SWE to assess the placenta in PE across any pregnancy trimester using keyword combinations.

SELECTION CRITERIA: We included all research published in English (original articles, case-control studies, prospective observational studies, including at least eight patients with PE in the study group), evaluating the accuracy of ultrasound elastography for measuring placental stiffness to screen or diagnose PE.

DATA COLLECTION AND ANALYSIS: We calculated true positive, false positive, false negative, and true negative values for each study. Using a random-effects model, we pooled the sensitivity, specificity, and diagnostic odds ratios, and created summary receiver operating characteristic (SROC) curves to evaluate the diagnostic accuracy of SWE for PE. The systematic review and meta-analysis were conducted adhering to PRISMA 2020 guidelines and were registered with INPLASY (INPLASY202460037).

MAIN RESULTS: There were 12 studies included in the meta-analysis that enrolled 1359 patients (367 patients with PE and 992 controls). The prevalence of PE in the study population was 27%. The pooled sensitivity of SWE for PE is 0.87, with 95% confidence interval (CI) of 0.83-0.90, and the pooled specificity is 0.87, with 95% CI of 0.85-0.89. The SROC curve for SWE had an area under the curve (AUC) of 0.9347 with a Q-value of 0.8708. Five studies used SWE for screening and seven for the diagnosis of PE. The pooled sensitivity for screening of PE was 0.90 (95% CI 0.83-0.95), and for diagnosis was 0.85 (95% CI 0.80-0.89). The pooled specificity for PE screening was 0.90 (95% CI 0.87-0.92) and for diagnosis was 0.80 (95% CI 0.76-0.85). The SROC curve for screening had an AUC of 0.9566 (Q-value 0.8996), and for diagnosis, it had an AUC of 0.9181 (Q-value 0.8512). However, these results need to be interpreted cautiously as most of the studies were found to have a high risk of bias.

CONCLUSIONS: SWE shows promise as a non-invasive diagnostic tool, potentially improving PE screening and early detection by identifying alterations in placental stiffness. However, the current evidence is limited by the small number of studies, variability in methodologies, and high risk of bias of included studies. Further large-scale, multi-center studies are necessary to validate SWE's diagnostic accuracy, establish standardized protocols, and determine clinically relevant reference values and thresholds for placental stiffness.