Diagnostic performance of different examination methods for detecting obstetric anal sphincter injuries: A meta-analysis comparing multiple diagnostic methods

Background: There was limited evidence on the comparative value of various examination methods for women with obstetric anal sphincter injuries (OASIS).

Objectives: To evaluate diagnostic performance of different examination methods for detecting OASIS.

Methods: We searched PubMed, EMBASE, Cochrane Library, and Web of Science to identify relevant studies from inception to December 2023. The Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool was used to assess methodological quality of included studies. We extracted sufficient data to construct 2 × 2 tables and then used STATA version 12.0 to perform data pooling, heterogeneity testing, and subgroup analysis.

Results: For external anal sphincter (EAS), 4 studies including 514 patients were included in analysis. The pooled sensitivity and specificity of endovaginal ultrasound (EVUS) were 0.59 (95 % CI: 0.33-0.85) and 0.71 (95 % CI: 0.50-0.92). The pooled sensitivity and specificity of transperineal ultrasound (TPUS) were 0.78 (95 % CI: 0.63-0.93) and 0.74 (95 % CI: 0.59-0.89). For internal anal sphincter (IAS), we analyzed 3 studies with 459 patients. The pooled sensitivity and specificity of EVUS were 0.54 (95 % CI: 0.44-0.65) and 0.90 (95 % CI: 0.87-0.94). The pooled sensitivity and specificity of TPUS were 0.47 (95 % CI: 0.29-0.65) and 0.93 (95 % CI: 0.89-0.97). Subgroup analysis showed that 3D images may have better sensitivity than that of 2D images when diagnosing EAS with either EVUS (0.74 vs 0.37) or TPUS (0.80 vs 0.74).

Conclusion: In evaluating OASIS, TPUS had better diagnostic value than EVUS in detecting EAS. For examining IAS, TPUS and EVUS are comparable in terms of diagnostic accuracy. Due to limited data available, more studies with rigorous methods are required to confirm our findings.