BackgroundDistinguishing hydatidiform moles (HMs) from nonmolar specimens and the subclassification of HM are important because complete hydatidiform mole (CHM) is associated with an increased risk of development of gestational trophoblastic neoplasia. However, diagnosis based solely on morphology has poor inter‐observer reproducibility. Recent studies have demonstrated that the use of p57KIP
2 immunostaining improves diagnostic accuracy for CHM.ObjectivesTo evaluate the accuracy of p57KIP
2 immunostaining compared with molecular genotyping for the diagnosis of CHM.Search strategyMajor databases were searched from inception to March 2017 using the terms ‘hydatidiform mole’, ‘p57’, and ‘genotyping’, with their variations, and the search limit for the relevant study design.Selection criteriaAny cross‐sectional study, case series, case–control study, cohort study, or clinical trial that evaluated the accuracy of p57KIP
2 immunostaining for the diagnosis of CHM compared with genotyping was included. Case reports, narrative reviews, expert opinions, and animal testing were excluded.Data collection and analysisExtracted accuracy data were tabulated and pooled using a hierarchical bivariate random effects model.Main resultsBivariate meta‐analysis produced a summary sensitivity of 0.984 (95% CI: 0.916–1.000) and specificity of 0.625 (95% CI: 0.503–0.736) with significant heterogeneity for specificity (I
2 = 71.8, chi‐square P = 0.029). The pooled summary diagnostic odds ratio was 56.54 (95% CI: 11.03–289.74) with no heterogeneity (I
2 = 0.00%, chi‐square P = 0.67). The diagnostic performance of the test was high with an area under the curve of (AUC) 0.980.Conclusionsp57KIP
2 immunostaining is accurate when diagnosing CHM. It can be used as an adjunct test in a combination algorithmic approach.Tweetable abstractA meta‐analysis to evaluate the accuracy of p57KIP
2 compared with genotyping to diagnose CHM.