RESUMO
OBJECTIVES: To perform a systematic review and meta-analysis of the diagnostic test accuracy of ultrasound and magnetic resonance imaging (MRI) and compare the performance of the two modalities in the diagnosis of placenta accreta spectrum (PAS). METHODS: This was a systematic review conducted following the Cochrane Diagnostic Test Accuracy Reviews guideline. A literature search was performed in five databases: PubMed, EMBASE, PMC, The Cochrane Library and BVS-Bireme between 27 July and 4 August 2020. The search was updated on 18 August 2021. We included observational studies evaluating diagnostic accuracy in women with risk factors for PAS who had undergone both ultrasound and MRI examinations, published in English between 2011 and 2021. Quality Assessment of Diagnostic Accuracy Studies-2 was used to evaluate the quality of the studies. Forest plots for sensitivity and specificity with 95% CIs and receiver-operating-characteristics curves for ultrasound and MRI were constructed. RESULTS: The literature search identified 266 studies. After reviewing the titles and abstracts of the articles, 51 were selected for full-text review and 17 studies including 1301 women with MRI and ultrasound data available were selected for the meta-analysis. The study population included 457 cases with PAS diagnosed using the gold standard method (intraoperative or histopathological analysis). The overall quality of the evaluated studies was considered satisfactory according to QUADAS-2. The meta-analysis revealed a sensitivity of 0.833 (95% CI, 0.776-0.878) and specificity of 0.834 (95% CI, 0.746-0.897) for ultrasound. For MRI, sensitivity was 0.838 (95% CI, 0.786-0.879) and specificity was 0.831 (95% CI, 0.770-0.878). There was no statistically significant difference between the two modalities. The Cochran's Q values indicated a high level of heterogeneity of sensitivity and specificity of ultrasound and MRI across studies. CONCLUSIONS: Ultrasound and MRI have similar accuracy in the diagnosis of PAS. These results suggest that, in a setting with a high prevalence of risk factors, the choice of imaging modality for initial screening for PAS should depend on the availability of equipment and the examiner's expertise. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.