Prenatal Diagnosis of Placental Invasion: A Systematic Review and Meta-analysis on Accuracy of Ultrasonography and MRI in Diagnosis of Placental Invasion

Objective: The aim of this systematic review and meta-analysis was to evaluate and compare the diagnostic accuracy of ultrasonography (US) and magnetic resonance imaging (MRI) in the diagnosis of placental invasion. Method: Two independent scientists carried out a series of searches to obtain relevant research, released from January 1, 2009, to December 31, 2018. National databases (Magiran and SID), KoreaMed, and LILACS were reviewed for literature, released in other languages. A series of MeSH keywords was employed as part of the searching strategy (e.g., pregnancy, pregnant, placental invasion, accreta). A forest plot was built with Meta-DiSc, version 1.4. Results: For placental invasion, the sensitivity and specificity of MRI were 89% (95% confidence interval [CI], 83%–93% with a 95% confidence interval) and 97% (95% CI, 93%–99%), respectively. The sensitivity and specificity of US were 73% (95% CI, 66%–79%) and 89% (95% CI, 84%–93%), respectively. In the detection of placenta accreta solely (as the first grade of placental invasion), the sensitivity and specificity of MRI were 89.3% (95% CI, 86%–92%) and 84% (95% CI, 77%–89.6%). The sensitivity and specificity of US detection were 95.4% (95% CI, 93.8%–96.6%) and 87.3% (95% CI, 81.4%–91.9%), respectively. Conclusion: Due to the increased cesarean sections, placental invasion may be increasing. The diagnosis of prenatal placental invasion is important to reduce maternal morbidity and mortality. Recent trends indicate an increased use of MRI to evaluate placental invasion as a complement to US. The most accurate imaging findings are using US for placental lacunae and MRI to detect the dark intraplacental band.