Summary ROC plot of sensitivity and specificity of peripheral and placental blood microscopy with placental histology as a reference test. The sensitivity of a test is plotted against 1-specificity, allowing comparison of both parameters at the same time for multiple tests. The rectangles and diamonds represent individual studies and size of the rectangles/diamonds is proportional to the number of patients included in the study. The thick round spots are the summary estimates of sensitivity and specificity and the dotted ellipses around the spots represent the 95% confidence intervals around the summary estimates. Black: peripheral blood microscopy; Red: placental blood microscopy. The reference test used to determine the plotted accuracies in this figure is placental histology.