Comparison of fern and evaporation tests for detection of ruptured fetal membranes

Timely diagnosis of ruptured fetal membranes during the pregnancy is important. This study in the Islamic Republic of Iran compared the sensitivity and specificity of the evaporation test that requires no special equipment with the standard fern test requiring a microscope. Two groups of 50 pregnant women were studied: 1 with artificially ruptured membranes (gold standard) and 1 with intact membranes. The positive and negative predictive values of the fern test were 92% and 96% and for the evaporation test were 89% and 98%. The evaporation test is a simple, easy and non-expensive diagnostic test for ruptured membranes.