The evaporation test for detecting rupture of the fetal membranes.

A method for detecting rupture of the fetal membranes, first described by Iannetta in 1984, has been tested. It is based on the heating of endocervical material on a glass slide to evaporate water, thus leaving a white residue if amniotic fluid is present and a brown residue if it is not. The method is simple, quick and inexpensive. The study showed the method to be reliable if the result is positive, but also to produce some false-negative results. Interpretation may in some cases be open to observer bias unless clearly positive. Positive results were seen as early as in week 26. This method may prove to be a valuable addition to other tests for detecting rupture of the fetal membranes.