Commonly used methods for detecting amniotic fluid in the vagina include research LA cells, ferning, nitrazina paper, ultrasound and dye injection. These methods are difficult to interpret or invasive. We have tested a new method which detects a fetal isoform of fibronectin in vaginal secretion when amniotic fluid is present. Clinical trials demonstrate the sufficient reliability in detecting amniotic fluid in the vagina of women with rupture of amniotic membranes.