AmniSure versus fern testing to assess the rupture of fetal membranes in pregnant women a review of the comparative accuracy, cost-effectiveness, and guidelines

Summary: Prelabor rupture of the fetal membranes is a complication in five to 10 percent of all pregnancies, and without timely detection is associated with increased perinatal morbidity. Accurate diagnosis of membrane rupture is important. Conventional techniques for diagnosing membrane rupture include speculum examination, nitrazine testing to detect pH changes in vaginal discharge, and fern testing. Fern testing involves the detection of a characteristic tree-like pattern resulting from amniotic fluid crystallization. Because of the intrusiveness and uncertainty of speculum examination and modest diagnostic reliability of other tests, particularly in the presence of urine, semen, or blood, there is a need for other detection methods. One such method is AmniSure, which is an immunoassay for placental alpha microglobulin-1 (PAMG-1). PAMG-1 is abundant in amniotic fluid, but is found in negligible amounts in vaginal secretions without membrane rupture. The purpose of this review is to compare the comparative diagnostic accuracy and cost-effectiveness of AmniSure compared with fern testing for detection of rupture of the fetal membrane. Evidence-based guidelines for the use of AmniSure will also be reviewed.