Comparison of two rapid bedside strip test for the detection of amniotic fluid

Objective: To compare two immunoassay rapid strip tests for the detection of amniotic fluid, ActimPROM Test® (Medix Biochemica, Finnland), based on the detection of insulin-like-growth-factor-binding-protein–1 (IGFBP–1), and AMNISure® (AMNISURE, Cambridge, MA, USA), based on the detection of placental α-microglobulin–1 (PAMG–1).

Aims: Placental α-microglobulin–1 (PAMG–1), a 34-kd protein, has been detected in amniotic fluid and has therefore been taken as marker for a new beside test. Up to now, the standard method for rapid detection of amniotic fluid is based on the detection of IGFBP–1.

Material and Methods: Amniotic fluid samples of 20 pregnant women between 22+0 and 40+4 gestational weeks were taken in pregnant women with clinically overt rupture of membranes (ROM) and pooling of amniotic fluid in the posterior fornix at speculum examination. These samples were diluted with 0.9% saline solution, and a dilution series was performed. Polyester swabs were then agitated in the diluent vials at dilutions of 1: 2, 1: 5, 1: 10, 1: 20, 1: 40, 1: 80, 1: 160, and 1: 320 and dipped into the test vials right before test strips following the manufacturers´ instructions. Results were read and confirmed by a second, independent physician.

Results: Samples of amniotic fluid were taken in 20 pregnant women with ROM at speculum examination. In 4 cases both test methods showed the same results, in all other 16 cases the AMNISure® proved to be superior by detecting amniontic fluid at least at one or two descending concentrations below the ActimPROM Test®.

Conclusion: The AMNISure® seems to be a more sensitive bedside test compared to the ActimPROM Test® for the detection of amniotic fluid.