Fern test. Fern test refers to detection of a characteristic 'fern like' pattern of cervical mucus when a specimen of cervical mucus is allowed to dry on a glass slide and is viewed under a low-power microscope. The fern test is used to provide evidence of the presence of amniotic fluid and is used in obstetrics to detect the rupture of membranes and the onset of labor. #ferntest #ferning #amnioticfluid #Microscopy #Obstetrics #ROM #Cervix #Cervical #Clinical