Fern test: A sterile cotton swab is used to collect fluid from the vagina and place it on a microscope slide. After drying, amniotic fluid will form a crystallization pattern called arborization which resembles leaves of a fern plant when viewed under a microscope. Fibronectin and alpha-fetoprotein blood tests

Classification
Prelabor rupture of membranes (PROM): when the fetal membranes rupture early, at least one hour before labor has started. Prolonged PROM: a case of prelabor rupture of membranes in which more than 18 hours has passed between the rupture and the onset of labor. Preterm prelabor rupture of membranes (PPROM): prelabor rupture of membranes that occurs before 37 weeks gestation. Midtrimester PPROM or pre-viable PPROM: prelabor rupture of membranes that occurs before 24 weeks gestation. Before this age, the fetus cannot survive outside of the mothers womb. Additional tests
The following tests should only be used if the diagnosis is still unclear after the standard tests above. Ultrasound: Ultrasound can measure the amount of fluid still in the uterus surrounding the fetus. If the fluid levels are low, PROM is more likely. This is helpful in cases when the diagnosis is not certain, but is not, by itself, definitive. Immune-chromatological tests are helpful, if negative, to rule out PROM, but are not that helpful if positive since the false-positive rate is relatively high (19–30%). Indigo carmine dye test: a needle is used to inject indigo carmine dye (blue) into the amniotic fluid that remains in the uterus through the abdominal wall.
Genetics
Many genes play a role in inflammation and collagen production, therefore inherited genes may play a role in predisposing a person to PROM. Diagnosis
To confirm if a woman has experienced PROM, a clinician must prove that the fluid leaking from the vagina is amniotic fluid, and that labor has not yet started. To do this, a careful medical history is taken, a gynecological exam is conducted using a sterile speculum, and an ultrasound of the uterus is performed. History: a person with PROM typically recalls a sudden "gush" of fluid loss from the vagina, or steady loss of small amounts of fluid. Sterile speculum exam: a clinician will insert a sterile speculum into the vagina in order to see inside and perform the following evaluations. Digital cervical exams, in which gloved fingers are inserted into the vagina to measure the cervix, are avoided until the women is in active labor to reduce the risk of infection.Pooling test: Pooling is when a collection of amniotic fluid can be seen in the back of the vagina (vaginal fornix). Sometimes leakage of fluid from the cervical opening can be seen when the person coughs or performs a valsalva maneuver. Nitrazine test: A sterile cotton swab is used to collect fluid from the vagina and place it on nitrazine (phenaphthazine) paper. Amniotic fluid is mildly basic (pH 7.1–7.3) compared to normal vaginal secretions which are acidic (pH 4.5–6). Basic fluid, like amniotic fluid, will turn the nitrazine paper from orange to dark blue.