The natural weakening of fetal membranes is thought to be due to one or a combination of the following. In PROM, these processes are activated too early:
Cell death: when cells undergo programmed cell death, they release biochemical markers that are detected in higher concentrations in cases of PPROM. Poor assembly of collagen: collagen is a molecule that gives fetal membranes, as well as other parts of the human body such as the skin, their strength. In cases of PPROM, proteins that bind and cross-link collagen to increase its tensile strength are altered. Breakdown of collagen: collagen is broken down by enzymes called matrix metalloproteinases (MMPs), which are found at higher levels in PPROM amniotic fluid. This breakdown results in prostaglandin production which stimulates uterine contractions and cervical ripening. MMPs are inhibited by tissue inhibitors of matrix metalloproteinases (TIMPs) which are found at lower levels in PPROM amniotic fluid. Infection
Infection and inflammation likely explains why membranes break earlier than they are supposed to. In studies, bacteria have been found in the amniotic fluid from about one-third of cases of PROM. Often, testing of the amniotic fluid is normal, but a subclinical infection (too small to detect) or infection of maternal tissues adjacent to the amniotic fluid, may still be a contributing factor. In response to infection, the resultant infection and release of chemicals (cytokines) subsequently weakens the fetal membranes and put them at risk for rupture. PROM is also a risk factor in the development of neonatal infections.
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.