premature rupture of membranes
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ABBR: PROM The rupture of membranes before onset of labor. When PROM occurs at term, labor either begins spontaneously or is induced after 24 hr. Risk factors for PROM include bacterial infection, smoking, and defects of the cervix. Other factors include uterine distention due to multiple pregnancies, previous premature rupture of membranes, vaginal bleeding, sexually transmitted diseases, or low socioeconomic status of the mother. The major maternal hazard of PROM is infection, including chorioamnionitis, endometritis, and sepsis. Fetal hazards include infections, compression or prolapse of the umbilical cord, respiratory distress syndrome, or placental abruption.
SEE: prematurity SEE TABLE: Tests for Premature Rupture of Membranes
PROM is diagnosed when amniotic fluid is found in the vaginal fornix. A sterile speculum is used to observe and collect amniotic fluid. The fluid can be tested with nitrazine paper (which will turn blue, demonstrating alkalinity), or it can be placed on a slide and observed for ferning. False positives can occur with both tests. Alpha-fetoprotein (AFP) and fetal fibronectin (fFN) tests have been used with varying results. An intra-amniotic dye injection is accurate but invasive. Ultrasonography can confirm gestational age, presentation, and amniotic fluid index. Digital exams should not be performed. The Amnisure test, which identifies a specific placental protein in the amniotic fluid, can be performed at the bedside and has high sensitivity and specificity. Delivery is indicated if there are signs of maternal infection or of compromise of the fetus. Antibiotics are ordered as needed, and corticosteroids are given to increase fetal lung maturity between 24 and 34 weeks. Tocolytics are given if the mother needs to be transported to a tertiary facility.
Tests for Premature Rupture of Membranes
|Test||How It Is Done||Discussion|
|Alpha-fetoprotein (AFP) kit||Detects abnormally high concentrations of AFP in vaginal fluids||Sensitivity and specificity are high, about 90-95%|
|Ferning||Assessment of the appearance of dried cervical mucus on a microscope slide. A branching appearance of the dried mucus represents a positive test.||Sensitivity and specificity are only fair (about 60-75%)|
|Fetal fibronectin (fFn) test||Sample cervicovaginal secretions for fFN with a qualitative immunoassay or dipstick indicator||Sensitivity and specificity are high, about 85-95%|
|Intra-amniotic dye injection||Phenol-sulfonphthalein (PSP) or other dye indicators are injected into the amniotic fluid, and assessments are made of the leakage of dye into the vagina.||Sensitivity and specificity are high, but the test is invasive.|
|Nitrazine test||pH indicator test—insert a strip of paper impregnated with nitrazine into the vaginal vault and observe for change in color.||Sensitivity and specificity are only fair (about 60-75%)|
|Ultrasonography||An ultrasound transducer is used transvaginally to determine the length of the cervix. Shorter lengths correlate with an increased risk of premature rupture of membranes.||Sensitivity and specificity are low, esp. in women at low risk for premature delivery. The test is sometimes used in conjunction with other studies.|