Two large studies have assessed the efficacy of AmniSure®. One visible line means a negative result for amniotic fluid, two visible lines is a positive result, no visible lines is an invalid result). This stripe appears when rabbit anti-mouse IgG antibody catches the mouse A-antibody with dye gold. A second stripe in the control region indicates that the test strip functioned properly. After five to ten minutes, immobilized colloidal gold conjugated PAMG-1 produces a brown/yellow stripe in the test region. The antigen-antibody complex migrates to the test region of the strip, which contains solid phase rabbit anti-mouse antibody that captures PAMG-1 antibody complexes flowing up from the Pad Region. These antibodies bind to PAMG-1, if it is present. The pad region of the test strip contains soluble murine monoclonal antibody to PAMG-1 that is conjugated with colloidal gold particles. After one minute, an AmniSure test strip is dipped into the vial. Amnisure is approved by FDA for use at any gestational age.Ī sterile swab is inserted into the vagina for one minute and then placed into a vial containing a solvent that extracts protein from the swab. AmniSure® assay does not require a speculum examination. PAMG-1 is not detected when fetal membranes are intact because the concentration of PAMG-1 in cervical vaginal secretions is less than 0.25 ng/mL. The analytical sensitivity of the test has been set at 5 ng/mL. The newest confirmatory test is the AmniSure®, which is a point of care immunochromatographic assay that detects trace amounts of placental alpha microglobulin-1 protein (PAMG-1) in vaginal fluid after rupture of fetal membranes. Well-estrogenized cervical mucus or a fingerprint on the microscope slide may cause a false-positive fern test false negatives can be due to inadequate amniotic fluid on the swab or heavy contamination with vaginal discharge or blood. Amniotic fluid produces a delicate ferning pattern, in contrast to the thick and wide arborization pattern of dried cervical mucus. Fluid from the posterior vaginal fornix is swabbed onto a glass slide and allowed to dry for at least 10 minutes. False positive results can be due to the presence of alkaline fluids in the vagina, such as blood, seminal fluid, soap, or some infections.Īnother confirmatory test is the presence of arborization (ferning). False negative tests results can occur when leaking is intermittent or the amniotic fluid is diluted by other vaginal fluids. Detection of premature rupture of the membranes. Am J Obstet Gynecol 1940 39:400 and Davidson, KM. The detection of rupture of fetal membranes with the nitrazine indicator. Am J Obstet Gynecol 1968 101:257).įalse-negative and false-positive test results occur in up to 5 percent of cases (Abe, T. Acid-base determinations in human amniotic fluid throughout pregnancy. Amniotic fluid has a pH range of 7.0 to 7.7 compared to the normally acidic vaginal pH of 3.8 to 4.2 (Seeds, AE, Hellegers, AE. If PPROM is not obvious after visual inspection, the diagnosis can be confirmed by testing the pH of the vaginal fluid, which is easily accomplished with nitrazine paper. The best method of confirming the diagnosis of PPROM is direct observation of amniotic fluid coming out of the cervical canal or pooling in the vaginal fornix. A clinical history suggestive of PPROM should be confirmed by visual inspection or laboratory tests to exclude other causes of wetness, such as urinary incontinence, vaginal discharge, and perspiration. However, many women describe intermittent or constant leakage of small volumes of fluid or a sensation of wetness within the vagina or perineum. The classic clinical presentation of PPROM is a sudden gush of clear or pale yellow fluid from the vagina. Complications of PPROM include maternal and neonatal infection, preterm delivery, abruptio placenta, and cord prolapse. A history of PPROM, genital tract infection, antepartum bleeding, and cigarette smoking are risk factors for PPROM. It occurs in 3 percent of pregnancies and is responsible for one-third of preterm births. Preterm premature rupture of membranes (PPROM) refers to rupture of fetal membranes prior to labor in pregnancies of less than 37 weeks.
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