Vaginal fluid prolactin: a reliable marker for the diagnosis of prematurely ruptured membranes. Comparison with vaginal fluid α-fetoprotein and placental lactogen

Abstract

The aim of this study is the evaluation of the reliability of vaginal fluid (VF) prolactin (PRL) for detecting prematurely ruptured membranes (PROM) and the comparison of this marker with vaginal fluid α-fetoprotein (AFP) and placental lactogen (HPL). In 21 pregnant women with recent or prolonged PROM from 20 to 41 weeks' gestation, in whom intact membranes were never found subsequently VF- and MS-PRL, -AFP and -HPL were measured by enzyme immunoassays, which are sensitive and very rapid. The same markers were also measured in MS, VF and urine samples (U) in 12 pregnant women of the same gestational age, without PROM, in whom the membranes were ruptured later during labor. In PROM, independently of prematurity and duration of PROM VF-PRL levels were significantly higher (2–10-fold) than the paired MS-PRL (p < 0.0001) and ranged from 130 to 2315 ng/ml. In contrast, VF-PRL and urine PRL concentrations in pregnancies without PROM were very low or undetectable (range: 0–5 ng/ml and 0.15–1 ng/ml, respectively). Vaginal fluid AFP values in PROM from 20th to the 33rd week of pregnancy were significantly higher (5–50-fold) than the paired MS-AFP (p < 0.01) and ranged from 103 to 5500 ng/ml. In PROM after the 33rd week of pregnancy, VF-AFP values were either lower ( 1 3 ), or equal to, or even higher (up to 2-fold) than MS-PRL. On the contrary in pregnancies with intact membranes, VF-AFP were always less than 9 ng/ml and urine AFP was undetectable (range: 0.2–1.1 ng/ml). In PROM the values of VF-HPL were always lower than the corresponding MS-HPL ( 1 40 – 1 5 ) and ranged from 100 to 1020 ng/ml, depending on the gestational age, while in pregnancies without PROM the values of VF-HPL were lower, around the detection limit of the assay (up to 68 ng/ml), and quite unexpectedly the urine HPL levels in the same cases were found to be elevated up to 100 ng/ml. Vaginal fluid prolactin is, therefore, a reliable marker of PROM, VF-AFP is a useful indicator of PROM up to the 33rd week of pregnancy, while VF-HPL could be used as an accessory index of PROM, especially in the third trimester.