Comparative study of three amniotic fluid markers in premature rupture of membranes: prolactin, beta subunit of human chorionic gonadotropin, and alpha-fetoprotein

OBJECTIVE: To evaluate whether prolactin, alpha-fetoprotein (AFP) or B-human chorionic gonadotropin (BHCG) is the most effective marker in vaginal fluid for diagnosing prelabor rupture of membranes (PROM). These proteins are present in amniotic and vaginal fluid and have been reported to be potent markers of PROM, but have not been used clinically nor compared to each other. STUDY DESIGN: A total of 100 pregnant women between 28 and 37 weeks of gestation were recruited for the study. Patients were divided into 2 groups. The first group consisted of 50 pregnant women diagnosed with ruptured membranes. The second group consisted of 50 normal pregnant women seen during routine antenatal clinic visit (control) group. All women underwent speculum examination aiming to sample prolactin, BHCG and AFP in the vaginal fluid. Ultrasonographic examination for gestational age and amniotic fluid index measurement was performed. The electrochemoluminescence (ECLIA) method was used for quantitative measurement of the three proteins (the total duration of the assay was 18 min). RESULTS: Vaginal fluid concentrations of the three markers were significantly higher in the PROM group than in the control group (p < 0.001). Receiver operator curve analysis indicated that AFP had 94% specificity, sensitivity, positive and negative predictive values, and efficiency. The other two markers have lower specificity, sensitivity, positive and negative predictive values, and efficiency: 70, 76, 71.7, 74.5 and 73% for prolactin and 72, 84, 75, 81.8 and 78% for BHCG, respectively. CONCLUSION: This work demonstrates that of the three markers investigated AFP has the highest diagnostic performance. Using the ECLIA method it can be an ideal marker for diagnosing PROM particularly in equivocal cases. The technique could be introduced into laboratory tests to meet clinical needs. Basel.