title: Alpha-fetoprotein as a tool to distinguish amniotic fluid from urine, vaginal discharge, and semen.
abstract: OBJECTIVE
  To estimate whether alpha-fetoprotein (AFP) can be used to distinguish amniotic fluid absorbed in sanitary pads from other similarly absorbed substances (semen, urine, and normal vaginal discharge).
  
  
  METHODS
  A prospective cohort study. Urine and amniotic fluid specimens were collected from 52 pregnant women admitted for labor. Semen specimens were collected from 17 men undergoing infertility evaluation. Alpha-fetoprotein concentrations were measured directly from urine, amniotic fluid, and semen and from pads instilled with samples from these specimens. Alpha-fetoprotein concentrations were also measured from pads absorbed with normal vaginal discharge collected from 27 pregnant women.
  
  
  RESULTS
  Alpha-fetoprotein levels in amniotic fluid (245.38 ± 21.03 ng/mL, n = 52) were significantly higher than those measured in maternal urine (0.84 ± 0.17 ng/mL, n = 52, P < .001), or semen (1.52 ± 0.35 ng/mL, n = 17, P < .001). The same trend was seen when AFP was extracted from pads: amniotic fluid levels (19.44 ± 1.98 ng/mL, n=52) were significantly higher than those of urine (undetectable, n=52), semen (undetectable, n = 17), or normal vaginal discharge (0.53 ± 0.16 ng/mL, n = 27, P < .001). Receiver operator characteristic curve analysis demonstrated 96.2% sensitivity and 100% specificity for distinguishing the presence of amniotic fluid from normal vaginal discharge on sanitary pads (cutoff 3.88 ng/mL, area under the curve 0.99).
  
  
  CONCLUSIONS
  When the diagnosis of rupture of membranes is in doubt, AFP levels can assist in differentiating amniotic fluid from other bodily fluids. A method that utilizes sanitary pads and an assay for AFP quantification may be an accurate and convenient way to confirm the diagnosis of rupture of membranes.
authors.affiliation: Department of Obstetrics and Gynecology, Maimonides Medical Center, and Genesis Fertility and Reproductive Medicine, Brooklyn, New York.
authors.forename: Amir
authors.initials: A
authors.lastname: Mor
authors.forename: Reshef
authors.initials: R
authors.lastname: Tal
authors.forename: Shoshana
authors.initials: S
authors.lastname: Haberman
authors.forename: Sandra
authors.initials: S
authors.lastname: McCalla
authors.forename: Mohamad
authors.initials: M
authors.lastname: Irani
authors.forename: Jaqueline
authors.initials: J
authors.lastname: Perlman
authors.forename: David B
authors.initials: DB
authors.lastname: Seifer
authors.forename: Howard
authors.initials: H
authors.lastname: Minkoff
mesh_terms: D000653:Amniotic Fluid / Q000737:chemistry*; D005260:Female; D006801:Humans; D008297:Male; D011446:Prospective Studies; D012661:Semen / Q000737:chemistry; D014556:Urine / Q000737:chemistry; D019522:Vaginal Discharge; D000509:alpha-Fetoproteins / Q000032:analysis*
chemical_list: D000509:alpha-Fetoproteins