The effect of common clinical contaminants on amniotic fluid fluorescence polarization results.
OBJECTIVE
To determine the effect of blood, meconium, and vaginal secretions on amniotic fluid (AF) fluorescence polarization results.


METHODS
Amniotic fluid was collected by transabdominal amniocentesis from women at 20-41 weeks of gestation and contaminated with blood, meconium, and vaginal secretions to concentrations of 0.5, 1, 2, 5, and 10%. An additional 20% concentration was performed with meconium and vaginal secretions. Fluorescence polarization was determined by a TDx Analyzer with the NBD-PC fluorescent probe. Results were compared for each contaminant by concentration level using repeated-measures analysis of variance.


RESULTS
Forty-eight samples from women at a mean gestational age of 35 weeks (range 20-41.5 weeks) were evaluated. Before contamination, 16 (33%) samples had fluorescence polarization values greater than 290 mPol (immature), 10 (21%) were 260- 289 mPol (transitional), and 22 (46%) were less than 260 mPol (mature). Contamination with blood significantly altered fluorescence polarization values in AF samples with baseline values in the immature and mature categories such that values trended toward the transitional range. Contamination of baseline immature samples with vaginal secretions at 20% contamination level resulted in more mature fluorescence polarization values. Contamination with meconium more than 2% in the baseline immature category or more than 20% in the baseline transitional category also resulted in significantly more mature fluorescence polarization values.


CONCLUSIONS
Amniotic fluid contamination with blood can result in more transitional range fluorescence polarization values, whereas contamination with meconium and vaginal secretions can result in more mature fluorescence polarization values.
Srouji
Serene S
SS
Department of Obstetrics and Gynecology, Brigham & Women's Hospital, Boston, MA, USA. ssrouji@partners.org
Carr
Darcy B
DB
Gardella
Carolyn M
CM
Benedetti
Thomas
T
Tait
Jonathan F
JF
D000649:Amniocentesis; D000653:Amniotic Fluid / Q000737:chemistry*; D001769:Blood; D001826:Body Fluids; D005189:False Positive Reactions; D005260:Female; D005325:Fetal Organ Maturity; D016231:Fluorescence Polarization Immunoassay; D006801:Humans; D008470:Meconium; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D014621:Vagina / Q000378:metabolism
D011933:Reagent Kits, Diagnostic