Objective: To determine whether fetal fibronectin (FFN) might serve as a ma
rker to distinguish intrauterine versus extrauterine pregnancy.
Design: Prospective cohort study.
Setting: Academic research center.
Patient(s): Cervicovaginal FFN samples were obtained from 46 women who were
at high risk for or presented with signs and/or symptoms of extrauterine p
regnancy.
Intervention(s): Samples of blood were analyzed for FFN with use of an enzy
me-linked immunoabsorbent assay (ELISA).
Main Outcome Measure(s): Fetal fibronectin level.
Result(s): The rate of extrauterine pregnancy in our study was 26.1%, with
12 extrauterine and 34 intrauterine pregnancies identified by ultrasonograp
hy or at time of surgery. Seventeen samples had FFN levels of >50 ng/mL and
were considered positive (range, 0-1,000 ng/mL). Positive FFN levels were
observed in 41.7% (5 of 12) of women with extrauterine pregnancies versus 3
5.3%) (12 of 34) of women with intrauterine pregnancies. The sensitivity, s
pecificity, and positive and negative predictive values for extrauterine pr
egnancy were 41.7%, 64.7%, 29.4%, and 75.9%, respectively.
Conclusion(s): The use of FFN does not appear to alter significantly the li
kelihood of identifying extrauterine pregnancy over current laboratory or u
ltrasonographic methods. (C) 1999 by American Society for Reproductive Medi
cine.