Diagnostic value of cervical fetal fibronectin in detecting extrauterine pregnancy

To determine whether fetal fibronectin (FFN) might serve as a marker to distinguish intrauterine versus extrauterine pregnancy.

Prospective cohort study.

Academic research center.

Cervicovaginal FFN samples were obtained from 46 women who were at high risk for or presented with signs and/or symptoms of extrauterine pregnancy.

Samples of blood were analyzed for FFN with use of an enzyme-linked immunoabsorbent assay (ELISA).

Fetal fibronectin level.

The rate of extrauterine pregnancy in our study was 26.1%, with 12 extrauterine and 34 intrauterine pregnancies identified by ultrasonography 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 35.3%) (12 of 34) of women with intrauterine pregnancies. The sensitivity, specificity, and positive and negative predictive values for extrauterine pregnancy were 41.7%, 64.7%, 29.4%, and 75.9%, respectively.

The use of FFN does not appear to alter significantly the likelihood of identifying extrauterine pregnancy over current laboratory or ultrasonographic methods.