Effect of digital cervical examination on the expression of fetal fibronectin.

OBJECTIVE: To determine whether oncofetal fibronectin (fFN) assays from symptomatic women are influenced by digital examination of the cervix.

STUDY DESIGN: Cervicovaginal fFN specimens were obtained from women at 22-34 weeks' gestational age with symptoms of preterm labor immediately prior to a digital examination of the cervix and two hours after. Fetal fibronectin was assayed by a specific enzyme-linked immunoassay. Results were reported as positive (> or = 50 ng/mL) or negative (< 50 ng/mL). Paired initial and repeat fFN results were compared for statistical difference, and the clinical outcomes were used to assess the accuracy of the initial and repeat results.

RESULTS: Fifty symptomatic women at an average gestational age of 29.3 +/- 2.0 weeks were enrolled. Eighty-six percent of the repeat fFN results remained unchanged after a digital examination, (P = .26, beta = .2). The predictive value of a negative fFN obtained after a digital examination was 97% for the absence of spontaneous preterm delivery in < 8 or < 15 days. Two of 16 initially positive results became negative after an examination, and one patient delivered two days later. Five of 34 initially negative fFN results became positive after an examination, and 5/5 delivered more than seven days later.

CONCLUSION: Digital examination of the cervix has an effect on fFN results. The routine use of fFN after a digital examination is not recommended.