Fetal fibronectin (FFN), a special form of the glycoprotein present in amniotic fluid and at the chorio-decidual interface, may be distinguished from adult fibronectin using monoclonal antibody FCD-6. Levels of the fetal form reportedly correlate strongly with the Bishop score, with positive fibronectin found more often where there is a favorable cervix. This study was an attempt to determine whether the presence of FFN in cervicovaginal secretions at term predicts the cervical response to prostaglandin E2 (PGE2) pessaries and successful induction of labor when the cervix is unfavorable. Secretions were tested before cervical ripening was attempted with PGE2 pessaries in 58 women with a singleton term or postterm pregnancy and a modified Bishop score less than 5 who were undergoing induction. Vaginal pessaries containing 3 mg of Prostin E2 were used. FFN was estimated by means of a solid-phase immunoassay using an anti-human fibronectin-gold colloid conjugate and FCD-6.
Nineteen of the 58 women in the study (32 percent) had a positive result on the immunoassay for FFN. All but two of them had a modified Bishop score of 5 or greater or entered labor within 4 to 6 hours after vaginal placement of a single pessary. Two women required a second pessary but underwent cesarean delivery, one because of failed induction and the other because of failure to progress. Nearly half of the FFN-negative subjects had an improved Bishop score or entered labor after a single PGE2 pessary. Seven of the other 20 women delivered vaginally after a second dose. Eight women received a third or fourth pessary, and five of them delivered vaginally. Five women received oxytocin and had the membranes ruptured, but only one of them delivered vaginally. FFN-negative women required more PGE2 and had longer induction-delivery intervals than FFN-positive women, but there was no significant difference in the length of the active phase of labor. Fewer operative deliveries were performed in the FFN-positive group, but this trend was not statistically significant. These findings suggest that the FFN assay be part of assessing cervical status when labor is to be induced.
Acta Obstet Gynecol Scand 1999;79:861–865