Pregnancy outcome, intra-amniotic inflammation and the value of repeated fetal fibronectin test in patients with a positive cervical fetal fibronectin

Hong, Joon Seok; Yoon, Bo Hyun

Abstract

OBJECTIVE
To determine the useful subsequent study after the positive cervical fibronectin test in asymptomatic woman, fibronectin test was repeated and amniocentesis for the diagnosis of intra-amniotic infection was done.
METHODS
Cervical fibronectin concentration in asymptomatic pregnant women between 23 and 31 weeks' gestation was determined. One hundred and sixty five singleton pregnant women with an initial positive fetal fibronectin test (>50 ng/mL) were divided into 4 groups. 1) Patients with two positive fibronectin tests (n=31); 2) Patients followed by a negative result (n=75); 3) Patients followed by a amniocentesis, not fibronectin test (n=31); 4) Patients followed no further study (n=28) The relationship between the results of serial testing and pregnancy outcome was determined.
RESULTS
1) Among women with an initial positive fetal fibronectin test, the rate of a second positive test within two weeks was 29.2% (31/106); 2) Women with two positive results had a higher rate of spontaneous preterm delivery before 34 weeks and 37 weeks of gestation than women with a positive test followed by a negative test (34 weeks: 13.8% (4/29) vs 2.7% (2/75) p<0.05, 37 weeks: 27.6% (8/29) vs 8.1% (6/74) p=0.02); 3) Among women with a positive fibronectin followed by a negative test, 91.9% (68/74) delivered at term and 97.3% (73/75) after 34 weeks of gestation. 4) In repeated positive results group, the change of concentration of fibronectin was not related to gestational age of delivery before 34 weeks.
CONCLUSION
Patients with two positive fibronectin tests are at a higher risk of spontaneous preterm delivery than patients with a positive test followed by a negative result.