P. Rozenberg et al., EVALUATING THE RISK OF PRETERM DELIVERY - A COMPARISON OF FETAL FIBRONECTIN AND TRANSVAGINAL ULTRASONOGRAPHIC MEASUREMENT OF CERVICAL LENGTH, American journal of obstetrics and gynecology, 176(1), 1997, pp. 196-199
OBJECTIVE: Our purpose was to compare the predictive values for preter
m delivery of fetal fibronectin and cervical length measured by transv
aginal ultrasonography and to determine whether performing both tests
improves their separate predictive values. STUDY DESIGN: This prospect
ive blinded study performed both tests on 76 patients hospitalized wit
h signs of premature labor between 24 and 34 weeks of gestation. The o
utcome measure was delivery before 37 weeks' gestation. RESULTS: The r
ate of preterm birth was 26.3% (20/76). The predictive values of fetal
fibronectin and of a cervical length of less than or equal to 26 mm,
considered separately, were approximately equal, and the negative pred
ictive value of each was excellent (86.6% and 89.1%, respectively). Th
is value improved slightly when positive fetal fibronectin, a cervical
length less than or equal to 26 mm, or both defined abnormality (nega
tive predictive value 94.4%). The positive predictive values, although
less helpful, were still useful (45.2% and 50.0%, respectively). Comb
ining both indicators did not noticeably improve the positive predicti
ve value (52.4%). The risk of preterm delivery for a patient with a po
sitive fetal fibronectin level and a short cervix was high (odds ratio
13.9, 95% confidence interval 3.7 to 52.2). CONCLUSION: Fetal fibrone
ctin and cervical length are approximately equivalent in their ability
to distinguish between patients at high and low risk for preterm deli
very. For physicians equipped to perform transvaginal ultrasonography,
however, the additional information about the fibronectin level provi
des only slight benefits.