[Predicating imminent preterm labour based on a determination of foetal fibronectin in a vaginal smear]

To determine the prognostic value of foetal fibronectin and cervical length for predicting imminent preterm labour among Dutch women, who in the Netherlands normally undergo a digital examination of the cervix prior to referral to a hospital or university medical centre.

Prospective observational cohort study.

Pregnant women with symptoms of preterm labour and a gestational age between 24 and 34 weeks were included. A fibronectin smear was taken from them and the cervical length was measured. Primary outcome was delivery within 7 days after inclusion. Sensitivity, specificity and a receiver-operating characteristics (ROC) curve were calculated.

13 (12%) of the 108 included patients delivered spontaneously within 7 days after inclusion. The fibronectin test had a sensitivity of 92% and specificity of 60%. The positive and negative predictive values were 27% and 98% respectively. For women who had undergone a digital examination prior to testing, the predictive value was slightly less but the difference was not significant. Although measurement of the cervical length scarcely had a predictive value, none of the patients with a cervical length above 35 mm delivered within 7 days.

In women with an imminent preterm labour, a negative fibronectin test virtually ruled out delivery within 7 days. The fibronectin test can therefore also be used in the Dutch situation. In women with a cervix length greater than 35 mm, the chance of a preterm labour within 7 days is very small and a fibronectin test does not need to be performed in their case.