Transvaginal ultrasound of cervical length and its correlation to digital cervical examination, time to spontaneous labor and mode of delivery.

PURPOSE

The objective of this study was to determine if transvaginal ultrasound (TVUS) examination of cervical length correlates to digital pelvic examination and if it can predict time to and mode of delivery in term pregnancies.

METHODS

We conducted a prospective cohort study of 726 consecutive non-laboring, term pregnant women presenting to University-based antenatal testing unit between 1 July 2001 and 31 March 2002. Subjects underwent a TVUS for cervical length followed by a digital cervical examination by a physician blinded to the results of the ultrasound. Linear regression analysis was used to correlate the findings of cervical length by ultrasound with cervical dilatation and effacement by digital examination.

RESULTS

In 726 women, the relationship between TVUS cervical length and cervical dilatation and effacement measured digitally were found to be significantly related (p < 0.001), but weak, with a 15 and 23% goodness of fit, respectively, based on the linear model. Using multivariate logistic and linear regression, respectively, TVUS cervical length predicted mode of delivery but did not predict time to spontaneous labor. Digital measurement of cervical dilatation was predictive of time to spontaneous labor.

CONCLUSIONS

There is a statistically significant correlation between TVUS measurement of cervical length and digital cervical exam though the correlation is weak. TVUS measurement of cervical length was predictive of mode of delivery while controlling for digital cervical examination, parity and time to spontaneous labor. Digital cervical dilatation was predictive of time to spontaneous delivery.