Dynamic Cervical Change: Prediction of Preterm Labor in Symptomatic Patients

Transvaginal ultrasound of the cervix has become a common tool to evaluate patients who are at risk for preterm delivery. A shortened cervical length has been associated with an increased risk of preterm delivery. Dynamic cervical change is visible shortening(>6mm) of the cervix seen during the ultrasound examination. Prior studies have shown that the presence of dynamic change in patients with a shortened cervical length(<3cm) is not independently predictive of preterm delivery. However, a subset of patients with normal initial cervical length(>3cm) and dynamic change did demonstrate an increased rate of preterm delivery. Because this was a small sub-group, the present study was designed to obtain a larger sample size for further evaluation. The second focus of this study involves patients with a dilated cervix and whether cervical length adds predictive value to gestational age at delivery.

Patients presenting to with symptomatic preterm labor(vaginal pressure or uterine contractions), who consent to the study, will undergo the standard evaluation for preterm labor(described in detail below.) The only additional evaluation is a prolonged transvaginal ultrasound of approximately 10 minutes to evaluate for the presence of dynamic change during a contraction.

Null hypothesis:

Symptomatic preterm labor patients, with normal initial cervical length(>3cm), who exhibit dynamic cervical change deliver at a gestational age equal to those without dynamic change.

Alternative hypothesis:

Symptomatic preterm labor patients, with normal initial cervical length(>3cm), who exhibit dynamic cervical change deliver at an earlier gestational age than those without dynamic change.