Comparison of cervical volume and cervical length to predict preterm delivery by transvaginal ultrasound.

The objective of this study was to evaluate predictive value of cervical volume and length measurement for preterm delivery in low-risk pregnancies by transvaginal ultrasound. Two hundred fifty pregnant women were underwent ultrasound examination at 22 weeks of gestation by transvaginal route. Cervical length, width, and anteroposterior diameters were measured and cervical volume was calculated. All subjects were observed until term. Predictive values of cervical length and cervical volume were calculated and compared with predict preterm delivery. Preterm delivery occurred in 18 patients (7.2%). Mean cervical length and volume were statistically different between term and preterm delivered patients ( P = 0.001). Areas under curves were 0.913 for cervical volume and 0.923 for cervical length; this difference was not statistically significant ( P = 0.289). Sensitivity of cervical volume was 73.3% for 32-mL cut-off value with 12.85% false-positive rate and cervical length had 80% sensitivity at the 33.15-mm cut-off value with 12.7% false-positive rate. Cervical volume measurement by two-dimensional ultrasound did not add any benefit compared with the cervical length measurement for prediction of preterm delivery.