Objective cervical portio length measurements: consistency and efficacy of screening for a short cervix.

OBJECTIVE: To determine the consistency of 4-quadrant cervical portio length measurements with an objective cervical measuring device and to identify patients who may benefit from transvaginal ultrasound.

STUDY DESIGN: Prenatal patients (12-34 weeks) derwent 4-quadrant cervical portio measurements and transvaginal ultrasound by different, blinded examiners. Cervical portio quadrant measures were analyzed by correlation analysis, and the predictive ability of cervical portio length measurements to identify short cervices with transvaginal ultrasound was assessed.

RESULTS: The right and left lateral cervical portio measurements were consistently available and correlated highly with each other. Cervical portio length had excellent sensitivity (88%), specificity (92%) and negative predictive value (99%) in identifying patients with a short cervix (< 30 mm) by transvaginal ultrasound.

CONCLUSION: Right and left lateral cervical portio length measurements are highly consistent and provide an effective screen for patients with short cervixes who may benefit from transvaginal ultrasound.