Transperineal versus transvaginal ultrasound cervical length measurement and preterm labor.

Abstract

The aim was to evaluate the agreement between and the reproducibility of transperineal and transvaginal ultrasound cervical length measurements performed by the duty obstetrical team in case of preterm labor. The acceptability of transperineal ultrasonography was also assessed. Pregnant patients between 25 and 34weeks of gestation with contractions and a clinically modified cervix were included. Order of ultrasonography examination (transperineal or transvaginal first) and rank of operator (resident or senior) were allocated randomly. Agreement was assessed using the intraclass correlation coefficient (ICC) and the Bland and Altman plot. The patient's discomfort and preference for either method were assessed with a questionnaire. 62 patients admitted for preterm labor between 25 and 34weeks of gestation were included. Six seniors and nine residents took part in the study. Among the 51 patients with an interpretable transperineal ultrasound scan, median cervical length measurements with the transperineal and the transvaginal technique were, respectively, 25mm (0-53) and 27mm (4-51). Concordance was good with an ICC of 0.83 [IC 95%=(0.73-0.90)]. Transperineal ultrasonography was preferred in 56.5% of cases. In case of preterm labor, cervical length measurement with transperineal ultrasonography seems reproducible and can be performed by the obstetric team on duty.