Use of transperineal sonography during preterm labor.

The gold standard for cervical length (CL) assessment is transvaginal ultrasound scan (TVUS). Transperineal ultrasound scan (TPUS) is an alternative route to CL measurement, which may be more acceptable to women. The primary outcome of this study was to investigate the reliability of TPUS performed by obstetrical team on duty in case of preterm labour (PL) and to compare transperineal to transvaginal CL measurements as a reference.