Transperineal ultrasound in routine uterine cervix measurement

Transvaginal ultrasound (TVUS) is used in routine practice to evaluate cervical length (CL). This technique is nevertheless invasive and often viewed as uncomfortable, which is less the case with transperineal ultrasound (TPUS). This study was conducted in light of recent technological improvements in the ultrasound field to evaluate whether TPUS could be used as an alternative to TVUS in CL assessment.

This was a prospective single-blind study. Pregnant women requiring CL measurement during their emergency consultation were offered a second assessment by TPUS after an initial TVUS. TPUS was performed by a third-year OBGYN resident, unaware of the CL measurement obtained via TVUS.

Seventy-three women were included. The mean ∂ was 0.59 mm. The interclass Pearson correlation coefficient between the two techniques was 0.8987 (95% CI [0.8429; 0.9353]). None of the tested factors were found to be associated with a difference between TPUS and TVUS CL measurements. ROC curve analysis indicated that a transperineal CL cut-off measurement of 24.9 mm was predictive of a transvaginal CL measurement below 25 mm. This threshold enabled a 95% sensitivity [75.1-99.9%] and a 100% specificity [93.3-100%] for the TPUS CL measurement technique.

TPUS should be acknowledged as a reliable alternative to TVUS for CL assessment in routine every day practice.