Introduction of universal transvaginal cervical length measurement does not decrease spontaneous preterm delivery rate compared to universal transabdominal screening with reflex cut-off: A pre-post study

Objectives

The objective of our study is to examine cervical length measurements, identification of short cervix, vaginal progesterone use, and rate of spontaneous preterm delivery before and after departmental transition to a universal transvaginal ultrasound screening protocol from a universal transabdominal screening protocol.

Methods

This is a retrospective observational pre–post study examining the year prior to and year following a transition to a universal transvaginal ultrasound screening protocol to assess cervical length at the time of the anatomy survey. Prior to this transition, universal transabdominal cervical length screening was performed, with reflex transvaginal ultrasound measurement if transabdominal measurement was <35 mm or was unable to be obtained.

Results

A total of 1760 charts were reviewed; 962 charts were from the pre-transition/transabdominal year and 798 charts were from the post-transition/transvaginal year. In the post-transition/transvaginal year, cervical length less than 20 mm was identified in 1.5% of cases, compared to 0.7% of cases in the pre-transition/transabdominal year (p = 0.114). There was no difference in the rate of spontaneous preterm delivery between the two groups (5.1% in the pre-transition/transabdominal year vs. 6.9% in the post-transition/transvaginal year; p = 0.111).

Conclusions

In this pre-post study, introduction of a universal transvaginal cervical length screening did not decrease spontaneous preterm delivery rates or detection of short cervix <20 mm, compared to a protocol of universal transabdominal cervical length screening with reflex to transvaginal for measurement <35 mm.