Feasibility, Reliability, and Agreement of Transperineal Ultrasound Measurement: Results from a Longitudinal Cohort Study

Angel H W Kwan; Piya Chaemsaithong; Wing Ting Tse; Kubi Appiah; Ka Chun Chong; Tak Yeung Leung; Liona C Poon

doi:10.1159/000507549

Feasibility, Reliability, and Agreement of Transperineal Ultrasound Measurement: Results from a Longitudinal Cohort Study

Fetal Diagn Ther. 2020 Jul 7:1-10. doi: 10.1159/000507549. Online ahead of print.

Authors

Angel H W Kwan¹, Piya Chaemsaithong¹, Wing Ting Tse¹, Kubi Appiah¹, Ka Chun Chong², Tak Yeung Leung¹, Liona C Poon³

Affiliations

¹ Department of Obstetrics and Gynaecology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, Hong Kong.
² The Jockey Club School of Public Health and Primary Care Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, Hong Kong.
³ Department of Obstetrics and Gynaecology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, Hong Kong, liona.poon@cuhk.edu.hk.

PMID: 32634805
DOI: 10.1159/000507549

Abstract

Objectives: To evaluate the feasibility, reliability, and agreement of serial transperineal ultrasound (TPU) assessment of fetal head station (parasagittal angle of progression [psAOP], head-perineum distance [HPD], and head-symphysis distance [HSD]) and sonographic cervical dilatation (SCD), compared to fetal head station and cervical dilatation determined by vaginal examination, respectively.

Methods: This was a prospective longitudinal study in singleton pregnancies undergoing induction of labor at term. Paired assessment of fetal head station and cervical dilatation by vaginal examination, with TPU assessment of psAOP, HPD, HSD, and SCD was made serially. Feasibility, correlation, reliability, and agreement were determined.

Results: 1,139 paired measurements among 326 women were included. psAOP and HPD were achievable in all assessments. HSD was not achievable in 3.4% (11/326) due to high fetal head station. Fetal head station by vaginal examination was positively correlated with psAOP (rho = 0.70) but negatively correlated with HPD (rho = -0.57) and HSD (rho = -0.52). The feasibility to measure SCD reduced as cervical dilatation increased. Cervical dilatation and SCD were positively correlated (rho = 0.96) with strong agreement (concordant correlation coefficient = 0.925).

Conclusions: Measurements of psAOP and HPD are feasible and correlate significantly with fetal head station by vaginal examination. Measurement of HSD is not feasible when fetal head station is high. Measurement of SCD is feasible, but it is more difficult in the advanced stage of labor. The correlation, reliability, and agreement between SCD and cervical dilatation by vaginal examination are high.

Keywords: Angle of progression; Cervical dilatation; Fetal head station; Head symphyseal distance; Head-perineum distance; Sonopartogram; Transperineal ultrasound.