Interobserver agreement in intrapartum estimation of fetal head station

Abstract

Objective: To determine interobserver agreement in estimation of fetal head station during labor, and the determinants of agreement.

Methods: A prospective study of fetal head station in 508 women in term labor. Vaginal examination of station was performed by a researcher at the same time as clinicians performed routine intrapartum assessments of the participants. Station 0 was considered to represent engagement.

Results: Station could be estimated by both the researcher and clinicians in 446 women (88%). The kappa statistic for agreement was 0.23 (95% confidence interval, 0.17-0.29). There was agreement in 166 cases (37%) and disagreement by 1 cm in 208 (47%) cases. Agreement was best (50%) when the researcher assessed the head at station minus 1. Multiple regression analysis showed that agreement was not influenced by level of experience of the attending clinicians, nor by obstetric factors.

Conclusion: Estimation of station as a method of determining the level of the fetal head in labor appears imprecise and poorly reproducible.