Accuracy and intraobserver variability of simulated cervical dilatation and effacement measurements

Objective: To assess the accuracy and intraobserver variability of clinical cervical diameter measurements among obstetric health care providers.Methods: Cervical dilatation and effacement simulators consisting of pelvic blocks composed of synthetic rubber were used for the study. The examiners had to rely solely on proprioception to determine dilatation and effacement.Results: A total of 828 simulated cervical diameter and effacement measurements were obtained from 69 different examiners. The overall accuracy for determining the exact diameter was 48.6%, which improved to 88.8% when an error of +/- 1 cm was allowed. Intraobserver variability for a given diameter measurement was 39.9%, which decreased to 14.0% when an error of +/- 1 cm was allowed. The overall accuracy for determining the exact effacement was 52.9%, which improved to 85.8% when an error of +/- 25% was allowed. Intraobserver variability for a given effacement measurement was 37.0%, which decreased to 7.3% when an error of +/- 25% was allowed.Conclusions: Cervical diameter and effacement measurements obtained by digital exam are precise when an error of +/- 1 cm in diameter and +/- 25% effacement is allowed. Intraobserver variability is > 35% and is an important consideration when evaluating dysfunctional labor.