ACCURACY AND INTRAOBSERVER VARIABILITY OF SIMULATED CERVICAL DILATATION MEASUREMENTS

OBJECTIVE: Our purpose was to assess the accuracy and intraobserver va riability of clinical cervical diameter measurements among obstetric h ealth care providers. STUDY DESIGN: Polyvinyl chloride pipes 1 to 10 c m in diameter were mounted in cardboard boxes and used to simulate cer vical examinations. The boxes were designed so that the examiner had t o rely solely on proprioception to determine the inner diameter. RESUL TS: A total of 1574 simulated cervical diameter measurements were obta ined from 102 different examiners in a two-part study. The overall acc uracy for determining the exact diameter was 56.3%, which improved to 89.5% when an error of ii cm was allowed. Intraobserver variability fo r a given diameter measurement was 52.1%, which decreased to 10.5% whe n an error of +/- 1 cm was allowed.CONCLUSIONS: Cervical diameter meas urements obtained by digital examination are precise when an error of +/- 1 cm is allowed for. Intraobserver variability is > 50% and is an important consideration when evaluating dysfunctional labor.