Cervical effacement: variation in belief among clinicians.

Cervical effacement may be described as a percentage or as residual cervical length in centimeters. For effective communication among clinicians, the percentage method requires agreement about the length of the uneffaced cervix. Variation in beliefs regarding cervical effacement and length was assessed among practicing obstetricians at a single medical center. The mean estimate for the length of the uneffaced cervix at term was 2.47 +/- 0.64 cm, with a range of 1-4 cm and a coefficient of variation of 26%. The mean estimate of physicians in private practice was significantly shorter (P less than .001) than that of faculty and house staff combined. There is the potential for miscommunication among physicians based on variation in beliefs about effacement. Adoption of the metric system for description of the cervix would eliminate hidden assumptions about cervical length and the concept of effacement.