Objective: The purpose of this study was to evaluate the accuracy of clinical measurement of cervical dilation with a position-tracking system during vaginal examination.
Study design: This prospective study that was conducted in Poissy, France, Brooklyn, NY, and Haifa, Israel, included 333 measurements that were performed in 188 women with term singleton vertex uncomplicated pregnancies during the active stage of labor. Ninety measurements with clinical diagnosis of full dilation were excluded from analysis. Measurements were performed with a sensor attached to the midwife's index fingertip and a position-tracking system that was based on a low magnetic field. Evaluations were done when cervical examinations were clinically indicated.
Results: Results were similar in all centers. Mean error was 10.2 +/- 8.4 mm and ranged from 7.5 +/- 7.3 mm, when cervical dilation was > 8 cm, to 12.5 +/- 8.7 mm when cervical dilation was between 6.1 and 8 cm.
Conclusion: This first evaluation of cervical assessment accuracy during vaginal examination with a position-tracking system shows limited precision.