Factors influencing the accuracy of digital examination for determining fetal head position during the first stage of labor.

OBJECTIVE The objective of this study was to explore factors influencing the accuracy of transvaginal digital examination for determining fetal head position during the first stage of labor. MATERIALS AND METHODS Fetal head position was assessed in 87 women in the first stage of labor at term with normal singleton cephalic presentation. Transvaginal digital examinations were performed by attending midwives and were followed immediately by transabdominal ultrasound assessments performed by a single sonographer. Accuracy was defined as agreement of the results of each examination. Multivariate logistic regression analysis was performed to determine the independent factors influencing accuracy. RESULTS In only 40.3% of patients (n = 35) were transvaginal digital examinations consistent with ultrasound assessments. Multivariate logistic regression analysis showed that the accuracy of digital examinations was significantly associated with cervical dilatation more than 7 cm (odds ratio, 3.01; 95% confidence interval [CI], 1.03-9.4), birth weight less than 2,500 g (odds ratio, 8.68; 95% CI, 1.08-86.28), and the anterior occiput position group (odds ratio, 4.73; 95% CI, 1.76-13.49). CONCLUSIONS The present study demonstrates that transvaginal digital examination is less accurate than ultrasonography for determining fetal head position during the first stage of labor. The results suggest that ultrasound assessments should be routinely performed in patients with a cervical dilatation less than 7 cm, an estimated fetal body weight more than 2,500 g, the occiput posterior position, or the occiput transverse position.