Fetal head position during the second stage of labor: Comparison of digital vaginal examination and transabdominal ultrasonographic examination

Abstract

Objective To study the correlation between digital vaginal and transabdominal ultrasonographic examination of the fetal head position during the second stage of labor. Methods Patients ( n = 110) carrying a singleton fetus in a vertex position were included. Every patient had ruptured membranes and a fully dilated cervix. Transvaginal examination was randomly performed either by a senior resident or an attending consultant. Immediately afterwards, transabdominal ultrasonography was performed by the same sonographer (OD). Both examiners were blind to each other's results. Sample size was determined by power analysis. Confidence intervals around observed rates were compared using chi-square analysis and Cohen's Kappa test. Logistic regression analysis was performed. Results In 70% of cases, both clinical and ultrasound examinations indicated the same position of the fetal head (95% confidence interval, 66–78). Agreement between the two methods reached 80% (95% CI, 71.3–87) when allowing a difference of up to 45° in the head rotation. Logistic regression analysis revealed that gestational age, parity, birth weight, pelvic station and examiner's experience did not significantly affect the accuracy of the examination. Caput succedaneum tended to diminish ( p = 0.09) the accuracy of clinical examination. The type of fetal head position significantly affected the results. Occiput posterior and transverse head locations were associated with a significantly higher rate of clinical error ( p = 0.001). Conclusion In 20% of the cases, ultrasonographic and clinical results differed significantly (i.e., >45°). This rate reached 50% for occiput posterior and transverse locations. Transabdominal ultrasonography is a simple, quick and efficient way of increasing the accuracy of the assessment of fetal head position during the second stage of labor.