Introduction: High fetal head station has been associated with prolonged labor and delivery outcomes. Although clinical assessment of fetal head station is both subjective and unreliable, women with prolonged labor are subjected to multiple digital vaginal examinations. The use of ultrasound has been proposed to aid in the management of labor since 1990s. Ultrasound examination is more accurate and reproducible than clinical examination in the diagnosis of fetal head station and in the prediction of arrest of labor. Ultrasound examination can, to some extent, distinguish those women destined for spontaneous vaginal delivery and those destined for operative delivery and may predict the outcome of instrumental vaginal delivery. Such a technique has the potential to reduce the frequency of intrusive internal examinations and associated infection and could be useful in allowing the assessment of women in whom digital VE is traumatic or contra-indicated. Intrapartum ultrasound not only provides objective and quantitative data in labor, but also helps to make more reliable clinical decisions aiming to improve obstetric outcomes of both the mother and fetus as a supplementary tool for active management.
Aim of the work: This study aims at assessing the value of intrapartum transperineal ultrasonography as a quantitative and objective tool in the evaluation of progress of labor and prediction of mode of delivery.
Subjects: This study was a prospective observational study conducted on 600 primiparous women in active first stage of labor admitted to Kasr Al Ainy maternity hospital from January 2017 to June 2018. The studied population was divided into two groups. Group A of 300 women with normal progress of labor and group B of 300 women with prolonged 1st stage of labor.
Methods: Fetal head station(FHS) was assessed clinically by digital vaginal examination (dVE) and sonographically by transperineal ultrasound measurement of head perineal distance (HPD) and angle of progression (AOP). Intrapartum care of the patient continued as normal based only on digital vaginal examinations using the modified WHO partogram. (1). Statistical analysis was targeted towards assessing the potential of the intrapartum ultrasonography in the evaluation of progress of labor and prediction of mode of delivery.
Results: All studied parameters for assessment of FHS (dVE, HPD, and AOP) significantly corelated with each other and with both progress of labor and mode of delivery with P value (<0.001). The highest sensitivity for prediction of progress of labor is observed using dVE (83%), the highest specificity is observed using AOP (78.3%). The highest sensitivity for prediction mode of delivery is for combined HPD & AOP (97.7%) while the highest specificity is for AOP (81%). When combining both HPD and AOP for prediction of mode of delivery, the assessment of both parameters was found to have a high sensitivity of 97.7% and a high positive predictive value of 86.63%.
Conclusion: Intrapartum ultrasound examination is a valuable tool in the prediction of progress of labor and mode of delivery. The assessment of fetal head station by transperineal ultrasound measurement of HPD and AOP is much more informative of the progress of labor and the mode of delivery than digital assessment of fetal head station.
Keywords: Labor, intrapartum ultrasound, Angle of progression, Head perineal distance, fetal head station, digital vaginal examination.
Transperineal sonographic assessment of angle of progression as a predictor of successful vaginal delivery following induction of labor
