The role of static and dynamic changes in intrapartum ultrasonography in labor

Objective: To investigate the success of intrapartum ultrasonography during the active phase of the first stage of labor in predicting labor outcomes. Materials and Methods: A total of 104 singleton, head-presenting, active labor and ruptured amniotic membrane pregnancies (39 nulliparous and 65 multiparous) were included in this prospective study. Maternal characteristics, induction or augmentation with oxytocin, episiotomy, cervical dilatation, effacement, fetal head level, mode of delivery, intrapartum ultrasonography parameters and neonatal findings were recorded. Transperineal ultrasonography was used to measure the angle of advancement (AoP) in the sagittal plane, midline angle (MLA) in the transverse plane and head perineal distance (HPD). The measured parameters were recorded during resting and active straining. The data obtained were compared statistically. Results: Of the pregnant women, 65 (62.5%) were multiparous and 39 (37.5%) were nulliparous. In the spontaneous vaginal delivery group, the means of the angle of advancement AoP1 (at rest) and AoP2 (at pushing) were statistically significantly higher than the other two groups (p<0.001 in both cases). Head perineum distance HPD1 (resting state) and HPD2 (straining state) averages were found to be statistically significantly higher in the cesarean section group than the other two groups (p=0.031, p=0.041, respectively). The mean midline angle MLA1 (resting state) and MLA2 (straining state) were significantly lower in the spontaneous vaginal delivery group than in the other two groups (p=0.002, p=0.001, respectively). There was a significant positive correlation between cervical dilatation, effacement and head level and AoP1 and AoP2, while there was a significant negative correlation between HPD1, HPD2, MLA1 and MLA2. Conclusion: This study shows that intrapartum transperineal ultrasonography can provide an objective assessment and contribute to clinical decision-making. Keywords: intrapartum transperineal sonography, angle of progression, midline angle, head-perineum distance, labor