Prediction of Successful Normal Vaginal Delivery by Intrapartum Transperineal Ultrasonographic Measurement of the Angle of Progression

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Methakawin Treetrong
Sudtawin Krainara


Objectives: This study aimed to evaluate the angle of progression’s predictive ability for successful normal vaginal delivery, establishing its cutoff value and clinical application.
Materials and Methods: In this prospective, diagnostic accuracy study, we enrolled pregnant women admitted to the labor room with term singleton cephalic presentation pregnancies, excluding those at risk of undergoing cesarean delivery with indications other than cephalopelvic disproportion. The angle of progression was measured using transperineal ultrasound during the active phase of labor.
Results: A total of 114 pregnant women were included in the study. Among these participants, 102 underwent vaginal delivery (89.5%), while 12 underwent cesarean delivery (10.5%). No significant differences were observed in age, body mass index, gestational age, cervical dilatation, amniotic membrane status, or fetal birth weight among the participants. However, multiparous women displayed a tendency towards higher vaginal delivery rates than nulliparous ones. The angle of progression’s cut-off value, assessed by the area under the receiver operating characteristic curve, was 0.703. The optimal threshold on the curve, maximizing the area under the curve, was identified at 96.9 degrees, with a sensitivity of 82.4%, specificity of 58.3%, positive predictive value of 94.4%, and negative predictive value of 28% for predicting successful of normal vaginal delivery.
Conclusion: Transperineal ultrasound measurement of the angle of progression greater than 96.9 degrees showed good potential for predicting the success of normal vaginal delivery in pregnant women during the active phase of labor.

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How to Cite
Treetrong, M.; Krainara, S. . Prediction of Successful Normal Vaginal Delivery by Intrapartum Transperineal Ultrasonographic Measurement of the Angle of Progression. Thai J Obstet Gynaecol 2024, 32, 205-213.
Original Article


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