Background: In the recent years, there has been a definite increase in the ratio of caesarean sections. A caesarean section entails a bigger threat to the health and life of the woman giving birth compared to natural childbirth. Since the trend of increasing ratio of caesarean sections is an alarming one. Transperineal ultra-sonography (TPU) has been suggested to be a useful tool for monitoring labor progress and for predicting the mode of delivery. The angle of progression (AOP) is a parameter obtained by measuring the angle between the long axis of the symphysis pubis and a line extending from its most inferior edge tangentially to the fetal skull.
Objective: This study aims at evaluating the role of measuring the ‘angle of progression’ (AOP) at the onset of the active phase of labor in prediction of vaginal delivery in primiparous women.
Patients and Methods: Study Design: A diagnostic test accuracy study (prospective). Study setting: Department of obstetrics and gynecology at Ain Shams University Maternity Hospital (labour ward). Study time: Between May 2020and May 2021. Study population: Pregnant women attended Ain Shams University Maternity Hospital with the following criteria:
Results: This diagnostic test accuracy prospective study was conducted at Ain Shams University Maternity Hospital starting from May 2020 to evaluate the role of measuring the angle of progression (AOP) at the onset of the active phase of labor in prediction of vaginal delivery in 56 full term primiparous women. Statistical analysis of our results showed that vaginal delivery was in more than nine tenths (51 vs. 5) of the studied cases and no significant differences according to mode of delivery were detected between studied women regarding maternal age, BMI, fetal gestational age and fetal weight. Also, rupture of membranes was non-significantly more frequent in cases that delivered vaginally while station of fetal head, cervical dilatation, cervical effacement and angle of progression were significantly higher in cases that delivered vaginally. We can deduce that, angle of progression had significant high diagnostic performance; station of fetal head had significant moderate diagnostic performance, while cervical dilatation and cervical effacement had significant low diagnostic performance. Finally, angle of progression ≥97.0° had highest diagnostic characteristics, followed by station ≥0.0 station followed by cervical dilatation ≥5 cm and cervical effacement ≥75%. Different cut points had their sensitivity & NPV higher than their specificity & PPV.
Conclusion: In prediction of progress of spontaneous vaginal delivery in primiparous women, transperineal ultra-sonographic angle of progression with cutoff value ≥97.0° had highest predictive and diagnostic value, followed by station of fetal head ≥0.0 followed by cervical dilatation ≥5 cm and cervical effacement ≥75%. On the other hand rupture of amniotic membranes, maternal age, BMI, fetal gestational age and fetal weight had no significance in delivery progress prediction.