OP17.06: Performance of angle of progression AOP in predicting Caesarean delivery in first stage of labour in relation to cervical dilatation

Our aim was to assess performance of AOP predicting CD in relation to the degree of cervical dilatation, both for static & dynamic measurements. In this prospective observational study, we included women in active first stage of labour for whom we obtained static and dynamic measurements (at uterine contraction and maternal bearing down) of AOP using 2D ultrasound, then vaginal examination was performed and degree of cervical dilatation recorded (US images stored, AOP measurement was done by second operator blind to examination and obstetricians conducting delivery were blinded to US). AOP were compared between women with Caesarean delivery (CD) and those with vaginal delivery. Receiver–operating characteristics (ROC) curves were constructed to assess the accuracy in the prediction of CD. Further classification was done to compare performance of AOP measured with cervical dilatation ≤5cm & >5cm, both static and dynamic. 119 women were included in the study. 90 (76%) delivered vaginally while 29 had CD (24%). Women undergoing CD had significantly narrower AOP at rest (93 vs 104,P=0.001) and under maternal pushing (102 vs 118,P<0.0001). AUC for AOP prediction of CD was 69% (95%CI, 58-80%)(P=0.002) and 74% (95%CI, 64-84%) (P<0.001), for static and dynamic assessment, respectively. Comparing ROC curves for dynamic versus static assessment, the difference was not statistically significant p = 0.2. AUC for AOP measured at cervical dilatation ≤5cm was 72% (95%CI,57-86%)(P=0.005) and 64% (95%CI,48-80%)(P=0.1) for cervical dilatation>5cm. While in dynamic assessment, AUC for prediction of CD; for AOP measured at cervical dilatation ≤5cm was 78% (95%CI,66-90%)(P<0.001) and 64% (95%CI,46-81%)(P=0.1) at cervical dilatation>5cm. Comparing ROC curves for early versus late assessment, the difference was not significantly significant p = 0.2 both in static and dynamic measurements. Performance AOP in predicting CD, measured in first stage of labour static or dynamic, is not dependant on degree of cervical dilatation. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.