Intrapartum ultrasound measurement of angle of progression at the onset of the second stage of labor for prediction of spontaneous vaginal delivery in term singleton pregnancies: a systematic review and meta-analysis

Objective This study aimed to investigate the diagnostic performance of transperineal ultrasound–measured angles of progression at the onset of the second stage of labor for the prediction of spontaneous vaginal delivery in singleton term pregnancies with cephalic presentation. Data Sources We performed a predefined systematic search in PubMed, Embase, Scopus, Web of Science, and Google Scholar from inception to February 5, 2021. Study Eligibility Criteria Prospective cohort studies that evaluated the diagnostic performance of transperineal ultrasound–measured angles of progression (index test) at the onset of the second stage of labor (ie, when complete cervical dilation is diagnosed) for the prediction of spontaneous vaginal delivery (reference standard) were eligible for inclusion. Eligible studies were limited to those published as full-text articles in the English language and those that included only parturients with a singleton healthy fetus at term with cephalic presentation. Study Appraisal and Synthesis Methods Study quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 tool. Summary receiver operating characteristic curves, pooled sensitivities and specificities, area under the curve, and summary likelihood ratios were calculated using the Stata software. Subgroup analyses were done based on angle of progression ranges of 108° to 119°, 120° to 140°, and 141° to 153°. Results A total of 8 studies reporting on 887 pregnancies were included. Summary estimates of the sensitivity and specificity of transperineal ultrasound–measured angle of progression at the onset of the second stage of labor for predicting spontaneous vaginal delivery were 94% (95% confidence interval, 88%–97%) and 47% (95% confidence interval, 18%–78%), respectively, for an angle of progression of 108° to 119°, 81% (95% confidence interval, 70%–89%) and 73% (95% confidence interval, 57%–85%), respectively, for an angle of progression of 120° to 140°, and 66% (95% confidence interval, 56%–74%) and 82% (95% confidence interval, 66%–92%), respectively, for an angle of progression of 141° to 153°. Likelihood ratio syntheses gave overall positive likelihood ratios of 1.8 (95% confidence interval, 1–3.3), 3 (95% confidence interval, 2–4.7), and 3.7 (95% confidence interval, 1.7–8.1) and negative likelihood ratios of 0.13 (95% confidence interval, 0.07–0.22), 0.26 (95% confidence interval, 0.18–0.38), and 0.42 (95% confidence interval, 0.29–0.60) for angle of progression ranges of 108° to 119°, 120° to 140°, and 141° to 153°, respectively. Conclusion Angle of progression measured by transperineal ultrasound at the onset of the second stage of labor may predict spontaneous vaginal delivery in singleton, term, cephalic presenting pregnancies and has the potential to be used along with physical examinations and other clinical factors in the management of labor and delivery.