Association between level of training and reliability of intrapartum transperineal ultrasound measurement of angle of progression

Objectives: Intrapartum transperineal ultrasound (ITU) is an accepted tool for assessing fetal head position and station prior to operative vaginal delivery attempt. However, the validity of intrapartum ultrasound in real-life obstetrics with operators at different proficiency level is yet to be established. We aimed to investigate the association between operator level of training and reliability of angle of progression (AOP) measurements in real-life obstetrics. Methods: This was a retrospective study in one university medical center. We included women who underwent ITU for the measurement of AOP, before vacuum assisted delivery from November 2017 to September 2020. AOP measurements performed by residents and their correlation to head station were compared to those performed by specialists. Results: A total of 320 cases met the inclusion criteria. In 234 of them, AOP measurements were performed by specialists and in 86 by residents. Average AOP for each station was similar between the specialists and the residents groups, indicating similar accuracy. However, measurements in the residents group were more scattered (median deviation 11.4° vs. 8.9°, respectively, p =.021), indicating poorer precision. Conclusions: AOP measurements performed by obstetrics and gynecology (OBGYN) specialists are more precise than those performed by residents. Efforts should be taken to improve ITU training and to implement assessment of performance programs.