Learning curve for detection of the distal part of ureters by transvaginal sonography (TVS): a feasibility study.

Objective To investigate how many examinations it takes to be able to identify the pelvic parts of the ureters on transvaginal sonography (TVS). Methods This was a prospective study including consecutive women attending a gynecological outpatient clinic in a tertiary referral setting. Prior to commencement of the study, three trainees, with a focus on gynecological surgery and TVS but with no experience in identifying ureters, each observed an expert examiner performing 10 routine TVS examinations, including identification of both ureters. All were standardized gynecological TVS examinations, with visualization of the pelvic part of both ureters. Consecutive women were then examined, first by the expert, unobserved by the trainees, and then by one of the three trainees, in the presence of the expert. To ensure that identification of the pelvic parts of the ureters could be incorporated feasibly into routine gynecological TVS in a tertiary referral setting, a time limit of 150 s was set for successful identification of each ureter. A successful examination was defined by identifying both ureters within the time limit. The number of women examined by each trainee was determined by how quickly they achieved proficiency, which was evaluated using the learning curve cumulative summation (LC-CUSUM) score. Results Between January 2017 and June 2017, a total of 140 women were recruited for the study, with 135 patients being included in the final analysis. The three trainees were able to identify the right ureter after a maximum of 48 (range, 34-48) TVS examinations, and the left ureter after a maximum of 47 (range, 27-47) TVS examinations. Conclusions Sonographers and/or gynecologists who are familiar with gynecological TVS should be able to become proficient in identifying both ureters after 40-50 TVS examinations. Detection of the ureters is a feasible part of the TVS workup of patients attending a clinic in a tertiary referral center. (c) 2019 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.