Is the clinician an independent variable in embryo transfer outcomes under standardized direct and indirect supervision? A 5-year observational cohort study

Objective: To compare the cumulative pregnancy rate (CPR) for experienced clinicians and trainees naive to the skill of embryo transfer (ET) during an assisted reproductive treatment (ART) cycle. To establish the minimum number of procedures required to achieve consistent outcomes. Method: A non-interventional retrospective observational cohort study looking at all consecutive ETs undertaken over a 5-year study period. The CPR was determined by a self-reported urinary home pregnancy test undertaken 16 days after oocyte retrieval. Results: The CPR did not differ between an experienced clinician (39%) and trainee (45%) for the first 50 (p=0.41) and last 50 (40.7% versus 42.7%) (p=0.81) ET procedures. The CPR for the individuals remained consistent with their peaks and troughs mirroring the overall success rate of the unit. This pattern continued when the data was further stratified for co-variables (age [≤37 years of age], catheter type [soft] and embryo quality [expanded blastocyst of grade ≥2]): CPRs for experienced clinicians was 65.7% (first 50 transfers) and 40.9% (last 50 transfers); CPR for trainees was 66.7% (first 50 transfers) and 53.6% (last 50 transfers); p=0.95 and p=0.37, respectively. The trainees, however, were more likely to use a stylet catheter with a 2-step transfer technique, with a cost over clinical implication. Furthermore, patients expressed a preference for an experienced clinician to perform their procedure, despite being informed that the grade of the clinician had no impact on the cycle outcome after an analysis of the unit’s data. Conclusion: The clinician's grade and duration of service have not been shown to significantly impact the outcome of the ART cycle. The findings, however, should be interpreted with caution, as they reflect the culture of training in the unit, where there is a strong emphasis on adequate direct and indirect supervision. Furthermore, the relationship between the volume of work and outcomes is established in postgraduate medical education, with the exact number required to achieve clinical competence being dependent on the procedure and intensity of the workload.