P-748 The impact of trained vs. untrained ultrasound operators on clinical pregnancy rate following embryo transfer: a retrospective cohort study
Authors: Hizkiyahu R , Bezalel M , Esh-Broder E , Bentov Y , Godin M , Adler Lazarovits C , Weizel I , Hershko Klement A 
Published: July 2024

Study question

What is the impact of ultrasound guidance performed by a well-trained versus untrained medical personnel on clinical pregnancy rate following embryo transfer (ET)?

Summary answer

The utilization of a trained versus untrained ultrasound operator during ET did not demonstrate an improvement in the clinical pregnancy rate.

What is known already

ET represents the crucial final step in in vitro fertilization (IVF) cycles. While various aspects of the procedure have been studied for their potential impact on treatment outcomes, the influence of ultrasound operator guidance during ET has not been extensively explored in practice guidelines. Notably, only two previous studies compared trained and untrained medical staff for US guidance during ET and have not shown significant differences in clinical outcomes.

Study design, size, duration

This retrospective cohort study encompassed all ET procedures conducted in a single university-affiliated IVF unit between February 1st, 2023, and December 1st, 2023. The study compared the clinical pregnancy rate between patients undergoing ET with US guidance by an experienced sonographer versus guidance provided by an untrained medical staff. The study setting allowed for a natural experiment, as the availability of experienced personnel was based on random availability.

Participants/materials, setting, methods

Experienced sonographers included ultrasound technicians or fertility reproductive medicine senior physicians (referred to as “trained transfers”). Unexperienced sonographers comprised operating room nurses (referred to as “untrained transfers”). Covariates tested as possible confounders included age at oocyte retrieval, Body Mass Index (BMI), treatment indication, endometrial thickness, frozen versus fresh embryo transfer, number of embryos transferred, and embryo developmental stage.

Main results and the role of chance

A total of 694 embryo transfers were analyzed; 316 performed by trained operators (45.5%) and 378 by untrained personnel (54.4%). Demographic characteristics were comparable, with mean age and BMI not significantly different between untrained (33.3±6.6 years, 26±5.6 kg/m²) and trained transfers (33.5±6.7 years, 25.9±5.4 kg/m², p = 0.7, 0.9). Day of transfer and mean number of embryos transferred were similar (p = 0.4, 0.9). Although clinically sufficient, endometrial thickness differed statistically (9.9mm±0.4 untrained vs. 9.4mm±1.9 trained, p &lt; 0.01). Main diagnosis distribution varied (p = 0.02), with both groups mainly treated for male and unexplained infertility. Proportion of frozen transfers differed significantly (66.9% untrained vs. 81.5% trained, p &lt; 0.01). Regarding the main outcome measure, clinical pregnancy rate, crude rate was similar (35.7% untrained vs. 31.0% trained, p = 0.2). Clinical pregnancy crude rate, the main outcome measure, was similar (35.7% untrained vs. 31.0% trained, p = 0.2). In order to address unevenly distributed variables, a stepwise conditional logistic regression analysis was conducted. The trained operator was not a significant contributor to the clinical pregnancy rate (p = 0.14). Frozen embryo transfer positively correlated with successful implantation (p = 0.01), as did the main diagnosis (p = 0.03).

Limitations, reasons for caution

The retrospective nature of the study introduces limitations. Confounding variables were addressed through regression modeling. The random availability of trained assistants, independent of the procedure team, mitigates bias.

Wider implications of the findings

This study contributes evidence to the refinement of the embryo transfer procedure, suggesting that with US guidance, the contribution of a trained sonographer is not a significant factor in the standardized protocol for the transfer.

Trial registration number

not applicable