Received February 04, 2021
Accepted June 20, 2021

Objective: To present a modified transvaginal ultrasound (TV-US) technique, and analyze its efficacy in comparison with conventional transabdominal ultrasound (TA-US) guidance during fresh embryo transfer (ET) in an unselected population of Brazilian women. Methods: This retrospective observational case-control study involved 447 fresh ET cycles, 221 guided by TV-US (Group 1), conducted between June 2016 and February 2019, and 226 by TA-US (Group 2), conducted between July 2012 and December 2015. Main outcome measured was the pregnancy rate. Groups were compared using the Z test at a level of significance of 95% (p≤0.05). Results: The age of patients ranged from 21 and 48 years, mean age of 37.7 in Group 1 and 38 years in Group 2. Overall, patients that underwent TV-US fresh ET guidance demonstrated significantly higher pregnancy rates than those that underwent TA-US fresh ET guidance (p=0.0107). TV-US fresh ET guidance also showed significantly higher pregnancy rates in the subgroups of women aged between 36 and 39 years (p=0.0037), and those ≥ 40 years (p=0.0025). However, no significant differences in pregnancy rates were observed between the groups in women aged ≤ 35 years (p=0.0905). Conclusions: The results suggest that the TV-US technique described for fresh ET was at least as effective as TA-US in the studied sample. Pending further prospective studies to better ascertain the effect of TV-US during ET, the technique presented deserves consideration since it can offer better visualization, more comfort to patients, and requires only one operator, without negatively affecting pregnancy results.