Setti PEL, Cirillo F, Morenghi E, et al. - Although there was a wide variation among operators, the rate of difficult transfers was significantly higher in the direct embryo transfer (ET) group compared with the afterload ET group.

• Between September 2017 and March 2019, 352 ultrasound-guided ETs were assigned to either direct ET or afterload ET in this prospective randomized unblinded controlled clinical trial.

• The rate of difficult transfers in the direct ET group was significantly higher than in the afterload group: 68 (38.6%) vs 17 (9.7%), respectively.

• The mean percentage of difficult transfers per operator was 22.5%, with 36.1% in the direct group and 8.6% in the afterload group.

• The operator's difficult transfer rate ranged from 0% to 43.8%.

• The clinical pregnancy rates did not differ significantly between groups.