OC06.01: Follicular tracking with three‐dimensional ultrasound increases ovarian stimulation efficiency in oocyte donors

3D ultrasound is used to monitor follicular development during controlled ovarian hyperstimulation cycles (COH). The technique is accurate, fast, and highly reproducible among users. However, measurements by 3D differ slightly from those obtained by 2D, potentially swaying medical decisions in COH. This retrospective study compares OSC performance after 2D or 3D follicular tracking in a large multi-operator clinical setting. 2969 COH cycles stimulated with GnRH antagonist protocol were analyzed. The first control was performed at COH day 6, and further ones as appropriate. A Voluson-i, with 2D and 3D modes and SonoAVC 8.0.1. software was used. 2D (n = 1426) follicular sizes were calculated with two diameters (2D AA); 3D ones (n = 1543) with sonoAVC relaxed sphere algorithm. Triggering criteria: ≥ 3 follicles ≥ 18 mm; t-test was used for data analysis. The length of the COH was slightly shorter for 3D (9.17 ± 1.6 vs. 8.98 ± 1.5 days, P < 0.001); the amount of gonadotrophins used (2108 ± 556 vs. 2082 ± 577 IU; P = 0.21) and the length of GnRH antagonist administration (5.48 ± 3.6 vs. 5.46 ± 2.3 days; P = 0.85) per cycle was comparable in the 2 groups. A higher number of follicles > 10 mm (5.86 ± 4.47 vs. 7.17 ± 4.5, P < 0.001), > 14 mm (0.59 ± 1.68 vs. 0.80 ± 1.48, P < 0.001), and > 16 mm (0.13 ± 1.74 vs. 0.19 ± 0.73, P = 0.026) was recorded for 3D at the first follicular control. Similarly, the follicle number at the last follicular control was higher for 3D: 18.54 ± 7.45 vs. 19.3 ± 8.31 (> 10 mm, P = 0.003); 11.3 ± 4.74 vs. 11.46 ± 4.86 (> 14 mm, P = 0.036); 7 ± 3.28 vs. 7.24 ± 3.45 (> 16 mm, P = 0.052); 3.26 ± 2.24 vs. 3.49 ± 2.35 (> 18 mm, P = 0.006). COCs were recovered in comparable numbers (14.01 ± 7.5 vs. 14.32 ± 7.8, P = 0.27). Interestingly, the MII and fertilized oocytes number were higher for 3D (10.38 ± 5.82 vs. 11.42 ± 6.49, P < 0.001, and 7.47 ± 4.71 vs. 8.16 ± 5.3, P < 0.001). 3D follicular tracking allows for a more accurate timing of triggering in a multi-operator setting, likely leading to higher follicular cohort efficiency.