Single blastocyst transfer: does PGS improve outcome? comparison of single thawed euploid embryo transfers (STEET) with fresh (FSET) and frozen (ZSET) morphology-based single embryo transfers in good prognosis patients (GPP)

Abstract

One ASRM 2015 prize abstract [1] suggested that STEET in young GPP was equivalent to FSET. We extended this analysis to assess if embryo selection using chromosome screening was superior, inferior, or equivalent to FSET and/or ZSET. Retrospective cohort study of STEET, FSET and ZSET procedures performed in women age < 41y who had at least 3 Gardner’s Stage 2BC or 2CB blastocysts or better at a single, large university-based center from 2008 to 2015. We compared 131 STEET (median age: 35 y, IQR: 32-37 y) vs. 207 FSET (median age: 33, IQR: 31-36 y) vs. 95 ZSET (median age 33 y, IQR: 30-35 y) in GPP. Data was mined for: implantation rate (IR), live birth / ongoing pregnancy rate (LBR), and spontaneous abortion rate (SABR). Exclusion criteria included: age > 40 y; > 2 prior ART procedures; > 2 prior spontaneous abortions; endometrial thickness < 6 mm at progesterone start, or uterine pathology (fibroids or synechiae). Fisher’s exact test (two-tailed) was used for statistical analysis. When grouping all cycles of women age < 41y, IRs for STEET, FSET, and ZSET were 82/131 (63%), 126/207 (61%), and 50/95 (53%) respectively; p=NS. LBRs were 73/131 (56%), 99/207 (48%), and 39/95 (41%), respectively (LBR was significantly higher with STEET vs. ZSET; p=0.03 but vs. not FSET). SABRs were 8/82 (10%), 24/126 (19%), and 11/50 (22%), respectively; p=NS. The Table divides the data by age. For women age < 35 y, no differences in IR or LBR were noted. In women age 35-37 y, IR and LBR were significantly higher with STEET and FSET vs. ZSET. For women age 38-40 y, IR was not different, but LBR was significantly higher with STEET vs. FSET. SABRs were not statistically different within any of the age groups. In younger (age < 35 y) GPP, FSET and ZSET appear equally beneficial to STEET, but as female age advances (38-40 y), STEET may have the advantage of producing a higher chance for live birth. While the SABR is not statistically lower with STEET in this data set, it is in others [2], and the lack of statistical significance here may be due to small sample size, especially in the older age groups. The financial costs, emotional burden, and time of storage and transfer of abnormal embryos, miscarriage, and pregnancy termination of chromosomally abnormal fetuses need to be considered when choosing not to perform STEET, especially in older patients, and GPP should be counseled accordingly. We will continue to collect data.Tabled 1STEET vs. FSET vs. ZSET by age. n = number of patients (pt), embryo transfers (ET).IRLBRSABR< 35 y: STEET (n=43 pt, 57 ET)34/57 (60%)28/57 (49%)5/34 (15%)< 35 y: FSET (n=131 pt, 133 ET)79/133 (59%)63/133 (47%)14/79 (18%)< 35 y: ZSET (n=60 pt, 70 ET)40/70 (57%)32/70 (46%)8/40 (20%)35-37 y: STEET (n=36 pt, 43 ET)28/36 (78%)a27/36 (75%)d1/28 (4%)35-37 y: FSET (n=49 pt, 49 ET)36/49 (73%)b29/49 (59%)e6/36 (17%)35-37 y: ZSET (n=16 pt, 18 ET)7/18 (39%)c5/18 (28%)f2/7 (29%)38-40 y: STEET (n=25 pt, 31 ET)20/31 (65%)18/31 (58%)g2/20 (10%)38-40 y: FSET (n=24 pt, 25 ET)11/25 (44%)7/25 (28%)h4/11 (36%)38-40 y: ZSET (n=7 pt, 7 ET)3/7 (43%)2/7 (29%)1/3 (33%)P values: a-c <0.01, b-c 0.02, d-f <0.01, e-f 0.03, g-h 0.03, other comparisons: NS Open table in a new tab