Low dna and inconclusive results after pgt-a: relationship with day of biopsy (day 5 vs day 6) and embryo quality

To investigate whether day of embryo biopsy and embryo quality has a direct effect on the incidence of low DNA and inconclusive results on PGT reports. Retrospective analysis of patients undergoing PGT-A cycles (Oct. 2019 and March 2023). Embryos were cultured in benchtop incubators with single step culture media until reaching blastocyst stage, when trophectoderm biopsy was performed (either day 5 or 6). SART embryo morphology grading criteria were used, and embryos were classified into three groups (good, fair, and poor). Chi-square was used for statistical analysis and p< 0.05 considered significant. A total of 1,294 embryos were biopsied, 853(65.9%) on day 5 and 441 (34.1%) on day 6. The rate of euploid embryos was higher on day 5 (470/853, 55.1%) than day 6 (161/441, 36.5%) (p< 0.001). Aneuploidy rates were lower on day 5 embryos (299/853, 35%) than on day 6(210/441, 47.7%) (p<0.008). Embryo mosaicism on day 5 was 2.46% (21/853) vs 2.72% (12/441) on day 6. The incidence of low DNA among day 5 embryos was 4.45% (38/853) vs 8.84 (39/441) on Day 6 (p<0.003). The incidence of inconclusive result was 2.93% (25/853) vs 4.31% (19/441) on day 5 and 6, respectively (p=0.211) (table).Tabled 1Table 1. Comparison between low DNA on day 5 and day 6 according to GradesGradesDay 5Day 6P-valueN%N%Good26/5354.88%11/10610.38%0.039*Fair12/2724.41%21/2179.68%0.032*Poor0/460.0%7/1185.93%0.101 Open table in a new tab There were 535 good, 272 fair, and 46 poor embryos on day 5 of development and the incidence of low DNA was 4.84% (26/535), 4.41 (12/272), and 0% (0/47), respectively. There were 106 good, 217 fair, and 118 poor embryos on day 6 and the incidence of low DNA results was significantly higher than the corresponding day 5 embryos 10.38% (11/106), 9.68% (21/217), and 5.93% (7/118) (p= 0.039) and (p=0.032) for good and fair morphology, respectively. There was no significant difference in the incidence of low DNA in poor embryos between day 5 and day 6, although it was more frequent on day 6 (p 0.101). The incidence of inconclusive results according to good, fair, and poor morphology grading (on day 5) were 1.68% (9/535), 5.15% (14/272) and 4.35% (2/14), respectively; while on day 6 were 3.77% (4/106), 2.76% (6/217), and 7.63% (9/118), respectively, (p=NS). Embryo grade and the day of biopsy showed a direct correlation on the incidence of low DNA and inconclusive results after PGT-A. It is plausible that embryos with a slower growth rate (day 6 blastocysts) and of poorer morphological grading are trying to eliminate apoptotic cells that could be biopsied, leading to a higher incidence of no actionable results.