Cumulus cell DNA fragmentation in relation to oocyte yield and blastocyst quality

Abstract The objective of this study was to evaluate whether cumulus cell (CC) DNA fragmentation is associated with oocyte yield and the probability of obtaining at least one good-quality Day-5 blastocyst in intracytoplasmic sperm injection (ICSI) cycles. A prospective cohort study was conducted in 112 infertile couples undergoing ICSI between March 2024 and November 2025. CC DNA fragmentation was assessed using a chromatin dispersion assay and expressed as the percentage of fragmented cells. The primary outcome was the probability of obtaining at least one good-quality Day-5 blastocyst (≥3BB). Higher CC DNA fragmentation was negatively correlated with the numbers of collected cumulus–oocyte complexes (COCs) and metaphase II oocytes (all p <0.05). In adjusted negative binomial regression models, higher DNA fragmentation remained independently associated with fewer collected COCs (incidence rate ratio 0.97, 95% confidence interval 0.96–0.98; p < 0.001) and fewer metaphase II oocytes (incidence rate ratio 0.97, 95% confidence interval 0.96–0.99; p = 0.001). However, no evidence of an association between CC DNA fragmentation and the probability of obtaining at least one good-quality blastocyst was observed after adjustment for female age, BMI, and total motile sperm count. These findings suggest that higher CC DNA fragmentation is associated with reduced oocyte yield, whereas its association with blastocyst quality remains uncertain. Lay Summary Eggs develop inside the ovary surrounded by supporting cells called cumulus cells. These cells help nourish the egg and may provide information about its quality. In this study, we investigated whether damage to the DNA of cumulus cells was associated with the outcomes of fertility treatment. We studied 112 couples undergoing intracytoplasmic sperm injection (ICSI) and measured the amount of DNA damage in cumulus cells collected during treatment. We found that higher levels of DNA damage were associated with fewer eggs being obtained. However, DNA damage in cumulus cells was not associated with the chance of obtaining a high-quality blastocyst. These findings suggest that cumulus cell DNA damage may not reflect embryo quality but could provide insight into egg development.