Impact of smooth endoplasmic reticulum aggregates in oocytes on embryo development and clinical outcomes in ICSI cycles: a meta-analysis

The impact of smooth endoplasmic reticulum aggregates (SERAs) in oocytes on embryo development and clinical outcomes in intracytoplasmic sperm injection (ICSI) cycles remains controversial, creating uncertainty in clinical decision-making, particularly regarding whether SERA-containing oocytes should be used or excluded during ICSI. This meta-analysis evaluates the effect of SERAs on these outcomes and provides evidence to inform clinical practice in assisted reproductive technology. A systematic search was conducted in PubMed, EMBASE, Cochrane Library, Web of Science, EBSCO, and CBM to identify studies assessing impact of SERAs on embryo development and clinical outcomes in ICSI cycles. Both prospective and retrospective observational studies were included. Only ICSI cycles were included, and studies were eligible if they reported at least one relevant embryological or clinical endpoint. Study quality was assessed using the Newcastle–Ottawa Scale, and meta-analysis was conducted RevMan 5.3 to estimate fertilization rate, Day 3 high-quality embryo, blastocyst formation, implantation, clinical pregnancy, miscarriage, and live birth. Sixteen studies were included, comprising 17,001 SERA-negative cycles and 2,336 SERA-positive cycles. Meta-analysis revealed no differences between SERA-positive and SERA-negative groups in fertilization rate (I2 = 69%, odds ratio (OR) = 0.90, 95% confidence interval (CI) 0.78–1.05; P = 0.18), Day 3 high-quality embryo rate (I2 = 96%, OR = 1.03, 95% CI 0.67–1.60, P = 0.88), blastocyst formation rate (I2 = 90%, OR = 0.90, 95%CI 0.71–1.14, P = 0.37), implantation rate (I2 = 61%, OR = 0.97, 95%CI 0.77–1.20, P = 0.73), clinical pregnancy rate (I2 = 27%, OR = 1.02, 95%CI 0.92–1.14, P = 0.68), miscarriage rate (I2 = 0%, OR = 1.17, 95%CI 0.94–1.45, P = 0.17), and live birth rate (I2 = 58%, OR = 1.06, 95%CI 0.82–1.36, P = 0.65). This meta-analysis indicates that SERAs in oocytes do not significantly affect embryo development or clinical outcomes in ICSI cycles, suggesting that SERA-positive oocytes may not need to be routinely discarded during clinical decision-making.