Zercan KALI, Fatma Didem YUCEL YETISKIN, Fatma Tanilir CAGIRAN
Ankara City Hospital Medical Journal - 2026;5(2):37-46
Introduction: To evaluate the association between the systemic immune-inflammation index (SII) measured on the day of embryo transfer (ET) and clinical pregnancy outcomes in patients with recurrent implantation failure (RIF) undergoing euploid frozen-thawed embryo transfer (FET) cycles. Methods : This retrospective cohort study included 160 RIF patients who underwent PGT-A-confirmed euploid blastocyst transfer between January 2022 and December 2024. SII was calculated as platelet count x (neutrophil count / lymphocyte count) using blood samples obtained on the morning of ET. Multivariable logistic regression and receiver operating characteristic (ROC) curve analyses were performed to evaluate predictive factors. Results: Clinical pregnancy was achieved in 29.4% (47/160) of patients. SII levels were lower in patients with clinical pregnancy compared to those without (321.4 +/- 115.0 vs. 448.6 +/- 166.8; p=0.009). Each 100-unit decrease in SII was independently associated with an increased likelihood of clinical pregnancy (OR: 1.29; 95% CI: 1.03-1.62; p=0.025). ROC analysis identified an optimal cut-off value of 380 (AUC=0.68). Clinical pregnancy rates were higher in the low SII group (<380) compared to the high SII group (40.3% vs. 20.5%; p=0.009). Conclusion: SII measured on the day of ET is an independent predictor of clinical pregnancy in euploid FET cycles among RIF patients and may serve as a practical, non-invasive marker for risk stratification.
