#341 : Does Only the Stage Matters? Influence of a Blastocyst Scoring System on Clinical Pregnancy and Live Birth Outcomes with Fresh Set: A Concluding Study

Abstract

Background: Blastocyst culture with single embryo transfer (SET) is now routinely offered to our IVF patients at KK IVF. We have been using a simplified scoring system since 2016 in our routine assessment of blastocysts. Aims: This retrospective study aims to conclude our centre’s scoring system for fresh blastocyst for Day 5(D5) ET. Method: Data of 694 patients with fresh Intracytoplasmic Sperm Injection (ICSI) cycle and SET on D5 done between Jan 2018 and Dec 2020 were analysed. Only patients with 1[Formula: see text] cycle stimulation attempt and embryos cultured in single-step media under pre-mixed incubator conditions were included in this study. Rates of clinical pregnancy (CPR), multiple pregnancy (MPR), miscarriage (MISCR) and livebirth (LBR) were investigated. Data were classified into stage and grade of blastocyst transferred respectively as: Fully Expanded (FE), Early Expanded (EE), Early Blastocyst (EBL); A, B, C and Pseudo (P-; with at least 20% blastomeres excluded from the formation of blastocyst) and subjected to Chi-square test for significance, p<0.05. Blastocysts are scored in our centre first according to the stage of blastocyst development, followed by a grading assessment on the cohesion and cell number of the inner cellular mass (ICM) and trophectoderm cells (TE). The blastocyst grade equivalent by Gardner’s classification system of the ICM and TE is in parentheses - A=(AA), B=(AB, BA,BB) and C=(AC,CA,BC,CB). Blastocysts void of ICM are deemed non-transferrable. Results: CPR significantly different across stages of BL transferred (p = 0.00001). Transferring EBL is associated with a significantly higher MISCR (p=0.004). Multiple pregnancy was observed in groups with expanded blastocyst transferred only and MPR appears higher when top grade BL transferred (p=0.45). LBR is incremental with better quality BL transferred (p=0.000049). Conclusion: Stage of blastocyst development and a graded ICM at ET improve pregnancy and livebirth outcomes. Miscarriage risk is incremental with early blastocyst transferred. Suboptimal embryos remain transferrable as can still result in viable pregnancies and livebirths when there’s no better selection.