P-153 Clinical outcome of different embryo transfer strategies after late rescue ICSI procedure: A cohort study based on over 140 thousand ART cycles

Abstract

Abstract Study question How effective and safe is freeze-all blastocyst transfer in combination with late rescue intracytoplasmic sperm injection (r-ICSI)? Summary answer Freeze-all blastocyst stage embryo transfer (ET) serves as an optimal strategy to support late r-ICSI. What is known already Late r-ICSI has not been widely adopted due to the time-dependent in vitro deterioration of oocyte quality and endometrial growth not being synchronised with embryo development. Study design, size, duration This was a retrospective cohort study. All participants received treatment between 2009 and 2019. 2,270 patients in the aggregate encountered unexpected total fertilisation failure (TFF) during 149,054 cycles of in vitro fertilisation (IVF) and adopted a late r-ICSI procedure, whilst meeting the inclusion criteria for this study. Participants/materials, setting, methods Patients were grouped according to transfer strategies (926 women in Group 1 underwent fresh ET, 365 women in Group 2 underwent freeze-all ET, 716 women in Group 3 experienced blastulation failure, and 263 women did not have available D3 embryos). Patients received different ET strategies after r-ICSI, with the main outcome measures included live birth rate (LBR), cumulative live birth rate (cLBR), and conservative cLBR. Main results and the role of chance TFF occurred in 7.4 % of all IVF cycles. Group 1 tended to be older at oocyte retrieval [33.00 (30.00–37.00) vs. 31.00 (29.00–35.00), P < 0.001], with more infertile years [5.00 (3.00–8.00) vs. 3.00 (2.00–6.00), P < 0.001], higher follicle-stimulating hormone (FSH) levels [7.10 (5.71–8.69) vs. 6.61 (5.25–7.95) mIU/mL, P < 0.001], higher gonadotropin consumption [2850.00 (1950.00–4125.00) vs. 2325.00 (1800.00–3150.00) IU, P < 0.001], and fewer oocytes retrieved [10.00 (6.00–15.00) vs. 13.00 (9.00–19.00), P < 0.001]. Group 2 exhibited considerably better LBRs following the first ET cycle (37.53 % vs. 4.64 %) and cLBR (52.60 % vs. 8.21 %). After adjustment for covariates using binary logistic regression analyses, Group 2 still showed better obstetric performance in LBR (OR:11.77, 95 % CI (8.42–16.45)], cLBR (OR:11.29, 95 % CI (7.84–16.27)], and conservative cLBR (OR:2.55, 95 % CI (1.83–3.55)]. Additionally, the two groups showed similar miscarriage rates, whilst no new-borns with malformations or congenital diseases were reported. Limitations, reasons for caution This study was based on a retrospective cohort, which is inevitably associated with a skewed data distribution and inherent biases. Wider implications of the findings Our study highlights r-ICSI as a safe and effective alternate solution for unexpected TFF to aid frustrated couples. However, for women with limited oocytes available for r-ICSI use, weighing the benefits against the costs of the procedure might be prudent before implementing in vitro blastulation. Trial registration number NA