Hyaluronan-enriched transfer medium in cleavage-stage frozen-thawed embryo transfers increases implantation rate without improvement of delivery rate

Objective: To investigate the efficacy of hyaluronan-enriched transfer media in cleavage-stage frozen embryo transfer cycles. Design: Two commercially available transfer media were prospectively compared in an observational study. Setting: Hospital-based in vitro fertilization clinic. Patient(s): Patients (n = 425) undergoing frozen-thawed embryo transfer (FET). The embryos transferred were included in either a study group (high hyaluronic acid [HA], n 199) or a control group (low HA, n = 226). Intervention(s): Delivery rate per FET; positive hCG rate, biochemical pregnancy rate, clinical pregnancy rate, implantation rate, and clinical abortion rate were secondary outcomes. Result(s): The use of HA in the transfer media significantly increased the positive hCG rate (37.2% vs. 25.2%) and implantation rate (23.1% vs. 15.8%) without increasing the delivery rate (21.6% vs. 21.2%). More subjects in the study group with a positive hCG test experienced biochemical pregnancy (28.4% vs. 8.9%). Conclusion(s): Addition of HA to transfer media seems to favor attachment of early embryos in FETs without increasing the delivery rate. (Fertil Steril (R) 2010;94:1669-73. (C) 2010 by American Society for Reproductive Medicine.)