Middle to lower uterine segment embryo transfer improves implantation and pregnancy rates compared with fundal embryo transfer

Objective: To assess differences in pregnancy and implantation rates as a function of the embryo placement. Design: Prospective cohort study. Setting: A tertiary care center. Subject(s): All fresh, nondonor IVF cycles performed in 2001. Intervention(s): Alteration in embryo transfer (ET) target location from the fundal region to the middle to lower uterine segment. Main Outcome Measure(s): Clinical pregnancy rate (sonographic sac evidence/number of transfer cycles), implantation rate (number of sacs/number of embryos transferred), patient age, peak E-2, and fertilization rate. Result(s): A total of 393 fundal and 273 lower to middle uterine segment ETs were performed. The pregnancy (PR), implantation, and birth rates were significantly higher after a middle to lower uterine segment ET compared with fundal ET (39.6% vs. 31.2%; 21% vs. 14%; and 34.1% vs. 26.2%, respectively). Groups did not differ regarding patient age, basal FSH, peak E-2, number of intracytoplasmic sperm injection (ICSI) cycles, fertilization rate, embryo quality, or number of embryos transferred. Conclusion(s): Both PR and implantation rates are favorably affected by directing embryo placement to the lower to middle uterine segment. By some unknown mechanism, it appears that this endometrial location provides a more favorable region for embryo deposition. (Fertil Steril((R)) 2004;81:1273-7. (C)2004 by American Society for Reproductive Medicine.).