125 A COMPARISON OF SEQUENTIAL MEDIUM WITH NON-SEQUENTIAL MEDIUM: DO SOME PATIENTS' EMBRYOS CULTURE BETTER IN ONE THAN IN THE OTHER?

Abstract

The development of sequential media is often reported as one of the reasons why human IVF pregnancy rates have increased over the last 10 years. The objective was to determine if a single culture medium (global) is as effective in human embryo culture as a sequential medium (G series) and whether embryos of some patients prefer one medium over the other. Patients (n = 144) were placed into one of three treatment arms. Treatment 1, sequential: culture in G Series medium. Treatment 2, nonsequential: culture in global medium. Treatment 3, split: After fertilization, a patient’s embryos are split between the above two treatments. All patients with embryos from April 2007 to January of 2008 (PGD patients were excluded) were allocated to one of the three treatments. Eggs were collected in and fertilized in vitro Life media (GMOPS and GFert, respectively). In treatment 1, patients’ embryos (n = 346) were cultured in sequential media. In treatment 2, patients’ embryos (n = 482) are cultured in nonsequential media. In treatment 3, embryos (n = 420) from each patient are split between sequential and nonsequential media after rinsing in the treatment medium. Patients whose embryos met the criteria (at least 2 embryos, >6 cells, grade excellent to good) were transferred on day 5. All embryos remaining after embryo transfer were frozen on day 5. A maximum of 2 embryos was transferred per patient. Frequencies were compared with a chi square test. Results: The percentage of cases that achieved transfers on Day 5 (an indication of embryo quality) were 44.0%, 50.0% and 68.4% for sequential, nonsequential and split, respectively. Split was significantly different from the sequential (P < 0.05). The percentage of transferrable blastocysts was 27% for sequential, 43% for nonsequential and 39% for split (difference between sequential and the other two was significant at P < 0.0005). Pregnancy rates and implantation rates were 32%/19.0%, 36%/22.5% and 50%/32.2% for sequential, nonsequential and split. (Only implantation rates between split and sequential were significant P < 0.05). For embryos in the split treatment, development to transferable blastocysts was 37.0% in sequential media v. 41.6% in nonsequential medium (not significant). In conclusion, a single medium (nonsequential) for culture to blastocyst yields results similar to embryos cultured in the more complex sequential medium. There is some evidence that a benefit can be gained by splitting embryos between two culture media to increase implantation rates. Further studies need to be done to see if this will result in increased pregnancy rates.