A retrospective analysis of the in-vitro development of ‘spare’ human in-vitro fertilization preimplantation embryos using ‘in-house’ prepared medium and ‘Medi-Cult’ commercial medium

In-house prepared medium was used routinely in our in-vitro fertilization (IVF) facility prior to the introduction of the commercial ‘Medi-Cult’ products. A comparative study of the in-vitro development of embryos cultured in two [T6 and Earle's balanced salt solution (EBSS)] humaninactivated serum (HlS)-supplemented media from days 0 to 5 showed that 44.7% (46/103) of the embryos developed to the blastocyst stage in the T6 medium compared with 22.3% (23/103) in EBSS. Following the introduction of the commercial Medi-Cult IVF M2 medium, which is used routinely to culture fertilized eggs from days 0 to 2, new baseline data were required for the in-vitro development of ‘spare’ embryos from days 2 to 5. When Medi-Cult M3 medium was used, 35.6% (37/104) of the ‘spare’ day 2 embryos achieved the blastocyst stage. However, if morphologically similar (four normal nucleated blastomeres with no fragmentation) day 2 embryos were selected, an increase in the blastocyst rate to 50.0% (33/66) was achieved. This compared favourably with the 45.0% blastocyst rate (published in the Medi-Cult literature) for M2/M3 medium cultured human embryos. A small series of experiments with T6 $ HIS medium and human serum albumin (HSA)- supplemented Ham's F-10, MCDB 302 and M3 media was undertaken to identify a suitable medium which could be used for the culture of M2 medium day 2 embryos. Results show that M2 medium cultured embryos placed in Ham's F-10 medium supplemented with 10 mg/ml HSA gave an acceptable 37.8% (14/45) blastocyst rate. Therefore, this medium could be substituted for M3 medium in an emergency. A total of 483 IVF embryos donated by patients, which were surplus to the therapeutic IVF programme, were used for these studies over a period of 30 months. Late day 2 IVF spare embryos were assigned an embryo score based on a high-power phase-contrast microscopic examination prior to being placed in culture. The embryo score provides an effective in-vitro parameter with which embryos from different patients can be compared. The cleavage and development of individual embryos were monitored on days 2 to 5. In some cases, the continuing normal development and viability of the day 5 cultured embryo were assessed by monitoring the hatching, attachment and outgrowth of the cavitated blastocyst.