Cancelled Cycles
The maturity of oocytes varies considerably and not all fertilize. The average fertilization rate is about 65%. In rare cases no eggs fertilize. Sometimes the sperm prove incapable of fertilization despite a normal semen analysis. In such cases, ICSI can be done the day after retrieval ("rescue ICSI"). While fertilization can usually be established, the pregnancy rate with "rescue ICSI" is lower than in cycles with timely fertilization. At other times the eggs are not as ready to be fertilized as they appear to be by ultrasound and blood tests. Finally, cell division and embryo development may fail to occur despite apparently normal fertilization. In some cases embryo quality may not be optimal or the embryos may stop developing.
Obviously the embryo transfer would have to be canceled if one of these problems arose, but fortunately they are quite uncommon and over 90% of patients in our program either undergo transfer of fresh embryos or have embryos frozen for a future transfer.
Handling of the eggs, which are very minute, outside of the body is inherently hazardous and requires great skill and care. On occasion, an egg or an embryo, fresh or frozen, may get stuck to the side of a culture dish and cannot be found. These kinds of mishaps are rare but you need to be aware of their possibility.