Dartmouth-Hitchcock

Fertilization

1. The harvested eggs are placed in an incubator, in a solution that will support their growth and development.
2. In a petri dish, eggs are combined with sperm from either your male partner or a donor, if you are using one. Semen from a male partner can be fresh (ideally, within about an hour of when your eggs are retrieved) or frozen, but semen from a donor must have been frozen and quarantined for at least six months. Because there are fewer moving sperm in frozen semen, the use of fresh semen is preferred. However, we recommend that a semen sample be collected and frozen as a back-up before egg retrieval, in the event that a fresh sample cannot be obtained. If the standard procedure of fertilization does not occur, your doctor may recommend intracytoplasmic sperm injection (ICSI), a procedure that injects the sperm directly into the egg.
3. If fertilization occurs, the fertilized eggs (embryos) will continue to develop in the laboratory for two to four days. We keep eggs, sperm and embryos under the best possible conditions of temperature, atmosphere and nourishment.
4. In order to successfully implant in the uterus and establish a pregnancy, embryos must hatch out of the protective coating (zona pellucida) that surrounds them during early development. In some patients, this hatching does not happen and the embryos do not implant. A laboratory procedure called assisted hatching can help embryos to implant in the uterus by weakening the zona pellucida around them. The procedure involves making a small hole in the zona pellucida with a weakly acidic solution before the embryo is transferred to you. You may need assisted hatching if you have had a number of unsuccessful IVF cycles, or your eggs have unusually thick zona pellucidae.