IVF (In Vitro Fertilization)
In vitro fertilization literally means "fertilized in glass." It is the most advanced procedure in the ART repertoire, where the egg and sperm are combined in the laboratory, incubated, and the resulting embryos are transferred into the woman's uterus. In 2007, more than 99% of all ART procedures were IVF procedures.
There are two types of transfers that can occur in an IVF procedure: a standard 2-3 day transfer or a blastocyst transfer. Since close to half of standard 2-3 day old embryos are chromosomally abnormal, culturing these embryos for an additional 2 to 3 days, often results in more chromosomally normal embryos. The chromosomally abnormal embryos are selected out naturally and develop to the blastocyst (5-day-old) stage while in the laboratory. Usually, only the best embryos have the ability to grow to the blastocyst stage and the Implantation rate per blastocyst transferred is twice that of 3-day-old embryos. Read more about Blastocyst transfer here.
Depending on the needs of the patient, there are a number of IVF procedures that can be conducted in the laboratory before the embryo is transferred. Two of these procedures are ICSI and assisted hatching.
The ICSI (intracytoplasmic sperm injection) procedure is a treatment specifically used for male factor infertility. With this procedure the IVF cycle is conducted exactly in the same manner as a typical IVF cycle. However, after the eggs are retrieved, instead of mixing the sperm with the egg, the embryologist utilizes a thin glass pipette to immobilize the sperm, suck it up into the pipette, and then inject it directly into the egg's cytoplasm.
Assisted hatching was developed in response to this theory that some women may fail multiple cycles of standard IVF because their eggs have a thicker shell. The assisted hatching procedure, like ICSI, is carried out by a technique known as micromanipulation. In small dishes the embryos, which now contain an average of six to eight cells, are stabilized by a holding pipette, while on the opposite side a small pipette containing acidified Tyrode's solution creates a small defect in the zona. By creating a minor defect in the zona (shell) the result is a greater chance of the embryo "hatching," or shedding its shell, allowing for a better chance of implantation in the endometrium. In our studies, assisted hatching had improved the success rate in women between 35 and 40 so much that it began exceeding the results of our women under 35.
