IVM is a variation of in vitro fertilization (IVF), wherein the eggs are aspirated from the ovaries with minimal hormonal stimulation. The eggs are then matured for 24 to 48 hours in the laboratory, fertilized with intracytoplasmic sperm injection (ICSI), and the resulting embryos are transferred to the uterus. This procedure prevents the need for stimulation of the eggs to full maturation in vivo, thus avoiding the discomfort of multiple injections, elevated hormone levels, and the risk of ovarian hyperstimulation syndrome (OHSS). The cost is somewhat less than regular IVF. Correspondingly the success rate is lower (about 30-35%) compared with regular IVF in comparable high-responding women (50-60%). The principal advantage is in avoiding OHSS, which can be very uncomfortable, require removal of fluid from the abdomen, sometimes require hospitalization, and rarely be complicated by serious complications or extremely rarely, by death. One disadvantage is the need to transfer more embryos to achieve this rate of success, exposing the patient to a risk of high order (more than twins) multiple pregnancy. With regular IVF now many of these highest prognosis patients can elect to have single embryo transfer (SET) with their risk of twins therefore being minimal. The most important risk is whether the increased exposure to in vitro conditions could increase abnormalities of the offspring compared with regular IVF. To date about 500 babies have been born with as yet no indication of an increased risk of fetal abnormalities, but until many thousands have been born (over a million IVF babies have been born world-wide), it will not be possible to determine whether IVM procedures are entirely safe. For this reason, IVM is still considered experimental.
The aspects of IVM that are being investigated to attempt to improve the outcomes are timing and preparation before egg retrieval, culture conditions, and improving implantation. For example, it has been found that when human chorionic gonadotropin (hCG) is given to the woman prior to egg retrieval, the rate and speed of in vitro maturation is accelerated. Various additives are being investigated in the culture medium, such as gonadotropins, fetal serum, and even newer substances that improve maturation of the egg nucleus and cytoplasm. Women with polycystic ovaries (PCO) are prime candidates for this procedure, but have a higher rate of miscarriage with IVM. One method that could reduce that risk would be metformin, which favorably affects a number of factors that influence implantation.
With improving culture conditions and embryo quality with regular IVF allowing more women to have SET, and with adjunctive treatments such as metformin, and cabergoline that reduce the risk of OHSS, it is difficult at present to say whether IVM is likely to be an advantage as an alternative to regular IVF in the future. Reproductive Partners UCSD Regional Fertility Center is constantly monitoring the progress of such techniques and will implement IVM at the point where it is clearly shown to be both safe and advantageous for our patients.
