In vitro fertilization (IVF) can be a miraculous boon to couples who long for a child, but the procedure is not without its risks. A small number of women undergoing treatment with this procedure, some 5%, develop a complication known as ovarian hyperstimulation syndrome, and another 1-2% experience a life-threatening illness as a result. Ovarian hyperstimulation syndrome results as a response to medications taken prior to IVF for the purpose of stimulating ovulation.
IVF On Hold
When implantation of an embryo takes place during ovarian hyperstimulation, there are risks to both mother and child. Within the last two years, researchers at the Mayo Clinic responded to this issue by developing a method that avoids implantation at the time a woman's ovaries are liable to become hyperstimulated. The embryos are frozen until any risk of hyperstimulation is past. The cryopreservation of the embryos gives mother and baby the best chance of a healthy, happy pregnancy and birth.
Senior study researcher Charles Coddington, M.D., a Mayo Clinic reproductive endocrinologist, discussing the steps taken by his team in minimizing ovarian hyperstimulation syndrome as an issue states, "If we feel that there's a good chance a woman would get this syndrome, then we would recommend complete cryopreservation -- freezing -- of her embryos and waiting about a month or so to complete the embryo transfer."
Normal ovaries are about the size of a walnut, however, stimulating ovulation can sometimes cause a woman's ovaries to respond by enlarging, sometimes to the point where they are orange or even grapefruit-sized. This enlargement is painful since the ovarian sheathing does not have the capacity to stretch. The enlarged ovaries can also secrete fluid into the abdomen, leading to a sense of fullness and sometimes, breathing difficulties. The secreted fluid may also cause kidney disease or thrombosis. In rare cases, blood clots can form in a woman's legs, which may lead to pulmonary embolism.
The Mayo Clinic study was conducted over the course of four years, with 188 patients who were found to be at risk for ovarian hyperstimulation syndrome due to high estrogenic hormone levels and the development of many ovarian follicles. The women were divided into three groups, with one group having their ovary stimulating medication withheld for one day, one group treated in the usual manner, and one group having their embryos undergo cryopreservation with a subsequent delay for implantation into the uterus. It was clear that the freezing and delaying procedure yielded the best results. "The quality and pregnancy potential of the frozen embryos remains excellent, as demonstrated by the high cumulative live birth rate per patient," concluded Dr. Coddington.