BIOPSIES are a pain. When they're medically necessary we put up with them. When they're not, most of us would just as soon remain un-punctured.
When the patient is a 3-day-old embryo, it's especially fair to ask for some evidence of a clear medical benefit.
Pre-implantation genetic diagnosis, or PGD, is a procedure sometimes performed in conjunction with in vitro fertilization to improve the quality of the embryos selected. It entails the careful isolation of one of a 3-day-old embryo's eight or so cells, then analysis of that cell's genetic contents. Based on what is found, IVF patients and doctors can decide which embryos to transfer into the woman's uterus.
Use of PGD has risen exponentially since its inception 17 years ago. In the U.S., where PGD isn't formally tracked, about 3,000 procedures were performed in 2005, according to a recent report from the Genetics & Public Policy Center, which is affiliated with Johns Hopkins University. Experts estimate its frequency is rising annually by 15% to 30%.
In Europe, where more accurate numbers are available, a reporting system found a more than 20-fold jump in PGD procedures between 1999 and 2003, the most recent year for which figures are available.
But specialists are concerned that much of the rise in PGD is for an unproven goal: improving the successful pregnancy rates of older women undergoing IVF. "There's a lot of controversy in the field as to how PGD should be appropriately applied," says Catherine Racowsky, director of the IVF lab at Boston's Brigham and Women's Hospital.
Virtually everyone in the fertility community agrees that PGD is valuable for its original use: preventing the transmission of certain serious inherited disorders. But many are far less confident about use of the costly procedure on the embryos of otherwise healthy mothers whose only problem is the decline in fertility that inevitably comes with advancing age.
Experts say there is a lack of solid evidence that PGD results in an actual increase in the so-called "take-home baby rate."
They say the procedure mostly makes sense for women who have experienced repeated miscarriages while undergoing in vitro fertilization and want to avoid any more of them.
Some experts also harbor suspicions that, just maybe, removing a cell from an early-stage embryo could be harmful, although there is not much evidence to support such a fear.
