Another complication that appeared on occasion was ovarian torsion, which occurs when the ovary twists around on itself, cutting off its blood supply. In a study of 1,500 women who underwent in vitro fertilization (IVF), torsion occurred in 0.13 percent of the cycles. The torsion occurred late, 6 to 13 weeks after the oocyte retrieval, and since the risk of torsion increases with the softening of the ligaments that appears in pregnancy, it seems that torsion is a complication that is mainly associated with women who get pregnant with IVF, according to Dr. Murphy. Later in the workshop, Dr. Zev Rosenwaks, director of the Center for Reproductive Medicine and Infertility at Cornell University, said that torsion can also occur with hyperstimulation in the absence of pregnancy.

Various things can be expected to increase the potential risk of complications for women undergoing oocyte retrieval, Dr. Murphy said. Previous surgeries make complications more likely, for example, because the surgeon finds structures where they’re not supposed to be, or else the structures don't move the way they’re supposed to move. A history of pelvic inflammatory disease (PID) is also an important risk factor, as are endometriosis and pelvic adhesions. Generally speaking, all of these things are much more likely to be found in women undergoing in vitro fertilization—because of their history of infertility and various efforts to get pregnant—than in women serving as egg donors.

In conclusion, Dr. Murphy said, the data indicate that the potential risks of surgical complications from oocyte retrieval are generally very small. There are very few data that are specific to egg donors—as opposed to infertile women undergoing oocyte retrieval and, later, the implantation of embryos—but all of the evidence implies that the potential surgical risks should be much lower in oocyte donors.

POTENTIAL RISKS OF ANESTHESIA

Besides the potential risks associated with the surgical retrieval, women undergoing oocyte retrieval also face certain potential risks from the anesthesia used to handle their pain during the surgery. Lawrence Tsen, associate professor in anesthesia at the Harvard Medical School, spoke at the workshop about these potential risks.

When discussing the use of anesthesia, Dr. Tsen said, there are three basic subjects to cover: whether anesthesia is needed for a particular pro-



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