[What results can be expected from in vitro fertilization and other technics of assisted fertilization?].

Results of assisted reproductive techniques (IV, GIFT and ZIFT) have improved progressively during the last years but they are still not satisfactory specially when they are analyzed in terms of cost efficacy. During 1990, in the world literature, the following successful results were reported: pregnancy rates of 20% and delivery rates of 15% for IVF-ET, 29% and 22% for GIFT and 21% and 16% for ZIFT. In spite of the small number of cases reported in Chile, results are similar to those of USA and Europe. Results of assisted fertilization techniques have improved with the use of Gn-RH agonists and are worse in patients older than 35 years of age than in younger ones. Pregnancies rates are higher when the number of transferred ovocytes increases although transfer of more than 3 or 4 ovocytes or embryos is contraindicated because of the risks of multiple pregnancies. When more than 3 or 4 embryos are obtained those not transferred are usually cryopreserved. IVF-ET is the first choice of treatment in cases of infertility due to severe tubal damage and/or extensive and dense pelvic adhesions. In cases of infertility with normal tubes, intrauterine inseminations in 3 to 4 controlled hyperstimulated cycles are recommended before indicating an assisted fertilization procedure. The most risky complication of assisted reproduction, besides multiple pregnancy, is severe ovarian hyperstimulation syndrome (SOHS). This syndrome is prevented by not injecting HCG or by not transferring ovocytes or embryos in cases of high estradiol levels after HMG and/or FSH administration.