SOGC TECHNICAL UPDATE Preimplantation Genetic Testing

Objective: To review the techniques and indications of preimplantation genetic testing, including preimplantation genetic diagnosis and screening. Options: Limited to an introductory discussion about the genetic aspects of preimplantation reproductive techniques. Outcomes: This update does not discuss in detail the adverse outcomes that have been recorded in association with assisted reproductive technologies. Evidence: The Cochrane Library and Medline were searched for articles relating to preimplantation testing that were published from 1990 to February 2008, using the following terms: preimplantation genetic diagnosis, preimplantation genetic screening, and in vitro fertilization. Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies. Additional publications were identified from the bibliographies of these articles. Randomized controlled trials were considered evidence of the highest quality, followed by cohort studies. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology assessment-related agencies, clinical practice guideline collections, clinical trial registries, and from national and international medical specialty societies. Values: This update is a consensus of the Genetics Committee of the Society of Obstetricians and Gynaecologists of Canada. The recommendations were made according to guidelines developed by the Canadian Task Force on Preventive Health Care. Benefits, Harms, and Costs: This update educates readers about new genetic concepts, directions, and technology. The major harms and costs identified are those of assisted reproductive technologies. Sponsor: The Society of Obstetricians and Gynaecologists of Canada. Conclusions: Preimplantation genetic diagnosis is an alternative to prenatal diagnosis for the detection of genetic disorders in couples at risk of transmitting a genetic condition to their offspring. Preimplantation genetic screening has been proposed to improve the effectiveness of in vitro fertilization in women of advanced maternal age or in couples with recurrent miscarriage or implantation failure, but the benefits of this approach are debated.