Single embryo transfer after IVF/ICSI : present possibilities and limits
Faculty of Medicine and Health Sciences
The Journal of Obstetrics and Gynecology of India. - -
, p. 26-47
This review evaluates the importance of single embryo transfer (SET) in preventing multiple pregnancies (MP) after IVF/ ICSI. The incidence of MP (twins and higher-order pregnancies) after IVF/ICSI is much higher (~30%) than after natural conception (~1%). Approximately half of all the neonates are multiples. The obstetrical, neonatal and long-term consequences for the health of these children are enormous and costs incurred extremely high. Judicious SET is the only method to decrease this epidemic of iatrogenic multiple gestations. Clinical trials have shown that programs with >50% of SETs maintain high overall ongoing pregnancy rates (~30% per started cycle) while reducing the MP rate to <10%. Experience with SET remains largely European although the need to reduce MP is accepted world wide. An important issue is how to select patients suitable for SET and embryos with a high putative implantation potential. The typical patient suitable for SET is young (<36 years of age) and in her first or second IVF/ICSI trial. Embryo selection is performed using one or a combination of embryo characteristics. Available evidence suggests that, for the overall population, day 3 and day 5 selections yield similar results but better than zygote selection results. Prospective studies correlating embryo characteristics with documented implantation potential, utilising databases of individual embryos, are needed. The application of SET should be supported by other measures: reimbursement of IVF/ICSI (earned back by reducing costs), optimized cryopreservation to augment cumulative pregnancy rates per oocyte harvest and a universal way of reporting results. To make SET the standard of care in the appropriate target group, there is a need for more clinical studies, intensive counselling of patients, and increased sense of responsibility in patients, health care providers and health insurers.