To PGD or not to PGD: is there a magic number of oocytes to start with?

Abstract

PGD results decrease significantly number of embryos available for transfer by 30–70%. In order to better counsel patients on IVF-PGD outcome, we investigated PGD efficiency to produce embryos suitable for ET and pregnancy with low and high number of oocytes at different age groups and by the indication to PGD. Retrospective data analysis. During 4 years period (11/02 to 11/06), 562 consecutive IVF-PGD cycles were performed at IHR with RGI in Chicago. 251 PGD cycles were for Aneuploidy (AS), 168 cycles for 51 Single Gene Disorders (SGD), 99 cycles for HLA matched embryos ± SGD ± AS, and 44 PGD cycles for translocations ± AS. Patient's ovarian reserve was estimated before treatment by age, antral follicle count, and day-3 FSH levels, and accordingly changes in the stimulation protocol or increase in medication dosage to try to improve oocyte yield were implemented. Data were analyzed for all cycles, by the indication for PGD, and by age. Figure 1 summarizes % cycles with embryos suitable for ET, % ET/retrieval, and clinical PR/ET by number of oocytes retrieved for all women age 22–45. Increase number of oocytes increased patient chance to have an ET with suitable embryos, as well as to conceive and to have surplus blastocysts cryopreserved. In the younger age group (≤35), most patient reached ET even with 1–7 oocytes (mean # of zygotes = 3) and had good PR/ET. PR/ET for patient at age 36–42 years was 10–15% with ≤7 oocytes, but once ≥16 oocytes were retrieved, they achieved excellent outcome. Percent of cycles with normal/unaffected cryopreserved blastocysts increased significantly with the increase in oocyte number (P<0.01). Number of oocytes retrieved had no significant effect on % aneuploidy. Routine canceling of PGD cycles because of low number of oocytes should be reconsidered. Individually adjusted ovarian stimulation based on estimated ovarian reserve for patients undergoing IVF-PGD may improve outcome. These results suggest that once patients were adequately stimulated and wish to conceive with her own eggs, oocyte retrieval and PGD may be continued even with very low number of oocytes or embryos.