PCOS - Polycistic Ovarian Syndrome
Intrinsic oocyte quality in PCOS patients is normal. In light of term maturation theory, the low quality of their embryos in IVF is likely due to difficulties of ovarian stimulation in these patients.
What was described in 1935 by American gynecologists Irving F. Stein, Sr. and Michael L. Leventhal as multiple cysts in the ovaries were not the cysts, but normal functional follicles stuck in limbo: unable to proceed to ovulation, yet unable to become atretic.
PCOS is a classic chicken or egg first story, where the chicken and egg are ovarian cysts or hyperandrogenism. There is also a question on whether insulin resistance is a part of the syndrome. Lately, some experts have started to question whether the original key features of the syndrome – ovarian cysts is a necessary feature of PCOS. We recently published a hypothesis on the origin of PCOS where we suggest the existence of a triggering event.
Term Maturation explains why PCOS patients have poor quality oocytes in IVF
The current paradigm is that patients with PCOS have intrinsically poor-quality oocytes. This conclusion is drawn from the observation that PCOS patients have low fecundity. However, low fecundity in these patients can also be attributed to an irregular cycle, which is not controlled by eggs and therefore cannot possibly reflect their properties.
Within the framework of Term Maturation, the lower quality of oocytes obtained after controlled ovarian stimulation from PCOS patients can be explained in the same way as for very young patients. The stimulation and the respective follicular phase in these patients is usually shorter than average, because a very large cohort of eggs is recruited irrespective of age. Rapidly rising E2 poses a risk of potentially life-threatening hyperstimulation, forcing a physician’s hand to trigger earlier. As the result, the vast majority of the oocytes are deprived of the opportunity to achieve term stimulation, similarly to very young patients.