Can a woman get breakthrough bleeding in pcos without endometerium hyperplasia?

PCOS ?'s: Endometrial hyperplasia is certainly a complication of PCOS, but even marginal increases in the thickness of the endometrium (caused by sustained estrogen production w/o ovulation in PCOS ) can lead to "breakthrough bleeding". If PCOS has been diagnosed, it is best to be on low dose oral bcp's to avoid over-stimulation of the uterine lining and later abnormalities.