I'm not entirely sure. I don't know a lot about PCOS other than what it is and possible symptoms.
But I suppose when a woman experiences bleeding when she, for whatever reason, doesn't ovulate could be likened to how women bleed when taking birth control pills (which stops ovulation). A shift in hormones causes bleeding that is like actual menstruation, but not.
Does that answer your question kinda? Which symptoms of PCOS do you mean?