If a female has pcos can she use clear blue pregnancy test to see if shes pregnant 5 days before missed period?

An accurate diagnosis of "PCOS" usually will occur with menstrual irregularities, so a pregnancy test may be negative since it is difficult to determine if your "period is missed". If pregnancy is not desired at this point, ask your GYN physician about low dose oral bcp's, which is the treatment of choice for PCOS, to avoid long term effects of continued estrogen on the endometrial lining.