My girlfriend has pcos and she has been tested positive for an std. is it possible that the issue associated with pcos cause a false positive result?

Highly unlikely,,,: This is highly unlikely. Pcos (polycystic ovary syndrome) is a condition where the ovaries develop cysts because the follicles containing the egg rupture less often and so ovulation doesn't happen normally. This has practically no relation to an std which is due to contact with an infected individual. Pcos can cause high hormone levels but an std tests for se kind of infection. Best of luck.