Took a urine sample to gp for dip test&she said it was cytitis, but would she have known by the dip if it was an sti? bleeding a little after sex

No: The dip test is a simple one and can be interpreted to suggest a UTI or cystitis based on the material found in the specimen. It is more a screening test than a definitive one and assumes there is not a reason to look for STD's. Some STD's can be screened for with urine, not all, and there are significant limitations to that source.It is sent to a lab. I don't think she looked.