Doctor did urine pregnancy test two weeks after unprotected sex. came back negative. how accurate?

Accurate, but...: Urine pregnancy tests are accurate and not affected by food, herbs, common illnesses, sexually transmitted diseases, vaginal spotting, or medications. A test gives a very reliable result 3 weeks after sex (3 weeks after when conception might have happened) or 1 week after missing a period. If done sooner, a negative result may be due to testing too early such as less than 2 weeks after conception.