I had a low risk / no risk exposure on April 16. I took a 4th generation combo / duo test on May 14 exactly 28 days past last exposure for peace of mind. My exposure was performing oral sex on a male without ejaculation. I know the answer for oral sex is no risk but I tested because I am married. Today my results came back negative. My question; is a 4th gen. Combo / duo test conclusive at exactly 28 days and can I resume sexual relations with my wife?