The urine pregnancy test (home pregnancy test or HPT) checks for the presence of the pregnancy hormone hCG in the urine. hCG is made by the implanting blastocyst and first appears in the maternal blood around implantation, on average 9 days (range: 6-12 days) after ovulation. Blood hCG levels then rise rapidly to reach a peak at 7-10 weeks. They decline after that time.
A negative HPT result 10+ days after the missed period makes a pregnancy unlikely. With the present generation of test kits, false-positive results due to interfering materials are extremely unlikely. Pregnancy tests have now reached a level of sensitivity and specificity that is unlikely to be surpassed either by better tests or alternative technology.