A pregnancy can indeed exist when a pregnancy test appears dark and light. Because the days of pregnancy are relatively short, the concentration of HCG in the urine is not particularly high at the time of the test, and the test paper will appear to be one shade darker and one shade lighter. When you are sure that you are not pregnant, you should consider whether there will be errors when you take the test, for example, whether the urine is too full when you take the test, whether the vagina has expired, whether the test has been put together with other pollutants after taking the test, and also whether the observation time has exceeded a certain range, which will cause certain errors. In this case, as far as possible, after 8-10 days after intercourse, go to the hospital to draw blood HCG value, the accuracy can reach 99%, because the accuracy of urine HCG exists 85%-95%, not as high as the accuracy of blood HCG.