Physical examination can detect AIDS, but there are prerequisites, not the window period, the window period is that the patient is considered to be infected with AIDS, after the infection of HIV and then to the time when the body appears antibodies is called the window period. The window period is considered to be 4-8 weeks, some books say it is about 5 weeks, the length of time can only be an approximation, there is no very accurate. Some books 4-8 weeks, some books are about 5 weeks, easy to appear antibodies, clinical can do check blood tests, check the HIV antibody test, note that not antigen, must be antibody test. If before the window period, not yet over the window period, the physical examination can not be found, the test can not be found, in relative terms, the interval of a few months or so, and then check can basically be ruled out, the longest time are 2 months, 4-8 weeks, after the window period more than 98% can be checked.