In general, the anus may open when you open your legs to pass gas. For the human body, when you open your legs to ventilate, the muscles around the anus are pulled outward and to the sides by the legs, which will lead to the anus opening, if there is no obvious discomfort after the anus opens, this is a normal physiological phenomenon, do not have to worry too much. But for the anus open, there are other obvious discomfort symptoms, such as accompanied by fecal discharge, anal pain and other adverse symptoms, it is recommended that such people go to the regular hospital in a timely manner, early treatment of positive symptoms, so as not to delay the treatment of the disease. In daily life, but also pay attention to the anal clean and dry, so as to avoid bacterial growth and perianal diseases.