From the appearance of the anus, the top of the anus should be the reproductive and urinary organs. What is different between men and women is that the genital organs of men and women have different shapes due to their different physiological structures. In women, the urethra is short and the genital organs are more easily exposed, closer to the anus and more susceptible to external contamination, so it is important to pay attention to vulvar hygiene. From a three-dimensional perspective, above the anus should be the anal sinus and rectum. The anal sinus is a pocket-like structure, and long-term diarrhea and constipation are extremely susceptible to infection, leading to inflammation of the anal sinus, specifically manifested as anal pain, which may also develop into a perianal abscess or anal fistula. The rectum is connected to the sigmoid colon, which is the site of many internal hemorrhoids and is also a common site for the opening of the internal opening of anal fistulas, often leading to perianal abscesses due to bacterial infection, which can lead to anal fistulas if not actively treated.