The internal opening of a perianal abscess is mainly identified through digital rectal examination and with the aid of a probe and perianal ultrasonography. Typically, during the onset of a perianal abscess, there is noticeable redness, swelling, heat, and pain around the anus. Inside the anal canal, digital rectal examination and anoscopy reveal swollen mucosa at the anal crypt, accompanied by the discharge of pus. Using a probe for exploration can clearly identify the presence of the internal opening locally. Once the internal opening of a perianal abscess is located, prompt surgical treatment is necessary. Surgery for perianal abscesses generally involves a one-time radical procedure complemented by incision and drainage. If an internal opening exists and involves the sphincter, further surgery involving incision, drainage, and seton placement may be required.