An anal fistula with an internal opening and no external opening may be caused by a perianal abscess, rectal-anal injury, perineal surgery, etc.
1. Perianal abscess: Most anal fistulas are caused by abscesses around the rectum and anal canal. The abscess ruptures or forms an external opening in the skin around the anus after incision and drainage. The external opening heals on its own, and without the opening, an anal fistula is formed with an internal opening but no external opening.
2. Rectal-anal injury: due to swallowing bones, trauma or metal, anoscopy, etc., may damage the anal canal, rectum, etc., causing bacterial invasion of the wound, resulting in anal fistula with internal but not external opening.
3. perineal surgery: internal hemorrhoid injection mistakenly into the muscle layer, postpartum perineal suture infection, post-surgical infection, prostate or urethra surgery infection, etc., may cause the phenomenon of anal fistula with internal mouth without external mouth.
Anal fistula with internal mouth without external mouth should go to the hospital in time to check, clear the cause of the disease under the guidance of the doctor, give appropriate treatment and treatment.