What causes intermittent contracting pain in the anus?

Intermittent anal pain with spasmodic contractions may be caused by various factors. Anal fissures are a common cause; when the skin of the anal canal is injured, the裂口 (crack) becomes irritated during bowel movements, causing severe pain and triggering spasm of the anal muscles, resulting in episodic contraction pain. Hemorrhoids can also lead to such pain, particularly when complicated by infection, prolapse with incarceration, or thrombosis, which may stimulate nerves around the anus and induce discomfort. Perianal abscesses are another frequent cause—due to infection in perianal soft tissues and tissue spaces, inflammation and edema develop, leading to pain. Other contributing factors include anal sphincter spasm and intestinal obstruction. It is recommended to seek medical attention promptly when this symptom occurs, so that the underlying cause can be accurately diagnosed and appropriately treated.