What is the cause of anal swelling and pain

The anus, as a place for human defecation, actually contains a large number of bacteria. However, due to the body's own immune function and the anus's ability to secrete mucus that kills bacteria, no pathological changes occur. However, once this situation becomes unbalanced, pain, redness, swelling, and even suppuration will occur in the anal area. When it comes to anal pain, there are actually many reasons, because most anal-related diseases have this symptom.

The pain caused by anal fissure is cyclical and often occurs during or after defecation. It is mainly caused by irritation from feces and expansion of the ulcer fissure. The pain is paroxysmal burning or knife-like pain and can last for several minutes; the pain subsides after the stool passes. In addition, due to the stimulation of defecation, the internal sphincter may be in continuous spasm, causing severe and persistent pain in the ulcer fissure; it can often last for several hours, and the patient is restless and in great pain; in severe cases, the pain can last for more than 24 hours. In addition to pain, anal fissures are often accompanied by symptoms such as bleeding and constipation.

Anal sinusitis generally presents with slight pain and distension in the anus. During bowel movements, stool presses on the inflamed anal sinus, causing burning pain in the anus. If the sphincter contracts due to stimulation, the pain will intensify and radiate to the buttocks and posterior thigh. It is often accompanied by a small amount of purulent or mucous secretion with a foul odor, which may cause moisture, itching and other discomforts around the anus over time.

In mild cases of thrombosed external hemorrhoids, there is a foreign body sensation, which is often accompanied by swelling and pain. Due to damage to the perianal veins, blood clots form thrombi, and purple round hard nodules appear under the outer skin of the anus, usually at 3 o'clock and 9 o'clock in the lithotomy position.

The main symptom of perianal abscess is distension and pain, and the pain is like chicken pecking when pus forms. Due to different factors such as the location of perianal abscess, size of abscess, pathogenic bacteria and patient's body resistance, the symptoms and signs that appear are also different. Common ones include subcutaneous abscess around the anus, ischiorectal abscess, pelvic rectal abscess, retrorectal abscess, and tuberculous abscess. In addition to the different main symptoms, these abscesses generally have fever, chills, constipation, and difficulty urinating. Unlike other parts of the body, more than 90% of perianal abscesses can form anal fistulas, which have a longer course of disease.

The main symptoms of incarcerated internal hemorrhoids are distension and burning pain. They are mostly caused by varicose veins, damaged blood vessels, and thrombosis, which result in restricted tissue circulation and prolapse of the anus. The hemorrhoids cannot be retracted and are more common in stage II and III internal hemorrhoids. Therefore, it is necessary to reduce or surgically treat the tumor as soon as possible, otherwise the surface mucosa will easily bleed, be damaged, or even become infected.

The main symptoms of external hemorrhoid edema are distension and burning pain, manifesting as a localized lump at the edge of the anus, which is hard, smooth, shiny and obviously tender. It is mostly caused by fatigue, straining during defecation, or surgical stimulation.