Edema, or anal edema, has the highest incidence after surgery for external and mixed hemorrhoids. Edema occurs due to local blood and lymphatic circulation disorders, increased vascular permeability, and water retention in the tissue interstices. Anal swelling is not only swollen and painful, but also causes the connective tissue to proliferate and affects healing, so it must be actively prevented and treated. I. Etiology Circulation disorder at the trauma edge: the original venous and lymphatic circulation pathways at the trauma edge are destroyed due to surgery, or the trauma surface is compressed too tightly, local circulation is obstructed and tissue fluid is retained, which is an important cause of anal swelling after mixed hemorrhoid surgery. Improper surgical operation: improper selection of incision for external hemorrhoids, poor flap alignment, low injection position for internal hemorrhoids, etc., resulting in edema caused by obstruction of lymphatic and blood return in the anus. After surgery, premature squatting, dry stool, difficult stool, and obstruction of venous reflux in the anus caused by the patient’s struggle with the toilet. Or diarrhea, which frequently stimulates the wound within a short period of time. Postoperative wound infection causes inflammation of the anal tissues, followed by edema. Second, prevention and treatment Choose the correct surgical method, the anal margin surgical incision should be radially centered on the anus as much as possible, the flap should be neatly matched, and there should be enough skin bridges between the anal canal incisions; the internal hemorrhoid injection ligation point should not be too close to the tooth line to avoid causing edema due to impaired blood circulation in the anal canal. Clamping of healthy tissues at the trauma edge should be avoided as much as possible to reduce tissue loss during surgery. The subcutaneous venous plexus within the “V” shaped incision at the anal verge should be completely removed and the tip of the “V” shaped incision should be extended outward by 0.5-1 cm to facilitate drainage. For those who have tight anus, it can be considered to loosen part of the internal and external anal sphincter during the operation, so that the edema caused by the obstruction of circulation in the anus due to the spasm of the sphincter can be removed. Keep the patient’s urine and stool unobstructed after surgery, and give laxative and urinary treatment to those who have difficulty in urinating and defecating, avoid squatting for a long time, and actively deal with diarrhea and reduce the number of bowel movements if diarrhea occurs. Daily fumigation of the anus after defecation and drug exchange should be given to prevent infection in the anus caused by wound contamination. For patients with edema, add a decoction of bitter ginseng soup to fumigate the anus and take a sitz bath to clear heat and remove dampness, reduce swelling and relieve pain. The affected area should be treated with Huanglian paste and fine mannitol, etc., and local irradiation with TDP light. For edema due to infection, local treatment should be accompanied by active anti-infection treatment. If the edema is accompanied by thrombosis, the thrombus should be removed in time. If the edema is not significantly improved after the above treatment and has been fixed, trimming under local anesthesia can be considered. III. Afterword The special nature of the surgical area, perianal surgery is very likely to cause edema. However, after active treatment, edema will generally subside. In fact, this is a misconception. The edematous part is a large area of skin, and any treatment before it is set may lead to excessive trimming of the perianal skin, causing anal skin defect and causing anal stenosis. So, being positive, being patient and sometimes, waiting is one thing we must do with mostly satisfactory results.