An acute purulent infection in the soft tissues around the anal canal and rectum or in the interstices around them, and the formation of an abscess, is called a perianal or perirectal abscess. Perianal abscesses are not uncommon in small infants. Most perianal abscesses in infants occur within 6 months of age. Most affected children are boys. The common causative organisms of pediatric perianal abscesses are Staphylococcus aureus, but also Escherichia coli, Streptococcus and Pseudomonas aeruginosa, and occasionally anaerobic bacteria and Mycobacterium tuberculosis. Etiology and pathogenesis The soft tissues around the anal canal are divided into multiple gaps by the anal raphe and pelvic fascia, and the gaps are rich in blood vessels, lymph, fat, and connective tissue, which are easily infected. Pediatric perianal abscesses arise from inflammation of the anal crypt and anal glands. Clinical manifestations The child is crying and restless, has a loss of appetite, and has a fever of 38-39℃. Older children complain of perianal pain, which is aggravated by walking and defecation. Physical examination reveals local redness, swelling, high skin temperature, and marked tenderness. The abscess is hard at the beginning, and fluctuating sensation appears after abscess formation. The disease progresses rapidly and systemic symptoms appear in 2 to 3 days. Diagnosis and differential diagnosis Based on the symptoms and signs, the diagnosis is not difficult. Conservative treatment. Many children can be cured by treatment with bed rest, stool softening and systemic application of antibiotics before abscess formation. Other methods include sitz baths with warm water at 39-40°C or retention enemas with warm saline. Surgical treatment Abscess incision and drainage: This is the traditional treatment for perianal abscess. The recurrence rate is high. It is suitable for children with abscess formation. Before incision, it should be accurately positioned, and a radial incision should be made for superficial abscesses, while a straight incision should be made for deep abscesses to avoid damaging the sphincter, and the size of the incision should be consistent with the abscess. Remove the drainage strip 48-72 hours after surgery, replace it with oil gauze, and take a daily sitz bath with 1:5000 potassium permanganate solution. Drainage should be thorough: the abscess cavity should be explored after incision and the fibrous septum in the abscess cavity should be separated to facilitate drainage. Prognosis Perianal abscesses may form anal fistulas after the first incision and may also form anal fistulas due to abscess recurrence. Perianal abscesses eventually form fistulas in 10-20% of children. The disease is curable. Only 6 to 19% of the cases are poorly treated.