Short bouts of dull pain in the anus, often for short periods of time, or pain lasting several hours, are common clinical signs of anal sinusitis. Sinusitis, also known as anal cryptitis, is often a focal point of infectious disease in the rectal area of the anus and is easily overlooked because of the lack of symptoms. The cause is related to infection and injury. The anal sinus, with the sinus floor underneath and the opening facing upward, has a pouch shape and poor drainage, which can easily store feces and cause infection and injury, and the edge of the anal sinus has a free semilunar anal flap, which can also be easily bruised by dry fecal masses or torn by defecation. Frequent stimulation of the anal sinus and flap due to increased frequency of bowel movements, enteritis, dysentery, diarrhea, constipation, etc. The body and local resistance is reduced, or there are chronic wasting diseases, feces and foreign bodies accumulate in the anal sinus, the sinus tract is blocked, so that the anal fluid secreted by the anal glands is not drained, plus the decomposition of feces, germs multiply, the anal sinus is inflamed and swollen. The common pathogenic bacteria include Escherichia coli, Staphylococcus, Mycobacterium avium, Streptococcus, Mycobacterium tuberculosis, Pseudomonas aeruginosa, etc., of which Escherichia coli accounts for 60% to 70%.