Anal swelling and wanting to exhaust gas can be caused by phytoneurotic dysfunction, proctitis, rectal cancer and other diseases. 1. Phytoneurological dysfunction: the causes of this disease include heredity, gender, nutritional metabolism abnormality, excessive mental stress, poisoning, trauma and so on. Patients will have symptoms such as chest tightness, dizziness, gastric distension, gastric pain, insomnia, anal swelling, etc. Some patients feel that they want to ventilate but can’t do so. 2. Proctitis: the occurrence of this disease is related to chlamydia, genital herpes and other pathogenic microbial infections, but also with radioactive damage, foreign body injury, unsafe sex, dietary disorders and other factors. Patients will mainly have abdominal pain, anus falling sensation, acute and severe symptoms, which can be manifested as anal swelling and wanting to exhaust gas discharge. 3. Rectal cancer: the cause of this disease is still unclear, which may be related to improper diet, heredity, chemical carcinogens, smoking, ulcerative colitis, schistosomiasis and other factors. Typical symptoms include incomplete bowel movement, bleeding, etc. Patients may also have anal swelling and want to expel gas but can’t do so. In addition, there may be prolapsed internal hemorrhoids, rectal polyps, urinary tract infections, sinusitis and other diseases. It is recommended that patients who have anal distension and want to pass gas but can’t get it out, go to the hospital in time to see a doctor, to clarify the cause of the disease and give treatment, so as not to delay the treatment.