Colonic distention is a common cause of ulcerative colitis (UC), an inflammatory disease of the rectum or colon of unknown origin. It mainly involves the rectum, sigmoid colon and descending colon and is characterized by mucosal congestion, edema, multiple superficial ulcers, advanced wall thickening and luminal narrowing with polyp formation. The disease is characterized by persistent diarrhea, mucus stools, bloody or purulent stools, abdominal pain and urgency, and may be accompanied by extraintestinal manifestations such as fever, anemia, arthritis, skin lesions and liver disease. The onset of the disease is rarely acute, but most of them have a slow onset and a long course, often with recurrent episodes of variable length, also known as chronic non-specific ulcerative colitis. In the early stages, abdominal pain, diarrhea and bloody stools may occur. Abdominal pain of varying degrees is caused by spasm of the colonic muscles, distension of the colon and inflammation stimulating local sensory nerves. Abdominal distension is mostly confined to the left lower abdomen or lower abdomen, with paroxysmal mild pain. When the lesion is severe, it may present as colic. The main symptoms: diarrhea or constipation, the symptoms are mild at the beginning of the disease, there is mucus on the surface of the stool, later the number of bowel movements increases, in severe cases 10-30 times a day, the stool is often mixed with pus and blood and mucus, can be paste-like soft stool. Blood in the stool is a common symptom, mainly due to local ischemia of the colonic mucosa and an increase in the activity of fibrinolysis. It is usually a small amount of blood in the stool, but in severe cases, it can be a large amount of blood in the stool or bloody water-like stool. The abdominal pain is mostly confined to the left lower abdomen or lower abdomen, or may not be present in mild cases, but may increase with the development of the disease and may be relieved after defecation. The posterior urgency is due to inflammatory irritation of the rectum, and there is often sacral discomfort. Indigestion often manifests as anorexia, fullness, belching, epigastric discomfort, nausea, vomiting, etc. Systemic manifestations are seen in patients with acute fulminant severe disease, with fever, water-electrolyte imbalance, vitamin and protein loss, anemia, and weight loss. Signs: pressure pain in the left lower abdomen or the whole abdomen, the descending colon, especially the sigmoid colon, can be felt in the form of a hard tube with pressure pain, sometimes abdominal muscle tension, anal sphincter spasm can be found on anal examination, mucus or bloody mucus secretion in the finger sleeve, and tenderness in the rectum. In some cases, large liver can be palpated, which is related to fatty liver. 1.Types According to the clinical manifestations and course, there are 4 types. (1) Primary type The symptoms vary in severity, with no previous history of ulceration, and can be transformed into chronic relapsing type or chronic persistent type. (2) Chronic relapsing type The symptoms are mild and most common in clinical practice, and there is often a remission period of varying length after treatment. Recurrence peaks in spring and autumn, but less frequently in summer. During the episodic colonoscopy, there are typical ulcerative nodal lesions, while the remission period examination only shows mild congestion and edema, and the mucosal biopsy is chronic inflammation, which can be easily mistaken for irritable bowel syndrome. Some patients may turn into chronic persistent type. (3) Chronic persistent type After the onset of the disease, there is often persistent diarrhea of varying severity, intermittent bloody stools, abdominal pain and systemic symptoms, lasting for weeks to years, during which there may be acute attacks. This type has a wide range of lesions, progressive colonic lesions, many complications, and severe symptoms during acute attacks, requiring surgery. (4) Acute fulminant form Less reported in China, accounting for about 2 or 6% of ulcerated nodes, and 20% of foreign reports. It is mostly seen in adolescents, with rapid onset, severe systemic and local symptoms, high fever, diarrhea 20-30 times a day, large amount of blood in stool, anemia, dehydration, electrolyte disorders, hypoproteinemia, weakness and emaciation, and prone to toxic colonic dilatation, intestinal perforation and peritonitis, often requiring emergency surgery, and high mortality rate.