text: <unk>  was first discovered by Marshak and Lester in 1950. Jalen criteria was developed by Jalen et al to diagnose<unk>  in 1969.<unk>  results from severe inflammation extending into the smooth-muscle layer and paralyses the colonic smooth muscle leading to dilatation. The extent of dilatation associated with the depth of inflammation and ulceration. Nitric oxide, an inhibitor of smooth-muscle tone, has an important role in the pathogenesis of<unk> . Nitric oxide is produced by neutrophils and smooth-muscle cells in the inflamed colon. The most common cause of<unk>  include inflammatory bowel disease and Clostridium difficile pseudomembranous colitis. The most common cause of<unk>  include inflammatory bowel disease and Clostridium difficile pseudomembranous colitis. The precise incidence of<unk>  is unknown in general population. The incidence of<unk>  in the associated disorders including ulcerative colitis and Crohn's disease is 1000-2500 in 100,000 cases and 4400-6300 in 100,000 cases, respectively. The mortality rate of<unk>  associated with Clostridium difficile is approximately 38%-80%. Common risk factors in the development of<unk>  include discontinuation of steroids, use of barium enemas, colonoscopy, chemotherapy, antidiarrheal drugs, anticholinergic drugs, narcotics, Severe chronic obstructive pulmonary disease, organ transplantation, cardiothoracic procedures, diabetes mellitus, immunosuppression, renal failure. If left untreated,<unk>  in patients with ulcerative colitis lead to death in 0.2% patients. Common complications of<unk>  include perforation, bleeding, shock, sepsis. Prognosis is generally good. The diagnostic criteria for<unk>  is Jalan diagnostic criteria. Common  symptoms of<unk>  include abdominal pain and cramping, diarrhea and fever. Less common symptoms include constipation and disorientation.Patients with<unk>  usually appear ill. Physical examination of patients with<unk>  is usually remarkable for abdominal pain, rebound tenderness and guarding, hypotension and tachycardia. Laboratory findings consistent with the diagnosis of<unk>  include anemia and leukocytosis. Some patients with<unk>  may have elevated concentration of  Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)  , which is usually suggestive of inflammation. An x-ray may be helpful in the diagnosis of<unk> . Findings on an x-ray diagnostic of<unk>  include dilated transverse colon (>6cm), thumbprinting, free intraperitoneal air and intraluminal soft-tissue masses. Ultrasound  may be helpful in the diagnosis of<unk> . Findings on an ultrasound suggestive of<unk>  include loss of haustra coli of the colon, hypoechoic and thickened bowel walls with irregular internal margins in the sigmoid and descending colon and significant dilation of the transverse colon. Abdominal CT scan may be helpful in the diagnosis of<unk> . Findings on CT scan diagnostic of<unk>  include dilated transverse colon, loss of colonic haustrations, segmental parietal thinning,Intraluminal soft-tissue masses. Medical therapy of<unk>  include stablizing the patient, decompression and medications. Medications for<unk>  include corticosteroids, immunosuppresants and antibiotics. The mainstay of treatment for<unk>  is medical therapy. Surgery is usually reserved for patients with either     failed medical therapy, progressive<unk> ity or dilation and signs of perforation. There are no established measures for the prevention of<unk> .
option_0: Toxic megacolon
option_1: Proteus syndrome
option_2: Myoneurogastrointestinal encephalopathy syndrome
option_3: Distal intestinal obstruction syndrome
option_4: Mesenteric ischemia
option_5: Megacolon
option_6: Clostridial necrotizing enteritis
option_7: Short bowel syndrome