This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
[{'content': 'A 56-year-old woman has not passed stools for the last 14 days. Xray shows no air fluid levels. Probable diagnosis is - \nSelect and explain. \nA. Paralytic ileus, B. Aganglionosis of the colon, C. Intestinal pseudo-obstruction, D. Duodenal obstruction', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The information provided in the question is too less, but we have to come to a diagnosis based on the provided information. Lets see each option one by one.\n\nParalytic ileus\n\nmultiple air fluid levels are noted, hence ruled out.\n\nAganglionosis of the colon or Hirshprung\'s ds.\n\npresents in infancy or childhood hence ruled out\n\nDuodenal obstruction\n\nmultiple air-fluid levels are not noted, but the dominant symptom is recurrent, vomiting, which is not mentioned, hence ruled out.\n\nIntestinal pseudo-obstruction\n\nit\'s the most likely diagnosis, as air-fluid levels are not seen in it.\n\nHarrison writes - "The symptom of chronic pseudo-obstruction are chronic or intermittent constipation, crampy abdominal pain, anorexia and bloating. Abdominal x-rays reveal gaseous distention of the large and small bowel and occasionally of the stomach. Air-fluid levels are unusual and should raise the possibility of mechanical obstruction."\n\n\nAcute pseudoobstruction involves only the colon and presents with features of colonic obstruction (as described before). Air-fluid level is also not a feature of colonic obstruction.\n\nAbout the fluid levels remember the following points\n\nup to 3 to 5 fluid levels less than 2.5 cm in length may be normal.\nmultiple air-fluid levels are a feature of mechanical small intestinal obstruction and paralytic liens. They are not seen in colonic obstruction and pseudo-obstruction.\nThey may be seen in colonic obstruction if the ileocecal valve is incompetent.', 'role': 'assistant'}]