A 56 year old woman has not passed stools for the last 14 days. Xray shows no air fluid levels. Probable diagnosis is :

Air fluid levels are unusual in intestinal pseudoobstruction and should raise the possibility of mechanical obstruction. Ref: Harrison's Internal Medicine, 14th Edition, Page 1650 and 15th Edition, Page 1697; Update Gastroenterology 2004: New Developments in the Management of Benign gastrointestinal Disorders, 2004, Page 103.