<prompt> A 34 year old lady presented with bilious vomiting but no bowel distension. X-ray showed no air fluid level. What can be the diagnosis?Ca rectumDuodenal obstructionAdyanamic ileusPseudo obstruction  <response>: Ans: b Duodenal obstruction Ref: BaileySome features of duodenal obstr uctionEarly features--pain and vomitingNo bowel distensionNo air fluid level- no gas enter intestine, but the gases already present can pass out of the body.Low small bowel obstructionPain is predominant with distension--vomiting is delayedMultiple central fluid levels in X-rayLarge bowel obstructionDistension really prominentPain mild and vomiting and dehydration are lateProximal colon and caecum distended.Paralytic ileusor adynamic ileus:Paralytic ileus 2o to NM failure i.e., Auerbach andor Meissner plexusPseudo obstruction: colonic Ogilvy syndromePresent as ac large bowel obstruction. In abscense of mechanical and ac intra abdominaldisease.Marked caecal distension is a common feature. 