<s>[INST] context: Let's see each option one by one

Adynamic ileus or Paralytic ileus

is seen commonly after abdominal operations, or post inflammatory conditions of abdomen eg Appendicitis, peritonitis, pancreatitis. Metabolic abnormalities are also a cause.
Abdominal distention, usually without the colicky abdominal pain, is the typical & most notable finding.
Vomiting may occur but may also be absent.
Absent or hypoactive bowel sounds.
Multiple air-fluid levels on x-ray.
Points b & e help in ruling out dynamic ileus.

Pseudo-obstruction

This condition describes an obstruction, usually of the colon in the absence of any mechanical cause
This may occur in acute or chronic form (Acute form is k/a Ogilvie syndrome*) Acute form usually involves only the colon.
Vomiting appears late or even absent.
Abd. cramps appear late.
Abd. distention is the chief symptom.
Since it usually involves the colon air-fluid level are not seen if the ileocecal valve is intact.


Points c, d, e help in ruling out Pseudo obstruction in this pt.

Ca Rectum : 

Usually ads. of old age
Obstruction is not a common presentation Even if obstruction occurs, it is insidious in onset with pain & vomiting a late feature. There will be abdominal distention.
These point help in ruling Ca Rectum out.

Duodenal obstruction

Features of this pt. match perfectly with duodenal obstruction as
Pain and vomiting are early features.
No distention of the bowel
No air-fluid level. (There is no distention of bowel and no air fluid level as the whole of the intestinal tract distal to the obstruction is patent allowing free passage to gas and the fluids out of the body. Obstruction to duodenum prevent further entry of gas or fluids into the intestines). [/INST] question: A Pseudo-obstruction of 35-year-old comes to the emergency department with symptoms of pain in abdomen and bilious vomiting but no distension of bowel. Abdominal x-ray showed no air fluid level. Diagnosis is | options: A: CA rectum B: Duodenal obstruction C: Adynamic ileus D: Pseudoobstruction | answer: B </s>