Post operative ileus ( mechanical obstruction vs paralytic )

Hey Awesomites

Under normal circumstances, bowel movements usually do not appear till 72 hours after a certain abdominal or non - abdominal surgery, with a characteristic pattern of initiation of small bowel movements within 24 hours, stomach within 48 and colonic ( proximal to distal ) within 72 hours after surgery.

The assessment of gastrointestinal recovery is done with consideration to certain factors like the time taken to ingestion of first solid food, and time to either bowel movements or the first flatus passed, whichever occurs later.

Prolonged post operative paralytic ileus means:
- No return of bowel movements ( on auscultation ) after 72 hours
- Absence of flatus or stool on day 6 after surgery
- Feeling of discomfort, nausea or vomiting on oral intake, thus requiring i.v. support, NG tube placement by PO day 5.
- Partial return of bowel movements after PO day 5.

On the other hand, post operative ileus due to mechanical obstruction, inspite of sharing many signs and symptoms, is an important differential to exclude. Most of the patients with PO mechanical obstruction in the bowel ( due to herniation, adhesions, stomas, masses, etc. ) have an initial return of bowel function that may be partial/ complete, and oral intake, after a physiological period of 72 hours post operatively. 

It is then followed by intermittent episodes of nausea, feculent vomiting abdominal intense cramping pain and distension, that is often paroxysmal and rapidly progressing..

Also, patient with mechanical bowel obstruction after surgery may have other signs suggestive of ischemia of bowel loop distal to the obstruction, such as localised tenderness, fever, tachycardia, and peritoneal signs, which would mean immediate surgical intervention so as to prevent further complications !!
( Refer to UpToDate)

Thats all
Hope this helps :)

- Jaskunwar Singh