The area of the bowel after the blockage will be collapsed. When a
NG tube is placed, alot of fluid will be released
and the distention will improve. This type of obstruction can be surgically corrected.
On the other hand, if there are multiple areas of obstruction, the bowel cannot dilate except between the two blocked segments. But placing a NG tube maybe not release alot of fluid. It is less likely to be able to surgical correct this.