The gas that accumulates in distended bowel, can only come from three places;
In fact, a considerable amount of the distension in intestinal obstruction is due to gas, most of this is swallowed. Accumulation of gas in the bowel can be reduced by; getting the patient to swallow less and passage of a naso-gastric tube with is put on free drainage and aspirated regularly (usually every four hours).
At surgery, gas can be emptied from the intestine by milking it back towards the stomach where the anaesthetist will aspirate it via the NG tube. A large caliber needle may be attached to a sucker and passed into the bowel. Or a larger sucker may be inserted via an enterotomy to empty the intestine of fluid and gas.