Intestinal ileus is an obstruction, usually of the small intestine, that prevents bowel contents, such as stool, fluid and gas, from moving through the intestine, which becomes distended.
A mechanical ileus is an obstruction caused by something directly blocking the intestine so contents cannot pass. A functional ileus is an obstruction caused by paralysis or abnormal functioning of the bowel.
As gas and fluid expand the obstructed intestine, you will feel severe abdominal pain and your abdomen will become distended and hard. You may have nausea and vomiting and be unable to pass gas or have a bowel movement.
Mechanical ileus may be caused by tumors, adhesions, impacted stool, hernias or abscesses. Possible causes of functional ileus include surgical manipulation, neurological disorders (such as Parkinson's disease), endocrine disorders (such as diabetes), spinal injuries or medications (such as narcotics).
As the pressure in the intestine increases, gas and fluid press against veins and arteries and cause swelling that can interfere with circulation and cause necrosis (death) of part of the bowel, as well as perforation.
You may need surgery for mechanical ileus. But functional ileus often is treated by placing a tube through your nose to the intestine, in order to drain fluid and gas and allow the bowel to recover.