Distinguishing postoperative ileus from early small-bowel obstruction

What it is

After an abdominal operation a distended abdomen has two very different causes. In paralytic ileus the bowel has stopped moving. In early postoperative small-bowel obstruction the bowel is mechanically obstructed. Both give distention, and what is done next is not the same for the two, so telling them apart is the whole point.

Causes and risk

Paralytic ileus after an operation is put down to the post-op state itself, to morphine, and to hypokalemia, since DNS has no electrolytes and a patient who is not taking orally should be given potassium replacement as KCl. Mechanical small bowel obstruction has two most common causes, adhesions and obstructive hernia: in a non-virgin abdomen it is adhesions, and in a virgin abdomen the causes listed are obstructive hernia, intussusception, foreign body and gallstone ileus.

How it presents

Paralytic ileus a few days after surgery shows as significant abdominal distention with mild nausea and anorexia while the patient denies any pain, and often the patient has not been able to eat properly since surgery.