Positive Pressure Room Why Would A Doctor Do Surgery If They Weren't Positive That The Surgery Was Needed?

Why would a doctor do surgery if they weren't positive that the surgery was needed? - positive pressure room

My grandfather was an emergency operation Monday morning. He went to the emergency room for stomach problems - could not stop vomiting and stools - but the shots were pure liquids. It was really bad.

In any case, doctors thought it could be a blockage in the intestine was the cause of the problem, you do emergency surgery on him.

Come and discover, there is no blockade. But during the surgery, the blood pressure falls, and now struggling to recover.

It is in the intensive care unit, intensive care is now possible with each tube and to monitor connected. I tried to visit him, but I saw yesterday and had to leave the room.

What I do not understand - Why did the doctor perform the operation if they were not sure that surgery is necessary? I do not understand.