What Are The Ill Effects Of Smoking Marijuana?

My son had a tonsillectomy 7 days ago. About 11 days before that, he brilliantly decided to try marijuana for the first time. What effect can this have on his tonsillectomy? He had an artery open up 3 days after surgery and had to go into the OR again to have it cautorized (sp?). He lost 2-3 liters of blood (1 was pumped out of his stomach). Could the marijuana have caused this?