The rock `n` roll legend - who died on the toilet in 1977 from what has always been believed to have been heart failure - is said to have refused surgery which would have relieved him of the problem, according to a doctor close to the star.
Doctor George `Nick` Nichopoulos was with the `Viva Las Vegas` singer when he died, and believes his refusal to deal with the problem killed him.
He said: "We didn`t realise until the autopsy that his constipation was as bad. We found stool in his colon which had been there for four or five months because of the poor mobility of the bowel.
"He would get embarrassed. He`d have accidents onstage. He`d have to change clothes and come back because of the way we were trying to treat his constipation."
According to Dr. Nichopoulos, Elvis suffered from a hereditary condition called bowel paralysis, and the autopsy revealed his colon was five to six inches in diameter, compared to the usual two to three inches.
Speaking to Fox News about the release of his book `The King and Doctor Nick`, he said: "If they had done the colostomy then, he`d probably still be here."