At the time of his death it was reported that The King had died from cardiac arrhythmia, an irregular heartbeat brought on by drug addiction, obesity and a bum ticker.
But now El's pal and personal physician Dr. George "Nick" Nichopoulos, who tried to resuscitate him that fateful day, has finally revealed the true cause of death in his book The King and Dr. Nick.
"After he died we weren't sure (the exact cause of death) so I continued to do some research and I had some doctors call me from different places and different med schools that were doing research on constipation and different problems you can get into with it. " Dr.Nick writes.
According to the physician, now retired, the autopsy revealed Presley's colon was 5 to 6 inches in diameter (the normal width is usually 2 to 3 inches) and instead of being 4 to 5 feet in length, his colon was 8 to 9 feet in length.
"We didn't realize until the autopsy that his constipation was as bad – we knew it was bad because it was hard for us to treat, but we didn't realize what it had done.
"We just assumed that the constipation was secondary to the meds that he was taking for his arthritic pain and for his insomnia."
In 1975, the primary treatment was a colostomy, the removal of the colon but according to the book, Presley's "ego" got in the way.
"He was 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.
"If they had done the colostomy then, he'd probably still be here," Nichopoulos said.