Gibb, 53, died Sunday, three days after suffering cardiac arrest prior to undergoing emergency surgery for an intestinal blockage.
Dr. Bruce Hyma, the Miami-Dade County medical examiner, said Gibb died because a condition called ischemic enteropathy restricted the flow of blood to his bowel. He did not return a call seeking further explanation.
However, Dr. Jeffrey Raskin, interim chief of gastroenterology at the University of Miami School of Medicine, said a twisted bowel could cause a lack of blood supply to the organ and an array of other internal problems.
"It can lead to a cardiovascular collapse and possibly could have contributed to the cardiac arrest," said Raskin, who was not involved in Gibb's treatment. "The event itself leads to a bunch of metabolic and potentially infectious cardiovascular things which lead to a death."
Gibb's brothers, Robin and Barry Gibb, have questioned the decision by doctors at Mount Sinai Medical Center in Miami Beach to operate after their brother's cardiac arrest. A hospital spokeswoman declined comment Thursday.
Carol Peters, a spokeswoman for Bee Gees manager Allen Kovac, was flying back to California on Thursday and could not be reached for comment.
Gibb played bass and keyboard for the Bee Gees, who won seven Grammy Awards, were enshrined in the Rock and Roll Hall of Fame and were best known for disco hits like "Stayin' Alive." His funeral was held Wednesday.