Medical presumptions are causing Maori to be twice as likely to die, after bowel cancer surgery

University of Auckland research reveals Maori patients are more prone to complications following the operation - such as infections, or organ failure - but have much lower survival rates than non-maori.

Deaths from complications halved in 16 years for non-maori, but stayed the same for Maori.

Lead Author Dr Cameron Wells, says that disparity's driven by unconscious bias and poor communication.

He says small assumptions, and decisions, made by doctors and staff every day, can eventually snowball.