In Mr Hill's report, released today, Dr D told Mr A and his wife the couple's best option was surgery.
Mr A had a section of his sigmoid colon removed as a result. He stayed in hospital for nearly three weeks after the March 1, 2012, operation.
Other complications arose later in the year and Mr A underwent another surgical procedure - performed by a second surgeon.
Despite this and further medical intervention, Mr A's health continued to deteriorate and he eventually died.
Mr Hill said Mr A had not been able to give informed consent to his March 1 surgery. He recommended Dr D send a written apology to Mr A's family and review his practice regarding patients with severe co-morbidities.
He also noted the Medical Council of New Zealand process were ongoing in relation to Dr D.