Expert witness Dr Gregor Campbell-Hewson told the inquiry the decision to discharge Ronald Gilmour in April 2008 was "an error of judgment".
He told the inquiry at Perth Sheriff Court that a combination of factors in Mr Gilmour's case meant it would have been safer to admit him overnight to Perth Royal Infirmary.
But Mr Gilmour, 78, whose leg ulcer had burst, was sent home and died a few hours later when the leg started bleeding copiously again.
Dr Campbell-Hewson, of Addenbrooke Hospital, said if Mr Gilmour had been kept in hospital for observation he could easily have been treated if there were complications.
He said several factors - such as Mr Gilmour living alone in a remote area a long way from the hospital, and using the anti- coagulant drug Warfarin - indicated that he should not have been discharged.
"It was ill-advised," he told the inquiry's third day of evidence. "It is well recognised that you can have a fatal haemorrhage from a varicose vein."
Asked if it was a clinical mistake to discharge Mr Gilmour, he replied: "I think it was an error of judgment, yes.
"I think if things had been satisfactory and there had been no further bleeding, he would have been discharged the following day."
The doctor who made the decision to send Mr Gilmour home has already told the inquiry that she regrettedit "every day".
Dr Katherine Harper also told the fatal accident inquiry that it was her first shift working in Accident and Emergency after spending 20 months away in other departments.
She admitted having made a mistake by sending Mr Gilmour home and said she should have admitted him to the hospital overnight.
The inquiry, before Sheriff Michael Fletcher, continues.