A hospital patient died because of a "series of missed opportunities and serious errors in judgment" by a senior doctor at a private hospital, a court has heard.
James Hughes received "exceptionally bad" care from surgeon David Sellu, jurors were told.
Mr Hughes died at the Clementine Churchill Hospital in Harrow, north west London, on Valentine's Day in 2010.
Sellu, of Croft Close in Hillingdon, west London, was charged with gross negligence manslaughter after he "simply ignored" the urgency of Mr Hughes' case, jurors at the Old Bailey were told.
Mr Hughes, a 66-year-old retired builder, had the planned left knee replacement on February 5.
The operation went well but while recovering from surgery he developed abdominal pain and was transferred to the care of Sellu - who has been a doctor for four decades, prosecutors said.
Sellu, a general surgeon with a specialism in colorectal surgery, suspected that there had been a rupture in Mr Hughes' bowel - a potentially life-threatening condition that requires surgery, jurors heard.
But instead of immediately performing surgery he ordered a CT scan for the next day, the court heard.
The scan confirmed the medic's suspicions but he "failed" to carry out the surgery immediately and instead carried on with his own clinic, prosecutor Bobbie Cheema QC said.
After being in pain for around 40 hours, Mr Hughes was sent to the operating theatre at 9pm on February 12.
But by this point the situation had deteriorated so badly that intensive care specialists had to work to stabilise Mr Hughes before Sellu could operate on his bowel.
Four hours later, at 1am, 66-year-old Sellu was eventually able to operate, she said.
"He did what he could at that late stage to repair the damage," Ms Cheema told jurors.
She said that after surgery Mr Hughes was transferred to the intensive care unit but he died there the following day.
"That death was avoidable," she said.
"Had (Sellu) operated the night before or even earlier on February 12, Mr Hughes would have had a very good chance of survival.
"Mr Sellu's care of this patient on this occasion fell very far below an acceptable standard.
"There was a series of missed opportunities and serious errors in judgment in the care of this patient and they combined to cause Mr Hughes' death.
"The standard of care was exceptionally bad."
Me Cheema added that the urgency the case demanded was "simply ignored".
Sellu has also been charged with perjury.
The doctor is accused of lying to Mr Hughes' inquest while under oath.
He is alleged to have told the hearing that he viewed Mr Hughes' scan results seven hours before the time he actually saw them, Ms Cheema said.
The medic denies both charges.
The court was told that Mr Hughes, a "family man" from County Armagh, Northern Ireland, was active and in good health.
But he fell unexpectedly ill after recovering from the knee surgery, the court heard.
Jurors went through his hospital medical records and saw that he was progressing after his elective surgery but complained of abdominal pain six days later.
His self-reported pain levels went from 0/10 to 9/10, they saw.
Mr Hughes' physiotherapist recorded in his medical notes that he was suffering from "terrible" and "severe" stomach pain, the hospital notes state.
Ms Cheema told the court that Mr Hughes felt he was in a great deal of pain and was not getting sufficient help from staff in the private hospital.
So from his hospital bed he telephoned a friend, who is also a doctor and had recommended for him to receive treatment at the hospital, she said.
The friend told him to call the consultant orthopaedic surgeon who had operated on his knee, jurors heard.
The surgeon, John Hollingdale, visited Mr Hughes and examined him.
"Mr Hollingdale took it seriously because he knew him to be a stoic man - not someone who easily complained of pain," Ms Cheema said.
"He was concerned something was wrong... unrelated to his knee surgery and asked for an X-ray to be completed urgently."
Mr Hollingdale sought out help from Sellu, an "experienced professional", who went on to examine the patient that evening, Ms Cheema said.
Following the examination, Sellu ordered a CT scan for the next morning, she added.
Mr Hollingdale was "surprised" to learn that the k ey diagnostic test was to be delayed until the next morning - especially as the private hospital had the facilities to perform the tests 24 hours a day, Ms Cheema told jurors.
The case, which is expected to last between three and four weeks, was adjourned for the day.