A coroner has found a litany of blunders from a private hospital in connection to the death of a Sydney grandmother.

June Nutter, 55, died in front of her high school sweetheart husband Eric in Campbelltown Private Hospital in 2015.

She had gone to the hospital the day before for a colonoscopy, but flatlined the next day.

Mrs Nutter died of natural causes from late stage stomach cancer, Deputy State Coroner Derek Lee found, not the procedure the day before.

But the deputy coroner was scathing of the hospital's clinical practice.

The inquest findings noted paramedics had trouble entering the hospital because they weren't given the access code.

There was a seven-hour block where June's condition wasn't checked.

One registered nurse didn't know how to use the ward's defibrillator.

One doctor testified that the resuscitation attempt on Mrs Nutter was the most challenging of his career.

Mr Lee recommended the private hospital start simulation-based training in basic and advanced life support.