Sian Hollands, 25, suffered a pulmonary embolism after leaving Darent Valley Hospital, Dartford, in November 2015.
Dr Kamran Khan previously claimed he had not seen Ms Hollands' notes and was unaware of the seriousness of her pain.
However, during cross-examination he admitted having the notes but not reading them.
The General Medical Council is now investigating him.
Ms Hollands, a mother of three, went to Darent Valley Hospital complaining of breathing difficulties and chest and stomach pain. She had suffered an ectopic pregnancy three weeks earlier.
Gravesend Coroner's Court heard the former drug user was taking methadone to treat her addiction, but had stopped for a few days.
Ms Hollands was given an electrocardiogram (ECG) and methadone, and was given her discharge papers.
Her former partner Carl Alleyne said she was in pain and not breathing properly, but was told the hospital "needed the bed space".
He refused to take her home and she died a few hours later from a blockage in the artery carrying blood from the heart to the lungs.
Dr Khan put her symptoms down to drug withdrawal, the inquest heard.
He claimed not to have seen the medical notes labelling her as "at risk" and detailing her chest pain, which would have made him consider a pulmonary embolism.
But the medical notes were found with Dr Khan's own writing on the back, proving he had seen, but not properly read, the vital information on the paper.
Ms Hollands' family's barrister, Edward Ramsay, asked the doctor: "It means you could not have read what was staring you in the face?"
"Yes," he replied.
"Simply turning over the page and Sian may well be alive - do you accept that?" Mr Ramsey added. Dr Khan agreed.
Mr Ramsay said Ms Hollands was "labelled a heroin addict and nobody considered any other diagnosis".
Her mother, Nicole Smith, said that more than 500 days since her daughter's death, they were finally getting the truth.
"She was recovering, trying to put her life right, and they condemned her and stopped her from ever moving forward."
A spokesman for Darent Valley Hospital said: "We extend our sincere condolences to the family and friends of Sian Hollands. We await the outcome of the coroner's inquest."
The inquest has been adjourned until 10 April.
A mother who died hours after being given her hospital discharge papers may have lived if a doctor had read her medical notes, an inquest heard.