Jeanne Todd, 79, sliced her leg on the Peugeot 208 car door as she returned home on September 11 2016 - causing a five inch wound which "constantly wept fluid".
She died less than six weeks later from sepsis caused by the cut, Bradford Coroners Court heard.
Opening the inquest, assistant coroner Peter Merchant said: "Mrs Todd had a history of hypertension and diabetes.
"In September 2016 Mrs Todd had been driving her Peugeot 208 vehicle when she alighted from it, sustaining an injury.
"She required bandaging from the nursing team.
"Sadly her condition deteriorated and her injury constantly wept fluid.
"She was admitted to hospital after not eating or drinking for several days.
"Sadly she failed to respond on arrival and sadly passed away."
The court heard that Jeanne Todd was a retired St Johns Ambulance nurse who had "very good health" until the incident.
On September 11 she had been returning home with her husband Walter, 80, and had reversed the car in to her drive in Dewsbury, West Yorks., as usual.
As she swivelled her body and stood up out of the driver side door, she caught her leg on a sharp rear corner edge which caused the five inch cut.
Describing the morning when Mrs Todd cut her leg, her husband Walter said in a written statement: "My wife drove the vehicle in to the driveway as usual.
"I got out of the vehicle to get my walking frame from the boot and went into our house.
"Suddenly, my wife called out "Help, can you help me Walter please' and I went out to see blood pouring from her leg.
"I helped her down the driveway and in to the house.
"She told me she had opened her door and as she stood up had caught it on the sharp corner of the car door.
"Due to the size of the the cut my son found the door to be very sharp on the corner."
Speaking from the witness box, her son Russell Todd, 47, added his mum's condition had deteriorated rapidly since she cut her leg due to district nurses using 'odds and sods' bandages.
He told how he had attended his mother's house the night before she died after a distressing phone call from Walter and found his mum slumped in the hallway in "one of the most sickening sights" he had ever seen.
She sadly died in Deswbury hospital the next day after a cardiac arrest whilst being moved to a high dependency unit.
The inquest heard from pathologist Dr Faisal Ali who conducted Mrs Todd's post-mortem, who said the cause of death was multiple organ failure due to underlying sepsis.
He said her infected left leg ulcer was "likely to be the underlying cause of death".
The court also heard from expert engineers who concluded the defect in the door was due to "a varying amount of sealant not covering the edge of the door skin, leaving a sharp corner exposed".
The report also suggested "the door was defective" and "on the balance of probabilities caused the injury".
The inquest, which is expected to last four days, continues.