Dr. Alan McKinney was giving evidence at an inquest in Enniskillen Courthouse on Mrs. Elizabeth McTeggart, from Cappog Road, Enniskillen.
The pensioner was a front-seat passenger in a car involved in a head-on collision on the Sligo Road in Enniskillen on April 20, 2009. She complained of chest pains and was taken by ambulance to the Erne Hospital in Enniskillen. She was then sent home and died there four days later.
Coroner Brian Sherrard adjourned the hearing after what he described as a "possible" difference of opinion between Dr. McKinney and Northern Ireland State Pathologist Jack Crane about the cause of death.
Professor Crane told an earlier sitting of the court that he carried out an autopsy on the body of Mrs. McTeggart and found that nine of her right ribs had been fractured, five of them in two places. There were also fractures to three of her left ribs and a fracture to her sternum.
"It was these chest injuries that were ultimately responsible for her death," he concluded.
However, when the inquest resumed yesterday (Wednesday) Dr. McKinney, who has been a consultant in the Accident and Emergency Department of Altnagelvin Hospital for 20 years, gave a "slightly different" interpretation of how the pensioner died.
He said five of Mrs. McTeggart's right ribs had been fractured in two places and he believed she had suffered a "flail segment" where the ribs were displaced inwardly, preventing air from being properly drawn into the lungs, affecting blood circulation, and this continued over a period days until she had heart failure.
"This a very unusual case," he stated.
He said that as the ribs were still attached to the muscle when the patient stopped breathing they came to rest in their normal position.
Barrister Michael Copeland, representing the McTeggart's family, said the court found itself in an unusual situation as the evidence of the post mortem was that death was a result of the rib and sternum fractures.
The coroner said the fractures to Mrs. McTeggart's ribs and sternum didn't fully explain her death.
Barrister David Sharpe, for hospital management at the Western Health and Social Care Trust, submitted that what Dr. McKinney was saying was only "slightly different" from Professor Crane's findings.
Mr. Copeland said that it was with reluctance that he was asking for the hearing to be adjourned.
The coroner said an issue had arisen about the actual mechanism of death. Professor Crane had given quite detailed evidence about the actual mode of death. Dr. McKinney had taken a "slightly different" approach.
"It seems to me we have a difference of opinion, possibly, concerning the precise mode of death and that is a fact that makes me rather unhappy about the way the inquest has proceeded," he said.
He adjourned the hearing to enable Professor Crane to address the issue of the cause of death and comment on Dr. McKinney's view about the cause of death.
Earlier Dr. McKinney had given evidence that the X-ray taken of Mrs. McTeggart's chest had been reviewed by at least three Accident and Emergency consultants and three consultant radiologists and none of them could see the 17 rib fractures.
"I don't believe the injuries were identifiable," he stated.
He explained that the chest X-ray was "specifically not to see the ribs" but was focused on the internal organs to see if they were injured.
He said that if Mrs. McTeggart had been admitted to hospital it would have been for a day or two for observation and to stabilise her pain relief before sending her home.
Dr. McKinney explained that there was no treatment for the fractures to the left ribs and sternum and treating the right rib fractures would involve putting the patient on a ventilator for four or five weeks. It was an injury which older patients "rarely survive".
"Mortality would be in excess of 50 per cent," he stated.
Earlier the court had heard that following Mrs. McTeggart's death the Western Trust completed an Incident Review Report containing a number of findings and recommendations.
Dr. McKinney said that one of the recommendations was that a written record should be kept when, as in Mrs. McTeggart's case, one doctor hands over a patient to another.
He said no other Accident and Emergency Department in the United Kingdom followed this practice.
"This is a radical departure from normal A. and E. procedure," he stated.
He explained that a pilot scheme had taken place at Alnagelvin Hospital and the procedure has been implemented by the Northern Health Trust and is to be introduced at the new South West Acute Hospital in Enniskillen as "a matter of urgency".
No date has been set for a resumption of the inquest.