The Belfast Crown Court jury of five women and seven men heard that while she was undergoing her training in paediatric medicine, a parent once complained that Dr Mary Donnelly was "being rough" with their child while taking a blood sample.
The revelation came as Dr Donnelly was being cross examined at the trial of a husband and wife who are charged with the manslaughter of their profoundly disabled 14-year-old granddaughter Rebecca McKeown who died in March 2001.
They are David Johnston, aged 88, and his 86-year-old wife Sarah, from Carwood Drive in Newtownabbey.
The couple also deny a further offence of child cruelty five days previously on 19 March, in relation to what the Crown claim was a sexual assault which caused an internal tear and, according to them, lead to her eventual death.
The jury have already heard that Rebecca had a plethora of life-limiting medical conditions including spastic cerebral palsy and scoliosis of the spine.
Registered blind, she had severe epilepsy which could cause up to 30 seizures a day.
She was confined to a specially moulded wheelchair, could neither walk, talk nor eat for herself and required round the clock care.
The teenager, who had the body mass of a six-year-old child, died after contracting pneumonia which, according to the prosecution, came as a direct result of an alleged sexual assault she suffered at the hands of one or other grandparent.
Last week Dr Donnelly, who was working as an out-of-hours Locum GP at the time, recounted how she was called to see Rebecca because she was bleeding, telling the court that initially, she believed the young girl had started her first period.
Her testimony, however, is the first time in more than 11 years that anyone has heard her admit the details of the medical examination she carried out on Rebecca.
Taking the witness box and still under cross examination from Mrs Johnston's defence SC Philip Magee, she said that she didn't think she "would ever have been rough."
When the lawyer asked if anyone had previously ever complained about her being rough "taking the blood of a child," Dr Donnelly admitted: "There may have been an incident in paediatrics....I can recall that there was an incident."
No details of the "incident" were opened to the court but later, during an exchange with trial judge Mr Justice McLaughlin, it emerged it had happened during her training period.
Later, the jury heard evidence from Consultant Obstetrician and Gynaecologist Dr Suresh Tharma who examined Rebecca in the early hours of 20 March.
He told the court that Rebecca had a number of internal tears.
Asked by prosecuting QC Toby Hedworth what that meant, the doctor told him: "That the force was significant."
He told the jury the infliction of the injury would have caused significant bleeding at the time and would have been "excruciating" to such an extent that a patient would have been "crying, shouting and screaming".
Having been shown the transcript of Dr Donnelly's evidence where she described what happened, the consultant maintained: "I don't think it was possible for her to have done that."
However Mr Gallagher suggested to him "isn't this a case of the medical profession closing ranks" but Dr Tharma refuted that, telling the lawyer "no".
After receiving further information on Dr Donnelly's examination, he conceded it "could have caused some tearing".
The trial continues.