Victoria Arnott admitted stopping en route to the woman's home to do personal shopping while on duty in Fife on July 4 last year.
The former Scottish Ambulance Service worker agreed she had visited a store without seeking authorisation from the ambulance control centre, but denied misusing an ambulance for personal purposes.
Ms Arnott appeared before the Health and Care Professions Council's (HCPC) conduct and competence committee today.
A three-member panel heard that Ms Arnott, who joined the ambulance service in 1999, had been allocated a doctor's urgent call to attend the home of a depressed and suicidal woman and take her to hospital.
Rowena Rix, representing the HCPC, said: "On that same date the control room supervisor reported to the duty shift manager that there had been a delay in Ms Arnott's crew responding to this call.
"She admitted she had stopped the ambulance en route to the urgent call in order to undertake some personal shopping."
The paramedic had acted unprofessionally and had put her own interests before those of the patient, Ms Rix said.
Witness Iain Morgan, who was the east ambulance control centre duty shift manager at the time, told the panel that investigations showed the ambulance had deviated from its route for around seven minutes.
"I spoke to Victoria and she informed me she picked up something to do with her computer," he said.
Ms Rix asked: "In your experience is it ever acceptable to stop en route to an urgent call?"
"No, it's not," Mr Morgan said.
But Alice Stobart, counsel for Ms Arnott, suggested that there was a procedure for paramedics to stop en route and others had been authorised to do so in the past.
"There isn't any procedure to allow that, I can only say in my experience that's not the case," Mr Morgan said.
"They would not be allowed to do it while en route to a call."
The call was at the second lowest level of priority for the ambulance service with a response window of one to four hours, the panel was told.
It had initially been received by the control room at 11.41am and was not allocated to Ms Arnott's crew until 3.35pm.
Ms Stobart said given such a window, her client might expected to know from experience that there was unlikely to be clinical or medical attention necessary.
The hearing is expected to last two days. The panel will rule on whether misconduct has been proved and if so, whether Ms Arnott's fitness to practise is impaired.
The Scottish Ambulance Service said Ms Arnott is no longer an employee.