Necrotising fasciitis is a rare condition but fatal in 70 to 80% of cases

In business the wrong decision may wipe thousands off a share price but in medicine it could be the difference between life and death.

Increasingly doctors can use computer programmes based on statistical data as a tool for diagnosis but is this always the right way to treat a patient?

Jack Dowie, emeritus professor at University College London, who has developed a computer programme to help decision making believes it is not adequate for doctors to tell patients about their intuitive diagnosis.

"You are going to have to communicate with your patient and many patients won't be satisfied with the response 'its in my gut' that this is the best course of action," he told BBC Radio 4's More Or Less.

He said of doctors who say they backed their hunch: "We can go into the psychological literature on that and see that it is a bias that is very prevalent in human beings - including myself I fear - of the good things that happened as a result of what we did.

"Availability bias I believe it is called."

However Dr Atul Gawande, author of "Better - a surgeon's notes on performance", says his intuitive diagnosis saved a woman's life.

The 23-year-old woman was admitted to hospital after an antibiotic seemed to have no effect on a skin infection on her leg.

The question that popped into my head was could this be the flesh eating bacteria necrotising fasciitis? Dr Atul Gawande

His colleagues suspected all that was needed was another antibiotic.

"The question that popped into my head was could this be the flesh-eating bacteria, necrotising fasciitis?" he said.

The condition is extraordinarily rare - 150 cases a year in the USA - but is fatal in 70 to 80% of cases.

Biopsies must be taken of skin and muscle but with 3,000,000 ordinary skin infections Dr Gawande knew he could look foolish, inflicting pain and scarring on the patient.

"But there was something in my gut that made me nervous about this woman's leg," he added.

The woman was very scared and could not see why she had to go to the operating theatre for a "little redness" on her leg.

'Foolish decision'

But the medic backed his hunch, opting for the biopsy which found the bacteria was spreading up her leg.

His next decision was whether to amputate.

The surgeon operating with him felt that he could not justify amputation.

"I thought that that was just being sentimental," said Dr Gawande.

But the surgeon followed his instinct removing much of the leg's skin and several of the muscle groups but left the leg intact.

She was put in an experimental hyperbaric oxygen chamber for several hours a day.

"I thought it was foolish that we did that but this time his gut feeling was right."

Should surgeons trust theit gut instincts rather than the stats?

"She kept her leg and she's incredibly grateful for it."

He added: "What occurred in that moment, I couldn't articulate it, but I felt I recognised that this infection was different. Was I totally positive that this was necrotizing fasciitis, no?

"But that sense of recognition is not something that is easily reduced to an algorithm and that is where it gets very interesting.

"Human beings have pattern recognising ability which is against the algorithm which can sometimes not recognise the pattern and is simply adding up the attributes you see."

However Dr Gawande believes in general that statistics and computer programmes are more reliable.

Heart attacks

"You have individuals and you have statistics - I don't advocate actually making everybody the exception. Science is your ability to group phenomena together so that you can recognise patterns among what can otherwise seem like totally unique events."

He cited instances that 25% of patients who come to hospital with chest pains will have their heart attack undiagnosed.

A computer programme, designed at the University of Pennsylvania, takes all the information supplied to the physician which consistently catches the heart attacks.

"People still don't believe it - you have lots of people who have gone up against this programme and claim to have beaten it but the truth is you look at the statistics and it wins more often."