Investagation into DVT death reveals case of 'bad luck'

Published on Monday 11 October 2004 02:17

THE parents of a student who died from deep vein thrombosis (DVT) have been told by doctors that even a good clinician has only a 50 per cent chance of detecting the condition.

The family of Katie McPherson were told the most common method for identifying the condition is flawed and is being replaced with a system that is potentially even less reliable.

The 23-year-old died on 26 January 2003, from DVT - a condition she was told she did not have, despite her own repeated insistence that she did.

In September, her family finally met Dr Derek Bell, associate medical director of Edinburgh Royal Infirmary, Dr Graham McKillop, a consultant radiologist, and nursing sister Betty Campbell.

During the meeting, which was recorded openly by the family, Dr Bell stated that the likelihood of accurate clinical diagnosis of DVT was low.

Dr Bell, who has a particular medical interest in DVT, said: "DVT can be relatively difficult to diagnose and on average good clinicians don’t get it right 50 per cent of the time. But the average figure is one in three, just from a clinical perspective, of getting the diagnosis right."

He said that these odds were not good and any symptoms had to be investigated to ensure people got the right treatment.

Dr McKillop said the investigation process was an inexact science: "A venogram is the gold standard, the best test to detect a clot in the legs. But it’s not a perfect test. Unfortunately it’s a test that requires interpretation and there are various variants of normal that can make interpretation difficult."

A venogram involves inserting dye into the leg and counting the number of veins which show up. Dr McKillop continued: "On the day of the test, which was done by two of my colleagues, I reviewed it and asked other consultants to review it and would have all called it negative. So at the time, there was not sign of a clot.

"There should be six veins that run in the calf and in a classic situation you would fill all six. But there are variants; often people don’t have six veins, they have three, four, five, six or seven. Sometimes if you don’t fill a vein, you don’t know if it is because there may be a clot in it, or it’s a vein that’s just not there."

He said ultimately, the test had failed Ms McPherson. "We have to accept that a clot has moved and the venogram did not detect it. But that genuinely was the best test we had."

Despite Dr Bell’s statement during the meeting that procedures for diagnosis had not changed significantly since Ms McPherson’s death, ERI has since introduced a new system of diagnosis, which replaces the venogram as the primary use of detection with ultrasound.

However, Dr Bell did admit that in the detection of DVTs in calf muscles, the ultrasound technique was known not to be as effective as venogram and there "had been a lot of debate as to the best test, especially for a the clot in a calf vein".

On the morning of 17 January, 2003, Ms McPherson woke up in her Edinburgh flat suffering a sore calf muscle. Despite her self-diagnosis of DVT, with the help of a medical student friend, tests at the Edinburgh Royal Infirmary carried out three days later indicated that she did not have DVT.

A venogram was carried out but proved inconclusive. Ms McPherson was sent home with advice to take pain-killers and to buy crepe bandage for her swollen leg.

Her health deteriorated as the pain increased, but visits to her GP and Royal Alexandria Hospital in Paisley, insisting on both occasions that she had DVT, brought no further testing, both taking the ERI tests as acceptable.

On 26 January, nine days later, she woke in the early hours of the morning at her family home in Langbank with breathing difficulties and it was while she was being transported in an ambulance that she went into seizure and stopped breathing.

During the meeting last month, Dr Bell also said that the symptoms Ms McPherson had shown were a common sight to doctors. He said: "DVT is a very common suspected diagnosis, but the reality is that a small number of patients have DVT. There’s a range of diagnosis for DVT symptoms. Quite often the answer is ‘we don’t know’.

"At the time, we were using the international recognisable standard which came back negative. We then had to say that the result is negative. We reviewed those images and they did not show evidence on DVT."

The post-mortem examination showed, in the words of the physician who carried it out, that Ms McPherson’s leg was "riddled" with clots.

When the family asked about what policy was when a patient disagrees with the diagnosis, Dr Bell replied: "If a patient disagrees with us, the advice is to monitor the situation."

He added, however, that if a patient’s symptoms persisted, they should be reassessed: "If thrombotic disease is there and if it progresses, the patient’s symptoms will progress. When this happens it is time to reinvestigate and re-evaluate. There is no test which I am aware of which is 100 per cent perfect."

However, Dr Bell said that in the end clinicians had to rely on tests over clinical judgment as, in the past, simple judgment calls had meant that they had "lost patient after patient".

Speaking after the meeting, the family said that the interview had shown how unlucky their daughter had been.

"It was pure bad luck that it happened to be Katie," Jane McPherson, her mother, said. "It could have been somebody’s auntie, somebody’s granny, somebody’s father; it was just pure bad luck."

Gordon McPherson, the student’s father, said: "We would also like an apology. Nobody has said they are sorry for the mistakes which ultimately caused the death of Katie."

Dr Bell told The Scotsman: "This condition lacks an diagnostic test. It is better than it was a decade ago and much better than 20 years ago. And in relation to people representing themselves, would it be good to have absolute conformity across the NHS? Yes, absolutely."

However, at the meeting with the family he had said "it would be difficult to implement".