Is wrong diagnosis negligent?

Getting the diagnosis right is not always easy. Some conditions are hard to diagnose. Patients may have symptoms which could suggest more than one condition. But sometimes mistakes are made in reading x-rays or scans or in analysing blood or tissue.

A patient may for instance have a scan where a tumour is missed. Or a sample of skin seen under the microscope may be said normal when in fact there is skin cancer there.

A case of missed melanoma (skin cancer)

This is what happened to Mr Muller. He had come back from holiday with a wound on his foot. He thought he must have stood on something sharp in the sea. He saw a specialist who sent a tissue sample to be examined by a pathologist. The pathologist though it showed a harmless ulcer. In fact it was a rare melanoma, a form of skin cancer. His condition was not diagnosed until months later. By that time his chance of survival was much lower.

He brought a claim against his hospital and the case went to trial in 2016. The experts on both sides agreed that the pathologist had made a mistake but the expert for the hospital said that although wrong, it was a reasonable mistake to make. Interpreting samples is not always easy and it is possible to get result wrong without negligence.

This was only the second reported case where the issue was not whether the patient had been advised or treated correctly but was only whether a misdiagnosis was negligent. This seems odd because there are many claims brought in these circumstances, although many are settled before trial.

Cervical smears misinterpreted

The last ‘pure diagnosis’ case had been in 2000. It concerned mistakes made by screeners looking a cervical smears. The screeners considered some samples normal when they were not. They should have been passed on to a specialist to consider more carefully. They showed changes which could become cancerous. Several women sadly went on to develop cervical cancer and brought claims.

When is a misdiagnosis negligent?

In both cases the courts considered what the test should be of when mistakes in diagnosis are negligent. The test should probably be whether the specialists used ‘reasonable care and skill’. That reflects the fact that there are skilled judgments to be made. Not all interpretation is easy and even skilled people will sometimes get the answer wrong.

In fact the courts decided that they had to apply the same test as to whether treatment is negligent. That is known as the ‘Bolam test’ (named after the case that gave rise to it). Under the Bolam test an act is not negligent if there is a responsible body of specialists who would have done the same. It speaks of a responsible body to recognise that there are different schools of thought in medicine as to how things should be done. Where there is more than one approach, the court will not sit in judgment over them, provided both are accepted by responsible bodies.

That test makes sense where there is a difficult task of balancing the risks and benefits of different ways of doing things. Some doctors may think one thing. Others may think another. However, it makes little sense in the context of scans or tissue samples. There are no different schools of thought. An answer is either right or wrong. If it is wrong it is either a reasonable mistake or a negligent one.

In Mr Muller’s case, the hospital’s expert said there was a responsible body who might have got the diagnosis wrong. But on the facts of that case the judge was not persuaded. He thought that it would have been illogical to miss the abnormalities.

A missed infection

In a very recent case in 2020, a Ms Brady became ill after having surgery for appendicitis. She had a CT scan. It showed abnormalities which were in fact caused by infection. The radiologist mis-read it and thought she had a very rare condition called an omental infarction, where the blood supply in the abdomen is disrupted. As a result her diagnosis happened months later. By then she needed to have a sequence of operations and suffered a lot of pain.

Again the court heard expert evidence. The experts again agreed that the scan had been misinterpreted but the hospital’s expert said the mistake was a reasonable one. The judge again applied the Bolam test. This time he agreed that the scan was difficult to interpret. Both the right and the wrong interpretation suggested rare conditions. The mistake was an understandable one. Ms Brady’s claim failed.

These 2 cases show that getting the diagnosis wrong is not always negligent, although it is sometimes. They also provide guidance on how the Bolam test should be used – before the court can accept that a responsible body of doctors can get the answer wrong, it has to be satisfied that they have taken a logical approach.

Where misdiagnosis leads to a claim

Some of the common areas where wrong diagnosis leads to claims are:

• Fractures being missed on x-rays or scan. This can sometimes cause harm where the fracture gets worse because it has not been treated or where unstable bones cause injury elsewhere. In a couple of recent cases, for instance, patients suffered disability from spinal cord injuries after fractures or injuries to the spine were missed.
• Brain scans showing bleeding where the patient then suffers a serious stroke.
• Ischaemic bowel injuries – where scan shows signs that the blood supply to the bowel has been disrupted.
• Cervical smears being wrongly interpreted and leading to cervical cancer.
• Melanoma being missed on tissue sample.
• Lung cancer being missed on x-rays.
• Breast cancer being missed on mammograms or biopsy sample.