The Test of Breach of Duty – Paul Sankey in the Personal Injury Law Journal

10 Min Read

Speech bubble

in April, the Personal Injury Law Journal carried a feature written by our own Paul Sankey.  The full article is reproduced here with the PILJ’s kind permission:

The test of what amounts to breach of duty in relation to medical treatment is clear. But what is the test in pure diagnosis cases?

For treatment the Bolam test applies. Treatment is not negligent if there is a responsible body of specialists practising that discipline who would have done the same, provided the view of that responsible body is capable of logical analysis (the Bolitho qualification). The test reflects the fact that when it comes to medical management, there is often a weighing of options, of risks and benefits. There is scope for differences of opinion.

In pure diagnosis cases the patient’s condition is unknown. The alleged negligence is diagnosis of that condition without a decision or advice about further management, There is no weighing of options, of risks and benefits. There is just a diagnostic decision, which can be right or wrong, and if wrong, reasonable or not reasonable. The Bolam test makes little sense in this context. A better test would be one  of ‘reasonable skill and care’.

The authorities

Oddly there have been very few reported ‘pure diagnosis’ cases.


In Penney v East Kent Health Authority [1999] the Court of Appeal considered the issue. Four cervical smears had been wrongly reported by screeners as showing no abnormalities. Each claimant went on to develop adenocarcinoma of the cervix requiring surgery. Earlier detection would have resulted in minor surgery only. Strictly speaking this should probably not be described as a ‘pure diagnosis’ case because it was not the job of the screeners to diagnose – only to identify abnormalities which would need a diagnostic decision by others. This was a pre-diagnostic stage. However the same issue arises as in diagnosis.

At first instance the judge thought the Bolam test did not apply. It was ‘ill-fitting’ to the facts of Mrs Penney’s case. There was no issue as to whether a particular course of practice was acceptable. The question was whether it was correct to say that the samples were normal and, if not, whether it was ‘excusable’ – in other words reasonable although wrong. The experts agreed that the slides had been misreported. The judge found that this was inconsistent with acceptable practice.

However, in case that approach was wrong, the judge justified his rejection of the defendant’s experts by applying the Bolam test in the light of the Bolitho qualification. The evidence of the defendant’s experts was not sufficient to exonerate the screeners because it did not stand up to logical analysis. In the Court of Appeal, Lord Woolf, giving the majority judgment, unfortunately did not take the opportunity to reject the application of the Bolam test. Instead of addressing the merits of the judge’s rejection of the test, he applied it but used the Bolitho qualification to justify rejecting the defendant’s expert evidence.

He said there were three questions to be answered:

  • What was to be seen on the slides? This was a question of fact although one to be determined with the aid of expert evidence. Expert evidence was needed as to what the slides actually showed. The Bolam test does not apply to this question. It is not answered by showing that there is a respectable body of medical opinion favouring one interpretation. The judge had to decide what was actually there on the basis of expert opinion.
  • Could a reasonably competent screener, aware of what a screener exercising reasonable care would observe on the slide, treat the slide as negative?
  • Could a screener exercising reasonable care fail to see what was on the slide?

The second and third questions involved questions of fact and of opinion. Expert opinion evidence was needed as to the standard of care screeners should have exercised.

Insofar as they involved opinion Lord Woolf applied the Bolam test.


The judgment in Penney was considered by Kerr J in Muller v Kings College Hospital NHS Foundation Trust [2017].

This was a case where a pathologist had failed to note abnormalities on a pathology sample suggestive of a rare type of malignant melanoma and diagnosed a benign ulcer.

This was a pure diagnosis case. In those circumstances the judge thought it would have been better to discard the Bolam test:

“In a case involving advice, treatment or both, opposed expert opinions may in a sense both be ‘right’, in that each represents a respectable body of professional opinion. The same is not true of a pure diagnosis case… where there is no weighing of risks and benefits, only misreporting which may or may not be negligent. The experts expressing opposing views on that issue cannot be both be right.”

However, because of the Court of Appeal decision in Penney he could not do so. Instead he had to apply the Bolam test. But since the experts could not both be right, the Bolitho qualification enabled him to reject one side’s expert evidence.

In referring to the way that qualification had been used in Penney, he described it as ‘a liberal invocation of Lord Browne-Wilkinson’s Bolitho exception’. This was ‘no doubt because this was… not a case in which there was any “weighing of risks and benefits”’.

In their joint statement the experts had agreed that there were features inconsistent with a benign ulcer. In expressing the view that a pathologist exercising reasonable skill and care could miss those features, the defendant’s expert was applying too lax a standard. It did not stand up to logical analysis. The judge formulated the question to address in Bolam terms: ‘whether the practice of the professional making the diagnosis accorded with a respectable body of opinion within the profession’. In the context of pure diagnosis that question was in fact indistinguishable from the question ‘was the error one which could be made by a professional exercising reasonable skill and care’.

In other words, the judge reached the right answer to the straightforward question ‘did the professional exercise reasonable care and skill?’, but had to use a route through Bolam and Bolitho to get there.


The same approach was applied in the case of Brady v Southend University Hospital NHS Foundation Trust [2020], although unlike Penney and Muller, this was a case where the claimant failed.

This was a third case to involve issues of ‘pure diagnosis’ (although it also involved issues of treatment). The claimant sought damages for delay in diagnosing an actinomyces infection in 2013. The infection led to the need for surgical drainage of a psoas abscess, abdominal scarring and continuing symptoms.

She had undergone an appendectomy for acute appendicitis at Southend University Hospital (SUH) in May 2013. In August she was investigated for  acute epigastric pain. A CT scan of  5 August 2013 was reported as showing  a mass in the right upper quadrant which was said ‘most likely’ to be due  to omental infarction. That diagnosis was accepted by clinicians. She continued to suffer pain and attended outpatient appointments in August and September 2013. She was treated with antibiotics.

On 20 September 2013 she underwent a second CT scan.  The reporting radiologist noted an abdominal mass. She was uncertain of the diagnosis, discussed it with a surgeon and recommended urgent evaluation by biopsy. On 25 September 2013 the surgeon spoke to a specialist upper GI surgeon at the Royal  London Hospital who apparently reviewed the scans with colleagues  and diagnosed an omental infarction.  Her condition then improved with antibiotic management and she was discharged.

The claimant was reviewed in November 2013 again complaining  of pain. Examination again suggested an abdominal mass. Her surgeon arranged a gastroscopy (which she failed to attend) and planned another CT scan in a month.

On 14 February 2014 she attended the emergency department of SUH. A CT scan showed a left-sided psoas abscess. She underwent surgical drainage and a number of surgical procedures under general anaesthetic. Microbiological analysis indicated that the infecting organism was actinomyces. She was discharged on  26 February 2014.

The claimant claimed damages and alleged that the mass seen on the CT scans of August and September 2013 was an actinomycosis infection and not an omental infarction resulting from her earlier appendicitis. The scans were negligently incorrectly interpreted. There was then a negligent failure of treatment in not arranging a biopsy which would have led to the correct diagnosis and successful antibiotic treatment.

The defendant’s case was that she probably had two rare conditions: an omental infarction and actinomycosis; but it was reasonable to conclude it was an omental infarction and manage it conservatively.

This was a case therefore that involved both diagnosis and treatment.

In relation to the allegations of negligent diagnosis, the judge followed the approach in Penney and Muller:

“Insofar as I am required to assess [the radiologists’] views on advancing differential diagnoses… there can be no question but that the Bolam test with the Bolitho qualification, applies.”

The first issue addressed by the test in Penney is one of fact – what was seen on the scans. On a careful consideration of the expert evidence the judge found that the mass seen in 2013 was not an omental infarction but an infection. The radiologist reporting the August CT scan was therefore wrong. However, in relation to the second and third questions – the standard of care – he was not negligent in wrongly concluding that omental infarction was the most likely diagnosis. The radiological appearances formed a proper basis for that opinion.

In relation to the September CT scan, he again found that the radiologist’s conduct was not negligent. Her report was sub-optimal in that it did not identify differential diagnoses but it did provide a clear view from a radiological perspective as to how to investigate further.

Although the judge was applying the Bolam test, the decision was based on the Bolitho qualification. He accepted the defendant’s expert evidence because it was grounded in logical analysis.

In relation to the failure to carry out a biopsy – an issue of management and not diagnosis – the judge found that it was reasonable to have taken a second opinion from the Royal London Hospital. Having done so, and the claimant having improved, it was reasonable not to proceed to biopsy. The claim therefore failed.


Although there has been a surprising lack of reported cases dealing with the test of breach of duty in ‘pure diagnosis’ cases, the three cases of Penney, Muller and Brady make clear that the Bolam test applies. However, these are cases where the experts cannot both be correct. There is no weighing of risks and benefits or alternative bodies of opinion. A  ‘liberal invocation’ of the Bolitho qualification enables the judge to  weigh that expert evidence and  prefer one expert to another.

Although Brady failed, Penney and Muller both succeeded. Bolitho provided a route by which the judges could reach the same decision they would have reached had they been  able to apply the simpler and more coherent test of ‘reasonable care  and skill’.

It is regrettable that they have to use the route. The Bolam test makes little sense in the context of pure diagnosis. This is an issue which would merit review by the Supreme Court in the way that the law in relation to consent was reformulated by Montgomery v Lanarkshire Health Board [2015]. It would be much more straightforward and logically coherent to replace the Bolam test in pure diagnosis cases with a test of ‘reasonable skill and care’.

Bolam v Friern Hospital Management Committee [1957] 1 WLR 582

Bolitho v City and Hackney Health Authority [1997] UKHL 46

Brady v Southend University Hospital NHS Foundation Trust [2020] EWHC 158 (QB)

Montgomery v Lanarkshire Health Board  [2015] UKSC 11

Muller v Kings College Hospital NHS Foundation Trust [2017] EWHC 128 (QB)

Penney & Ors v East Kent Health Authority [1999] EWCA Civ 3005