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Disclosing the minuscule risk for consent

The foreseeable risks associated with clinical practice seem innumerable, and when seeking a patient’s consent for treatment, we are faced daily with the prospect of trying to identify what we will and will not disclose. An obvious criterion for making this judgement is the frequency with which the risk occurs. Historically, clinicians, most notably surgeons, chose an arbitrary number - perhaps 1% or 0.1% frequency of the risk crystallising - below which they would not disclose the risk when seeking a patient’s consent. At least 30 years ago, the common law guided us away from this practice, requiring us to disclose risks that would be seen as significant to the reasonable person in the position of the patient we are dealing with, providing no comment as to what magnitude of risk that reasonable person might regard as significant.

In the Supreme Court’s recent case of Montgomery, the current view was reiterated; the doctor must make the patient aware of any material risks. And that the test of materiality is:

  • (i) whether in the circumstances of the particular case, a reasonable person in the patient’s position would be likely to attach significance to the risk, or
  • (ii) the doctor should be reasonably aware that the particular patient would be likely to attach significance to it.

The clinical duty is of ‘reasonable care’. This indicates that no absolute duty is involved, and for that reason there is no requirement to disclose all risks. Material risks must however be disclosed. This is all very well, but does the court give illustrations as to the relevance of frequency?

In a 2015 decision, the High Court considered the case of Mrs A who conceived with the aid of in vitro fertilisation, and whose third trimester ultrasound scans revealed poor foetal growth. Following full term delivery, it became obvious that the baby was severely disabled as a result of a balanced 4:11 chromosomal translocation. Mrs A claimed that if she had known of the risk of chromosome anomaly antenatally she would have undergone amniocentesis, and on confirming the presence of this translocation, would have terminated her pregnancy.

The court was told that the actuarial antenatal risk of poor foetal growth in this baby’s case being due to a chromosomal anomaly was in the order of 0.1%. The court found that a reasonable person in Mrs A’s position would consider a risk of 0.1% as being negligible, theoretical or background, and would not have attached significance to it. Nonetheless, the court indicated that if the risk had been in the order of 1-3%, it would have regarded this a risk that a reasonable person would have attached significance to, and thus regarded as material. In addition, the court noted that in her evidence, Mrs A attached no significance to the fact that (during her pregnancy) she ran a 1:1,750 risk that she could be carrying a baby with Down syndrome. She refused investigations to exclude this diagnosis, since she did not want to endanger her foetus by premature delivery. The court found that in the same way, Mrs A herself would not have considered a risk of 0.1% significant.

The role of the particular patient’s attitude to a risk in different circumstances is demonstrated by the Australian case of Maree Whittaker. She had suffered a penetrating injury to her eyeball as a child, and considered herself disfigured by the subsequent appearance. Forty years later, she sought cosmetic surgery for the deformed globe. She was adamant that she would not have surgery if it entailed risk to her healthy contralateral eye, since she feared blindness. Assured there was none; she underwent surgery, and suffered sympathetic ophthalmia, where the sight of her healthy eye was severely damaged. The risk of sympathetic opthalmia was 1:14000, a miniscule risk. But the court held that the particular patient, Maree Whittaker, plainly attached significance to the risk of blindness that transpired in her non-operated eye, and should have had this risk disclosed to her, irrespective of its rarity. Her case was decided in 1992, and remains good law.

It can be seen that ‘materiality’ is slowly taking shape. The courts, on behalf of the reasonable person in the patient’s position, indicate that risks of 1-3% would be regarded as material, but 0.1% risks are not. But when considering the particular patient in the context of the facts of her case, a 1:14,000 risk may be highly significant; and thus found to be material, necessary to disclose. If a patient voices fears about the possibility of a particular risk, irrespective of its frequency, it seems natural to disclose its existence.

Mrs A gives no authority for the proposition that background, negligible or theoretical risks cannot be material. As Whittaker shows us, they can be. Such ‘miniscule’ risks may be engaged as material risks in elective, non-therapeutic or cosmetic procedures where the option of no treatment or conservative non-surgical treatment is available.

Read the full court report from Mrs A's case in the downloads section on the right.

Robert Wheeler

Department of clinical law, May 2018