It is a legal requirement that consent be obtained from a patient before any medical care can be provided, with the exception of emergencies where consent cannot be obtained.

Consent can take two forms: implied or express. When patients attend for low-risk procedures consent is often implied and has been taken by the referring clinician prior to the patient arriving in the radiology department on behalf of the reporting clinician, for example a chest radiograph.

Express consent is required for more complex procedures. It may be appropriate for this to take the form of verbal consent; as long as the discussion and granting of consent are documented in the patient notes, for example a nephrostogram.

The General Medical Council (GMC) requires written consent to be obtained in the following circumstances (GMC 2008):¹

The three components of consent are: voluntariness, information and capacity. For consent to be valid consent must be voluntarily given, the patient must have information regarding the treatment concerned and must be competent to do so.

Consent should be given freely without undue influence to either accept or refuse treatment. It is the responsible clinician’s duty to ensure that the patient is not under pressure from relatives or carers to consent to medical treatment. Doctors should also guard against exerting pressure on patients, especially if the patient’s wishes do not agree with their own.

It is useful to create a suitable environment to facilitate voluntary consent taking. It is good practice to take consent prior to the patient entering the operating room, as this environment places the patient under pressure and may invalidate consent.² Suitable environments, which allow privacy and sufficient time for the patient to understand the information provided and to ask questions, include outpatient clinic and ward quiet rooms.

After taking consent the patient may change their mind and decline to confirm consent at the time of the procedure. The doctor should explore the patient’s decision without being coercive and provide any support or additional information that the patient requests. The withdrawal of consent and subsequent discussion should be clearly documented in the patient’s notes.

Patients may occasionally withdraw consent during a procedure. Should this occur, the doctor should immediately stop the procedure (even temporarily) and explore the patient’s concerns. Medication or pain may affect the patient’s capacity at this time. However, if the patient wishes the procedure to end and there is no possibility of immediate harm, the patient’s wishes should be accepted as a withdrawal of consent and the procedure halted.²

Patients who are detained by the Police, Criminal Justice systems and Immigration Authorities and those detained under Mental Health legislation may be particularly vulnerable to coercion. Doctors should ensure that patients understand their rights to refuse or withdraw consent. Patients who are detained under Mental Health legislation can be treated for their mental illness and not physical illness. Where mentally ill people also lack capacity to consent to interventions, the advice below should be followed.