treatment at a time when a decision is necessary, in such cases surgery may be performed on a patient without consent.A patient may issue an advance healthcare directive specifying how they would like to be treated if they are unable to consent to treatment. In the UK, a healthcare worker does not need to follow an advanced directive but they will influence decisions. Alternatively, a surrogate decision-maker such as a relative, friend or healthcare professional may make decisions on a patients behalf if a patient is unable to. Competent adults The faith of Jehovah's Witnesses forbids blood transfusion. Courts in the United States have consistently upheld the right of competent adults to decline blood transfusion even when it would be life-saving, though there have been exceptions where the death of a patient could leave a child orphaned. In the United States, courts have ordered pregnant women to involuntarily undergo caesarean section, intrauterine transfusion, and enforced bed rest. There are cases of clinicians threatening pregnant patients with removal of child custody or withdrawal of care if they decline treatment. In the UK, courts are unable to force treatment on pregnant women who are deemed to have capacity, however as of 2016 there were no cases of still pregnant woman being deemed to have capacity by a court. Children Parents or medical doctors may make decision about the treatment of children, a principle known as parens patriae. In the United States, doctors are responsible for providing a good standard of care for patients who are children which can lead them to make decisions at odds with the parents wishes. Parents have less autonomy to make decisions about their children's care than adult patients have over their own care. Treatment may take place even if a child or adolescent disagree with treatment, though the wishes of child patient are taken more into account the more burdensome treatment is and the worse the prognosis. If a child does not assent to treatment they may be physically held while a procedure or anaesthesia is carried out. For some procedures a child may be distracted to allow for treatment. In Italy, court orders have been used to give children of Jehovah's Witnesses life-saving blood transfusion that were refused by their parents. Prevalence There is a lot of variation in the rate of involuntary commitment between countries. A review in Europe in 2004 found a thirty-fold difference