There are three types of consent: Implied, expressed or informed.

Implied consent

An implied consent is a consent which is not written; however, it is legally effective.

Implied consent is when a patient makes an appointment with the doctor, enters the doctor’s office by his own free will and submits to a physical examination without any objection and follows the instructions of the doctor.

Express consent

An express consent is one the terms of which are stated in distinct and clear language. It may be oral or in writing. Though oral consent is as valid as written consent where it is properly witnessed, written consent is regarded superior because it is invaluable as evidence. 

Expressed consent in written form should be obtained for surgical operations and invasive investigative procedures or examination especially in a female patient.  

Informed consent

Informed consent is authorization of an activity, based on an understanding of what that activity entails and in the absence of control by others.

Informed consent is one of the 16 basic principles of bioethics pertaining to all aspects of scientific work defined in Section II of the Universal Declaration on Bioethics and Human Rights adopted by UNESCO.

The four main principles of medical ethics are justice, non-maleficence, autonomy and beneficence. Patient autonomy is the underlying ethical principle for informed consent.

Disclosure of adequate information to enable the patient to make an “informed” decision is essential before taking informed consent from the patient. Not doing so puts the doctor at risk of litigation. This information should be provided in a language that the patient understands. Use of medical terminology should be minimum.

Adequate information includes information about the condition that the patient has; natural course of the disease; recommended treatment or diagnostic/surgical procedure and the known possible risks, complications, and anticipated benefits; available treatment options, alternative to the recommended treatment, expected outcomes, follow-up, cost of treatment, consequences of non treatment, and the inability to accurately predict results.