If something goes wrong when a person is undergoing medical treatment, it is called a ‘medical accident’ or ‘adverse event’. If the treatment does not work or there have been complications, it does not always mean that there has been a mistake, or that someone is to be blamed. 

In certain cases, errors or complications are unavoidable risks of the treatment and, the doctor or other healthcare professional should not be blamed. For instance, when a patient has undergone a major surgery, some risks are expected because of the surgery. Complications can occur with minor procedures as well.