Surgery may be categorized according to the scope of the operation and the degree of urgency. Thus the category of emergency surgery is reserved for injuries or medical crises of a life-threatening nature requiring immediate surgical intervention, as in embolisms (blood clots), massive wounds, and widespread major burns. Situations requiring prompt but not immediate attention, as in many cases of cancer, are classified as urgent surgery. Medical conditions that must be dealt with surgically but that can await attention for a period of weeks or months, as in cases of cataract, fall into the category of required surgery. Elective surgery involves conditions that preferably should be dealt with surgically but where an operation is not considered essential, as in removal of a minor cyst or burn scars. Finally, operations such as those dealing with unessential, cosmetic changes are called optional surgery.
Minor surgical operations, such as the removal of a small skin growth, may be performed in a surgeon's office or hospital facilities on an outpatient basis. Major surgery, however, involves the use of hospital operating rooms and large teams of medical personnel. For operations conducted on other than an emergency basis, a detailed program of preoperative and postoperative procedures must also be observed. A coronary bypass operation may be used as an example of major surgery, because cardiac surgery is in many respects a model for the direction of modern surgery. The surgeon works with an assistant surgeon as a member of a large team that includes cardiologists, catheterization teams, heart-lung pump teams, radiologists performing angiography (X-ray visualizations of the heart and blood vessels), anesthesiologists, echocardiography teams, and nurses such as the scrub nurse who hands the surgeon the needed tools that have been laid out in proper order by the supply nurse. A host of other hospital workers is also involved.
Prior to the operation a medical history is obtained of the patient, who signs a form consenting to surgery; the patient's physical examination enters the hospital records. A nurse also conducts a nursing assessment of the patient, and an anesthesiologist inquires about possible allergic problems with anesthetics and other drugs. The patient is not fed for several hours before the operation (to avoid the danger of choking on vomited food under anesthesia) and is given a sedative about an hour before being taken into the operating room.
The bypass operation itself involves the removal of a portion of a large vein from the leg and grafting it between the aorta and a portion of the coronary artery that lies beyond the point of obstruction or other problem that necessitated the operation. Once this maneuver is completed in the germfree area of the operating field, the chest incisions are closed and the patient is wheeled to a special room for recovery from anesthesia. The patient is then removed to an intensive-care unit and monitored to detect any postoperative problems. Returned to a hospital bed, the patient is released from the hospital when recovery is sufficiently complete.