Surgery is the use of operative procedures to treat injuries, diseases, and disorders. These procedures include the mending of wounds and broken bones; the repair or removal of diseased or injured tissues, organs, and limbs and their replacement if possible; and the remodeling of body structures. Surgical practice also includes \Tdiagnosis\t, preoperative and postoperative care, and supervision of patients during rehabilitation (see \Trehabilitation medicine\t). Surgery and nonsurgical medicine have vied with each other throughout history in dealing with medical problems. Medicine was dominant until the 20th century, and surgery's chief concern was mainly obvious injuries, such as those stemming from accidents or war. At one time the vast majority of \Thospital\t patients were medical, whereas in the 20th century surgical cases tend to occupy the majority of hospital beds, and the surgeon in gown and gauze mask came to epitomize modern medicine. Although the introduction of a large array of drugs has decreased the need for surgical intervention, the role of surgery in modern medicine is not likely to be seriously challenged. HISTORICAL BACKGROUND Surgery has been practiced since long before recorded history (see \Tmedicine, history of\t). For example, skulls of the Neolithic Period from North and South America, Europe, northern Africa, and the South Pacific region all indicate the practice of trephining, or the cutting or drilling of a hole in the skull of a live human being. Whether this was performed as a magic rite, as a way to relieve head pains, or as a treatment of skull fracture, however, is not known. The earliest recorded medical writing, which is found in Egyptian papyri, describes the surgical treatment of injuries to the head, shoulders, chest, and spine. At least 2,000 years ago, surgeons in India were able to remove urinary stones, as well. Even the earliest known practitioners of surgery made use of a wide range of tools. These included knives (scalpels and lancets), awls, drilling devices, scissors, saws, forceps, clamps, syringes, mirrors (specula), tubes for viewing or extracting fluids or foreign materials from body canals (catheters), needles, sutures, casts, splints, and bandages. Prosthetic devices such as simple \Tartificial limbs\t made of wood and metal were also employed in ancient times, as were glass eyes and other simple cosmetic replacements of body parts. in addition, early practitioners of surgery were well aware of the desirability of pain relief for patients, but few recourses were possible except the use of alcohol or other stupefying agents. Variations of the tools of the early surgeon remain in use today. Surgery nevertheless remained only a skilled trade until knowledge of human anatomy could be based on observation rather than simply on the writings of \TGalen\t and other ancient authorities. In Europe, anatomy based on human dissection did not begin until the late 13th century, with the work of Italian anatomist Mondino de Luzzi (c.1275-1326). By the 16th century the monumental De humani corporis fabrica (On the Structure of the Human Body) by the Flemish physician Adreas \TVesalius\t had swept away the errors of Galen and disposed of an accumulated baggage of medieval superstitions and legends. The most enthusiastic support of Vesalius's work was Ambroise \TPare\t, the preeminent surgeon of his time. He made the book popular among physicians and surgeons and wrote a short, clear version in French. Pare is often considered the father of modern surgery. Surgeons who were equally knowledgeable as anatomists and practitioners could be found throughout Europe by the 18th century, and in the following century anatomical knowledge encompassed virtually all structures visible to the naked eye. Nonetheless, except in rare circumstances, no surgeon dared to enter a body space such as a joint or the abdomen. What a surgeon could do was limited by the pain of operating on a conscious person, the danger of postoperative infection, and the difficulty of making a diagnosis before surgery. The modern use of \Lanesthe\lsia to deal with pain began with the demonstration of American dentist William \TMorton\t, in 1846, that diethyl ether could be safely applied to produce unconsciousness. (Other anesthetic agents had been used earlier with success, but the medical profession was unaware of these events.) Besides relieving pain, anesthetic agents enabled surgeons to work slowly and carefully and thus to carry out procedures never before possible. Anesthesiology quickly became an important subspecialty of modern medicine. The problem of postoperative infection was addressed in 1847 by the Hungarian physician Ignaz \TSemmelweis\t. Working in Vienna, he showed that puerperal sepsis, a uniformly fatal infection that sometimes followed childbirth, was probably transmitted to women in labor by the unwashed hands of physicians or attendants. He work was met with violent opposition, however, by the medical establishment of the day. When French chemist Louis \TPasteur\t later proved that infections were the result of bacterial invasion, this suggested to British surgeon Joseph \TLister\t that putrefaction of wounds could be prevented by the use of an \Tantiseptic\t during surgery so as to kill microorganisms contaminating the site of the operation. The first operation to use Listerian antiseptic procedures was performed on Aug. 12, 1865. Henceforth it would be impossible to consider entering body cavities with some assurance that surgery would do more good than harm. Over the next three decades the operating room became a nearly germ-free environment, as antiseptic surgery gave way to the aseptic surgery practiced today. The third need for modern surgery was to develop diagnostic methods that went beyond those practiced at least since the days of Hippocrates. One major landmark was the introduction, in 1819, of the use of the \Tstethoscope\t for listening to chest sounds. Another was the development of techniques for analyzing blood and urine. A third was the development by the German physician Rudolph \TVirchow\t of cellular pathology. Perhaps the discovery with most immediate effect on surgery was that of X RAYS, in 1895. Within days the discovery was applied to the setting of fractures, and within months X rays were being used to visualize the internal structures of living patients. MODERN SURGERY In the 20th century a vast number of diagnostic and supportive techniques were developed, particularly in recent decades. Progress in the imaging of internal structures for diagnosis (see \Tradiology\t) included the invention of computerized axial tomography (the \Tcat\t scan), \Tnuclear magnetic resonance\t \Limagin\lg, and a number of other methods. Computer technology made possible automatic chemical and cellular analyses of blood and other samples. Through the development of long, flexible tubes called \Lendoscope\ls, surgeons were in some cases enabled both to visualize and to operate on deep-lying regions of the body with minimal trauma to the patient. Advances in the ability to maintain vital body functions before, during and after surgery were at least as dramatic. Support machinery developed for these purposes included the \Theart-lung machine\t, inhalation therapy devices, anesthesia machines, cardiac-monitoring devices, and cardiac defibrillators. The development of \Lblood bank\ls as resources for transfusions was also of major importance. Surgical capabilities were also greatly widened by the introduction of the techniques of microsurgery, or the use of magnifying systems and very precise tools to operate at the microscopic level. Using such methods, surgeons could re-attach vessels and nerves of severed limbs, operate on the inner ear, remove tumors of the spinal cord, and other such operations once considered impossible. Through drug advances and other developments, surgeons also became increasingly able to transplant organs (see \Ttransplantation, organ\t) and to replace organs and other body structures with \Tartificial organs\t (see also \Tartificial limbs\t). Among other technologies adapted for surgical use are those of the \Tlaser\t and of \Tultrasonics\t. The laser's intense beam of light can be used as a cutting and cauterizing tool in many circumstances, and the focused pulses of sound waves from ultrasonic devices can be employed in diagnostic imaging and for breaking up kidney stones and gallstones. With such expanding technical possibilities, the era when a surgeon might be expected to practice any type of operation has long since passed. Ten major divisions of modern surgery are recognized in the United States and canada and, to a large extent, in the rest of the world. Some of these divisions have been in existence since the 19th century, especially in the great hospitals of the major cities of the world. These divisions include \Tgynecology\t, which deals with the female genital organs and lower urinary tract; \Tobstetrics\t, which is concerned with pregnancy and childbirth problems (and is now combined with gynecology as a single surgical division); \Tophthalmology\t, or the study and treatment of diseases of the eye; \Torthopedics\t, which deals with problems related to bones, joints, and related structures; otolaryngology, which treats diseases of the ear, nose, throat, and larynx; and urology, which deals with diseases of the urinary tract. Each surgical division has its own accrediting board for the training of surgeons, and several of the boards have subspecialty fields with additional requirements. The accrediting agencies have mandated different training schedules for each division. A surgeon-to-be first obtains a medical license, following a program previously accepted by the Residency Review Committee for the speciality in question. At the conclusion of training, the appropriate specialty board conducts an examination for certification. The surgeon must then become entitled to make use of the facilities of a given hospital. Each hospital has a series of committees that review all surgical cases, with an emphasis on cases with less than optimal results. The hospital is in turn regularly reviewed by the Joint Commission on the Accreditation of Hospitals. The quality of hospital-based practice is monitored in this complex, perhaps cumbersome manner in order to guarantee that a patient needing surgery will received competent care by an adequately trained staff. General Surgery This is the largest surgical field. It is devoted to the care of diseases of the digestive tract, abdominal organs, the breast, and endocrine glands (mainly the thyroid, parathyroids, and pancreas); to the management of injuries; and to surgery involving blood vessels, except those in the skull (see neurosurgery, below) and the heart and the great vessels adjacent to it (see thoracic surgery, below). Many general surgeons confine themselves to surgery of the breast or the intestines, or to traumatic surgery (the surgical treatment of injuries and accidents). Two subspecialties of general surgery are recognized, each with a set of training requirements in addition to those of general surgery. These are pediatric surgery, or surgery on infants and young children, and hand surgery. For the latter the basic training may be in general surgery, orthopedic surgery, or plastic surgery. Training in general surgery demands five years beyond medical school, with at least one additional year for pediatric or hand surgery. Following formal training, many surgeons then spend one to three years in a fellowship devoted to one special area. Thoracic Surgery This division originated among surgeons who devoted themselves to surgery of the lungs. Development of newer technologies, however, made cardiac and major-vessel surgery possible. Thoracic surgeons now deal with surgical conditions of the chest wall, the lungs, the heart, the major blood vessels found in the chest, and organs such as the esophagus that pass through the chest. Vascular surgery, which deals with blood vessels other than those in the chest, is a subspecialty of thoracic surgery as well as of general surgery. Many thoracic surgeons are now exclusively cardiac surgeons. They perform heart transplants, bypass operations on the coronary arteries, implantations of cardiac pacemakers, replacements of diseased heart valves with artificial ones, surgical corrections of congenital heart and vessel defects, and surgery for diseases of the major blood vessels. Cardiac surgery is in many respects a model for the direction of modern surgery. The surgeon works 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), echocardiography teams, and nursing teams, as well as the staff of the intensive care unit and a host of others. A person wishing to become a thoracic surgeon must first complete training in general surgery and then spend two additional years devoted to thoracic surgery. Plastic Surgery This division arose as a branch of other surgical fields, mainly general surgery. Its role is the repair and restoration of function to the skin and underlying structures when injuries arise through accidents or extensive surgery (typically, cancer surgery). The plastic surgeon also deals with congenital deformities, especially those involving the face. Many plastic surgeons devote their time to cosmetic surgery, ameliorating the effects of age or modifying features that the patient feels undesirable. Training in plastic surgery requires completion of three years of general surgery followed by two in plastic surgery. An important subspecialty, hand surgery, requires a year of training following training in plastic surgery, orthopedic surgery, or general surgery (see \Tplastic surgery\t). Colon and Rectal Surgery Practitioners in this division deal with patients who have disorders of the anus, such as hemorrhoids and fissures; disorders of the rectum and colon, such as polyps or cancer; and inflammatory diseases of the lower digestive tract. A five-year program in general surgery is required, followed by a year exclusively in colon and rectal surgery. Neurological Surgery This division deals with disorders of the brain, spinal cord, nerves throughout the body, and diseases of the blood vessels of the brain and spinal cord. A very important aspect of this specialization is the proper treatment of head injuries. Proper diagnosis and treatment requires high technology, including \Tcat\t scans. Training for neurological surgery requires at least one year in general surgery and five within the field. Most trainees also spend time in neuroradiology. Orthopedic Surgery Orthopedic surgeons deal with problems related to bones, joints, and related structures. Subspecialties include hand surgery, pediatric orthopedic surgery, orthopedic \Tsports medicine\t, and musculoskeletal oncology. The last named refers to physicians who treat tumors of the bones, joints, and related structures. Orthopedic surgery requires four to five years of training beyond medical school. Accreditation in a subspecialty requires a minimum of one year of training beyond the normal training. Obstetrics and Gynecology This division combines two specialties. Obstetrics deals with pregnancy, childbirth, the care of women following childbirth, and problems arising from parturition. The use of \Lmidwi\lves in assisting a woman in labor is probably as old as human society. The use of physicians trained to care for women in pregnancy and childbirth became significant by the 17th century, but the introduction of antisepsis and of anesthesia was required before this field of surgery could flourish. Gynecology refers to the care of females with problems arising from or extending to the genital organs and lower urinary tract. The principal structures involved are the uterus and cervix, fallopian tubes, and ovaries. Gynecological surgeons, however, increasing look upon themselves as primary care physicians for women in addition to practicing a surgical specialty. At present, four years of training beyond medical school are mandated for this division. Ophthalmology The study and treatment of diseases of the eye is among the most ancient fields of medicine. Even the cataract operations being performed in India by the 5th century AD were based on much earlier ophthalmic surgery. The ophthalmologist treats medical conditions of the eye such as bacterial infections, surgical conditions such as those resulting from injury to the eye or surrounding skull, cataracts, strabismus (unequal movement of the two eyes), \Tglaucoma\t, and refractive errors (see \Teye diseases\t). In addition to a general knowledge of medicine and surgical skill, the ophthalmologist must have a considerable knowledge of optics, and may make extensive use of laser beams to perform surgery on the retina. Four years of training are required following medical school. The last three years are devoted to study of the eye, and the first is in some more general area such as internal medicine or general surgery. Otolaryngology This surgical specialty treats diseases of the ear, nose, throat, and larynx. Like ophthalmology, it has a medical nonoperative component, a surgical component, and a component related to the fact that it deals with a sense organ. The major mission of the otolaryngologist in relation to the ear is the prevention or treatment of deafness. In addition to treatment of medical and surgical conditions of the nose, the otolaryngologist performs cosmetic surgery on that organ. Otolaryngologists are skilled in endoscopy, or the use of tubes containing a light source, lenses, and a channel through which specially designed instruments may be passed. The laryngoscope is capable of visualizing the larynx and removing biopsy specimens. The bronchoscope can reach far into the lungs, and the esophagoscope can reach the upper end of the stomach. Training requirements for otolaryngology include one or two years of general surgery and three or four years of specialization, for a total of five years combined. Urology This division deals with surgical diseases of the urinary tract, including the kidneys, ureters, urinary bladder, and urethra. It is also the discipline that deals with male genital tract. Although surgery for stones in the bladder has been done since ancient times, urology flourished only following the invention of the cytoscope by the German physician Max Nitze in 1877. This is another version of the endoscope. Most prostatectomies today are accomplished by means of the resectoscope, a specially modified cytoscope. Also basic to modern urology were the discovery of X rays and the later introduction of dyes opaque to X rays, enabling the entire urinary tract to be seen in the patient. A more recent development is ultrasound, or the use of \Tultrasonic\t vibrations to break up kidney stones without surgery. SURGICAL PROCEDURES 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 the 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 germ-free 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. Aaron D. Freedman, M.D. Bibliography: Beck, R. Theodore, The Cutting Edge: Early History of the Surgeons of London (1974); Bishop, William John, The Early History of Surgery (1960); Cartwright, Frederick F., The Development of Modern Surgery (1967); Christian, Rebecca, et al., eds., The Prevention Guide to Surgery and Its Alternatives (1980); Earle, A. Scott, ed., Surgery in America: From the Colonial Era to the Twentieth Century 2d ed. (1983); Franklin, John, and Doelp, Alan, Not Quite a Miracle (1983); Hardy, J. D., The World of Surgery, 1945-1985 (1986); Manjo, Guido, The Healing Hand: Man and Wound in the Ancient World (1975); Meade, Richard H., An Introduction to the History of General Surgery (1968); Milne, John S., Surgical Instruments in Greek and Roman Times (1970); Rogers, S. L., Primitive Surgery: Skills before Science (1985); Selzer, Richard, Confessions of a Knife (1979); Wangensteen, Owen H. and Sarah D., The Rise of Surgery (1979): Williams, Guy, The Age of Miracles (1987).