Medical specialty

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Amedical specialtyis a branch of medical practice that is focused on a defined group of patients, diseases, skills, orphilosophy. Examples include those branches of medicine that deal exclusively with children (paediatrics), cancer (oncology), laboratory medicine (pathology), or primary care (family medicine). After completingmedical schoolor other basic training,physiciansorsurgeonsand othercliniciansusually further theirmedical educationin a specific specialty of medicine by completing a multiple-yearresidencyto become a specialist.^[1]

To a certain extent, medical practitioners have long been specialized. According toGalen, specialization was common among Roman physicians.^{[citation needed]}The particular system of modern medical specialties evolved gradually during the 19th century. Informal social recognition of medical specialization evolved before the formal legal system. The particular subdivision of the practice of medicine into various specialties varies from country to country, and is somewhat arbitrary.^[2]

Medical specialties can be classified along several axes. These are:

• Surgical or internal medicine
• Age range of patients
• Diagnostic or therapeutic
• Organ-based or technique-based

Throughout history, the most important has been the division into surgical and internal medicine specialties. The surgical specialties are those in which an important part of diagnosis and treatment is achieved through major surgical techniques. The internal medicine specialties are the specialties in which the main diagnosis and treatment is never major surgery. In some countries,anesthesiologyis classified as a surgical discipline, since it is vital in the surgical process, though anesthesiologists never perform major surgery themselves.

Many specialties are organ-based. Many symptoms and diseases come from a particular organ. Others are based mainly around a set of techniques, such asradiology, which was originally based aroundX-rays.

The age range of patients seen by any given specialist can be quite variable. Pediatricians handle most complaints and diseases in children that do not require surgery, and there are several subspecialties (formally or informally) in pediatrics that mimic the organ-based specialties in adults. Pediatric surgery may or may not be a separate specialty that handles some kinds of surgical complaints in children.

A further subdivision is the diagnostic versus therapeutic specialties. While the diagnostic process is of great importance in all specialties, some specialists perform mainly or only diagnostic examinations, such aspathology,clinical neurophysiology, and radiology. This line is becoming somewhat blurred withinterventional radiology, an evolving field that uses image expertise to perform minimally invasive procedures.

Specialty	May be subspecialty of	Age range of patients	Diagnostic (D) or therapeutic (T) specialty	Surgical (S) or internal medicine (I) specialty	Organ-based (O) or technique-based (T)
Allergy and immunology	Internal medicine Pediatrics	All	Both	I	O
Adolescent medicine	Pediatrics Family medicine	Pediatric	Both	I	T
Anesthesiology	None	All	T	Both	Both
Aerospace medicine	Family Medicine	All	Both	Neither	Both
Bariatrics	Several	All	Both	Both	Both
Cardiology	Internal medicine	Adults	T	I	O
Cardiothoracic surgery	General surgery	Adults	T	S	O
Child and adolescent psychiatry	Psychiatry	Pediatric	T	I	T
Clinical neurophysiology	Neurology	All	D	I	Both
Colorectal surgery	General Surgery	All	Both	S	O
Dermatology	None	All	T	I	O
Developmental pediatrics	Pediatrics	Pediatric	T	I	Neither
Emergency medicine	Family Medicine	All	Both	Both	Both
Endocrinology	Internal medicine	Adults	Both	I	Multidisciplinary
Family Medicine	None	All	Both	Both	Multidisciplinary
Forensic pathology	Pathology	All	D	Neither	T
Forensic psychiatry	Psychiatry	All	D	I	T
Gastroenterology	Internal medicine	Adults	T	I	O
General surgery	None	Adults	T	S	T
General surgical oncology	General surgery	Adults	T	S	T
Geriatrics	Family medicine Internal medicine	Geriatric	T	I	Multidisciplinary
Geriatric psychiatry	Geriatrics Psychiatry	Geriatric	T	I	Neither
Gynecologic oncology	Obstetrics and gynecology	All	T	S	O
Hematology	Internal medicine Pathology	Adults	D	I	Neither
Hematologic pathology	Hematology Pathology	All	D	Neither	T
Infectious disease	Internal medicine Pediatrics	All	Both	I	Neither
Internal medicine	None	Adults	Both	I	Neither
Interventional radiology	Radiology	All	Both	-	Multidisciplinary
Intensive care medicine	Anesthesiology Emergency medicine Internal medicine	All	T	Both	Both
Maternal-fetal medicine	Obstetrics and gynecology	Adults	T	S	Both
Medical biochemistry	Internal medicine	All	D	I	Neither
Medical genetics	None	All	D	I	Neither
Medical oncology	Internal medicine	Adults	D	I	Neither
Neonatology	Pediatrics	Neonatal	T	I	Neither
Nephrology	Internal medicine	All	T	I	O
Neurology	Internal medicine	All	Both	I	O
Neuropathology	Pathology	All	D	Neither	T
Neurosurgery	None	All	T	S	O
Nuclear medicine (Nucleology)	None	All	Both	I	T
Obstetrics and gynecology	Family medicine	All	T	S	O
Occupational medicine	Family medicine Internal medicine	Adults	T	I	Multidisciplinary
Ophthalmology	None	All	T	S	O
Orthopedic surgery	None	All	T	S	O
Oral and maxillofacial surgery	None	All	T	S	O
Otorhinolaryngology	None	All	T	S	O
Palliative care	Family Medicine Internal medicine Pediatrics	All	Both	Neither	Neither
Pathology	None	All	D	Neither	T
Pediatrics	None	Pediatric	Both	I	Neither
Pediatric allergy and immunology	Pediatrics	Pediatric	T	I	O
Pediatric cardiology	Pediatrics	Pediatric	T	I	O
Pediatric emergency medicine	Pediatrics	Pediatric	Both	Both	Both
Pediatric endocrinology	Pediatrics	Pediatric	Both	I	Multidisciplinary
Pediatric gastroenterology	Pediatrics	Pediatric	T	I	O
Pediatric hematology and oncology	Pediatrics	Pediatric	T	I	O
Pediatric infectious disease	Pediatrics	Pediatric	T	I	O
Pediatric nephrology	Pediatrics	Pediatric	T	I	O
Pediatric respiratory medicine	Pediatrics	Pediatric	T	I	O
Pediatric rheumatology	Pediatrics	Pediatric	T	I	O
Pediatric surgery	General surgery	Pediatric	T	S	O
Physical medicine and rehabilitation	None	All	T	I	Multidisciplinary
Plastic, reconstructive and aesthetic surgery	General surgery	All	T	S	O
Psychiatry	Family medicine	All	Both	I	T
Public health	Family medicine	All	Neither	Neither	T
Radiation oncology	None	All	T	Neither	T
Radiology	None	All	Both	I	T
Reproductive endocrinology and infertility	Obstetrics and gynecology	Adults	T	S	T
Pulmunology orRespiratory medicine	Internal medicine	Adults	T	I	O
Rheumatology	Internal medicine	Adults	T	I	Neither
Sports medicine	Family medicine	All	Both	Neither	Multidisciplinary
Thoracic surgery	General surgery	Adults	T	S	T
Toxicology	Emergency Medicine	All	Both	Neither	O
Transfusion Medicine	None	All	Both	Neither	Both
Neuroradiology	Radiology	All	Both	I	Both
Urology	None	All	T	S	O
Vascular surgery	General surgery	All	T	S	O

The European Union publishes a list of specialties recognized in the European Union, and by extension, the European Economic Area.^[3]There is substantial overlap between some of the specialties and it is likely that for example "Clinical radiology" and "Radiology" refer to a large degree to the same pattern of practice across Europe.

In this table, as in many healthcare arenas, medical specialties are organized into the following groups:

• Surgicalspecialties focus on manually operative and instrumental techniques to treat disease.
• Medicalspecialties that focus on the diagnosis and non-surgical treatment of disease.
• Diagnosticspecialties focus more purely on diagnosis of disorders.

Specialty	Code	Group	Sub-specialties	Focus
Allergyandimmunology				Allergic reactions, asthma, and the immune system.
Anesthesiology	AN, PAN	Surgery[4][citation needed]	Pediatric anesthesia Pain management Intensive care Critical care Obstetrics and gynaecology Cardiothoracic anesthesiology Trauma care Pre- and Post-Operative Assessment and Care Generalist (covers all the sub-specialties)	Anesthesia
Bariatrics				Deals with the causes, prevention, and treatment ofobesity.
Cardiology		Medicine	Interventional cardiology Echocardiography Electrocardiography Sports cardiology Cardiogeriatrics Preventive cardiology and Cardiac Rehabilitation Pediatric cardiology	Disease of thecardiovascular system.
Cardiovascular surgery		Surgery		The operation ofheartand majorblood vesselsof thechest.
Clinical laboratorysciences		Diagnostic	Transfusion medicineis concerned with the transfusion ofbloodandblood component, including the maintenance of a "blood bank". Cellular pathologyis concerned with diagnosis using samples from patients taken as tissues and cells usinghistologyandcytology. Clinical chemistryis concerned with diagnosis by making biochemical analysis of blood, body fluids, and tissues. Hematologyis concerned with diagnosis by looking at changes in the cellular composition of thebloodandbone marrowas well as thecoagulation systemin the blood. Clinical microbiologyis concerned with thein vitrodiagnosis of diseases caused bybacteria,viruses,fungi, andparasites. Clinical immunologyis concerned with disorders of theimmune systemand related body defenses. It also deals with diagnosis ofallergy.	Application of diagnostic techniques inmedical laboratoriessuch asassays,microscopeanalysis.
Dermatology	D, DS	Medicine	Dermatology,Mohs surgery	Skinand its appendages (hair,nails,sweat glandsetc.).
Dietetics	RD[5]			Food and nutrition
Emergency medicine	EM	Medicine	Disaster medicine Emergency medical services Hospice and palliative medicine International Emergency Medicine and Global Health Medical toxicology Pediatric emergency medicine Research Simulation Sports medicine Toxicology Ultrasound Undersea and hyperbaric medicine Wilderness medicine	The initial management of emergent medical conditions, often in hospitalemergency departmentsor the field.
Endocrinology		Medicine		Theendocrine system(i.e.,endocrine glandsandhormones) and its diseases, includingdiabetesandthyroiddiseases.
Family medicine	FM	Medicine	Addiction medicine Adolescent medicine Anesthesia Emergency medicine Care of the elderly (geriatric medicine) Clinical environmental health Global health HIV care Hospital medicine Indigenous health Low-risk obstetrics Medical education Medical oncology Medical simulation Pain medicine Palliative care Point of Care Ultrasound (POCUS) Research Sleep medicine Sports and exercise medicine Women's health	Continuing, comprehensive healthcare for the individual and family, integrating the biological, clinical and behavioral sciences to treat patients of all ages, sexes, organ systems, and diseases.
Forensic medicine		Medicine
Gastroenterology	GI	Medicine		Thealimentary tract
General surgery	GS	Surgery	Colorectal surgery Gastrointestinal surgery Transplant surgery Trauma surgery
Geriatrics	IMG	Medicine[4][citation needed]		Elderly patients
Gynecology				Female reproductive health
Hepatology		Medicine		Theliverandbiliary tract, usually a part of gastroenterology.
Hospital medicine		Medicine
Infectious disease	ID	Medicine		Diseases caused by biological agents.
Intensive care medicine		Medicine		Life supportand management of critically ill patients, often in anICU.
Internal medicine		Medicine
Medical research			Anatomy,Biochemistry,Embryology,Genetics,Pharmacology,Toxicology	Care of hospitalized patients
Nephrology		Medicine		Kidney diseases
Neurology	N	Medicine	Behavioral neurology Clinical neurophysiology Geriatric neurology Headache medicine Neuromuscular medicine Neurodevelopmental disabilities Neuro-oncology Neuroradiology Vascular neurology Hospice and palliative medicine Pain medicine Sleep medicine	Diseases involving the central, peripheral, and autonomicnervous systems.
Neurosurgery	NS	Surgery	Cerebrovascular Neurosurgical oncology Stereotacticand functional Spine Neurotrauma Skull base Peripheral nerve Pediatric neurosurgery	Disease of thecentral nervous system,peripheral nervous system, andspinal column.
Obstetrics and gynecology	OB/GYN	Surgery[4][citation needed]	Maternal-fetal medicine Reproductive medicine Fertility medicine Gynecologic oncology
Oncology	ON	Medicine	Radiation oncology– pertains to the use ofradiation therapy(themedicaluse ofionizing radiation) as part ofcancertreatment to controlmalignantcells (not to be confused withradiology).	Cancerand other malignant diseases, often grouped with hematology.
Ophthalmology	OPH	Surgery	Anterior segment surgery Cornea Glaucoma Neuro-ophthalmology Ocular oncology Oculoplastics and Orbital surgery Ophthalmic pathology Pediatric ophthalmology/strabismus Refractive surgery Medical retina Uveitis Vitreo-retinal surgery	Diseases of the visual pathways, including the eyes, brain, etc.
Oral and maxillofacial surgery	Maxfacs, OMS	Surgery	Oral and Craniofacial surgery (Head and neck) Facial cosmetic surgery Craniomaxillofacial trauma	Disease of the head, neck, face, jaws and the hard and soft tissues of the oral and maxillofacial region.
Orthopedic surgery	ORS	Surgery	Hand surgery,surgical sports medicine, adult reconstruction, spine surgery, foot and ankle, musculoskeletal oncology, orthopedic trauma surgery, pediatric orthopedic surgery	Injury and disease of themusculoskeletal system.
Otorhinolaryngology, or ENT	ORL, ENT	Surgery	Head and neck, facial cosmetic surgery,Neurotology, Laryngology	Treatment of ear, nose, and throat disorders. The termhead and neck surgerydefines a closely related specialty that is concerned mainly withthe surgical management of cancerof the same anatomical structures.
Palliative care	PLM	Medicine		A relatively modern branch of clinical medicine that deals with pain and symptom relief and emotional support in patients withterminal illnessesincludingcancerandheart failure.
Pathology	PTH	Diagnostic		Understandingdiseasethrough examination ofmolecules,cells,tissuesandorgans. The term encompasses both the medical specialty that uses tissues and body fluids to obtain clinically useful information and the relatedscientificstudy of disease processes.
Pediatrics	PD	Medicine	Children. Like internal medicine, pediatrics has many sub-specialties for specific age ranges, organ systems, disease classes, and sites of care delivery. Most sub-specialties of adult medicine have a pediatric equivalent such aspediatric cardiology,pediatric emergency medicine,pediatric endocrinology,pediatric gastroenterology,pediatric hematology,pediatric oncology,pediatric ophthalmology, andneonatology.	Deals with the medical care ofinfants,children, andadolescents(fromnewbornto age 16–21, depending on the country).
Pediatric surgery		Surgery	Treats a wide variety ofthoracicandabdominal(and sometimesurologic) diseases of childhood.
Physical medicine and rehabilitationOr Physiatry	PM&R	Medicine	Cancer Rehabilitation Pain Management Traumatic Brain Injury Spinal Cord Injury Sports Medicine Pediatrics Hospice & Palliative Medicine	Concerned with functional improvement after injury, illness, orcongenital disorders.
Plastic surgery	PS	Surgery	Cosmetic surgery Burn Microsurgery Hand surgery Craniofacial surgery	Elective cosmetic surgery as well as reconstructive surgery after traumatic or operative mutilation.
Podiatry	POD	Surgery	Forefoot surgery Midfoot surgery Rearfoot surgery Ankle surgery Soft tissue leg surgery	Elective podiatric surgery of the foot and ankle, lower limb diabetic wound and salvation,peripheral vascular diseaselimb preservation, lower limbmononeuropathyconditions. Reconstructivefoot & ankle surgery.
Proctology	PRO	Medicine		(orColorectal Surgery) Treats disease in therectum,anus, andcolon.
Psychiatry	P	Medicine	Addiction psychiatryfocuses on substance abuse and its treatment. Child and adolescent psychiatryfocuses on the care of children and adolescents with mental, emotional, and learning problems includingADHD,autism, and family conflicts. Consultation-Liaison psychiatryfocuses on the interface between general medicine and psychiatry. Forensic psychiatryfocuses on the interface of psychiatry and law. Geriatric psychiatryfocuses on the care of elderly people with mental illnesses includingdementias, post-stroke cognitive changes, and depression. Neuropsychiatryfocuses on affective, cognitive and behavioral disorders attributable to diseases of the nervous system Sleep medicinefocuses on the diagnosis and treatment of sleep disorders. Hospice and Palliative Medicine Pain medicine	Thebio-psycho-socialstudy of theetiology,diagnosis, treatment andpreventionofcognitive,perceptual,emotionalandbehavioraldisorders. Related fields includepsychotherapyandclinical psychology.
Pulmonology		Medicine		The lungs andrespiratory system.Pulmonologyis generally considered a branch ofinternal medicine, although it is closely related tointensive care medicinewhen dealing with patients requiringmechanical ventilation.
Public Health				Public health focuses on the health of populations. Physicians employed in this field work in policy, research orhealth promotion, taking a broad view of health that encompasses thesocial determinants of health.
Radiology	R, DR	Diagnostic and Therapeutic	Interventional radiologyis concerned with using expert imaging of the human body, usually via CT, ultrasound,fluoroscopy, or MRI to perform a breadth of intravascular procedures (angioplasty, arterial stenting, thrombolysis, uterine fibroid embolization),biopsiesand minimally invasive oncologic procedures (radiofrequency and cryoablation of tumors & transarterial chemoembolization) Nuclear medicineusesradioactivesubstances forin vivoandin vitrodiagnosis either using imaging of the location of radioactive substances placed into a patient or usingin vitrodiagnostic tests utilizingradioactivesubstances.	The use of expertise in radiation in the context ofmedical imagingfordiagnosisor image guided minimally invasive therapy.X-rays, etc.
Rheumatology	RHU	Medicine		Autoimmuneand inflammatory diseases of thejointsand other organ systems, such asarthritisand otherrheumatic diseases.
Surgical oncology	SO	Surgery		Curative and palliative surgical approaches tocancertreatment.
Thoracic surgery	TS	Surgery		Surgery of the organs of thethoracic cavity: the heart, lungs, and great vessels.
Transplant surgery	TTS	Surgery		Transplantation oforgansfrom one body to another.
Toxicology		Diagnostic and Therapeutic	Environmental Forensic Occupational Pediatric	Poisonings, Overdoses; Environmental, and Occupational Exposures
Urgent Care Medicine	UCM	Medicine		Immediate medical care offering outpatient care for the treatment of acute and chronic illness and injury.
Urology	U	Surgery		Urinary tractsof males and females, and themale reproductive system. It is often practiced together withandrology("men's health").
Vascular surgery	VS	Surgery		The peripheral blood vessels – those outside thechest(usually operated on bycardiovascular surgeons) and outside thecentral nervous system(treated byneurosurgery).

According to the 2022 Medscape Physician Compensation Report, physicians on average earn $339K annually. Primary care physicians earn $260K annually while specialists earned $368K annually.^[6]

The table below details the average range of salaries for physicians in the US of medical specialties:^[6][7]

Specialty	Average salary (USD)	Average hours work/week	Average salary/hour (USD)
Allergy & Immunology	$298K
Anesthesiology	$405K	59
Dermatology	$438K	44	103
Emergency medicine	$373K	44	180
Endocrinology	$257K
Cardiac Surgery	218,684 to $500,000
Cardiology	$490K	55
Critical care	$369K
Infectious disease	$260K
Internal medicine	$264K	55	58
Family medicine	$255K	51	58
Nephrology	$329K
Neurology	$301K	54	93
Obstetrics and Gynecology	$336K	59	83
Oncology	$411K
Ophthalmology	$417K	45
Orthopedic surgery	$557K	56
Otolaryngology	$469K	52
Oral and Maxillofacial Surgery	360,000 to $625,210	53
Pathology	$334K	44
Pediatrics	244K	52	69
Rheumatology	$289K
Physical Medicine & Rehabilitation	$322K
Podiatry	170,800 to $315,150	45	80
Preventative medicine	$243K
Pulmonary medicine	$353K	55
Psychiatry	$287K	46	72
Radiology(diagnostic)	$437K	56
Surgery(general)	$402K	58
Urology	$461K	59
Neurosurgery	350,000 to $705,000		132
Plastic surgery	$576K		114
Gastroenterology	$453K	55	93

There are 15 recognised specialty medical Colleges in Australia.^[8][9][10]The majority of these are Australasian Colleges and therefore also oversee New Zealand specialist doctors. These Colleges are:

Specialist College	Major Subspecialties	Approximate number of specialist doctors/trainees
Australasian College for Emergency Medicine	Paediatric emergency medicine	5,000
Australasian College of Dermatologists		700
Australasian College of Sport and Exercise Physicians	Exercise medicine	350
Australian and New Zealand College of Anaesthetists	Pain medicine	7,000
Australian College of Rural and Remote Medicine		4,500
College of Intensive Care Medicine	Paediatric Intensive care	1,200
Royal Australasian College of Medical Administrators		800
Royal Australasian College of Physicians	Addiction medicine, Adolescent and young adult medicine, Cardiology, Clinical Genetics, Clinical haematology, Clinical pharmacology, Community child health, Endocrinology, Gastroenterology, General and acute care medicine, General paediatrics Geriatric medicine, Haematology, Infectious diseases, Immunology and allergy, Neonatal and perinatal medicine, Nephrology, Neurology, Nuclear medicine, Occupational medicine, Oncology, Paediatric emergency medicine, Palliative medicine, Public health, Rehabilitation, Respiratory and sleep medicine, Rheumatology, Sexual Health	28,000
Royal Australasian College of Surgeons	Cardiothoracic, General surgery, Head & neck, Neurosurgery, Orthopaedics, Paediatric surgery, Plastics, Urology, Vascular	9,000
Royal Australian and New Zealand College of Obstetricians and Gynaecologists	Obstetrics, Gynaecology, Fertility medicine, Obstetric ultrasound, Gynaecological oncology, Urogynaecology	2,500
Royal Australian and New Zealand College of Ophthalmologists		1,100
Royal Australian and New Zealand College of Psychiatrists		5,000
Royal Australian and New Zealand College of Radiologists	Diagnostic, Interventional, Ultrasound, Nuclear medicine	3,500
Royal Australian College of General Practitioners		40,000
Royal College of Pathologists of Australasia	Anatomical, Chemical, Clinical, Forensic, Genetic, Haematological, Immunological, Microbiological Pathology	1,000

In addition, theRoyal Australasian College of Dental Surgeonssupervises training of specialist medical practitioners specializing inOral and Maxillofacial Surgeryin addition to its role in the training ofdentists. There are approximately 260 faciomaxillary surgeons in Australia.^[11]

TheRoyal New Zealand College of General Practitionersis a distinct body from the AustralianRoyal Australian College of General Practitioners. There are approximately 5100 members of the RNZCGP.

Within some of the larger Colleges, there are sub-faculties, such as:Australasian Faculty of Rehabilitation MedicineArchived2014-12-11 at theWayback Machinewithin theRoyal Australasian College of Physicians

There are some collegiate bodies in Australia that are not officially recognised as specialities by the Australian Medical Council but have a college structure for members, such as:Australasian College of Physical Medicine

There are some collegiate bodies in Australia of Allied Health non-medical practitioners with specialisation. They are not recognised as medical specialists, but can be treated as such by private health insurers, such as:Australasian College of Podiatric Surgeons

Specialty training in Canada is overseen by theRoyal College of Physicians and Surgeons of Canadaand theCollege of Family Physicians of Canada. For specialists working in the province ofQuebec, theCollège des médecins du Québecalso oversees the process.

In Germany these doctors use the termFacharzt.

Specialty training in India is overseen by theMedical Council of India, responsible for recognition of post graduate training and by theNational Board of Examinations. Education ofAyurvedain overseen byCentral Council of Indian Medicine(CCIM), the council conducts UG and PG courses all over India, whileCentral Council of Homoeopathydoes the same in the field of Homeopathy.

In Sweden, amedical licenseis required before commencing specialty training. Those graduating from Swedishmedical schoolsare first required to do a rotationalinternshipof about 1.5 to 2 years in various specialties before attaining a medical license. The specialist training lasts 5 years.^[12]

There are three agencies or organizations in the United States that collectively overseephysician board certificationofMDandDOphysicians in the United Statesin the 26 approved medical specialties recognized in the country. These organizations are theAmerican Board of Medical Specialties(ABMS) and theAmerican Medical Association(AMA); theAmerican Osteopathic Association Bureau of Osteopathic Specialists(AOABOS) and theAmerican Osteopathic Association; theAmerican Board of Physician Specialties(ABPS) and theAmerican Association of Physician Specialists(AAPS). Each of these agencies and their associated national medical organization functions as its various specialty academies, colleges and societies.

Certifying board	National organization	Physician type
ABMS	AMA	MD and DO
ABPS	AAPS	MD and DO
AOABOS	AOA	DO only

All boards of certification now require thatmedical practitionersdemonstrate, by examination, continuing mastery of the core knowledge and skills for a chosen specialty. Recertification varies by particular specialty between every seven and every ten years.

In the United States there are hierarchies of medical specialties in the cities of a region. Small towns and cities have primary care, middle sized cities offer secondary care, and metropolitan cities have tertiary care. Income, size of population, population demographics, distance to the doctor, all influence the numbers and kinds of specialists and physicians located in a city.^[13]

A population's income level determines whether sufficient physicians can practice in an area and whether public subsidy is needed to maintain the health of the population. Developing countries and poor areas usually have shortages of physicians and specialties, and those in practice usually locate in larger cities. For some underlying theory regarding physician location, seecentral place theory.^[13]

The proportion of men and women in different medical specialties varies greatly.^[14]Such sex segregation is largely due to differential application.^[15]

A survey ofphysicians in the United Statescame to the result that dermatologists are most satisfied with their choice of specialty followed byradiologists,oncologists,plastic surgeons, andgastroenterologists.^[16]In contrast,primary care physicianswere the least satisfied, followed bynephrologists,obstetricians/gynecologists, andpulmonologists.^[16]Surveys have also revealed high levels of depression among medical students (25 - 30%) as well as among physicians in training (22 - 43%), which for many specialties, continue into regular practice.^[17][18]A UK survey conducted of cancer-related specialties in 1994 and 2002 found higher job satisfaction in those specialties with more patient contact. Rates of burnout also varied by specialty.^[19]

• Branches of medicine
• Interdisciplinary sub-specialties of medicine, including
  • Occupational medicine– branch of clinical medicine that provides health advice to organizations and individuals concerning work-related health and safety issues and standards.Seeoccupational safety and health.
  • Disaster medicine– branch ofmedicinethat provides healthcare services to disaster survivors; guides medically relateddisaster preparation,disaster planning,disaster responseanddisaster recoverythroughout the disaster life cycle and serves as a liaison between and partner to themedical contingency planner, the emergency management professional, theincident command system, government and policy makers.
  • Preventive medicine– part ofmedicineengaged with preventingdiseaserather than curing it. It can be contrasted not only with curative medicine, but also withpublic healthmethods (which work at the level of population health rather than individual health).
  • Medical genetics– the application ofgeneticstomedicine. Medical genetics is a broad and varied field. It encompasses many different individual fields, includingclinical genetics,biochemical genetics,cytogenetics,molecular genetics, the genetics of common diseases (such asneural tube defects), andgenetic counseling.
• Specialty Registrar
• Federation of National Specialty Societies of Canada
• Society of General Internal Medicine