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Key Definitions, Acronyms, Specialty

Key definitions

  • Active physicians: Physicians (federal and nonfederal) who are licensed by a state are considered active, provided they are working more than 20 hours per week. Physicians who are retired, semi-retired, temporarily not in practice, not active for other reasons, or have not completed their graduate medical education are excluded. Active physicians include those working in direct patient care, administration, medical teaching, research, or other non-patient care activities. Active physicians include those with a Doctor of Medicine (MD) and a Doctor of Osteopathic Medicine (DO). The total number of active physicians may differ between tables in this report as a result of missing information in the data file. For example, to determine the percentage of active physicians who are female, the total number of active physicians excludes people whose sex was not reported in the data file.
  • U.S. MD: Physicians who received their MD degree from a U.S. medical school that is accredited by the Liaison Committee on Medical Education (LCME).
  • DO: Physicians who received their DO degree from a U.S. osteopathic school that is accredited by the American Osteopathic Association Commission on Osteopathic College Accreditation (COCA).
  • First-year residents and fellows: Physicians who are in their first year of a graduate medical education program in their specialty are considered first-year residents or fellows. In some cases, the resident or fellow may have had prior GME training in a different specialty.
  • International medical graduate: An individual who graduated from a medical school outside of the United States, Puerto Rico, or Canada is considered an international medical graduate (IMG). This includes U.S. citizens who completed their medical education outside the United States, Puerto Rico, or Canada. To be eligible for licensure and practice in the United States, all IMGs must be certified by the Educational Commission for Foreign Medical Graduates (ECFMG) and complete a residency training program in the United States. Graduates of Canadian medical schools are not considered IMGs because they do not have to be certified by the ECFMG to enter a residency training program in the United States. Please note that although graduates of Canadian medical schools who are practicing in the United States are not considered IMGs or U.S. MDs, they are included in the total for active physicians.

Commonly used acronyms

  • AAMC: Association of American Medical Colleges
  • ACGME: Accreditation Council for Graduate Medical Education
  • AMA: American Medical Association
  • DO: Doctor of Osteopathic Medicine
  • GME: Graduate medical education
  • IMG: International medical graduate
  • MD: Doctor of Medicine

Practice specialty

This report presents data on the specialties with the largest number of active physicians in 2017, which is defined as having more than 2,500 active physicians. Specialty designations for active physicians rely on the primary specialty selected by the physician on the AMA-administered Census of Physicians. Specialty designations for residents and fellows reflect the ACGME training program in which the physician is training. Note: As part of the transition to a single GME accreditation system, American Osteopathic Association (AOA) Sponsoring Institutions and AOA-approved programs began applying for ACGME accreditation in 2015.

The AMA Physician Masterfile lists more than 200 specialty categories, and there are more than 140 ACGME specialties and subspecialties. To give a more comprehensive and informative view of the specialty category, we grouped some related specialties together. Because of differences in the specialty designations between the AMA Physician Masterfile and the ACGME, specialty groupings used in this report will sometimes vary for active physicians and trainees as indicated in the table below.

One new specialty grew to exceed 2,500 physicians for the first time since previous reports and thus is included for the first time in this report: Sports Medicine (Orthopedic Surgery).

Specialty groupingAMA Physician Masterfile specialties includedACGME specialties and specialties included
Allergy and ImmunologyAllergy (A)
Allergy and Immunology (AI)
Immunology (IG)
Allergy and Immunology
Anatomic/Clinical PathologyAnatomic Pathology (ATP)
Anatomic/Clinical Pathology (PTH)
Chemical Pathology (PCH)
Clinical Pathology (CLP)
Chemical Pathology (Pathology)
Pathology-Anatomic and Clinical
AnesthesiologyAnesthesiology (AN)Anesthesiology
Cardiovascular DiseaseCardiovascular Disease (CD)Cardiovascular Disease
Child and Adolescent PsychiatryChild and Adolescent Psychiatry (CHP)Child and Adolescent Psychiatry (Psychiatry)
Pediatrics/Psychiatry/Child and Adolescent Psychiatry
Critical Care MedicineCritical Care Medicine (CCM, CCA)
Pulmonary Critical Care Medicine
Critical Care Medicine (Internal Medicine)
Critical Care Medicine (Anesthesiology)
Pulmonary Disease and Critical Care Medicine (Internal Medicine)
DermatologyDermatology (D)Dermatology
Emergency MedicineEmergency Medicine (EM)Emergency Medicine
Endocrinology, Diabetes and MetabolismDiabetes (DIA)
Endocrinology, Diabetes and Metabolism (END)
Endocrinology, Diabetes and Metabolism
Family Medicine/General PracticeFamily Medicine (FM, FP)
General Practice (GP)
Family Medicine
GastroenterologyGastroenterology (GE)Gastroenterology
General SurgeryGeneral Surgery (GS)General Surgery
Geriatric MedicineGeriatric Medicine (IMG, FPG)Geriatric Medicine (Family Practice)
Geriatric Medicine (Internal Medicine)
Hematology and OncologyHematology (HEM)
Hematology/Oncology (HO)
Medical Oncology (ON)
Hematology (Internal Medicine)
Hematology and Oncology (Internal Medicine)
Oncology (Internal Medicine)
Infectious DiseaseInfectious Disease (ID)Infectious Disease
Internal MedicineInternal Medicine (IM)Internal Medicine
Internal Medicine/Family Practice
Internal Medicine/PediatricsInternal Medicine/Pediatrics (MPD)Internal Medicine/Pediatrics
Interventional CardiologyInterventional Cardiology (IC)Interventional Cardiology (Internal
Neonatal-Perinatal MedicineNeonatal-Perinatal Medicine (NPM)Neonatal-Perinatal Medicine
NephrologyNephrology (NEP)Nephrology
Neurological SurgeryNeurological Surgery (NS)Neurological Surgery
NeurologyNeurology (N)Neurology
NeuroradiologyNeuroradiology (RNR)Neuroradiology (Radiology-Diagnostic)
Obstetrics and GynecologyGynecology (GYN)
Obstetrics (OBS)
Obstetrics and Gynecology (OBG)
Obstetrics and Gynecology
OphthalmologyOphthalmology (OPH)Ophthalmology
Orthopedic SurgeryOrthopedic Surgery (ORS)Orthopedic Surgery
OtolaryngologyOtolaryngology (OTO)Otolaryngology
Pain Medicine and Pain ManagementPain Medicine (APM, PMM, PMN)
Pain Management (PME, PMP)
Pain Medicine (Multidisciplinary)
PediatricsPediatrics (PD)Pediatrics
Pediatric CardiologyPediatric Cardiology (PDC)
Pediatric Cardiology (Pediatrics)
Pediatric Hematology/OncologyPediatric Hematology/Oncology (PHO) Pediatric Hematology/Oncology (Pediatrics)
Physical Medicine and RehabilitationPhysical Medicine and Rehabilitation (PM)Physical Medicine and Rehabilitation
Plastic SurgeryFacial Plastic Surgery (FPS)
Plastic Surgery (PS, PSI)
Plastic Surgery Within The Head and Neck (PSH)
Plastic Surgery
Plastic Surgery-Integrated
Preventive MedicineAerospace Medicine (AM)
General Preventive Medicine (GPM)
Occupational Medicine (OM)
Public Health and General Preventive Medicine (PHP)
Preventive Medicine
PsychiatryAddiction Medicine (ADM)
Addiction Psychiatry (ADP)
Psychiatry (P)
Psychoanalysis (PYA)
Psychosomatic Medicine (PYM)
Addiction Psychiatry (Psychiatry)
Psychosomatic Medicine (Psychiatry)
Pulmonary DiseasePulmonary Disease (PUD)Pulmonary Disease (Internal Medicine)
Radiation OncologyRadiation Oncology (RO)Radiation Oncology
Radiology and Diagnostic RadiologyDiagnostic Radiology (DR)
Radiology (R)
RheumatologyRheumatology (RHU)Rheumatology
Sports Medicine (Orthopedic Surgery)Sports Medicine (Orthopedic Surgery) (OSM)Sports Medicine (Orthopedic Surgery)
Thoracic SurgeryThoracic Surgery (TS, TSI)Congenital Cardiac Surgery (Thoracic Surgery)
Thoracic Surgery
Thoracic Surgery-Integrated
UrologyUrology (U)Urology
Vascular and Interventional RadiologyVascular and Interventional Radiology (VIR)Vascular and Interventional Radiology (Radiology-Diagnostic)
Vascular SurgeryVascular Surgery (VS, VSI)Vascular Surgery (General Surgery)
Vascular Surgery-Integrated

Note: Codes in parentheses represent the AMA Physician Masterfile Self-Designated Practice Specialties/Areas of Practice.