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Physician Specialty Data Report

2020 Key Definitions, Commonly Used Acronyms, and Practice Specialties

Key Definitions

Active physicians: Physicians who are licensed by one of the 50 U.S. states, District of Columbia, or Puerto Rico 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 nonpatient care activities. Active physicians include those with a doctor of medicine (MD) or doctor of osteopathic medicine (DO) degree. The total number of active physicians may differ among 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 gender was not reported in the data file.

U.S. MD: Physician who received their MD degree from a U.S. medical school — including in the District of Columbia and Puerto Rico1 — accredited by the Liaison Committee on Medical Education (LCME).

DO: Physician who received their DO degree from a U.S. osteopathic school accredited by the American Osteopathic Association Commission on Osteopathic College Accreditation (COCA).

First-year residents and fellows: Physicians in their first year of a graduate medical education (GME) 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 the United States, Puerto Rico,1 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 totals 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 practice specialties with the largest number of active physicians in 2019, meaning more than 2,500 active physicians. Specialty designations for active physicians rely on the primary specialty selected by the physician on the American Medical Association (AMA)-administered Census of Physicians. Specialty designations for residents and fellows reflect the ACGME-accredited training program in which the physician is training.

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. Specialty groupings used in this report are indicated in the table below.

Two new specialties grew to exceed 2,500 physicians for the first time since previous reports, and thus are included for the first time in this report: pediatric critical care medicine and pediatric anesthesiology (anesthesiology).

Specialty Grouping

AMA Physician Masterfile Specialties Included2

ACGME Specialties and Subspecialties Included2

Allergy and Immunology

Allergy (A)

Allergy and Immunology


Allergy and Immunology (AI)


Immunology (IG)





Anatomic/Clinical Pathology

Anatomic Pathology (ATP)

Chemical Pathology (Pathology)


Anatomic/Clinical Pathology (PTH)

Pathology-Anatomic and Clinical


Chemical Pathology (PCH)


Clinical Pathology (CLP)






Anesthesiology (AN)





Cardiovascular Disease

Cardiovascular Disease (CD)

Cardiovascular Disease




Child and Adolescent Psychiatry

Child and Adolescent Psychiatry (CHP)

Child and Adolescent Psychiatry (Psychiatry)


Pediatrics/Psychiatry/Child and Adolescent Psychiatry




Critical Care Medicine

Critical Care Medicine (CCM, CCA)

Critical Care Medicine (Internal Medicine)


Pulmonary Critical Care Medicine (PCC)

Critical Care Medicine (Anesthesiology)


Pulmonary Disease and Critical Care Medicine (Internal Medicine)



Dermatology (D)





Emergency Medicine

Emergency Medicine (EM)

Emergency Medicine




Endocrinology, Diabetes, and Metabolism

Diabetes (DIA)

Endocrinology, Diabetes, and Metabolism


Endocrinology, Diabetes, and Metabolism (END)





Family Medicine/General Practice

Family Medicine (FM, FP)

Family Medicine


General Practice (GP)






Gastroenterology (GE)





General Surgery

General Surgery (GS)

General Surgery




Geriatric Medicine

Geriatric Medicine (IMG, FPG)

Geriatric Medicine (Family Practice)


Geriatric Medicine (Internal Medicine)




Hematology and Oncology

Hematology (HEM)

Hematology (Internal Medicine)


Hematology/Oncology (HO)

Hematology and Oncology (Internal Medicine)


Medical Oncology (ON)

Oncology (Internal Medicine)




Infectious Disease

Infectious Disease (ID)

Infectious Disease




Internal Medicine

Internal Medicine (IM)

Internal Medicine


Internal Medicine/Family Practice




Internal Medicine/ Pediatrics

Internal Medicine/Pediatrics (MPD)

Internal Medicine/Pediatrics


Interventional Cardiology

Interventional Cardiology (IC)

Interventional Cardiology (Internal Medicine)




Neonatal-Perinatal Medicine

Neonatal-Perinatal Medicine (NPM)

Neonatal-Perinatal Medicine





Nephrology (NEP)





Neurological Surgery

Neurological Surgery (NS)

Neurological Surgery





Neurology (N)




Neuroradiology (RNR)

Neuroradiology (Radiology-Diagnostic)




Obstetrics and Gynecology

Gynecology (GYN)

Obstetrics and Gynecology


Obstetrics (OBS)


Obstetrics and Gynecology (OBG)






Ophthalmology (OPH)





Orthopedic Surgery

Orthopedic Surgery (ORS)

Orthopedic Surgery





Otolaryngology (OTO)





Pain Medicine and Pain Management

Pain Medicine (APM, PMM, PMN)

Pain Medicine (Multidisciplinary)


Pain Management (PME, PMP)


Pediatric Anesthesiology

Pediatric Anesthesiology (PAN)

Pediatric Anesthesiology (Anesthesiology)

Pediatric Cardiology

Pediatric Cardiology (PDC)

Pediatric Cardiology (Pediatrics)

Pediatric Critical Care Medicine

Pediatric Critical Care Medicine (CCP)

Pediatric Critical Care Medicine (Pediatrics)

Pediatric Hematology/Oncology

Pediatric Hematology/Oncology (PHO)

Pediatric Hematology/Oncology (Pediatrics)


Pediatrics (PD)





Physical Medicine and Rehabilitation

Physical Medicine and Rehabilitation (PM)

Physical Medicine and Rehabilitation




Plastic Surgery

Facial Plastic Surgery (FPS)

Plastic Surgery


Plastic Surgery (PS, PSI)

Plastic Surgery-Integrated


Plastic Surgery Within the Head and Neck (PSH)





Preventive Medicine

Aerospace Medicine (AM)

Preventive Medicine


General Preventive Medicine (GPM)


Occupational Medicine (OM)


Public Health and General Preventive Medicine (PHP)






Addiction Medicine (ADM)

Addiction Psychiatry (Psychiatry)


Addiction Psychiatry (ADP)



Psychiatry (P)

Psychosomatic Medicine (Psychiatry)


Psychoanalysis (PYA)


Psychosomatic Medicine (PYM)





Pulmonary Disease3

Pulmonary Disease (PUD)

Pulmonary Disease (Internal Medicine)


Radiation Oncology

Radiation Oncology (RO)

Radiation Oncology




Radiology and Diagnostic Radiology

Diagnostic Radiology (DR)



Radiology (R)






Rheumatology (RHU)





Sports Medicine (Orthopedic Surgery)

Sports Medicine (Orthopedic Surgery) (OSM)

Sports Medicine (Orthopedic Surgery)

Thoracic Surgery

Thoracic Surgery (TS, TSI)

Congenital Cardiac Surgery (Thoracic Surgery)


Thoracic Surgery

Thoracic Surgery-Integrated





Urology (U)



Vascular and Interventional Radiology

Vascular and Interventional Radiology (VIR)

Vascular and Interventional Radiology (Radiology-Diagnostic)




Vascular Surgery

Vascular Surgery (VS, VSI)

Vascular Surgery (General Surgery)



Vascular Surgery-Integrated


  1. In previous years of the report, physicians practicing in Puerto Rico were categorized as “IMG."
  2. Codes in parentheses represent the AMA Physician Masterfile Self-Designated Practice Specialties/Areas of Practice.
  3. In the late 1980s, pulmonology disease began to evolve into pulmonary critical care. As such, the single specialty of pulmonary disease is being replaced by pulmonary critical care.