This article contains a list of commonly used medical abbreviations and acronyms that start with the letter M and may be encountered in medicine and radiology (please keep the main list and any sublists in alphabetic order).

A - B - C - D - E - F - G - H - I - J - K - L - M - N - O - P - Q - R - S - T - U - V - W - X - Y - Z - misc

• M

  • male

  • marginal artery

  • mega- (SI prefix for 10⁶)

  • metastable (isotope)

  • metastatic (TNM system)

  • methionine (single letter amino acid code)

  • meter

  • mitotic (phase)

  • molar (=mols/L)

  • motor (GCS)

• m: milli- (SI prefix for 10^-3)

• M1-M4

  • segments in the Alberta stroke program early CT score (ASPECTS), also including M5-6

  • segments of middle cerebral artery

• MA: mitral annulus

• MAC

  • mastoid air cells

  • membrane attack complex

  • mitral annular calcification

  • Mycobacterium avium complex

• MACE: major adverse cardiovascular event

• MACI: matrix-induced autologous chondrocyte implantation

• MAD: mitral annulus disjunction

• MAFLD: metabolic associated fatty liver disease

• MAG: magnification

• MAG-3: mercaptoacetyltriglycine

• MAGiC: magnetic resonance image compilation (GE)

• MAHA: microangiopathic hemolytic anemia

• MAI

  • minimal aortic injury

  • miscarriage after infertility

  • Mycobacterium avium-intracellulare infection

• MAL: mid axillary line

• MALA: metformin-associated lactic acidosis

• MAM: mammogram

• MAMMO: mammogram

• MAO: monoamine oxidase

• MAP

  • magnesium ammonium phosphate

  • mean arterial pressure

• MAPSE: mitral annular plane systolic excursion

• MAR: metal artifact reduction

• mAs: milliampere-seconds

• MAV: mechanical aortic valve

• MAVRIC: multiacquisition variable-resonance image combination (GE)

• MAVRIC-SL: multiacquisition variable-resonance image combination

• Maxfax: maxillofacial surgery/surgeon

• MB

  • bachelor of medicine

  • megabyte

  • multiband (imaging)

  • myoglobin

• MBA: motorbike accident

• MBBS: bachelor of medicine and bachelor of surgery

• MBC: motorbike collision

• mBC: metastatic breast cancer

• MBL: monoclonal B-cell lymphoma

• MBq: megabecquerel

• MC

  • metacarpal

  • miscarriage

• M/C

  • miscarriage

  • motorcycle

• MCA

  • middle cerebral artery

  • middle colic artery

• MCB: medullary carcinoma of the breast

• MCD: molybdenum cofactor deficiency

• MCG/mcg: microgram (preferred to μg in medical notes)

• MCI: mass casualty incident

• mCi: millicurie

• MCL

  • mantle cell lymphoma

  • medial collateral ligament (of the elbow)

  • medial collateral ligament (of the knee)

  • midclavicular line

• MCN: mucinous cystic neoplasm

• MCP: middle cerebellar peduncle

• MCPJ: metacarpophalangeal joint

• mCRC: metastatic colorectal cancer

• mCRPC: metastatic castration-resistant prostate cancer

• MCS

  • microscopy, culture, and sensitivity

  • medial clear space

• MCTD: mixed connective tissue disease

• MCV: middle cardiac vein

• MD

  • doctor of medicine (Latin: medicinae doctor)

  • managing director

  • Meckel diverticulum

  • medical director

  • movement disorder

  • muscular dystrophy

• Md: mendelevium

• MDA criteria: MD Anderson criteria for assessing response of bone metastases to treatment

• MDCT: multidetector CT

• MDD: major depressive disorder

• MDI: multidirectional instability (of shoulder)

• MD-IPMN: main duct type intraductal papillary mucinous neoplasm

• MDM: multidisciplinary (team) meeting

• MDMA: 3,4-methylenedioxymethamphetamine

• MDP: methylene-diphosphonate

• MDR-TB: multidrug-resistant tuberculosis

• MDT: multidisciplinary team

• MDTM: multidisciplinary team meeting

• ME

  • mache unit

  • medical examiner

  • middle ear

  • myalgic encephalomyelitis

• ME/CFS: myalgic encephalomyelitis/chronic fatigue syndrome

• MEB: muscle-eye-brain disease

• MEDIC: multiecho data image combination (Siemens)

• MEDS: medication

• MEG: megalencephaly

• MELAS: mitochondrial encephalopathy with lactic acidosis and stroke-like episodes

• MELD (score): model of end-stage liver disease

• MEN: multiple endocrine neoplasia

• MEP: maximum expiratory pressure

• MERGE: multiple-echo recombined gradient echo (GE)

• MERRF: myoclonic epilepsy with red ragged fibers

• MESA

  • microsurgical epididymal sperm aspiration

  • multiethnic study of atherosclerosis

• MET

  • medical emergency team

  • medical expulsive therapy (ureteric calculi)

  • metabolic equivalent

  • metastasis

• Met

  • metastasis

  • methionine

• MetHb: methemoglobin

• Mets: metastases

• MeVO: medium vessel occlusion

• MF: middle finger

• MFC: medial femoral condyle

• MFFE: multiecho fast field echo (Philips)

• MFH: malignant fibrous histiocytoma

• MG

  • mammogram

  • middle grade (UK physician grade)

  • milligram

  • myasthenia gravis

• Mg: magnesium

• MGA: middle genicular artery

• MGHL: middle glenohumeral ligament

• mGy: milligray

• MGUS

  • monoclonal gammopathy of uncertain significance

  • monoclonal gammopathy of undetermined significance

  • monoclonal gammopathy of unknown significance

• MH: medical history (or M/H)

• MHC: major histocompatibility complex

• MHT: menopausal hormone therapy

• MHV: middle hepatic vein

• MHz: megahertz

• MI

  • mechanical index

  • mitral incompetence

  • myocardial infarct

• MIBC: muscle invasive bladder cancer

• MIBG: metaiodobenzylguanidine

• MIBI: methoxyisobutylisonitrile

• Micro

  • microbiology

  • microscopy

  • SI prefix for 10^-6

• MIDCAB: minimally invasive direct coronary artery bypass

• MIES: mask induced exhaustion syndrome

• Min: minute

• MinIP: minimum intensity projection

• MINOCA: myocardial infarction with non-obstructive coronary arteries

• MIP

  • maximum inspiratory pressure

  • maximum intensity projection

• MIS-C: multisystem inflammatory syndrome in children

• MISME: multiple inherited schwannomas, meningiomas, ependymomas

• ML

  • mediolateral

  • middle lobe

  • mobile lipids (MRS)

• mL: milliliter

• ml: milliliter

• MLA: minimal lumen area

• MLC: multileaf collimator

• MLD: midline deviation

• MLO: mediolateral oblique

• MLS: midline shift

• MM

  • malignant melanoma

  • medial meniscus

  • moyamoya

  • multiple myeloma

• mm: millimeter

• M&M: morbidity and mortality

• MMA: middle meningeal artery

• MMC: myelomeningocele

• MMD: moyamoya disease

• MMF: mycophenolate mofetil

• mmHg: millimeters of mercury

• MMN: multifocal motor neuropathy

• MMNCB: multifocal motor neuropathy with conduction block

• M-mode: motion mode (ultrasound)

• MMR

  • measles, mumps, and rubella (vaccine)

  • mismatch repair (genes)

• MMRV: measles, mumps, rubella, and varicella (vaccine)

• MMS: moyamoya syndrome

• MMSE: mini mental status exam

• MMUS: magnetomotive ultrasound

• Mn: manganese

• MND

  • mild neurocognitive disorder (in the context of HIV)

  • motor neuron disease

• MNG: multinodular goiter

• MNGIE: mitochondrial neurogastrointestinal encephalomyopathy

• MO

  • medical officer

  • modus operandi

  • morbid obesity

  • morphine

  • myositis ossificans

• Mo

  • molybdenum

  • month

• MoCA: Montreal cognitive assessment 

• MOCD: molybdenum cofactor deficiency

• Mol: mole (SI unit of quantity of substance)

• MOGAD: myelin oligodendrocyte glycoprotein antibody-associated disease

• MOTSA: multiple overlapping thin slab acquisition

• MP

  • megapixel

  • middle phalanx

• MPA

  • main pulmonary artery

  • microscopic polyangiitis

• mPAP: mean pulmonary arterial pressure

• MPC: metastatic pulmonary calcification

• MPD: main pancreatic duct

• mPFL: medial patellofemoral ligament

• MPGN: membranoproliferative glomerulonephritis

• MPN: myeloproliferative neoplasms

• MPO: myeloperoxidase

• MPP

  • malleable penile prosthesis

  • Mycoplasma pneumoniae pneumonia

• MPR: multiplanar reformation or reformats

• MPRAGE: magnetization-prepared rapid gradient echo

• MPS: mucopolysaccharidoses

• MPV: main portal vein

• MR

  • magnetic resonance

  • mitral regurgitation

• MRA: magnetic resonance angiogram

• MRCP

  • magnetic resonance cholangiopancreatography

  • Member(ship) of the Royal College of Physicians (UK)

• MRE

  • magnetic resonance elastography

  • magnetic resonance enterography

• mrem: millirem

• MRF: mesorectal fascia

• MRI: magnetic resonance imaging

• MRL: magnetic resonance lymphangiography

• MRN: medical record number

• mRNA: messenger ribonucleic acid

• MRONJ: medication-related osteonecrosis of the jaw 

• MRP: magnetic resonance perfusion

• MRPA: magnetic resonance pulmonary angiography

• MRPI: magnetic resonance parkinsonism index

• mRS: modified Rankin scale

• MRS

  • magnetic resonance spectroscopy

  • Melkersson-Rosenthal syndrome

• MRSA: methicillin-resistant Staphylococcus aureus

• MRV: magnetic resonance venogram

• MS

  • master of surgery

  • mitral stenosis

  • multiple sclerosis

• MSA

  • multiple system atrophy

  • muscle specific actin

• MSBD: mixed sclerosing bone dysplasia

• MSD: mean sac diameter

• MSE: mental status exam

• MSG: microcephaly with a simplified gyral pattern

• MSH: melanocyte-stimulating hormone

• MSK

  • medullary sponge kidney

  • musculoskeletal

• MSM: men who have sex with men

• MSSA: methicillin-susceptible/sensitive Staphylococcus aureus

• MSSU: midstream sample of urine

• MSU

  • midstream urine

  • monosodium urate

• MSUD: maple syrup urine disease

• mSv: millisievert

• MT: metatarsal

• MTA score: medial temporal lobe atrophy score

• MTC: medullary thyroid carcinoma

• MTOP: medical termination of pregnancy

• MTPJ: metatarsophalangeal joint

• MTS: mesial temporal sclerosis

• MTSS: medial tibial stress syndrome

• MTT: mean transit time

• MTX: methotrexate

• MUA: manipulation under anesthesia

• Multips: multipara

• MV: mitral valve

• MVA

  • manual vacuum aspiration

  • motor vehicle accident

• MVC: motor vehicle crash (or collision)

• MVE: Murray Valley encephalitis

• MVO: microvascular obstruction

• MVP: mitral valve prolapse

• MVR: mitral valve replacement

• MVV: maximal voluntary ventilation

• MWA: microwave ablation

• Mx

  • management

  • maxwell (CGS unit of magnetic flux)

  • metastases cannot be assessed (TNM)

• MZ

  • mid zone

  • monozygote