The MAC medical abbreviation carries more than one meaning, and which is most common depends on where you read it: in surgery and anesthesia it means monitored anesthesia care, in infectious disease it means Mycobacterium avium complex, and on a heart ultrasound report it means mitral annular calcification. A few less frequent meanings show up in pharmacology and nutrition as well.
Most patients meet MAC on a consent form or a procedure note before a colonoscopy, cataract operation or similar procedure. The setting, the specialty and the words around MAC almost always point to one meaning, and whoever wrote the entry can clear up any doubt. For other surgery shorthand, see the surgical abbreviations guide.
At a glance
Stands for
Monitored anesthesia care (surgery and procedures)Other meanings
Mycobacterium avium complex; mitral annular calcification; minimum alveolar concentrationPlural or forms
MACs, MAC case, MAC sedationWhere you see it
Anesthesia records, consent forms, culture results, echo reportsDo not confuse with
General anesthesia, written GA or GETA; MCASpecialty
Anesthesiology, pulmonology, infectious disease, cardiology
MAC medical abbreviation in surgery and anesthesia
Monitored anesthesia care is a type of anesthesia service in which an anesthesia professional watches breathing, heart rate, blood pressure and oxygen levels throughout a procedure and gives sedating and pain relieving medicines as needed. The depth can range from light relaxation to deep sedation, and the anesthesia team can convert to general anesthesia if the situation calls for it.
MAC is often paired with local anesthetic injected by the surgeon. It is common for endoscopy, cataract surgery, some hand and foot operations and many cardiology and radiology procedures. Patients usually breathe on their own without a breathing tube, which is the main practical difference from general anesthesia.
Reading MAC on an anesthesia record
Anesthesia plan: "MAC with propofol infusion, ASA class II, NPO since midnight, consent obtained." This says the plan is monitored anesthesia care using propofol, a short acting sedative given by IV. ASA class II is a health rating for someone with a mild, well controlled illness, and NPO means nothing by mouth.
A post procedure note may read Procedure completed under MAC, tolerated well, to PACU. PACU is the recovery room. The plural MACs appears in scheduling talk, as in two MACs in room 4, meaning two cases planned with monitored anesthesia care.
MAC as an infection: Mycobacterium avium complex
In lung clinics and infectious disease notes, MAC means Mycobacterium avium complex, a group of related bacteria found in soil and water. They belong to the nontuberculous mycobacteria, meaning they are cousins of the germ that causes tuberculosis but behave differently and do not spread from person to person in the usual way.
MAC lung disease tends to affect people with existing lung conditions such as bronchiectasis or COPD, and some older adults without known lung disease. In people with very weak immune systems, MAC can spread through the body. A culture result reading sputum AFB culture positive, MAC tells you which organism grew. Treatment uses several antibiotics for many months and is guided by a specialist.
MAC on a heart report: mitral annular calcification
On an echocardiogram or chest CT report, MAC usually means mitral annular calcification, a buildup of calcium in the ring of tissue that supports the mitral valve. It is common with aging and is often found by chance. A report may call the amount mild, moderate or severe.
Mild MAC often needs no specific treatment, but heavier calcium can affect how the valve opens or closes. A cardiologist interprets it alongside the rest of the study.
Telling the meanings apart
| Meaning | Setting | Typical clue |
|---|---|---|
| Monitored anesthesia care | Operating room, endoscopy, procedure units | Sedation drugs, ASA class, consent, PACU |
| Mycobacterium avium complex | Pulmonology, infectious disease, HIV care | Sputum culture, AFB, bronchiectasis, antibiotics |
| Mitral annular calcification | Cardiology, echo and CT reports | Mitral valve, grading, calcium |
| Minimum alveolar concentration | Anesthesia pharmacology | Inhaled anesthetic gas strength |
| Midarm circumference | Nutrition assessment | Measured in centimeters on the upper arm |
In pharmacy billing, MAC can also mean maximum allowable cost, a reimbursement term rather than a clinical one.
Questions to ask before a procedure under MAC
If your procedure paperwork lists MAC, these questions can help you prepare.
- How deeply will I be sedated, and might I remember parts of the procedure?
- When should I stop eating and drinking beforehand?
- Which of my usual medicines should I take that morning?
- Will I need someone to drive me home?
Condition shorthand from many specialties is gathered on the diagnosis abbreviations page.
This page offers general explanations of a multi meaning abbreviation. The anesthesia team, surgeon or specialist named in your record can confirm which sense of MAC applies in your case.
Frequently asked questions
What does MAC mean in surgery?
In surgery and procedures, MAC means monitored anesthesia care. An anesthesia professional gives sedation and watches vital signs closely, and the patient usually breathes without a breathing tube.
Is MAC anesthesia the same as being put to sleep?
Not exactly. MAC ranges from light to deep sedation, while general anesthesia makes a person fully unconscious, often with a breathing tube. During MAC some people drift in and out, and others remember little afterward.
What does MAC mean on a sputum culture?
On a culture, MAC means Mycobacterium avium complex, a group of bacteria related to the tuberculosis germ. A positive result is reviewed by a specialist, who decides whether it represents active infection.
What does MAC mean on an echo report?
On a heart ultrasound, MAC usually means mitral annular calcification, calcium in the ring around the mitral valve. It is common with age and its importance depends on how much is present.
What does the MACs medical abbreviation mean?
MACs is the plural, most often used for several procedures done under monitored anesthesia care. In a lab or clinic setting it may instead refer to more than one Mycobacterium avium complex isolate.