Medical abbreviations that begin with the letter "a" include: A, artery; ac or a.c., before a meal; AD, advance directive; AK, above the knee; and abd, abdomen. Also included are: AAA, abdominal aortic aneurysm; AF or AFIB, atrial fibrillation; and APAP, acetaminophen.
Other common medical abbreviations or acronyms are: ACL, anterior cruciate ligament; ADHD, attention deficit hyperactivity disorder; AIDS, acquired immunodeficiency syndrome; and AODM, adult onset diabetes mellitus or type 2 diabetes. Common abbreviations vary by medical speciality. Geriatric medicine frequently uses the abbreviations for activities of daily living, ADLs, and age-related macular degeneration, AMD. Some abbreviations are redundant, such as ADE and ADR, which stand for adverse drug event and adverse drug reaction, both of which signify a patient's negative reaction to a medication.
Abbreviations reduce the amount of time a physician takes to chart a patient's presenting symptoms, diagnosis and medications, but they cause problems when doctors use similar acronyms incorrectly or misunderstand them, such as ALP, ALS and ALT, which stand for alkaline phosphatase, amyotrophic lateral sclerosis and alanine aminotransferase, or AFB and AFP, acid-fast bacillus and alpha-fetoprotein. Letter case can sometimes be the only difference between two acronyms, as with AS, aortic stenosis, and As, astigmatism.