A
aedes / artery / ascaris
A2
angiotensin 2 / aortic second sound
A2RB
angiotensin 2 receptor blocker
A & E
accident and emergency
A & O
alert and orientated
AA
alcoholics anonymous / affected area
aa
equal quantities of each ingredient
AAA
abdominal aortic aneurysm
AAD
antibiotic associated diarrhoea
AAL
anterior axillary line
AAO
alert awake oriented
AB
abortion / abnormal
Ab
antibody
ABD
abdomen
ABG
arterial blood gas
ABN
abnormal
AEB
as evidenced by
AED
automatic external defibrillator
AC
acute
ACD
advanced care directive
ac
ante cibum (before food)
ACE
angiotensin converting enzyme
ACL
anterior cruciate ligament
ACLE
acute cutaneous lupus erythematosus