Browse Medical Abbreviations

O oxygen [element]; oral; other; ovulation
O&E observation and examination
O&G obstetrics and gynecology
O&P ova and parasites
O-A occipital-atlas
o.d. once daily (L. omni die)
O.D. right eye (L. oculus dexter)
o.h. every hour (L. omni hora)
o.m. every morning (L. omni mane)
o.n. every night (L. omni nocte)
O.S. left eye (L. oculus sinister)
O/E on examination
O/R oral, rectal
O2 oxygen
O2Sat Oxygen saturation (percent)
O3 Omega-3; ozone
o: objective
OA occiput anterior; osteoarthrosis; osteoarthritis
OAE oto acoustic emissions
OAG open-angle glaucoma
OAVS oculoauriculovertebral spectrum
OB obstetrics; occult blood
OB+ occult blood positive
OB-Gyn obstetrics and gynecology
OB/GYN obstetrics/gynecology
OBS organic brain syndrome; obstetrics
OBS/OBD organic brain syndrome/organic brain disorder
obsd observed
obst obstruct, obstruction
OBT over-bed table
OBUS obstetrical ultrasound
OC oral cavity; oleoresin capsicum; obstetrical conjugate; osteocalcin; oral contraceptive
occ occasional
OCD obsessive compulsive disorder
OCG oral cholecystogram
OCL orthopedic cast for limb
OCP oral contraceptive pill
OCR ossicular chain reconstruction
OCT optical coherence tomography; oxytocin challenge test
OD right eye (L. oculus dexter); overdose; Doctor of Optometry; optical density (equivalent to absorbance)
ODD oppositional defiant disorder
ODT orally disintegrating tablet
OE otitis externa
OFC occipital-frontal circumference
OFTT organic failure to thrive
OG orogastric
OGD oesophagogastroduodenoscopy
OGT oral glucose tolerance (test)
OGTT oral glucose tolerance test
OH oral hygiene
OH- hydroxyl ion
OHCA out-of-hospital cardiac arrest
OHSS ovarian hyperstimulation syndrome
OI osteogenesis imperfecta; opportunistic infection
OIC opioid-induced constipation
oint ointment
OL left eye (L. oculus laevus)
ol. oil
OLMC on-line medical control
OM otitis media; osteomalacia
OMA ocular motor apraxia
OMB operational management board
OMD organic mental disorders
OME otitis media with effusion
OMFS oral and maxillofacial surgery
OMH office for migrant health
omn. hor. every hour
omn. noct. every night
OmPC outer membrane protein complex
ONH optic nerve hypoplasia
ONJ osteonecrosis of the jaw
ONS oncology nursing society
OoA Office on Aging
OOB out of bed; out of breath
OOH out of hospital
OOR out of room
OOT out of town
OP occiput posterior; operative; outpatient
OPA outpatient appointment; oropharyngeal airway
OPCAB off-pump coronary artery bypass surgery
OPD outpatient department
OPER outpatient with extended recovery
OPG oculoplethysmography
Oph ophthalmology
OPHEP Office of Public Health Emergency Preparedness (HHS)
OPHS Office of Public Health and Science
Ophth ophthalmology; ophthalmoscope
OPMD oculopharyngeal muscular dystrophy
OPMS oropharyngeal motility study
opp opposite
OPQRST onset, provocation, quality, radiation, severity, time
OPROC outpatient procedure
opt optical; optimal
OPT outpatient
OPV oral polio vaccine
OR odds ratio; operating room
ORF open reading frame
org organization
ORIF open reduction and internal fixation
ORL otorhinolaryngology
ORM operational risk management
ORR objective response rate
ORS oral rehydration solution
Orth orthopedics
Ortho orthopedics
Os osmium [element]
OS left eye (L. oculus sinister)
os mouth; bone
OSA obstructive sleep apnea
OSAS obstructive sleep apnea syndrome
OSCE objective structured clinical examination
OSD over bed side drainage
OSHA Occupational Safety and Health Administration
OSHC Office of Science and Health Coordination
OSR open septo-rhinoplasty
osteo osteo myelitis
OT occupational therapy; occupational therapist
OTC over the counter; ornithine transcarbamylase
OTFC oral transmucosal fentanyl citrate
oto otoscope
OTR registered occupational therapist
OTW over-the-wire
OU both eyes (L. oculi unitas); each eye (L. oculi unitas); Orthodox Union (kosher food indicator)
OUD opioid use disorder
OV office visit
OXPHOS oxidative phosphorylation
OXT oxytocin
oz ounce