+ Sortable table Abbreviation Meaning o Nothing [ō—letter o with overbar] O2 oxygen OA osteoarthritis OAB Overactive bladder OAF osteoclast activating factorOB Occult blood OB OB-GYN ob-gyne obstetrics and gynecology Obl oblique OBOT Office-based Opioid Treatment OBS organic brain syndrome Occ occasional OCD obsessive-compulsive disorder OCG oral cholecystogram OCNA Orthopedic Clinics of North America OCP oral contraceptive pill OCT optical coherence tomography OD once daily (from Latin omne in die) right eye (from Latin oculus dexter) overdoseoccupational disease ODC ornithine decarboxylase OE otitis externa O/E on examination OFC orbitofrontal cortex OGTT oral glucose tolerance test OHL oral hairy leukoplakia OHS Obesity hypoventilation syndrome OHT Orthotopic heart transplantation Oint ointmentOMosteomyelitis otitis media om every morning (from Latin omni mane). Generally written in lowercase. OME otitis media with effusion (fluid in the inner ear without other symptoms)OMSOpsoclonus-myoclonus syndrome on every night (from Latin omni nocte). Generally written in lowercase. O/N overnight OOB out of bed OP outpatient department Osteoporosis O&P ova and parasitesOPATOutpatient parenteral antibiotic therapy OPD outpatient department OPPT oriented to person, place, and time OPV outpatient visit OR operating room (aka operating theatre) odds ratio ORIF open reduction internal fixation ORSA oxacillin-resistant staphylococcus aureus ORT oral rehydration therapy OS left eye (from Latin oculus sinister) orthopedic surgeryoverall survival OSA obstructive sleep apnea OSH outside hospital Osm osmolarity Osteo osteomyelitis OT occupational therapy OTC over-the-counter drug OTD out the door (discharged) OTPP oriented to time, place, and person OTTR Organ Transplant Tracking Record OU both eyes (from Latin oculi uterque) OV office visit (see ambulatory care) oz ounce
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