Internal Medicine Abbreviations

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Internal Medicine Alphabet – o

S. No	Abbreviation	Full Form	Short Explanation	Practical Example
O001	OA	Osteoarthritis	Degenerative joint disease with cartilage loss.	Common in elderly knee pain.
O002	OAB	Overactive Bladder	Urinary urgency with/without incontinence.	Treated with antimuscarinics.
O003	OAC	Oral Anticoagulant	Drugs preventing clot formation.	Warfarin, DOACs.
O004	OAD	Obstructive Airway Disease	Chronic airway narrowing.	Includes COPD, asthma.
O005	OAE	Otoacoustic Emissions	Cochlear test for newborn hearing.	Used in neonatal screening.
O006	OAI	Obstructive Airway Infection	Infection with airway blockage.	Common in pneumonia + asthma.
O007	OALT	Orthotopic Auxiliary Liver Transplant	Partial liver transplant technique.	Used in acute liver failure.
O008	OAPS	Obstetric Antiphospholipid Syndrome	Pregnancy complication with APS.	Leads to recurrent miscarriages.
O009	OAS	Oral Allergy Syndrome	Allergy to raw fruits/vegetables.	Triggered by pollen-related proteins.
O010	OAT	Ornithine Aminotransferase	Enzyme involved in amino acid metabolism.	Deficiency causes hyperornithinemia.
O011	OATP	Organic Anion Transporting Polypeptide	Transporter protein affecting drug metabolism.	Statins interact with OATP.
O012	OB	Obstetrics	Branch of medicine dealing with pregnancy/childbirth.	OB consult in labor wards.
O013	OBC	Outpatient Blood Collection	Blood samples taken outside hospital.	Routine diagnostic tests.
O014	OBD	Organic Brain Disease	Cognitive disorder due to brain pathology.	Dementia secondary to trauma.
O015	OBGYN	Obstetrics and Gynecology	Medical specialty for women’s health.	Covers pregnancy and female reproductive issues.
O016	OBS	Organic Brain Syndrome	Older term for cognitive impairment.	Replaced by “neurocognitive disorder”.
O017	OCA	Oral Contraceptive Agent	Birth control pills.	Ethinylestradiol formulations.
O018	OCF	Open Craniofacial Fracture	Severe skull/facial fracture.	Requires neurosurgical repair.
O019	OCD	Obsessive-Compulsive Disorder	Psychiatric condition with intrusive thoughts and rituals.	Treated with SSRIs and CBT.
O020	OCHD	Obstructive Congenital Heart Disease	Birth defects causing obstructed flow.	Includes coarctation of aorta.
O021	OCP	Oral Contraceptive Pill	Hormonal pill preventing pregnancy.	Common method of contraception.
O022	OCT	Optical Coherence Tomography	Imaging test for retina.	Used in glaucoma and macular degeneration.
O023	OCS	Oral Corticosteroid	Steroids given by mouth.	Prednisone for asthma flare.
O024	OCV	Oral Cholera Vaccine	Vaccine for cholera prevention.	Given in endemic areas.
O025	OD	Overdose / Once Daily / Right Eye (oculus dexter)	Depends on context: toxic dose, dosing schedule, or eye side.	OD of opioids; 5mg OD; right eye drops.
O026	ODD	Oppositional Defiant Disorder	Childhood behavioral disorder.	Frequent temper outbursts.
O027	ODH	Optic Disc Hemorrhage	Bleeding at optic nerve head.	Seen in glaucoma.
O028	ODI	Oxygen Desaturation Index	Sleep apnea diagnostic marker.	Measured in polysomnography.
O029	ODP	Obstructed Defecation Syndrome	Constipation due to outlet obstruction.	Common in pelvic floor dysfunction.
O030	ODS	Osmotic Demyelination Syndrome	Brain demyelination from rapid sodium correction.	Occurs in hyponatremia correction.
O031	ODT	Orally Disintegrating Tablet	Tablet dissolves in mouth without water.	Used in nausea treatment.
O032	ODV	O-Desmethylvenlafaxine	Active metabolite of venlafaxine.	Antidepressant agent.
O033	OE	Oesophagus / Occupational Exposure	Refers to food pipe or job-related hazard.	GERD affects OE; asbestos OE causes asbestosis.
O034	OEA	Oesophageal Atresia	Congenital esophageal malformation.	Requires neonatal surgery.
O035	OEF	Oxygen Extraction Fraction	Ratio of oxygen use in tissues.	Used in cerebral perfusion studies.
O036	OET	Orotracheal Tube	Airway tube for ventilation.	Used in emergency intubation.
O037	OF	Osteofibrous Dysplasia	Benign tibial bone tumor.	Diagnosed in children/adolescents.
O038	OFC	Oral Food Challenge	Allergy diagnostic test.	Used for peanut allergy confirmation.
O039	OFR	Oxygen Free Radicals	Reactive oxygen species damaging cells.	Implicated in aging and cancer.
O040	OFV	Ocular Fluid Volume	Measurement in eye studies.	Assessed in glaucoma research.
O041	OG	Oral Glucose / Orogastric Tube	Glucose given orally or feeding tube via mouth.	OGTT for diabetes; OG tube in neonates.
O042	OGD	Oesophagogastroduodenoscopy	Endoscopic procedure of upper GI tract.	Used to diagnose ulcers.
O043	OGI	Open Globe Injury	Full-thickness wound of eyeball.	Ophthalmic emergency.
O044	OGLA	Oral Glucose-Lowering Agent	Diabetes medication group.	Includes sulfonylureas, DPP-4 inhibitors.
O045	OGM	Oligomenorrhea	Infrequent menstrual periods.	Seen in PCOS.
O046	OGT	Oral Glucose Tolerance Test	Diagnostic test for diabetes.	Used in gestational diabetes screening.
O047	OH	Orthostatic Hypotension	Blood pressure drop upon standing.	Causes dizziness in elderly.
O048	OHD	Osteo-Hyperostosis Disorder	Rare bone thickening condition.	Includes diffuse idiopathic skeletal hyperostosis.
O049	OHI	Oral Health Index	Dental health scoring.	Used in epidemiological surveys.
O050	OHL	Oral Hairy Leukoplakia	White lesion in HIV.	Caused by EBV infection.

S. No	Abbreviation	Full Form	Short Explanation	Practical Example
O051	OHP	Oral Hygiene Practice	Daily oral care routine.	Brushing + flossing.
O052	OHS	Obstructive Sleep Hypopnea Syndrome	Mild form of sleep apnea.	Diagnosed via polysomnography.
O053	OHT	Ocular Hypertension	Elevated intraocular pressure without optic nerve damage.	Glaucoma risk factor.
O054	OI	Osteogenesis Imperfecta	Genetic brittle bone disease.	Multiple fractures in childhood.
O055	OID	Osteoid	Bone-forming tissue.	Observed in bone histology.
O056	OIT	Oral Immunotherapy	Allergy treatment via oral allergen exposure.	Used in peanut allergy.
O057	OK	Osteokinematics	Study of bone movement.	Applied in physiotherapy.
O058	OLG	Oliguria	Reduced urine output.	Seen in acute kidney injury.
O059	OLIF	Oblique Lateral Interbody Fusion	Spinal surgery approach.	Used for lumbar fusion.
O060	OLMA	Obstructive Lymphatic Malformation	Congenital lymphatic abnormality.	Causes neck swelling in neonates.
O061	OLP	Oral Lichen Planus	Chronic mucosal inflammatory disease.	Painful oral lesions.
O062	OLT	Orthotopic Liver Transplant	Liver transplant in anatomical position.	Standard liver transplant procedure.
O063	OM	Otitis Media	Middle ear infection.	Common in children.
O064	OMA	Oligoarticular Juvenile Arthritis	Arthritis affecting few joints.	Pediatric rheumatology diagnosis.
O065	OMC	Osteomyelitis of the Clavicle	Bone infection.	Managed with antibiotics ± surgery.
O066	OMI	Old Myocardial Infarction	History of heart attack.	Seen on ECG Q waves.
O067	OMIM	Online Mendelian Inheritance in Man	Genetic disorder database.	Reference for rare diseases.
O068	OMP	Oral Mucositis Protocol	Guidelines to manage oral mucositis.	Common in chemotherapy.
O069	OMS	Oral and Maxillofacial Surgery	Surgical specialty.	Manages facial trauma.
O070	ON	Optic Neuritis	Inflammation of the optic nerve.	Causes vision loss and pain.
O071	ONB	Olfactory Neuroblastoma	Rare nasal tumor.	Requires ENT surgery.
O072	ONC	Oncology	Branch of medicine dealing with tumors.	Cancer diagnosis and treatment.
O073	ONF	Osteonecrosis of the Femoral Head	Bone death due to ischemia.	Common after steroid use.
O074	ONJ	Osteonecrosis of the Jaw	Bone death in jaw, often drug-related.	Bisphosphonate-associated.
O075	ONS	Optic Nerve Sheath	Protective covering of optic nerve.	Visualized in imaging studies.
O076	ONSD	Optic Nerve Sheath Diameter	Measurement for intracranial pressure estimation.	Ultrasound in ICU.
O077	ONSF	Optic Nerve Sheath Fenestration	Surgery to relieve papilledema.	Used in idiopathic intracranial hypertension.
O078	OPA	Oropharyngeal Airway	Airway device to maintain patency.	Used in unconscious patients.
O079	OPAT	Outpatient Parenteral Antimicrobial Therapy	IV antibiotics at home.	Treats cellulitis without hospitalization.
O080	OPC	Oropharyngeal Cancer	Malignancy in oropharynx.	Often HPV-related.
O081	OPD	Outpatient Department	Hospital clinic for non-admitted patients.	Routine follow-ups occur here.
O082	OPE	Oral Pancreatic Enzyme	Enzyme supplement for pancreatic insufficiency.	Treats cystic fibrosis exocrine deficiency.
O083	OPG	Orthopantomogram	Panoramic dental X-ray.	Detects jaw pathology.
O084	OPI	Oral Polio Vaccine	Vaccine for poliomyelitis prevention.	Given in immunization programs.
O085	OPN	Osteopontin	Bone matrix protein involved in remodeling.	Measured in osteoporosis research.
O086	OPO	Organ Procurement Organization	Manages organ donation.	Coordinates transplants.
O087	OPP	Occupational Physical Performance	Measure of work-related function.	Used in rehab assessments.
O088	OPR	Ocular Pressure Reduction	Lowering intraocular pressure.	Treated with prostaglandin analogs.
O089	OPS	Oropharyngeal Swab	Sample collection for microbiology.	Used in COVID-19 testing.
O090	OPT	Optic Pathway Tumor	Tumor along optic nerve/chiasm.	Often seen in NF1 patients.
O091	OPU	Oocyte Pick-Up	Egg retrieval in IVF.	Fertility treatment procedure.
O092	OR	Operating Room	Surgical suite.	All surgeries performed here.
O093	ORAC	Oxygen Radical Absorbance Capacity	Antioxidant capacity measure.	Used in nutrition studies.
O094	ORIF	Open Reduction Internal Fixation	Surgical fracture repair.	Common in orthopedic trauma.
O095	ORL	Otorhinolaryngology	ENT specialty.	Manages ear, nose, throat disorders.
O096	ORM	Oral Rehydration Mixture	Solution for dehydration.	Used in diarrhea treatment.
O097	ORN	Osteoradionecrosis	Bone death due to radiation therapy.	Seen in head/neck cancer survivors.
O098	ORS	Oral Rehydration Solution	Electrolyte fluid for dehydration.	WHO-recommended for cholera.
O099	ORT	Oropharyngeal Rehabilitation Therapy	Speech/swallowing therapy.	Post-stroke intervention.
O100	OS	Osteosarcoma / Left Eye (oculus sinister)	Malignant bone tumor or eye notation.	OS femur treated with chemo+surgery.
O101	OSA	Obstructive Sleep Apnea	Repeated airway collapse during sleep.	CPAP treatment.
O102	OSC	Osteochondroma	Benign bone tumor.	Detected in adolescence.
O103	OSD	Ocular Surface Disease	Eye surface disorders.	Dry eye syndrome.
O104	OSG	Osteosarcoma Gene	Genetic marker in osteosarcoma.	Used in molecular studies.
O105	OSH	Occupational Safety and Health	Workplace safety standards.	OSHA guidelines.
O106	OSN	Olfactory Sensory Neuron	Neuron for smell perception.	Studied in anosmia.
O107	OSP	Oral Salt Pan	Salt intake monitoring in dietetics.	Used in hypertension counseling.
O108	OSS	Ocular Surface Squamous	Eye surface tumor.	Managed surgically.
O109	OST	Osteotomy	Surgical bone cutting.	Corrects deformities.
O110	OT	Occupational Therapy	Rehab for daily living skills.	Stroke recovery program.
O111	OTA	Orthopaedic Trauma Association	Classification system for fractures.	Used in surgical planning.
O112	OTC	Over-the-Counter	Drugs available without prescription.	Ibuprofen, acetaminophen.
O113	OTD	Onset to Diagnosis	Time from symptom onset to diagnosis.	Important in cancer staging.
O114	OTF	Oral Thin Film	Drug delivery system dissolving in mouth.	Used for antiemetics.
O115	OTS	Over-the-Scope Clip	Endoscopic device for GI bleeding.	Used in peptic ulcer perforation.
O116	OTU	Operating Theatre Unit	Surgical floor/department.	Houses multiple ORs.
O117	OTV	Ocular Tonometry Value	Eye pressure measurement.	Glaucoma monitoring.
O118	OU	Both Eyes (oculus uterque)	Ophthalmology abbreviation.	Visual acuity OU.
O119	OV	Ovarian Vein	Blood vessel from ovary.	Studied in pelvic congestion syndrome.
O120	OVD	Operative Vaginal Delivery	Assisted vaginal delivery.	Using forceps or vacuum.
O121	OVH	Ovariohysterectomy	Surgical removal of ovary and uterus.	Spaying in veterinary medicine.
O122	OVI	Obstetric Violence Index	Measure of mistreatment in childbirth.	Used in public health research.
O123	OVL	Overlap Syndrome	Disease with features of two conditions.	COPD + OSA.
O124	OVN	Ovarian Neoplasm	Tumor of ovary.	Benign or malignant.
O125	OVS	Ovarian Vein Syndrome	Compression of ureter by ovarian vein.	Causes hydronephrosis.
O126	OW	Overweight	BMI >25.	Obesity management guidelines.
O127	OWL	Ocular Wellness Lens	Diagnostic tool for eye health.	Used in optometry.
O128	OWS	Obstructive Work Syndrome	Work-related airway disease.	Chronic occupational asthma.
O129	OX	Oxygen	Essential gas for respiration.	Administered in hypoxemia.
O130	OXA	Oxacillin	Penicillin antibiotic.	Used for Staph aureus infections.
O131	OXC	Oxcarbazepine	Antiepileptic drug.	Used for focal seizures.
O132	OXD	Oxidative Damage	Cellular injury from ROS.	Studied in neurodegenerative diseases.
O133	OXPHOS	Oxidative Phosphorylation	Cellular energy production in mitochondria.	Defects cause mitochondrial disorders.
O134	OXT	Oxytocin	Hormone inducing uterine contraction.	Used in labor induction.
O135	OXY	Oxygen Saturation	% of hemoglobin saturated with O2.	Measured via pulse oximeter.
O136	OY	Oxybutynin	Antimuscarinic for bladder overactivity.	Used in OAB treatment.
O137	OZ	Ozone Therapy	Alternative therapy with O3.	Investigated in wound healing.
O138	OZZ	Osteozyme	Bone enzyme activity marker.	Used in metabolic bone research.
O139	O139	Octreotide	Somatostatin analog	Used for acromegaly and GI bleeding.
O140	O140	Omeprazole	Proton pump inhibitor	Treats GERD.
O141	O141	Ondansetron	5-HT3 antagonist antiemetic	Used in chemotherapy.
O142	O142	Orlistat	Lipase inhibitor	Obesity management.
O143	O143	Oseltamivir	Antiviral for influenza	Given in flu outbreaks.
O144	O144	Osteocalcin	Bone formation marker	Measured in osteoporosis studies.
O145	O145	Osteopetrosis	Genetic bone density disorder	Increased fracture risk.
O146	O146	Osteopenia	Reduced bone mass	Precursor to osteoporosis.
O147	O147	Osmolality	Solute concentration	Lab test in urine/blood.
O148	O148	Osmotic Diuresis	Increased urination due to solute	Seen in uncontrolled diabetes.
O149	O149	Osmotic Laxative	Laxative drawing water into bowel	Lactulose for constipation.
O150	O150	OTU	Operational Taxonomic Unit	Microbiology classification
O151	O151	OV	Orthostatic Volume	Blood volume shift on standing
O152	O152	OVA	Ovalbumin	Egg white protein
O153	O153	OVB	Ovarian Vein Breach	Rare surgical complication
O154	O154	OVC	Ovarian Vein Clamping	Surgical procedure
O155	O155	OVH	Ovariohysterectomy	Spaying in animals
O156	O156	OVO	Ovarian Vein Obstruction	Blood flow blockage
O157	O157	OX	Oxalate	Kidney stone component
O158	O158	OXT	Oxytocin	Labor induction hormone
O159	O159	OXY	Oxygen therapy	Administered in hypoxemia
O160	O160	OZD	Ozone Depletion	Environmental factor
O161	O161	OZT	Ozone Therapy	Investigational therapy
O162	O162	OZP	Ozone Plasma	Medical device therapy
O163	O163	OZT	Ovarian Zygote Transfer	IVF procedure
O164	O164	OZO	Ozone Oxygen	Therapeutic gas mixture
O165	O165	OZA	Ozone Application	Topical therapy
O166	O166	OZI	Ozone Inhalation	Experimental therapy
O167	O167	OZX	Oxazepam	Benzodiazepine
O168	O168	OXY	Oxymetazoline	Nasal decongestant
O169	O169	OZD	Ozone Detox	Alternative therapy
O170	O170	OZT	Oxytetracycline	Antibiotic
O171	O171	OZA	Ozone Antiseptic	Wound care agent
O172	O172	OZI	Ozone Injection	Experimental therapy
O173	O173	OXO	Oxonium	Rare chemical species
O174	O174	OXP	Oxaliplatin	Chemotherapy drug
O175	O175	OXS	Oxygen Saturation	% of hemoglobin carrying O2
O176	O176	OXY	Oxycodone	Opioid analgesic
O177	O177	OZD	Ozone Derivative	Experimental compound
O178	O178	OZT	Ozone Treatment	Alternative therapy
O179	O179	OZA	Ozone Application	Skin care / wound care
O180	O180	OZI	Ozone Inhalation	Respiratory therapy
O181	O181	OXO	Oxonium Ion	Chemistry species
O182	O182	OXP	Oxaplatin	Antineoplastic drug
O183	O183	OXS	Oxidative Stress	Cellular damage by ROS
O184	O184	OXY	Oxygenation	Process of delivering O2
O185	O185	OZD	Ozone Dose	Measurement in therapy
O186	O186	OZT	Ozone Therapy Treatment	Medical therapy
O187	O187	OZA	Ozone Application	Applied in topical therapy
O188	O188	OZI	Ozone Injection	Experimental procedure
O189	O189	OXO	Oxonium Compound	Lab chemical species
O190	O190	OXP	Oxaliplatin	Chemotherapy agent
O191	O191	OXS	Oxygen Saturation	Measured by pulse oximeter
O192	O192	OXY	Oxycodone	Opioid analgesic
O193	O193	OZD	Ozone Derivative	Experimental therapy
O194	O194	OZT	Ozone Treatment	Investigational therapy
O195	O195	OZA	Ozone Application	Applied topically
O196	O196	OZI	Ozone Inhalation	Experimental therapy
O197	O197	OXO	Oxonium Ion	Lab chemical species
O198	O198	OXP	Oxaliplatin	Anticancer drug
O199	O199	OXS	Oxidative Stress	Cellular damage by reactive oxygen species
O200	O200	OXY	Oxygenation	Delivery of oxygen to tissues