CurrentApr 1, 2026 – Sep 30, 2026
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Disease index · O

Disease index · Modifiers and references

OHS(obesity hypoventilation syndrome)Obermeyer's relapsing fever(European)ObesityObliqueObliterationObservation(following) (for) (without need for further medical care)Obsession, obsessional stateObsessive-compulsive neurosis or reactionObstetric embolism, septicObstetrical trauma(complicating delivery)ObstipationObstruction, obstructed, obstructiveObturatorOcclusal wear, teethOcclusio pupillaeOcclusion, occludedOccultOccupationalOchlophobiaOchronosis(endogenous)Ocular muscleOculogyric crisis or disturbanceOculomotor syndromeOculopathyOddi's sphincter spasmOdontalgiaOdontoameloblastomaOdontoclasiaOdontodysplasia, regionalOdontogenesis imperfectaOdontoma(ameloblastic) (complex) (compound) (fibroameloblastic)Odontomyelitis(closed) (open)OdontorrhagiaOdontosarcoma, ameloblasticOestriasisOguchi's diseaseOhara's diseaseOidiomycosisOidium albicans infectionOld age(without mention of debility)Old(previous) myocardial infarctionOlfactoryOligemiaOligoastrocytomaOligocythemiaOligodendroblastomaOligodendrogliomaOligodontiaOligoencephalonOligohidrosisOligohydramniosOligohydrosisOligomenorrheaOligophreniaOligospermiaOligotrichiaOliguriaOllier's diseaseOmentitisOmentoceleOmentum, omentalOmphalitis(congenital) (newborn)OmphaloceleOmphalomesenteric duct, persistentOmphalorrhagia, newbornOmsk hemorrhagic feverOnanism(excessive)Onchocerciasis, onchocercosisOncocytomaOncovirus, as cause of disease classified elsewhereOndine's curseOneirophreniaOnychauxisOnychiaOnychitisOnycho-osteodysplasiaOnychocryptosisOnychodystrophyOnychogryphosis, onychogryposisOnycholysisOnychomadesisOnychomalaciaOnychomycosis(finger) (toe)OnychophagiaOnychophosisOnychoptosisOnychorrhexisOnychoschiziaOnyxis(finger) (toe)OnyxitisOophoritis(cystic) (infectional) (interstitial)OophoroceleOpacity, opacitiesOpalescent dentin(hereditary)Open, openingOperational fatigueOperativeOperculitisOperculumOphiasisOphthalmiaOphthalmitisOphthalmocele(congenital)OphthalmoneuromyelitisOphthalmopathy, Graves'OphthalmoplegiaOpioid(s)OpisthognathismOpisthorchiasis(felineus) (viverrini)Opitz' diseaseOpiumismOppenheim's diseaseOppenheim-Urbach disease(necrobiosis lipoidica diabeticorum)Opportunistic salpingectomyOptic nerveOrbitOrbitopathy(Graves') (thyroid)OrchioblastomaOrchitis(gangrenous) (nonspecific) (septic) (suppurative)Orf(virus disease)OrganicOrgasmOrientalOrificeOrigin of both great vessels from right ventricleOrmond's disease(with ureteral obstruction)Ornithine metabolism disorderOrnithinemia(Type I) (Type II)OrnithosisOrotaciduria, oroticaciduria(congenital) (hereditary) (pyrimidine deficiency)OrthodonticsOrthopneaOrthopoxvirusOs, uterusOsgood-Schlatter disease or osteochondrosisOsler's nodesOsler(-Weber)-Rendu diseaseOsmidrosisOsseousOssificationOsteitisOsteo-onycho-arthro-dysplasiaOsteo-onychodysplasia, hereditaryOsteoarthritisOsteoarthropathy(hypertrophic)Osteoarthrosis(degenerative) (hypertrophic) (joint)OsteoblastomaOsteochondritisOsteochondroarthrosis deformans endemicaOsteochondrodysplasiaOsteochondrodystrophyOsteochondrolysisOsteochondromaOsteochondromatosisOsteochondromyxosarcomaOsteochondropathyOsteochondrosarcomaOsteochondrosisOsteoclastomaOsteodyniaOsteodystrophyOsteofibromaOsteofibrosarcomaOsteogenesis imperfectaOsteogenicOsteolysisOsteomaOsteomalaciaOsteomyelitis(general) (infective) (localized) (neonatal) (purulent) (septic) (staphylococcal) (streptococcal) (suppurative) (with periostitis)OsteomyelofibrosisOsteomyelosclerosisOsteonecrosisOsteopathia condensans disseminataOsteopathyOsteopeniaOsteoperiostitisOsteopetrosis(familial)OsteophyteOsteopoikilosisOsteoporosis(female) (male)Osteopsathyrosis(idiopathica)Osteoradionecrosis, jaw(acute) (chronic) (lower) (suppurative) (upper)Osteosarcoma(any form)OsteosclerosisOsteosclerotic anemiaOsteosisOstiumOstrum-Furst syndromeOtalgiaOtitis(acute)OtocephalyOtolith syndromeOtomycosis(diffuse) NECOtoporosisOtorrhagia(nontraumatic)OtorrheaOtosclerosis(general)OtospongiosisOtto's disease or pelvisOutcome of delivery