ICD-10-CM Alphabetic Index · FY 2026 Letter O
Index Terms Starting With O ICD-10-CM
The letter O section of the FY 2026 Alphabetic Index carries 248 main terms, from Obermeyer's relapsing fever to Ozena. Terms with a direct code link straight to the code page, cross references point to the main term that holds the codes, and terms with a handful of sub-entries render in full right here. The largest terms open their own full index page.
✓ Built from the official CMS FY 2026 index fileEffective Oct 1, 2025 – Sep 30, 2026
248
Main Terms
2,197
Index Entries
99
Direct Codes
60
Cross-refs
- ObliterationSub-entries
- mixed thoughts and acts F42.2
- Obstetric embolism, septicCross-ref See: Embolism, obstetric, septic
- ObstipationCross-ref See: Constipation
- Obstruction, obstructed, obstructiveSub-entries
- Occlusio pupillaeCross-ref See: Membrane, pupillary
- Occlusion, occludedSub-entries
- OccultSub-entriesblood in feces (stools) R19.5
- OccupationalSub-entriesproblems NEC Z56.89
- psychogenic F45.8
- OculopathySub-entries
- OdontoameloblastomaCross-ref See: Cyst, calcifying odontogenic
- Odontoma (ameloblastic) (complex) (compound) (fibroameloblastic)Cross-ref See: Cyst, calcifying odontogenic
- upper jaw (bone) C41.0
- OestriasisCross-ref See: Myiasis
- OidiomycosisCross-ref See: Candidiasis
- Oidium albicans infectionCross-ref See: Candidiasis
- dementia F03 Non-billable
- OligemiaCross-ref See: Anemia
- OligoastrocytomaSub-entriesspecified site see Neoplasm, malignant, by siteunspecified site C71.9
- OligodendroblastomaSub-entriesspecified site see Neoplasm, malignantunspecified site C71.9
- OligodendrogliomaSub-entriesanaplastic typespecified site see Neoplasm, malignant, by siteunspecified site C71.9specified site see Neoplasm, malignant, by site
- OligodontiaCross-ref See: Anodontia
- OligophreniaSub-entries see also Disability, intellectualphenylpyruvic E70.0
- OligotrichiaCross-ref See: Alopecia
- OmentitisCross-ref See: Peritonitis
- OmentoceleCross-ref See: Hernia, abdomen, specified site NEC
- OncocytomaCross-ref See: Neoplasm, benign, by site
- Ondine's curseCross-ref See: Apnea, sleep
- congenital Q84.5
- OnychiaSub-entries see also Cellulitis, digit
- OnychitisSub-entries see also Cellulitis, digitwith lymphangitis see Lymphangitis, acute, digit
- congenital Q84.6
- congenital Q84.6
- OnyxitisSub-entries see also Cellulitis, digitwith lymphangitis see Lymphangitis, acute, digit
- Opacity, opacitiesSub-entries
- Open, openingSub-entriesabnormal, organ or site, congenital see Imperfect, closureangle withborderlinefindings
- OperculitisCross-ref See: Periodontitis
- OperculumCross-ref See: Break, retina
- Opioid (s)Sub-entriesabuse see Abuse, drug, opioidsdependence see Dependence, drug, opioidsinduced, without use disorderanxiety disorder F11.988
- OpiumismCross-ref See: Dependence, drug, opioid
- Oppenheim-Urbach disease (necrobiosis lipoidica diabeticorum)Cross-ref See: E08-E13 with .620
- OrganicSub-entries see also condition
- OrgasmSub-entriesanejaculatory N53.13
- OrientalSub-entries
- with infection N13.6
- anemia D53.0
- OrthodonticsSub-entries
- OssificationSub-entriesartery see Arteriosclerosisauricle (ear) see Disorder, pinna, specified type NECbronchial J98.09cardiac see Degeneration, myocardial
- ankle see Osteoarthritis, primary, ankleelbow see Osteoarthritis, primary, elbowfoot joint see Osteoarthritis, primary, foothand joint see Osteoarthritis, primary, hand joint
- OsteoblastomaSub-entries see Neoplasm, bone, benignaggressive see Neoplasm, bone, uncertain behavior
- Osteochondroarthrosis deformans endemicaCross-ref See: Disease, Kaschin-Beck
- OsteochondromaCross-ref See: Neoplasm, bone, benign
- syndrome Q78.4
- OsteochondromyxosarcomaCross-ref See: Neoplasm, bone, malignant
- OsteochondrosarcomaCross-ref See: Neoplasm, bone, malignant
- malignant see Neoplasm, bone, malignant
- OsteodyniaCross-ref See: Disorder, bone, specified type NEC
- OsteofibromaCross-ref See: Neoplasm, bone, benign
- OsteofibrosarcomaCross-ref See: Neoplasm, bone, malignant
- OsteomaSub-entries see also Neoplasm, bone, benignosteoid see also Neoplasm, bone, benigngiant see Neoplasm, bone, benign
- Osteomyelitis (general) (infective) (localized) (neonatal) (purulent) (septic) (staphylococcal) (streptococcal) (suppurative) (with periostitis)Sub-entries M86.9
- due todrugs see Osteonecrosis, secondary, due to, drugstrauma see Osteonecrosis, secondary, due to, traumaidiopathic aseptic M87.00
- borderline M85.8 Non-billable
- OsteoperiostitisCross-ref See: Osteomyelitis, specified type NEC
- Osteosarcoma (any form)Cross-ref See: Neoplasm, bone, malignant
- OsteosisSub-entries
- OstiumSub-entries
- Otalgia
- with effusion see also Otitis, media, nonsuppurativepurulent see Otitis, media, suppurativeadhesivechronic see also Otitis, media, chronic
- Otolith syndrome
- OtoporosisCross-ref See: Otosclerosis
- traumatic - code by Type of injury
- OtospongiosisCross-ref See: Otosclerosis
- Ovalocytosis (congenital) (hereditary)Cross-ref See: Elliptocytosis
- Ovaritis (cystic)Cross-ref See: Oophoritis
- Ovary, ovarianSub-entries see also condition
- OveractiveSub-entries see also Hyperfunction
- child see Disorder, attention-deficit hyperactivity
- OverbreathingCross-ref See: Hyperventilation
- OverdevelopmentCross-ref See: Hypertrophy
- OverdistensionCross-ref See: Distension
- Overdose, overdosage (drug)Cross-ref See: Table of Drugs and Chemicals, by drug, poisoning
- exhaustion T73.2 Non-billable
- OverfeedingSub-entries see Overeatingnewborn P92.4
- OvergrowthSub-entries
- Overheated (places) (effects)Cross-ref See: Heat
- Overlaid, overlying (suffocation)Cross-ref See: Asphyxia, traumatic, due to mechanical threat
- Overlapping toe (acquired)Sub-entries see also Deformity, toe, specified NECcongenital (fifth toe) Q66.89
- OverloadSub-entries
- OverproductionSub-entries see also Hypersecretion
- OverridingSub-entries
- heart see Hypertrophy, cardiac
- Ovulation (cycle)Sub-entries
- Ox heartCross-ref See: Hypertrophy, cardiac
- syphilitic, congenital A50.02
Related References
Source: Centers for Medicare & Medicaid Services, FY 2026 ICD-10-CM Index to Diseases and Injuries release files, effective October 1, 2025 through September 30, 2026.
