ICD classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. http://en.wikipedia.org/wiki/ICD It sounds like these are really used for Medicare reimbursement more than anything else (even though that wasn't the intent), and not clinically accurate.
UMLS: The Metathesaurus forms the base of the UMLS and comprises over 1 million biomedical concepts and 5 million concept names, all of which stem from the over 100 incorporated controlled vocabularies and classification systems. Some examples of the incorporated controlled vocabularies are ICD-9-CM, ICD-10, Me S H, SNOMED CT, LOINC, WHO Adverse Drug Reaction Terminology, UK Clinical Terms, Rx N O R M, Gene Ontology, and OMIM. http://en.wikipedia.org/wiki/Unified_Medical_Language_System
SNOMED/Snomed Ct SNOMED CT cross maps to such other terminologies as ICD-9-CM, ICD-O3, ICD-10, Laboratory LOINC and OPCS-4. It supports ANSI, DICOM, HL7, and ISO standards. http://en.wikipedia.org/wiki/SNOMED_CT
CPT: describes medical, surgical, and diagnostic services and is designed to communicate uniform information about medical services and procedures among physicians, coders, patients, Accreditation organizations, and payers for administrative, financial, and analytical purposes http://en.wikipedia.org/wiki/Current_Procedural_Terminology
- Feb'2015 ArgoNaut status
Me S H: subject headings/keywords for indexing medical journal articles, PubMed http://en.wikipedia.org/wiki/Medical_Subject_Headings