Enumerated medical terminologies usually contain 100,000 different phrases. These are usually grouped into chapters. For example, the following are the top level chapters of ICD-9-CM:
D Diseases
Di INFECTIOUS AND PARASITIC DISEASES
Dii NEOPLASMS
Diii ENDOCRINE, NUTRITIONAL AND METABOLIC DISEASES AND IMMUNITY DISORDERS
Div DISEASES OF BLOOD AND BLOOD-FORMING ORGANS
Dix DISEASES OF THE DIGESTIVE SYSTEM
Dv MENTAL DISORDERS
Dvi DISEASES OF THE NERVOUS SYSTEM AND SENSE ORGANS
Dvii DISEASES OF THE CIRCULATORY SYSTEM
Dviii DISEASES OF THE RESPIRATORY SYSTEM Dx DISEASES OF THE GENITOURINARY SYSTEM Dxi COMPLICATIONS OF PREGNANCY, CHILDBIRTH AND THE PUERPERIUM
Dxii DISEASES OF THE SKIN AND SUBCUTANEOUS TISSUE
Dxiii DISEASES OF THE MUSCULOSKELETAL SYSTEM AND CONNECTIVE TISSUE
Dxiv CONGENITAL ABNORMALITIES
Dxv CERTAIN CONDITIONS ORIGINATING IN THE PERINATAL PERIOD
Dxvi SYMPTOMS, SIGNS AND ILL-DEFINED CONDITIONS
Dxvii INJURY AND POISONING
E Supplementary classification of external causes of injury
and poisoning
O Procedures
Within each chapter, the terms are typically then grouped further into a hierarchy. The example below shows all terms relating to diseases of the thyroid gland, also taken from ICD-9-CM.
Diii ENDOCRINE, NUTRITIONAL AND METABOLIC DISEASES AND IMMUNITY DISORDERS
D24 Disorders of thyroid gland
D240 SIMPLE AND UNSPECIFIED GOITER
D240.0 GOITER, SPECIFIED AS SIMPLE
D240.9 GOITER, UNSPECIFIED
D241 NONTOXIC NODULAR GOITER
D241.0 NONTOXIC UNINODULAR GOITER
D241.1 NONTOXIC MULTINODULAR GOITER
D241.9 UNSPECIFIED NONTOXIC NODULAR GOITER
D242 THYROTOXICOSIS WITH OR WITHOUT GOITER
D242.0 TOXIC DIFFUSE GOITER
D242.00 TOXIC DIFFUSE GOITER WITHOUT MENTION OF THYROTOXIC CRISIS OR STORM
D242.01 TOXIC DIFFUSE GOITER WITH MENTION OF THYROTOXIC CRISIS OR STORM
D242.1 TOXIC UNINODULAR GOITER
D242.10 TOXIC UNINODULAR GOITER WITHOUT MENTION OF THYROTOXIC CRISIS OR STORM
D242.11 TOXIC UNINODULAR GOITER WITH MENTION OF THYROTOXIC CRISIS OR STORM
D242.2 TOXIC MULTINODULAR GOITER
D242.20 TOXIC MULTINODULAR GOITER WITHOUT MENTION OF THYROTOXIC CRISIS OR STORM
D242.21 TOXIC MULTINODULAR GOITER WITH MENTION OF THYROTOXIC CRISIS OR STORM
D242.3 TOXIC NODULAR GOITER, UNSPECIFIED TYPE
D242.30 TOXIC NODULAR GOITER, UNSPECIFIED TYPE, WITHOUT MENTION OF THYROTOXIC CRISIS OR STORM
D242.31 TOXIC NODULAR GOITER, UNSPECIFIED TYPE, WITH MENTION OF THYROTOXIC CRISIS OR STORM
D242.4 THYROTOXICOSIS FROM ECTOPIC THYROID NODULE
D242.40 THYROTOXICOSIS FROM ECTOPIC THYROID NODULE WITHOUT MENTION OF THYROTOXIC CRISIS OR STORM
D242.41 THYROTOXICOSIS FROM ECTOPIC THYROID NODULE WITH MENTION OF THYROTOXIC CRISIS OR STORM
D242.8 THYROTOXICOSIS OF OTHER SPECIFIED ORIGIN
D242.80 THYROTOXICOSIS OF OTHER SPECIFIED ORIGIN WITHOUT MENTION OF THYROTOXIC CRISIS OR STORM
D242.81 THYROTOXICOSIS OF OTHER SPECIFIED ORIGIN WITH MENTION OF THYROTOXIC CRISIS OR STORM
D242.9 THYROTOXICOSIS WITHOUT MENTION OF GOITER OR OTHER CAUSE
D242.90 THYROTOXICOSIS WITHOUT MENTION OF GOITER OR OTHER CAUSE, AND WITHOUT MENTION OF THYROTOXIC CRISIS OR STORM
D242.91 THYROTOXICOSIS WITHOUT MENTION OF GOITER OR OTHER CAUSE, WITH MENTION OF THYROTOXIC CRISIS OR STORM
D243 CONGENITAL HYPOTHYROIDISM
D244 ACQUIRED HYPOTHYROIDISM
D244.0 POSTSURGICAL HYPOTHYROIDISM
D244.1 OTHER POSTABLATIVE HYPOTHYROIDISM
D244.2 IODINE HYPOTHYROIDISM
D244.3 OTHER IATROGENIC HYPOTHYROIDISM
D244.8 OTHER SPECIFIED ACQUIRED HYPOTHYROIDISM
D244.9 UNSPECIFIED ACQUIRED HYPOTHYROIDISM
D245 THYROIDITIS
D245.0 ACUTE THYROIDITIS
D245.1 SUBACUTE THYROIDITIS
D245.2 CHRONIC LYMPHOCYTIC THYROIDITIS
D245.3 CHRONIC FIBROUS THYROIDITIS
D245.4 IATROGENIC THYROIDITIS
D245.8 OTHER AND UNSPECIFIED CHRONIC THYROIDITIS
D245.9 THYROIDITIS, UNSPECIFIED
D246 OTHER DISORDERS OF THYROID
D246.0 DISORDERS OF THYROCALCITONIN SECRETION
D246.1 DYSHORMONOGENIC GOITER
D246.2 CYST OF THYROID
D246.3 HEMORRHAGE AND INFARCTION OF THYROID
D246.8 OTHER SPECIFIED DISORDERS OF THYROID
D246.9 UNSPECIFIED DISORDER OF THYROID