2-3. GENERAL CHARACTERISTICS OF THE ICD-9-CM, TABULAR LIST (VOL I)
a. Volume I, The Tabular List. This volume of the ICD-9-CM is arranged in
seventeen major sections, each covering a category of diseases (see figure 2 -1). The
first category covers diseases caused by well-defined infective agents. The subsequent
categories cover : neoplasms; endocrine; nutritional, and metabolic diseases. Most of
the remaining diseases are arranged according to their principal anatomical site. There
are special sections for mental diseases, complications of pregnancy and childbirth,
certain diseases peculiar to the perinatal period, and ill-defined conditions including
b. A decimal system of numbering has been adopted in which the detailed
categories of the classification are designated by three-digit numbers . In many
instances, the first two digits of the three-digit number designate important or summary
groups of significance. The third digit divides each group into categories which
represent specific disease entities or a classification of the disease or condition
according to some significant axis, such as anatomical site.
(1) The fourth-digit subcategories provide further specificity or additional
information about the etiology or manifestations of the disease. Also, when appropriate
and possible to include residual subcategories for "other" and "unspecified," these have
been numbered consecutively 8 and 9, respectively.
(2) Optional fifth digits are provided in certain places; for example, for the
mode of diagnosis in tuberculosis and for anatomical site in musculoskeletal disorders.
2-4. GENERAL CHARACTERISTICS OF THE ICD-9-CM, DISEASES
(ALPHABETICAL) INDEX (VOL 2)
a. Volume 2 of the ICD-9-CM is referred to as an Alphabetical Index. This index
is used in conjunction with the Tabular List of Volume 1. In coding, you should always
refer to the Tabular List and its notes to ensure that the code given by the index fits the
circumstances of a particular case.
b. The ICD-9-CM Alphabetical Index is an essential adjunct to the Tabular List; it
contains a great number of diagnostic terms which do not appear in Volume 1. The
terms included in a category of the Tabular List do not make up an exhaustive list of
terms. Rather, the terms provide examples of the content of the category. The
Alphabetical Index, on the other hand, is intended to include all diagnostic terms
currently in use.
c. Because of its exhaustive nature, the Alphabetical Index inevitably includes
many imprecise and undesirable terms. Since these terms are still occasionally
encountered on medical records, coders need an indication of their assignment in the
classification, even if this is to a rubric (title) for residual or ill-defined conditions.