International statistical classification of diseases and related health problems

Introduction
Volume 3 of the International Statistical Classification of Diseases and Related Health Problems is an alphabetical index to the Tabular List of Volume 1. Although the Index reflects the provisions of the Tabular List in regard to the notes varying the assignment of a diagnostic term when it is reported with other conditions, or under particular circumstances (e.g. certain conditions complicating pregnancy), it is not possible to express all such variations in the index terms. Volume 1 should therefore be regarded as the primary coding tool. The Alphabetical Index is, however, an essential adjunct to the Tabular List, since it contains a great number of diagnostic terms that do not appear in Volume 1. The two volumes must therefore be used together. The terms included in a category of the Tabular List are not exhaustive; they serve as examples of the content of the category or as indicators of its extent and limits. The Index, on the other hand, is intended to include most of the diagnostic terms currently in use. Nevertheless, reference should always be made back to the Tabular List and its notes, as well as to the guidelines provided in Volume 2, to ensure that the code given by the Index fits with the information provided by a particular record. Because of its exhaustive nature, the 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 for residual or illdefined conditions. The presence of a term in this volume, therefore, should not be taken as implying approval of its usage.