Format of ICD-O in the Alphabetical Index

The alphabetical index is used to code topography (anatomical sites) and morphology (histological terms). Topography codes are identified by the letter C, the first character of codes in Chapter II ICD.

Table 1 shows the first topographic terms in the alphabetic index. Any word that appears as part of three or more terms is in bold type (such as "Abdomen," "Abdominal," and "Abdominal wall"), and the terms that include this word are indented under it.

The first lead term is "Abdomen." Since there are more than three modifying terms, Abdomen is in bold type. The "NOS" term is always listed first under a heading in the index (rather than in alphabetic order under N).

Updated: December 13, 2023