The postcoordination system allows adding more detail to the entity that is chosen. Different types of information can be added to different elements. For example, additional 'Histopathology' information could be added to most of the Neoplasm categories but it cannot be added to the categories elsewhere in the classification.
When you are on an entity in the ICD-11 Browser, the postcoordination area will only show the possible postcoordination axes that are applicable to that entity
Some categories contain information that is incomplete for the multiple purposes of ICD. In such cases the note (code also) indicates that information needs to be added for that axis.
Some of the postcoordination axes can get values from a smaller set of possible values such as Laterality whereas some axes can get values from a rather large value set such as Histopathology.
To build a code you need to click on the values that are displayed in the search results, in the hierarchy or in the shorter lists. The example below shows malignant neoplasm of breast detailed with laterality and specific anatomy. The code generated is shown at the top left area of postcoordination section.
The system allows one value per axis for most of the postcoordination axes. For example, when post-coordinating with "severity" you can't pick the value "mild" and "moderate" at the same time. However, for certain axes, the system allows providing multiple values. The axes that allow multiple values are listed below:
For these axes, you may provide more than one value. For example, when postcoordination with specific anatomy is allowed, you may select more than one site
And for some of the external causes axes, we allow multiple values only when they come from different blocks
For example, when post-coordinating Unintentional land transport traffic event injuring a pedal cyclist using the Transport event descriptor axis, we can use one value from the block "VEHICLE USER ROLE OF PERSON INJURED IN TRANSPORT RELATED EVENT" and another from the block "COUNTERPART IN LAND TRANSPORT CRASH" but we can't use two values from the same block.
When multiple values for an axis is not allowed and the user clicks on the second one, the system will replace the existing value. For example, when you are post-coordinating with severity and have already chosen mild as a value, clicking on moderate will replace the mild value with the moderate value.
In certain cases the combination built by the user may be equivalent to an existing entity in the classification. In these cases, the system will automatically use the pre-coordinated concept when it's building a code. In the example below, the user has chosen Invasive carcinoma of breast and post-coordinated it with Infiltrating duct carcinoma, NOS. However, instead of giving two codes, the system gives just one code because in the classification there is a category for this combination i.e. 2D00 Invasive ductal carcinoma of breast and therefore it is given as the code.
In certain cases the system may allow further specifiying the postcoordination values. (i.e postcoordinating the postcoordination values)