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SNOMED CT
SNOMED CT view
Viewing top-level concepts
The SNOMED CT view organizes concepts into a tree by their IS A relationships. The default setting shows only the top-level concepts of the SNOMED CT terminology.
SNOMED CT view, default setting displaying only top-level concepts
Browsing down the hierarchy
You can
expand and collapse the hierarchy by clicking the triangle to the left of the concept. Expanding a node reveals the children of a concept allowing you to browse down the hierarchy. As you continue to expand the children of a concept, you'll eventually reach the end of the line--a concept that doesn't have any more children. These concepts don't have an expand triangle.
SNOMED CT View, expanded hierarchy
SNOMED CT hierarchical navigator have been designed to show detailed information on concepts. Visualization of the concept tree via the
stated or the
inferred isA relationships can be toggled using the Authoring button in the application toolbar. Fully defined concepts can be highlighted (bold) in the tree by pressing the lightbulb toolbar button. Concept tooltips in the navigator display detailed information, including the Fully specified name, the concept ID and the module. The number of descendants is also displayed (if any).
New tooltips on the concept navigator display more detailed info
Viewing a sub-hierarchy
If you want to omit irrelevant high-level concepts or sibling concepts, you can
set the concept as a root. Either by using the corresponding toolbar button
or by right-clicking the concept and selecting
Set as root concept. To
display the full terminology again, use the “return to root concept” toolbar button
.
Setting concept as a root
The
Collapse all nodes button
closes the low level nodes in the view. If set a concept as a root, all nodes within the sub-hierarchy are collapsed and only the root concept and its children are displayed (see screenshot). If you expanded nodes in the full terminology, the view will reset to the default state displaying only the top-level concepts.
Collapse all nodes
Linking view to editor
You can connect or disconnect the SNOMED CT editor to the SNOMED CT view. If the link button
is activated a concept that is selected in the editor, is also displayed in the tree of the SNOMED CT view allowing you to see where it’s located in the hierarchy. Double-click a concept to
open the SNOMED CT editor, which shows detailed information about the concept and allows editing.
Linking SNOMED CT view to editor
The most frequent actions for navigation and editing are available in the context menu of the SNOMED CT view; you can invoke it by right-clicking on a concept in the view.
SNOMED CT Concepts view context menu
-
Add new child concept:
Creates a child of the selected concept with identical SNOMED CT descriptions.
-
Add new sibling concept:
Creates a copy of the selected concept that is placed in the same hierarchical level.
-
Set concept as root:
Displays sub-hierarchy with the selected concept as the root.
-
Add concept to the expression editor: This action is only enabled when an ESCG editor is active; see the section on
ESCG queries for further details.
-
Add concept to the active reference set: This action is only enabled when a reference set editor is active. For more information see the section on
reference sets.
-
Add concept and descendants to the active reference set: This action is only enabled when a reference set editor is active.
-
Inactivate concept: Before
inactivating a concept, the affected components are displayed for review.
-
Inactivate concept and descendants: Inactivates concept and all of its children.
-
Delete concept: Before
deleting a concept the affected components are displayed for review. Published components can not be deleted, only inactivated.
-
Add bookmark:
Bookmarked concepts can be retrieved from the bookmarks view; they are indicated by a small bookmark decorator.
-
Validate concept: Verifies that the concept conforms with the rules specified in the concept model; see the
validation section for details.
-
Validate concept and descendants: Validates the selected concept and all of its children.
Snow Owl can be set to operate in authoring and browsing mode. A toggle button enables the switching between authoring (stated) and browsing (inferred) views. The selected view is applicable universally throughout the application.
Authoring mode: Authoring is permitted when the lock is unlocked
Browsing mode: Authoring is not permitted when the lock is locked
In the SNOMED CT navigator, the stated view displays the tree based on the manually authored stated relationships. The inferred view displays all hierarchical relationships that were calculated by the classifier, meaning that concepts may appear under more specific parents in the hierarchy. By toggling this button the user can review the the outcome of the classification process and its impact on the parent-child relationships.
Icons as visual cues
Top-level concepts and dedicated icons
To facilitate working with SNOMED CT each top-level concept has its own
dedicated icon which is also used for its children (e.g. a heart icon
for clinical findings). This way, you can distinguish the different top-level hierarchies from each other, no matter where you are working within the hierarchy or what function of Snow Owl you are using.
These are the icons that are used in Snow Owl to identify top-level concepts and a bit of information about their content:
-
SNOMED CT concept: This is the SNOMED CT root concept.
-
Body structure: Normal (e.g.
Entire femur) or abnormal (e.g.
Vascular polyp) body structures. Anatomically abnormal body structures are found in the
Morphologically altered structure sub-hierarchy.
-
Clinical finding: Outcomes of clinical observation, assessment, or judgment, as well as normal and abnormal (e.g.
Pulse fast) states. Clinical states that are necessarily abnormal (e.g.
Acute allergic reaction) are found in the
Disease sub-hierarchy.
-
Environment or geographical location: Refers to different types of environments (e.g.
Intensive care unit,
Toxic environment,
Cold zone) and locations such as countries, states, and regions (e.g.
Burundi,
Arizona,
Island in the region of North America).
-
Event: Occurrences (e.g.
Accident,
Exposure to carbon dioxide,
Air travel,
Environmental event). Procedures and interventions are excluded from this category.
-
Observable entity: Entities that can be measured or observed (e.g.
Age at first symptom,
Blood pressure,
Body temperature).
-
Organism: Organisms that are relevant in human and veterinary medicine such as animals (e.g.
Canis lupus familiaris), plants (e.g.
Amaryllis), life-cycle forms (e.g.
Bacterial spore), trophic life forms (e.g.
Carnivore), chromista (e.g.
Oomycota), and microorganisms (e.g.
Fungus).
-
Pharmaceutical / biological product: Drug products (e.g.
Oral form aspirin,
Alcoholic disinfectant,
Lavender oil). This hierarchy has to be distinguished from the substance hierarchy, in which the chemical constituents used in pharmaceutical products are represented.
-
Physical force: Different kinds of physical influences that are connected to injury. Examples:
Detonation,
Air and water pressure,
Radiation,
Mechanical stress.
-
Physical object: Devices (e.g.
Industrial machine), materials (e.g.
Leather), instruments (e.g.
Firearm), vehicles (e.g.
Snowmobile) and other natural or man-made objects (e.g.
Hospital bed,
Silver jewelry).
-
Procedure: Activity in the healthcare sector such as administrative (e.g.
Death certification,
Formal complaint about GP), invasive (e.g.
Removal of wart), diagnostic (e.g.
Complete blood count), imaging (e.g.
Radiography of shoulder), educational procedures (e.g.
Diet education), as well as referrals (e.g.
Referral by clinical oncologist).
-
Qualifier value: Qualifier value concepts are used as values for other SNOMED CT attributes. For example, the values for specifying the laterality of an ulnar fracture (i.e.
Left,
Right) are contained here.
-
Record artifact: Documents that were created to provide information about healthcare related events or states of affairs (e.g.
Anesthesia record,
Birth certificate).
-
Situation with explicit context: Concepts in this hierarchy specify the circumstances of a procedure, a finding, or a condition. They refer to procedures and conditions in the past (e.g.
Injection given) or future (e.g.
Awaiting radiotherapy), findings that can be ruled out (e.g.
No cardiovascular symptom), or information about someone other than the patient (e.g.
Family history of alcoholism).
-
SNOMED CT Model Component: Core metadata concepts (provides structural information for international releases), foundation metadata concepts (reference sets, reference set attributes), linkage concepts (attributes, link assertions), namespace concepts, module concepts (e.g. national extensions), etc.
-
Social context: Social aspects that may influence health and treatment of a patient. Concepts refer to social status (e.g.
Lower middle class economic status), ethnic group (e.g.
Caucasian), religion (e.g.
Anglican), life style (e.g.
Eating habit), family (e.g.
Divorced parents), and occupation (e.g.
Factory worker).
-
Special concept: Inactive concepts (e.g. outdated concept) as well as some navigational concepts.
-
Specimen: Samples or specimens that were acquired for examination or analysis. Examples:
Blood sample,
Genetic sample,
Environmental swab,
Specimen from bone marrow obtained by biopsy.
-
Staging and scales: Concepts in this hierarchy refer to different instruments of testing and scaling: Assessment scales (e.g.
Stanford Binet intelligence scale), classifications (e.g.
Endometriosis classification of American Fertility Society), grading systems (e.g.
Nottingham histologic grading system), symptom ratings (e.g.
Chest pain rating) and tumor staging (e.g.
Cancer staging).
-
Substance: Substances and chemical constituents that are used for pharmaceutical and biological products, as well as body, dietary, and diagnostic substances. Examples:
Diclofenac,
Melatonin,
Urine protein,
Swimming pool water.
Flags for national extensions and modules
The module of a concept is indicated by a small decorator on the top right of the concept icon. National extensions can be identified by a small flag of the country.
For example, in Singapore concepts in both the SNOMED CT-SG module and the Singapore Drug Dictionary module show a miniature Singapore flag. A B2i flag indicates our examples module.
Singapore flag indicating the concept provenance
Parents View
The
Parents view displays the parents of a concept. The selected concept is displayed on the top and its parent or parents on the bottom. Expanding the nodes reveals the parent concept allowing you to browse up the hierarchy until you eventually reach the top-level concept and the SNOMED CT root concept. Multiple parents are displayed as nodes in the same hierarchy level (see screenshot).
Parents view displaying SNOMED CT concepts
The parents view is automatically linked to the concept navigator. Whenever you select a concept in the SNOMED CT view, its parents are displayed in the parents view. This works for all concept navigators (e.g. ATC, ICD-10).
SNOMED CT Graph Visualization view
In addition to the concept views, you can see the SNOMED CT hierarchical relationships in the Graph Visualization view. To browse down the hierarchy double-click a concept which will
expand the node. Opening a new sub-hierarchy in the same or in a higher level will
collapse the previously opened node.
You can
change the layout of the graphical view by dragging concepts into new positions.
The
color of the graph nodes indicates the concept's definition status: blue concepts are primitive, purple concepts are fully defined.
Graph Visualization view
You can switch between the SNOMED CT Model Component and the SNOMED CT Concept roots with the
Select root concept
button in the view's toolbar.