# Logical Model

## Introduction <a href="#id-5.1logicalmodel-introduction" id="id-5.1logicalmodel-introduction"></a>

This part represents the key entities and relationships within a laboratory order entry system specifically designed to support the integration of the **LOINC Extension** with **SNOMED CT**. The model focuses on standardizing and structuring laboratory data for test ordering, specimen management, and result reporting. While not exhaustive or fully detailed for implementation, it highlights critical components necessary to ensure interoperability and consistency in healthcare systems.

By focusing on test identification, specimen management, and result reporting, the model helps support the use of **LOINC** for laboratory test coding and **SNOMED CT** for representing clinical concepts such as specimens and test outcomes. This approach promotes efficient data exchange and interoperability in healthcare settings.

## Diagram <a href="#id-5.1logicalmodel-diagram" id="id-5.1logicalmodel-diagram"></a>

The diagram illustrates the relationships between the three main entities in the model: **Laboratory Order**, **Specimen**, and **Result**. Each entity is represented as a rectangular block, with its attributes listed inside. Arrows and cardinalities between the entities indicate how they relate to one another, providing a clear visual of the logical structure of the system.

Key relationships include:

* A **Laboratory Order** can result in one or more **Results**.
* A **Result** must be associated with a single **Specimen**.
* A **Specimen** is optionally linked to a **Laboratory Order**, offering flexibility in how samples are managed.

<figure><img src="/files/B5Syvywiumy9VxYo7BEk" alt=""><figcaption></figcaption></figure>

## Entities <a href="#id-5.1logicalmodel-entities" id="id-5.1logicalmodel-entities"></a>

* **Laboratory Order**:
  * Represents the details of a requested laboratory test.
  * Acts as the starting point for test processing and result generation.
* **Specimen**:
  * Refers to the physical sample collected for testing.
  * Plays a central role in linking the laboratory order with test results.
* **Result**:
  * Captures the outcomes of the requested laboratory test, including measured values and clinical interpretations.

## Attributes <a href="#id-5.1logicalmodel-attributes" id="id-5.1logicalmodel-attributes"></a>

* **Laboratory Order Attributes**:
  * ***code***: The identifier for the laboratory test being ordered
  * ***priority***: Indicates the urgency of the test request
  * ***status***: Reflects the current state of the order (e.g., pending, completed)
  * ***specimen***: Links the order to the specimen being tested
* **Specimen Attributes**:
  * ***code***: Identifies the type of specimen (e.g., blood, urine)
  * ***method***: Optionally specifies how the specimen was collected
* **Result Attributes**:
  * ***code***: Identifies the test linked to the result
  * ***specimen***: References the specimen used for the test
  * ***value***: The measured value or observation from the test
  * ***units***: Specifies the units of the test result value
  * ***interpretation***: Qualitative assessment of the result (e.g., normal, high)
  * ***reference range***: Indicates the expected range for the result value

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