EncounterDiagnosis

Associates a clinical diagnosis with a specific healthcare encounter, capturing the role, context, and priority of the diagnosis. Essential for clinical documentation, medical coding, billing, and quality measurement.

Overview

EncounterDiagnosis links coded diagnoses to encounters with context about how each diagnosis relates to the visit. Diagnoses are ranked by priority (principal vs secondary), categorized by use (admission, discharge, billing), and timestamped for clinical timeline reconstruction. This supports accurate coding, quality metrics, and clinical decision-making.

Key Concepts

Diagnosis Use

How the diagnosis relates to the encounter:

Use	Description	When Assigned
`admission`	Diagnosis at time of admission	At admission
`discharge`	Final diagnosis at discharge	At discharge
`billing`	Diagnosis used for claims	During coding
`chief-complaint`	Primary reason for visit	At registration
`comorbidity`	Pre-existing condition	Throughout
`complication`	Problem arising during care	When identified
`pre-op`	Diagnosis for planned surgery	Pre-operative
`post-op`	Diagnosis after surgery	Post-operative

Diagnosis Ranking

The rank field indicates priority:

Rank 1 = Principal diagnosis (primary reason for visit)
Rank 2+ = Secondary diagnoses

Proper ranking is critical for:

DRG assignment and reimbursement
Quality reporting
Clinical severity assessment

Coded Conditions

The condition field uses Coding:

ICD-10 for billing and statistics
SNOMED-CT for clinical detail
ICD-11 for newer implementations

Diagnosis Timeline

The onsetDateTime field captures:

When diagnosis was identified during encounter
Supports clinical progression analysis
Distinguishes pre-existing from hospital-acquired

Attribution

The recordedBy field links to the Practitioner who documented the diagnosis.

Use Cases

Admission Diagnosis

When patient is admitted:

Document admission diagnosis with use: "admission"
Set as rank 1 if principal reason
Code using ICD-10
Timestamp when identified
Record documenting provider

Comorbidity Documentation

For pre-existing conditions:

Add each comorbidity with use: "comorbidity"
Rank as secondary (2+)
Include conditions affecting care
Important for severity adjustment

Complication Recording

When problem arises during care:

Create diagnosis with use: "complication"
Set onsetDateTime when identified
Distinguish from admission conditions
Document in clinical notes

Discharge Coding

At discharge:

Finalize diagnoses with use: "discharge"
Confirm principal diagnosis (rank 1)
Sequence secondary diagnoses
Ensure specificity for billing

Quality Reporting

For quality measures:

Query diagnoses by ICD-10 code
Filter by encounter type and timeframe
Calculate measure numerator/denominator
Track hospital-acquired conditions

Related Entities

Entity	Relationship	Description
Encounter	Belongs to	Parent encounter
Coding	Contains	Coded diagnosis (ICD-10, SNOMED-CT)
Practitioner	References	Provider who recorded the diagnosis

Enums

use

Value	Description
`admission`	Diagnosis identified at time of admission
`discharge`	Final diagnosis documented at discharge
`billing`	Diagnosis used for insurance claims and reimbursement
`chief-complaint`	Primary symptom or concern prompting the visit
`comorbidity`	Pre-existing condition that affects care
`complication`	Problem that arose during the encounter
`pre-op`	Diagnosis documented before surgical procedure
`post-op`	Diagnosis documented after surgical procedure

7 properties

Schema

Properties

Property	Type	Mode	Description	Required
encounter	Encounter	stored	Reference to the healthcare encounter during which this diagnosis was identified, confirmed, or became clinically relevant. Links the diagnosis to the specific clinical context and timeframe. Example: `"encounter-12345"`	Required
condition	Coding	stored	The coded diagnosis using standard medical classification systems such as ICD-10, ICD-11, SNOMED CT, or other recognized coding standards. Represents the clinical condition identified during the encounter. Example: `{"system":"http://hl7.org/fhir/sid/icd-10","code":"E11.9","display":"Type 2 diabetes mellitus without complications"}`	Required
use	string	stored	Categorizes how the diagnosis is being used within the context of the encounter, distinguishing between clinical, billing, and documentation purposes. Determines the role and application of the diagnosis in workflow and reporting. Values: `admission, discharge, billing, chief-complaint, comorbidity, complication, pre-op, post-op` Example: `"discharge"`	Optional
rank	number	stored	Priority ranking of the diagnosis within the encounter context, where 1 represents the principal or primary diagnosis. Lower numbers indicate higher priority, supporting proper sequencing for billing, quality reporting, and clinical documentation. Example: `1`	Optional
onsetDateTime	DateTime	stored	The date and time when the diagnosis was first identified, documented, or became clinically relevant during the encounter. Supports timeline reconstruction and clinical progression analysis. Example: `"2024-03-15T10:30:00Z"`	Optional
recordedBy	Practitioner	stored	Reference to the healthcare practitioner who documented or recorded this diagnosis during the encounter. Supports accountability and clinical workflow tracking. Example: `"practitioner-789"`	Optional
note	string	stored	Additional clinical narrative or context about the diagnosis specific to this encounter, including clinical reasoning, severity observations, or documentation notes that support the diagnosis. Example: `"Patient presented with elevated HbA1c of 8.2%, diagnosis confirmed during annual physical"`	Optional

Examples

Example 1

{
  "@type": "EncounterDiagnosis",
  "encounter": "encounter-12345",
  "condition": {
    "system": "http://hl7.org/fhir/sid/icd-10",
    "code": "J18.9",
    "display": "Pneumonia, unspecified organism"
  },
  "use": "admission",
  "rank": 1,
  "onsetDateTime": "2024-03-15T10:30:00Z",
  "recordedBy": "practitioner-101",
  "note": "Principal diagnosis - Community-acquired pneumonia confirmed by chest X-ray showing right lower lobe infiltrate"
}

Example 2

{
  "@type": "EncounterDiagnosis",
  "encounter": "encounter-12345",
  "condition": {
    "system": "http://hl7.org/fhir/sid/icd-10",
    "code": "I10",
    "display": "Essential (primary) hypertension"
  },
  "use": "comorbidity",
  "rank": 2,
  "onsetDateTime": "2024-03-15T10:30:00Z",
  "recordedBy": "practitioner-101",
  "note": "Pre-existing condition, currently managed with lisinopril 10mg daily"
}

Example 3

{
  "@type": "EncounterDiagnosis",
  "encounter": "encounter-12345",
  "condition": {
    "system": "http://hl7.org/fhir/sid/icd-10",
    "code": "E87.6",
    "display": "Hypokalemia"
  },
  "use": "complication",
  "rank": 3,
  "onsetDateTime": "2024-03-17T14:45:00Z",
  "recordedBy": "practitioner-102",
  "note": "Hospital-acquired complication - Developed on day 3 of hospitalization, likely related to diuretic therapy. Potassium level 2.9 mEq/L"
}