FHIR Resources Explained: Patient, Observation, Encounter & More
Quick Summary:
FHIR Resources are the fundamental data building blocks of the HL7 FHIR standard. Each resource represents a specific healthcare concept — like a patient, medication, lab result, allergy, or clinical encounter — and is structured in a predictable, machine-readable format that supports fast, secure data exchange across healthcare systems.
What Are FHIR Resources?
FHIR defines healthcare data not as big documents, but as modular components called resources.
Each resource:
- Represents a real-world clinical or administrative entity
- Has a defined structure (fields, codes, references)
- Can stand alone or link to other resources
- Is easy for systems to exchange using web APIs (REST, JSON, XML)
Examples of common resources:
- Patient – demographic and identifiers
- Observation – vitals, labs, measurements
- Encounter – visit or admission
- Medication – prescribed drugs
- AllergyIntolerance – allergies and reactions
- CarePlan – plan of care
These resources make FHIR flexible, scalable, and interoperable.
Why FHIR Uses Resources (Not Monolithic Documents)
Traditional standards (HL7 v2, CDA) send large message blocks.
FHIR breaks information into small, atomized units.
This allows:
Easier data exchange
Systems can fetch only what they need (e.g., GET /Observation/123).
Better interoperability
Resources follow consistent structure + coding.
Improved analytics
Improved analytics
Improved analytics
Developers use familiar web patterns (URLs, JSON, HTTP verbs).
How FHIR Resources Are Structured
A typical resource contains:
| Component | Purpose |
|---|---|
| Metadata | Resource ID, versionId, lastUpdated |
| Narrative (text summary) | Human-readable clinical summary |
| Data elements | Fields unique to each resource (e.g., DOB for Patient) |
| Extensions | Site-specific custom fields |
| References | Links to other resources (e.g., Observation → Patient) |
Most Common FHIR Resource Types (With Examples)
1. Patient
Used for demographic information.
Examples: patient ID, name, contact, gender, DOB.
2. Observation
One of the most used resources.
Represents:
- Vitals (BP, pulse, temp)
- Lab results (cholesterol, CBC)
- Measurements (height, weight)
3. Encounter
Represents any interaction between patient & provider:
- OPD visit
- Emergency visit
- Teleconsultation
- Admission / discharge
4. Condition
Represents medical problems or diagnoses:
- Hypertension
- Diabetes
- Infection
- Injury
5. Medication & Medication Request
Used for drug details + prescriptions.
Includes: dosage, timing, frequency, route.
6. Procedure
Represents diagnostic or therapeutic procedures:
- Surgery
- Lab test performed
- Physiotherapy
- Imaging scan
7. Care Plan
Represents care pathway with:
- Goals
- Activities
- Planned steps
Useful for chronic disease management.
8. Practitioner
Represents clinicians: doctors, nurses, therapists.
How FHIR Resources Communicate With Each Other
FHIR uses “references” to link resources.
Example workflow:
- Patient →
- has an Encounter →
- Encounter records Observations →
- Observations support a Condition →
- Condition leads to MedicationRequest →
- Medication references Medication resource
This creates a clinical story through structured data.
Resource Formats: JSON & XML
FHIR primarily uses:
- JSON (most common, lightweight)
- XML (legacy support)
Both formats follow consistent structures, so different systems can interpret data correctly.
Profiles & Extensions (Local Customization)
FHIR allows standards to be adapted through:
1. Profiles
Rules that constrain resources for specific use-cases.
Examples:
- US Core Profiles
- NHS Digital Profiles
- mHealth Profiles
2. Extensions
Add fields when something isn’t in the base resource.
Example: “patient’s occupation” or “fall risk score.”
This balance of standardization + flexibility is why FHIR works globally.
FHIR Resources for Interoperability
Resources power interoperability through:
- Standard fields
- Standard codes (SNOMED CT, LOINC, ICD-10)
- Predictable API patterns
- References between resources
- Support for real-time data retrieval
This enables cross-system collaboration: EHR → Lab → Pharmacy → Payer → App.
Frequently Asked Questions
A FHIR resource is a standardized, structured data unit that represents a specific healthcare concept like a patient, diagnosis, medication, or lab result.
FHIR has 150+ resources across clinical, administrative, financial, and infrastructure categories, with the exact number depending on the FHIR version (R4 vs R5).
A resource is the base standard model.
A profile is a customized version of a resource tailored for a specific country, workflow, or organization.
Conclusion
FHIR Resources are the backbone of modern healthcare interoperability. They create a unified, modular language for representing clinical and administrative data — enabling faster integrations, better analytics, and seamless information exchange across EHRs, apps and provider networks.
Understanding resources is the first step toward implementing FHIR-based workflows, APIs and advanced healthcare applications.
Related Resources:
FHIR Basics | FHIR Resources | FHIR API and Security | FHIR Security Best Practices | FHIR Interoperability | FHIR vs HL7 | FHIR Integration | FHIR workflow automation | FHIR For SDOH | FHIR Implementation Cost and Guide
More About SocialRoots.ai Healthcare Suite:
Pillar Community Healthcare Management system
About SocialRoots.ai Interoperability Solutions;
Legacy EHR Migration – Guaranteed 90 Days shift