---
title: 'Observation (FHIR R4)'
description: 'Measurements and simple assertions made about a patient, device, or other subject. Used for vital signs (heart rate, tem'
nav: 'API / R4 / Observation'
order: 70
version: v1
fhir: r4
source: generated
updated: '2026-09-23'
---
# Observation (FHIR R4)
Measurements and simple assertions made about a patient, device, or other subject. Used for vital signs (heart rate, temperature, blood pressure), laboratory results, and clinical exam findings. LOINC codes are validated on write.
> This reference is generated from the canonical Huli Public API OpenAPI specification and the server's FHIR R4 CapabilityStatement — do not edit it directly.
## FHIR R4 Specification
Official spec: [Observation — HL7 FHIR R4](https://hl7.org/fhir/R4/observation.html)
## Supported Interactions
- **read** — Read a single resource by ID (`GET /fhir/R4/{Resource}/{id}`)
- **search-type** — Search resources with query parameters (`GET /fhir/R4/{Resource}?...`)
- **create** — Create a new resource (`POST /fhir/R4/{Resource}`)
- **update** — Update an existing resource (`PUT /fhir/R4/{Resource}/{id}`)
## Scopes
Scopes are shared across FHIR releases — the same `system/Observation.*` scope grants Observation access on both `/fhir/R4` and `/fhir/R5`.
- — see [scope reference](/v1/scopes#system-observation-rs)
- — see [scope reference](/v1/scopes#system-observation-cru)
## Search Parameters
| Parameter | Type | Notes |
|-----------|------|-------|
| `_id` | token | Exact match. For identifiers use `system|value` format. |
| `patient` | reference | Resource reference — supply the UUID of the referenced resource. |
| `encounter` | reference | Resource reference — supply the UUID of the referenced resource. |
| `code` | token | Exact match. For identifiers use `system|value` format. |
| `date` | date | Supports FHIR date prefixes: `eq`, `ne`, `gt`, `ge`, `lt`, `le`. Format: `[prefix]YYYY-MM-DD`. |
| `status` | token | Exact match. For identifiers use `system|value` format. |
| `category` | token | Exact match. For identifiers use `system|value` format. |
| `_count` | number | Integer. For `_count`: default 20, max 100. |
| `_cursor` | string | Case-insensitive partial match. |
## Endpoints
### Read Observation
Retrieve a single Observation resource by its ID.
**Required scope:**
#### Response — 200
```json
{
"resourceType": "Observation",
"id": "aa0e8400-e29b-41d4-a716-446655440040",
"status": "final",
"category": [
{
"coding": [
{
"system": "http://terminology.hl7.org/CodeSystem/observation-category",
"code": "vital-signs",
"display": "Vital Signs"
}
]
}
],
"code": {
"coding": [
{
"system": "http://loinc.org",
"code": "8867-4",
"display": "Heart rate"
}
]
},
"subject": {
"reference": "Patient/550e8400-e29b-41d4-a716-446655440001"
},
"encounter": {
"reference": "Encounter/990e8400-e29b-41d4-a716-446655440030"
},
"effectiveDateTime": "2026-05-20T10:15:00Z",
"valueQuantity": {
"value": 72,
"unit": "/min",
"system": "http://unitsofmeasure.org",
"code": "/min"
}
}
```
#### Code Samples
:::CodeGroup
```bash {label="cURL"}
TOKEN=$(curl -s -X POST https://api.huli.ai/auth/token \
-d "grant_type=client_credentials" \
-d "client_assertion_type=urn:ietf:params:oauth:client-assertion-type:jwt-bearer" \
-d "client_assertion=${CLIENT_ASSERTION}" \
-d "scope=system/Observation.rs" \
| jq -r .access_token)
curl -X GET https://api.huli.ai/fhir/R4/Observation/${RESOURCE_ID} \
-H "Authorization: Bearer ${TOKEN}"
```
```typescript {label="TypeScript"}
const token = process.env.HULI_ACCESS_TOKEN ?? "";
const response = await fetch(
`https://api.huli.ai/fhir/R4/Observation/${id}`,
{
method: "GET",
headers: {
"Authorization": `Bearer ${token}`,
},
}
);
if (!response.ok) throw new Error(`HTTP ${String(response.status)}`);
const data: unknown = await response.json();
```
```python {label="Python"}
import os
import requests
token = os.environ["HULI_ACCESS_TOKEN"]
headers = {"Authorization": f"Bearer {token}"}
resp = requests.get(
f"https://api.huli.ai/fhir/R4/Observation/{resource_id}",
headers=headers,
)
resp.raise_for_status()
print(resp.json())
```
```java {label="Java"}
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
public class getObservationExample {
public static void main(String[] args) throws Exception {
String token = System.getenv("HULI_ACCESS_TOKEN");
String resourceId = "RESOURCE_ID";
HttpClient client = HttpClient.newHttpClient();
HttpRequest request = HttpRequest.newBuilder()
.uri(URI.create("https://api.huli.ai/fhir/R4/Observation/" + resourceId))
.header("Authorization", "Bearer " + token)
.header("Accept", "application/fhir+json")
.method("GET", HttpRequest.BodyPublishers.noBody())
.build();
HttpResponse response =
client.send(request, HttpResponse.BodyHandlers.ofString());
System.out.println("status: " + response.statusCode());
System.out.println(response.body());
}
}
```
```go {label="Go"}
import (
"fmt"
"net/http"
"os"
)
func getObservationExample() {
token := os.Getenv("HULI_ACCESS_TOKEN")
req, _ := http.NewRequest("GET", "https://api.huli.ai/fhir/R4/Observation/"+resourceID+"", nil)
req.Header.Set("Authorization", "Bearer "+token)
resp, err := http.DefaultClient.Do(req)
if err != nil {
fmt.Println("error:", err)
return
}
defer resp.Body.Close()
fmt.Println("status:", resp.Status)
}
```
:::
#### Errors
| Code | Status | Description |
|------|--------|-------------|
| [HPB-00106](/v1/errors#hpb-00106) | 401 | Authentication failed |
| [HPB-00104](/v1/errors#hpb-00104) | 403 | Insufficient scope |
| [HPB-00102](/v1/errors#hpb-00102) | 404 | Resource not found |
| [HPB-00105](/v1/errors#hpb-00105) | 429 | Rate limit exceeded |
---
### Update Observation
Update an existing Observation resource.
**Required scope:**
#### Request Body
#### Request Example
```json
{
"resourceType": "Observation",
"id": "aa0e8400-e29b-41d4-a716-446655440040",
"status": "amended",
"category": [
{
"coding": [
{
"system": "http://terminology.hl7.org/CodeSystem/observation-category",
"code": "vital-signs",
"display": "Vital Signs"
}
]
}
],
"code": {
"coding": [
{
"system": "http://loinc.org",
"code": "8867-4",
"display": "Heart rate"
}
]
},
"subject": {
"reference": "Patient/550e8400-e29b-41d4-a716-446655440001"
},
"encounter": {
"reference": "Encounter/990e8400-e29b-41d4-a716-446655440030"
},
"effectiveDateTime": "2026-05-20T10:15:00Z",
"valueQuantity": {
"value": 74,
"unit": "/min",
"system": "http://unitsofmeasure.org",
"code": "/min"
}
}
```
#### Code Samples
:::CodeGroup
```bash {label="cURL"}
TOKEN=$(curl -s -X POST https://api.huli.ai/auth/token \
-d "grant_type=client_credentials" \
-d "client_assertion_type=urn:ietf:params:oauth:client-assertion-type:jwt-bearer" \
-d "client_assertion=${CLIENT_ASSERTION}" \
-d "scope=system/Observation.cru" \
| jq -r .access_token)
curl -X PUT https://api.huli.ai/fhir/R4/Observation/${RESOURCE_ID} \
-H "Authorization: Bearer ${TOKEN}" \
-H "Content-Type: application/fhir+json" \
-d @resource.json
```
```typescript {label="TypeScript"}
const token = process.env.HULI_ACCESS_TOKEN ?? "";
const response = await fetch(
`https://api.huli.ai/fhir/R4/Observation/${id}`,
{
method: "PUT",
headers: {
"Authorization": `Bearer ${token}`,
"Content-Type": "application/fhir+json",
},
body: JSON.stringify(payload),
}
);
if (!response.ok) throw new Error(`HTTP ${String(response.status)}`);
const data: unknown = await response.json();
```
```python {label="Python"}
import os
import requests
token = os.environ["HULI_ACCESS_TOKEN"]
headers = {"Authorization": f"Bearer {token}", "Content-Type": "application/fhir+json"}
resp = requests.put(
f"https://api.huli.ai/fhir/R4/Observation/{resource_id}",
headers=headers,
json=payload,
)
resp.raise_for_status()
print(resp.json())
```
```java {label="Java"}
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
public class updateObservationExample {
public static void main(String[] args) throws Exception {
String token = System.getenv("HULI_ACCESS_TOKEN");
String resourceId = "RESOURCE_ID";
String payload = "{}"; // your serialized FHIR resource
HttpClient client = HttpClient.newHttpClient();
HttpRequest request = HttpRequest.newBuilder()
.uri(URI.create("https://api.huli.ai/fhir/R4/Observation/" + resourceId))
.header("Authorization", "Bearer " + token)
.header("Accept", "application/fhir+json")
.header("Content-Type", "application/fhir+json")
.method("PUT", HttpRequest.BodyPublishers.ofString(payload))
.build();
HttpResponse response =
client.send(request, HttpResponse.BodyHandlers.ofString());
System.out.println("status: " + response.statusCode());
System.out.println(response.body());
}
}
```
```go {label="Go"}
import (
"fmt"
"net/http"
"os"
)
func updateObservationExample() {
token := os.Getenv("HULI_ACCESS_TOKEN")
req, _ := http.NewRequest("PUT", "https://api.huli.ai/fhir/R4/Observation/"+resourceID+"", body)
req.Header.Set("Authorization", "Bearer "+token)
req.Header.Set("Content-Type", "application/fhir+json")
// set req.Body to your serialized resource
resp, err := http.DefaultClient.Do(req)
if err != nil {
fmt.Println("error:", err)
return
}
defer resp.Body.Close()
fmt.Println("status:", resp.Status)
}
```
:::
#### Errors
| Code | Status | Description |
|------|--------|-------------|
| [HPB-00101](/v1/errors#hpb-00101) | 400 | Validation error |
| [HPB-00106](/v1/errors#hpb-00106) | 401 | Authentication failed |
| [HPB-00104](/v1/errors#hpb-00104) | 403 | Insufficient scope |
| [HPB-00102](/v1/errors#hpb-00102) | 404 | Resource not found |
| [HPB-00101](/v1/errors#hpb-00101) | 422 | Unprocessable entity |
| [HPB-00105](/v1/errors#hpb-00105) | 429 | Rate limit exceeded |
---
### Search Observations
Search for Observation resources using FHIR search parameters.
**Required scope:**
#### Query Parameters
#### Code Samples
:::CodeGroup
```bash {label="cURL"}
TOKEN=$(curl -s -X POST https://api.huli.ai/auth/token \
-d "grant_type=client_credentials" \
-d "client_assertion_type=urn:ietf:params:oauth:client-assertion-type:jwt-bearer" \
-d "client_assertion=${CLIENT_ASSERTION}" \
-d "scope=system/Observation.rs" \
| jq -r .access_token)
curl -X GET https://api.huli.ai/fhir/R4/Observation \
-H "Authorization: Bearer ${TOKEN}"
```
```typescript {label="TypeScript"}
const token = process.env.HULI_ACCESS_TOKEN ?? "";
const response = await fetch(
`https://api.huli.ai/fhir/R4/Observation`,
{
method: "GET",
headers: {
"Authorization": `Bearer ${token}`,
},
}
);
if (!response.ok) throw new Error(`HTTP ${String(response.status)}`);
const data: unknown = await response.json();
```
```python {label="Python"}
import os
import requests
token = os.environ["HULI_ACCESS_TOKEN"]
headers = {"Authorization": f"Bearer {token}"}
resp = requests.get(
f"https://api.huli.ai/fhir/R4/Observation",
headers=headers,
)
resp.raise_for_status()
print(resp.json())
```
```java {label="Java"}
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
public class searchObservationsExample {
public static void main(String[] args) throws Exception {
String token = System.getenv("HULI_ACCESS_TOKEN");
HttpClient client = HttpClient.newHttpClient();
HttpRequest request = HttpRequest.newBuilder()
.uri(URI.create("https://api.huli.ai/fhir/R4/Observation"))
.header("Authorization", "Bearer " + token)
.header("Accept", "application/fhir+json")
.method("GET", HttpRequest.BodyPublishers.noBody())
.build();
HttpResponse response =
client.send(request, HttpResponse.BodyHandlers.ofString());
System.out.println("status: " + response.statusCode());
System.out.println(response.body());
}
}
```
```go {label="Go"}
import (
"fmt"
"net/http"
"os"
)
func searchObservationsExample() {
token := os.Getenv("HULI_ACCESS_TOKEN")
req, _ := http.NewRequest("GET", "https://api.huli.ai/fhir/R4/Observation", nil)
req.Header.Set("Authorization", "Bearer "+token)
resp, err := http.DefaultClient.Do(req)
if err != nil {
fmt.Println("error:", err)
return
}
defer resp.Body.Close()
fmt.Println("status:", resp.Status)
}
```
:::
#### Errors
| Code | Status | Description |
|------|--------|-------------|
| [HPB-00106](/v1/errors#hpb-00106) | 401 | Authentication failed |
| [HPB-00104](/v1/errors#hpb-00104) | 403 | Insufficient scope |
| [HPB-00105](/v1/errors#hpb-00105) | 429 | Rate limit exceeded |
---
### Create Observation
Create a new Observation resource. The server assigns the resource ID. LOINC codes are validated.
**Required scope:**
#### Request Body
#### Request Example
```json
{
"resourceType": "Observation",
"status": "final",
"category": [
{
"coding": [
{
"system": "http://terminology.hl7.org/CodeSystem/observation-category",
"code": "vital-signs",
"display": "Vital Signs"
}
]
}
],
"code": {
"coding": [
{
"system": "http://loinc.org",
"code": "8310-5",
"display": "Body temperature"
}
]
},
"subject": {
"reference": "Patient/550e8400-e29b-41d4-a716-446655440001"
},
"encounter": {
"reference": "Encounter/990e8400-e29b-41d4-a716-446655440030"
},
"effectiveDateTime": "2026-05-20T10:15:00Z",
"valueQuantity": {
"value": 36.6,
"unit": "Cel",
"system": "http://unitsofmeasure.org",
"code": "Cel"
}
}
```
#### Code Samples
:::CodeGroup
```bash {label="cURL"}
TOKEN=$(curl -s -X POST https://api.huli.ai/auth/token \
-d "grant_type=client_credentials" \
-d "client_assertion_type=urn:ietf:params:oauth:client-assertion-type:jwt-bearer" \
-d "client_assertion=${CLIENT_ASSERTION}" \
-d "scope=system/Observation.cru" \
| jq -r .access_token)
curl -X POST https://api.huli.ai/fhir/R4/Observation \
-H "Authorization: Bearer ${TOKEN}" \
-H "Content-Type: application/fhir+json" \
-d @observation.json
```
```typescript {label="TypeScript"}
const token = process.env.HULI_ACCESS_TOKEN ?? "";
const response = await fetch(
`https://api.huli.ai/fhir/R4/Observation`,
{
method: "POST",
headers: {
"Authorization": `Bearer ${token}`,
"Content-Type": "application/fhir+json",
},
body: JSON.stringify(payload),
}
);
if (!response.ok) throw new Error(`HTTP ${String(response.status)}`);
const data: unknown = await response.json();
```
```python {label="Python"}
import os
import requests
token = os.environ["HULI_ACCESS_TOKEN"]
headers = {"Authorization": f"Bearer {token}", "Content-Type": "application/fhir+json"}
resp = requests.post(
f"https://api.huli.ai/fhir/R4/Observation",
headers=headers,
json=payload,
)
resp.raise_for_status()
print(resp.json())
```
```java {label="Java"}
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
public class createObservationExample {
public static void main(String[] args) throws Exception {
String token = System.getenv("HULI_ACCESS_TOKEN");
String payload = "{}"; // your serialized FHIR resource
HttpClient client = HttpClient.newHttpClient();
HttpRequest request = HttpRequest.newBuilder()
.uri(URI.create("https://api.huli.ai/fhir/R4/Observation"))
.header("Authorization", "Bearer " + token)
.header("Accept", "application/fhir+json")
.header("Content-Type", "application/fhir+json")
.method("POST", HttpRequest.BodyPublishers.ofString(payload))
.build();
HttpResponse response =
client.send(request, HttpResponse.BodyHandlers.ofString());
System.out.println("status: " + response.statusCode());
System.out.println(response.body());
}
}
```
```go {label="Go"}
import (
"fmt"
"net/http"
"os"
)
func createObservationExample() {
token := os.Getenv("HULI_ACCESS_TOKEN")
req, _ := http.NewRequest("POST", "https://api.huli.ai/fhir/R4/Observation", body)
req.Header.Set("Authorization", "Bearer "+token)
req.Header.Set("Content-Type", "application/fhir+json")
// set req.Body to your serialized resource
resp, err := http.DefaultClient.Do(req)
if err != nil {
fmt.Println("error:", err)
return
}
defer resp.Body.Close()
fmt.Println("status:", resp.Status)
}
```
:::
#### Errors
| Code | Status | Description |
|------|--------|-------------|
| [HPB-00101](/v1/errors#hpb-00101) | 400 | Validation error |
| [HPB-00106](/v1/errors#hpb-00106) | 401 | Authentication failed |
| [HPB-00104](/v1/errors#hpb-00104) | 403 | Insufficient scope |
| [HPB-00101](/v1/errors#hpb-00101) | 422 | Unprocessable entity |
| [HPB-00105](/v1/errors#hpb-00105) | 429 | Rate limit exceeded |
---