# Retrieve a patient's transition of care document

You can use this API action to access general clinical data for a patient represented in a transition of care document (CCD).

> **Prerequisite: Having a patient identifier**
>
> To use this API action, you must know the patient identifier. If you don’t have one, [search for a patient with demographics](/fhir-api-actions/patients/search-for-a-patient-by-demographics) to locate an appropriate identifier first.

## Use cases

This API action may be a good fit for your organization if you perform any of these use cases:

- Review a current snapshot of a patient as clinical background for determining treatment.
- Learn details about a patient’s visit at another organization.

We recommend only using this API action for these two use cases. For example, if you often work with another organization—by receiving transfers or seeing patients from that organization—this is a great option to get a summary of care. 

If you only need _pieces_ of data from the transition of care document, we recommend querying for those specific pieces instead.

## Supported systems

You can use this API action with the Redox FHIR API.

> **Talk to a Redoxer**
>
> It’s also possible to use the Redox Data Model API for this API action. [Talk to a Redoxer](https://redoxengine.com/forms/contact-us/) to learn about your options.

Your connection's system can return results with their own FHIR, SOAP-based CCD exchange, or query-based API. Or, they can use a push-based method, such as CCD push or DirectTrust messaging.

> **Using data on demand**
>
> Your connection's system may not support a query-based data exchange, but they may still be willing to provide results with a push-based method.
>
> However, we understand that you may not want to store all that data. Maybe you don't need _all_ the possible results and just want to query for what you want when you need it. If so, you can use this API action via our <u>data on demand</u> service, which stores the connection's data so that you can query from Redox "on demand." [Learn about data on demand](/basics/data-exchange-with-redox/data-on-demand).

## Things you need to know

<details>
<summary>Different organization, different data</summary>

Different organizations provide different amounts of data. Some may have very detailed information, whereas another may have only a high-level overview. In some cases, one organization may provide discrete data while another provides non-discrete information.

</details>

<details>
<summary>Patient versus visit document</summary>

The transition of care document may be either a patient or visit summary. Patient summaries represent a current (or nearly current) snapshot of the patient’s chart. Visit summaries contain a patient’s chart for a specific visit and should be treated as accurate as of the visit date.

The data included in either context may overlap, so you could receive visit data in a patient summary or patient data in a visit summary. An example of this would be a new diagnosis or allergy. If a diagnosis or allergy is documented as part of a visit, it would still appear later in the patient summary.

The point is you should understand the data in its appropriate context, whether patient or visit.

</details>

<details>
<summary>Timing of a visit</summary>

You may not get finalized data if searching for a visit summary before the visit's over (i.e., querying for data about an inpatient stay before the patient's discharge). We recommend waiting until a visit is complete and has been fully documented to receive a comprehensive picture of a visit.

</details>

<details>
<summary>CCD codes</summary>

By default, most EHR systems use SNOMED for CCDs. Some may be willing to support ICD-10 for problems, but this requires an update on the EHR side. 

</details>

<details>
<summary>Text fields</summary>

CDA documents contain two types of information: human-readable text (AKA narrative data) and machine-processable discrete data.

The `DocumentReference` resource and `ClinicalSummary` data model mostly contain discrete data. We convert any narrative data for you into XHTML for FHIR or HTML (or plain text) for data models.

</details>

> **What's next? **
>
> Does this API action seem like a good fit for your unique workflow? Let your Technical Account Manager know! To start development, download the resource schema noted in the related action step. Then decide which data elements you need.
>
> If you’re new to Redox, [use the Quickstart guide](/quickstart-for-redox) to dive in. If you’re not engaged with our sales team yet, [talk to a Redoxer](https://redoxengine.com/forms/contact-us/) to get started.