How to Classify Treatment Encounters in ICD-10-CM?

The World Health Organization has provided the International Classification of Disease to avoid the complexities in medical billing. This classification assists all healthcare professionals in patients’ data storage and retrieval. However, physicians, coders, health information managers, nurses, and other staff have benefited from ICD-9-CM. It is the 9th version of the clinical modification, effected up to 1999. After that, WHO made several revisions to it and imparted expandability to ICD-9. So, it replaced the ICD-9-CM with ICD-10-CM.

In this article, we will get to know a little bit about ICD-10-CM. Also, we will see how we can use initial and subsequent encounters in a code construct. And compare the use of subsequent vs sequela in any treatment encounter.

What’s ICD-10-CM?

ICD-10-CM is the 10th revision of Clinical Modification in the International Classification of Disease. Like ICD-9, it binds all providers and physicians in the US to follow this coding system. WHO has enhanced the data quality for tracking public health conditions such as;

  • Injury cause
  • Anatomical location
  • Complications

Now the injury code consists of 3 to 7 characters where the 7th character identifies the episode of care (initial, subsequent, and sequela).

How to Identify the Care Episode for Injury Codes?

Since ICD-10 is the expanded version of ICD-9. It has 19x procedural codes and 5x diagnostic codes than its Revision 9 CM. However, the most amazing modification in this new coding system is its 7th character. Through this character, physicians can get a more precise but detailed understanding of their patient’s condition. So, they can easily find the laterality, severity, and complexity of injury conditions.

The 7th character of ICD-10-CM defines treatment encounters in three forms.

7th Character ‘A’ for Initial Encounters

The term ‘Initial encounter’ refers to the condition when a patient receives active treatment for their injury for the first time.

One must not confuse it with the initial visit. A physician assigns character A by analyzing whether the patient is having active treatment or not. Who else is seeing a patient for the first time is not a criterion. Chapter 19 Guidelines in ICD-10-CM have depicted the rules for assigning an active treatment in the initial encounter.

A patient may receive the first episode of active treatment at the emergency department and then refer to the respective physician. Every physician attending such a patient will write A as the 7th character in their code.

Seems a little complicated? Let’s have an example for clarification.

A patient comes to the hospital with a leg burn. The burn covers less than 10% of the leg area. In this case, he will first receive active treatment in the emergency room.

  • The attending doctor will prepare the initial report and assign the respective code for the leg burn. This code is T24.032A for a burn on the leg with an unspecified degree.
  • Here, he will also use code T31.0 for burns in less than 10% leg area.
  • In addition to these, he will use X12.XXXA code for explaining the interaction with other body fluids.
  • Now, if the patient goes to another doctor during their active treatment, the physician can code A for the patient’s visit.
  • Likewise, if the patient comes back again to the doctor for changing the prescription and other such issues, still A as the 7th character is applicable.

Some other examples of initial encounters include the following:

  • Surgical Treatment
  • Emergency Department Encounter
  • Wound Vac Dressing Changes
  • Continuation of IV antibiotic administration
  • Evaluation and Continuation of Current Active Treatment

7th Character ‘D’ for Subsequent Encounters

A physician can use ‘Character D’ for coding the patient’s visit as a subsequent encounter. There is an immense debate about subsequent vs sequela encounters. However, expert and professional coders and physicians know the real difference between both.

The patient’s visit to the hospital during their recovery/healing phase falls under the subsequent encounter category. This implies that the subsequent encounter for treatment is the phase next to active treatment for an injury.

For example, consider if the same patient with a burnt leg visits a physician for a routine check-up as an outpatient for continuing the treatment.

  • Here, the doctor will code T24.032D for a burn on the leg of an unspecified degree.
  • In the same way, he will use X12.XXXD code for explaining the interaction with other body fluids.

However, it’s a limitation to some extent that ICD-10-CM lacks clear specifications to distinguish “active treatment” from “routine care”.

Usually, a physician makes a healthcare plan for the patient in their active treatment. On the other hand, the physician follows this plan in the patient’s subsequent encounters.

The following physician’s services are usually included in subsequent encounters:

  • External or Internal Fixation Removal
  • Cast Adjustment, Changing, or Wedging
  • Follow-up Appointments for Facture
  • Medication Adjustment
  • Rehabilitation Services
  • Routine Dressing Changes
  • Wound Checking
  • X-rays for finding the Healing Status

7th Character ‘S’ for Sequela Encounters

Character ‘S’ as the 7th character of a code represents that the patient is receiving care in their sequela encounter. ‘Sequela’ in other words covers the injury’s complications management like dealing with the late effects of the injury.

For example, in burn injuries, the late effect is scar formation. When patient visits for the treatment of scars, the treatment is referred to as sequela encounter treatment. This time, the physician will code it as T24.0032S.


The US Department of Health and Human Services (HHS) strictly binds all HIPAA-covered entities to ICD-10-CM codes. So, it might be a little difficult to start using initial, subsequent, and sequelae encounters. But we have no other option except using ICD-10-CM. This revision 10 of clinical modification in ICD is for the better management of a patient’s information. It can efficiently overcome Medical billing errors and reduce the over-coding or under-coding to a large extent.



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