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Initial vs. Subsequent vs. Sequela encounters in ICD-10 CM

ICD-10-CM codes are vital tools used by doctors and nurses to convey diagnoses and procedures to insurance companies. However, within this coding system there exists a hidden world of codes – ‘Initial,’ ‘Subsequent,’ and ‘Sequela’ – that explain the type of patient visit.

We have all found ourselves there, staring at the coding manual with furrowed brows, trying to decipher its mysteries.


Worry no more, this article will be your one-stop shop for unraveling the secrets behind these encounter codes.

We will break down the key differences, provide straightforward examples, and equip you with the understanding to confidently navigate initial, subsequent, and sequela encounters in ICD-10-CM.

Initial Encounter

INITIAL Encounter (marked by the letter “A”)

The first time a patient seeks care for a condition or injury, it’s called the initial encounter. Imagine your patient walks into the clinic for the first time with a new health concern. This is their initial encounter with that specific condition. The code used will reflect this fresh start, marked by the letter “A” as the 7th character in the ICD-10-CM code.

Say, for example, a patient visits for the first time complaining of chest pain. The initial encounter code for chest pain might be “R07.9A” -unspecified chest pain, initial encounter.

Some other examples of initial encounters include:

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

SUBSEQUENT Encounter (marked by the letter “D”)

After the initial diagnosis, your patient returns for follow-up visits related to the same condition. These are subsequent encounters, marked by the letter “D” as the seventh character in the coding.

For example, the patient with chest pain returns for a follow-up visit after initial tests. The subsequent encounter code could be “R07.9D” – unspecified chest pain, subsequent encounter.

The following medical services come under 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 to find the Healing Status
Sequela Encounter in Medical Coding

SEQUELA Encounter (marked by the letter “S”)

Sometimes, a complication or long-term effect arises from a previous illness or injury. This is where the sequela encounter comes in, requiring 7-character code for proper documentation.

For instance, a patient who suffered a fracture now experiences lingering difficulty walking is termed as sequela. This encounter code could be S72.21XS-displaced subtrochanteric fracture of right femur, sequela, referencing the original fracture.

In other words, the encounter codes that deal with the late effects of the injury come under sequela.

Take another example, the late effect in burn injuries is scar formation. Now, when the patient visits for the treatment of scars, the treatment is referred to as sequela encounter treatment. The encounter code for this will be T24.0032S.

Further examples of Sequelae encounters may include:

  • Chronic pain following a severe infection
  • Cognitive impairment after a traumatic brain injury
  • Muscle weakness post a prolonged period of bed rest
  • Respiratory complications following a bout of pneumonia
  • Vision impairment due to untreated diabetes
  • Hearing loss following exposure to loud noise
  • Digestive issues after a severe case of food poisoning
  • Emotional trauma resulting from a car accident
  • Skin discoloration as a sequela of a dermatological condition
  • Nerve damage following a surgical procedure
Initial vs. Subsequent vs. Sequela in Medical Coding

Initial Encounter vs. Subsequent Encounter vs. Sequela Encounter

Initial Encounters refer to the first time a patient seeks care for a condition. For example, when someone first goes to see the doctor for a nagging cough that has been bothering them for a week, that would be considered the initial encounter for that illness.

Subsequent Encounters refer to any follow-up visits related to that initial complaint. So if the patient returns a few days later for a checkup on that cough, or has to come back in for a test, those would be subsequent encounters. The doctor is seeing the patient again for the same reason as the first visit.

Sequela Encounters refer to visits that deal with the consequences or aftereffects of an initial illness or injury. For instance, if that cough the patient first came in for ended up developing into pneumonia, any visits focused on treating and overcoming the pneumonia would be considered sequela encounters. They are dealing with what resulted from the original health issue.

In summary, initial encounters refer to the first time a patient seeks care for a condition, subsequent encounters refer to any follow-up visits for the same condition, and sequela encounters refer to visits focused on the consequences or aftereffects of an initial illness or injury.

Medical billing coders need to understand the differences between these encounter types to properly assign the correct codes for maximum reimbursement. Proper coding is important to keep the clinic or hospital running smoothly.

Here’s what the 7th Character in ICD-10-CM fracture coding represents:

➡ “A” Initial encounter for closed fracture

➡ “B” Initial encounter for open fracture

➡ ”D” Subsequent encounter for fracture with routine healing

➡ “G” Subsequent encounter for fracture with delayed healing

➡ “K” Subsequent encounter for fracture with nonunion

➡ “P” Subsequent encounter for fracture with malunion

➡ “S” Sequela

Frequently Asked Questions

1). What is the 7th character in ICD-10-CM?

The seventh character in an ICD-10-CM diagnosis code offers essential information about the stage of care a patient is undergoing for that condition. It distinguishes between whether this visit is the first one for this issue, a later follow-up for the same instance, or the care is for lingering effects after the initial concern was treated. Clear coding in this way aids data analysis of the prevalence of diseases and how long treatment lasts. It also helps indicate where patients are in the cycle of medical services. Correct use of the seventh character supports a precise picture of population health.

2). When do I use the 7th character in ICD-10-CM?

The 7th character is only used with certain ICD-10-CM codes. These codes will typically have instructions in the tabular list specifying when to use a 7th-character extension.

Here are some common scenarios where the 7th character is used:

  • Encounter codes: These codes (A for Initial, D for Subsequent, S for Sequela) describe the stage of a patient’s treatment for a specific condition.
  • Laterality: This specifies the side of the body affected by a condition (e.g., X for bilateral, L for left, R for right).
  • Axis I or Axis II diagnoses: These are used in mental health coding to differentiate primary diagnoses (Axis I) from personality disorders or mental retardation (Axis II).

3). Where should I place the 7th character if the 6th character is missing?

Remember, the 7th character must always be the 7th character in the code.

If a code has less than 6 characters while the 7th character is required, the character X is used as a placeholder in certain codes. This X is assigned to all characters less than 6 as a placeholder to fill in the empty characters.

4). Is there a time limit on when a sequela code can be used?

No, there is no time limit on when a sequela code can be used in ICD-10-CM coding.

A sequela is a lasting consequence or complication arising from a previous illness or injury. The ICD-10-CM guidelines emphasize this by stating that a sequela code can be used “after the acute phase of an illness or injury has terminated.” This means the sequela can develop immediately after the initial event or it can manifest months or even years later.

To further elaborate look at the examples below:

  • Scarring from a burn: This is a common sequela that can develop shortly after the burn heals. The sequela code for scarring would be used alongside the code for the original burn injury, marked as a sequela (S).
  • Post-traumatic stress disorder (PTSD): This can develop as a sequela months or even years after a traumatic event. The sequela code for PTSD would be used with the code for the original trauma, marked as a sequela (S).

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