Oncology & Hematology Coding Alert

Hint: it’s not just about adding a seventh character.

The end of the acute phase of an illness does not always mean the illness is over. Some illnesses produce other problems or conditions that can last long after the initial condition has gone into remission. In some cases, these secondary problems may never go away, which may lead your oncologist to see the patient long after their cancer has gone into remission.

These conditions are known as sequelae, and they present some unique coding challenges, most notably knowing how the relationship between the initial condition and the sequela impacts code choice. So, this guide will help you determine when and how to code sequelae.

What Are Sequelae?

From a coding standpoint, a sequela is “the residual effect (condition produced) after the acute phase of an illness or injury has terminated. There is no time limit on when a sequela code can be used. The residual may be apparent early, such as in cerebral infarction, or it may occur months or years later, such as that due to a previous injury,” according to ICD-10-CM guideline Section I.B.10.

Or, to put it another way, “the easiest way to define sequela is to say, ‘the previous illness or injury is completely resolved/healed, but a new issue has developed due to the original illness/injury.’ So, a sequela code, or the seventh character, ‘S,’ allows us to show the relationship,” explains Chelle Johnson, CPMA, CPC, CPCO, CPPM, CEMC, AAPC Fellow, billing/credentialing/auditing/coding coordinator at County of Stanislaus Health Services Agency in Modesto, California.

What Sequelae Are Not

Even though most medical conditions are the result of a cause-and-effect relationship, it is important to note that causality does not always mean sequela. Symptoms of illnesses and conditions such as sepsis that are caused by organisms are not regarded as sequela. For example, cancer patients undergoing chemotherapy are at high risk of developing infections that can lead to sepsis. But the sepsis is not regarded as a sequela of the infection; rather, the sepsis is regarded as a result of the ongoing infection.

Coding Sequelae With 7th Character S

Sequelae that occur in relation to an injury, accident, and surgical and medical care do not have their own codes. Instead, as ICD-10-CM guideline I.C.19.a notes, for certain codes in the S00-T88 and V00-Y99 sections, including the T80-T88 (Complications of surgical and medical care, not elsewhere classified) codes, “the 7th character ‘S’, sequela, is for use for complications or conditions that arise as a direct result of a condition. The ‘S’ is added only to the injury code, not the sequela code. The 7th character ‘S’ identifies the injury responsible for the sequela. The specific type of sequela … is sequenced first, followed by the injury code.”

Example 1: Your provider treated a patient for testicular cancer with the drug cisplatin. The cancer is now in remission, but the patient has developed bilateral tinnitus. Your provider determines the tinnitus is a long-term late effect of the cisplatin therapy, so you would use the following diagnosis codes:

• H93.13 (Tinnitus, bilateral)
• T45.1X5S (Adverse effect of antineoplastic and immunosuppressive drugs, sequela)

Coding Sequelae With Other, Specific Codes

“These codes that are explicitly labeled as sequela codes do not involve use of the seventh character, ‘S,’ which is added only to the injury code (or other cause of the sequela), not the sequela code itself,” notes Kent Moore, senior strategist for physician payment at the American Academy of Family Physicians.

In the same way as you would code sequelae from an external cause, ICD-10-CM guidelines tell you to code sequelae using a specific sequela code “in the following order: the condition or nature of the sequela is sequenced first. The sequela code is sequenced second.”

Example 2: Several years after undergoing radiation for breast cancer, which is now in remission, a patient is diagnosed with lymphedema, which your provider determines is a result of the radiation treatment. In this case, the lymphedema would be considered a sequela of the treatment, and you would code the diagnosis as:

• I89.0 (Lymphedema, not elsewhere classified)
• Y84.2 (Radiological procedure and radiotherapy as the cause of abnormal reaction of the patient, or of later complication, without mention of misadventure at the time of the procedure).

Take note of these exceptions: First, if a notation in the Tabular List indicates that the code for the sequela is followed by the manifestation, this would take precedence over the guideline direction.

Secondly, if the sequela code has been expanded (at the fourth, fifth or sixth character levels) to include the manifestation(s), you will only report this one code as it captures all the necessary information.

And remember: The ICD-10-CM code for the acute phase of the illness is never used with a code for the late effect. So, you must “make sure that the original or previous illness or injury is completely resolved. Oftentimes, I see providers using the seventh character ‘S’ without a clear understanding of sequela,” Johnson cautions.