A common question asked among coders is, “is this a complication or is this a sequela”?  Following specific coding guidelines will ensure that costly errors are avoided for these two very different coding situations.

A sequela (formerly known as “late effects”) is a residual or produced condition that is a result of a past illness or injury. This condition may be apparent in the early stages following an acute phase of an illness or may appear later. However, it is important to note that with a sequela, the acute phase of an illness or injury has resolved or healed, and the sequela is left. Conversely, a complication is a condition that occurs as a result of treatment, or a condition that interrupts the healing process from an acute illness or injury. The acute illness or injury is not healed in a scenario involving a complication.

Two codes are (usually) required for sequela

Most of the time when you’re coding a sequela, you’ll need to use two codes. One of those two codes describe the nature of the sequela (that is, the residual or what you’re seeing right now) and one will describe the now-healed illness or injury that led to the current condition. Coding guidelines stipulate that the residual should be coded first, followed by the healed illness/injury.

For example, if a patient develops a right elbow contracture after a third degree burn in the same area heals, the contracture is the residual and would be coded first with M24.521 (Contracture, right elbow) and immediately followed by T22.321S (Burn of third degree of right elbow, sequela). The seventh character “S” indicates that the burn is no longer an active condition, but rather than it healed and left behind a sequela, according to coding guidelines.

Scenario:   Epilepsy due to Traumatic Brain Injury (TBI)

A 65-year-old woman was a passenger in a car accident five years ago and suffered a TBI. As a result of the TBI, she has recurrent seizures and is admitted to home health for instruction on new medications to help control the seizures.

Primary and Secondary Diagnoses

M1021a:  Epilepsy, unspecified, not intractable without status epilepticus


M1023b:  Unspecified intracranial injury without loss of consciousness, sequela


M1023c:  Car passenger injured in collision with other type car in traffic accident, sequela



*Recurrent seizures are sequenced first, as they describe the nature of the sequela.

*A seventh character “S” on the TBI code is used to indicate that the TBI healed but left behind a sequela.

*The appropriate external cause code should be coded using a 7th character of “S” indicating the cause of the accident.

*Even though this accident was 5 years ago, there is no time limit on when sequelae codes can be used.


To read more on Sequelae, you can look for our article in the September edition of Decision Health. To view additional scenarios, see the online version of this story on the Home Health Coding Center at www.HHCodingCenter.com.


About The Contributor

Sheri Ikner, RN, BSN, COS-C, HCS-D

Sheri is a Clinical Manager for OASIS and Coding Services at McBee. She holds the HCS-D and COS-C certifications and has been performing OASIS and coding reviews for 10 years.