How to Properly Assign ICD-10-CM Codes for Pain

by  Wyn Staheli, Director of Content - innoviHealth
Jul 14th, 2021

Pain is a common diagnosis among all specialties so it should not be surprising to find there are 162 ICD-10-CM codes for reporting it and over 80 mentions in the ICD-10-CM Official Guidelines for Coding and Reporting which describe when certain types of pain should be reported and how the codes should be sequenced. For quick reference, pain codes are in the following ICD-10-CM chapters. 

Chapter	Title	Range
5	Mental, Behavioral, and Neurodevelopmental Disorders	F00-F99
6	Diseases of the Nervous System	G00-G99
7	Diseases of the Eye & Adnexa	H00-H59
9	Disease of the Circulatory System	I00-I99
13	Disease of the Musculoskeletal System and Connective Tissue	M00-M99
18	Symptoms, Signs & Abnormal Clinical & Laboratory Findings, NEC	R00-R99
19	Injury, Poisoning, and Certain Other Consequences of External Causes	S00-T88

TIP: Find-A-Code search tools make it easy to locate important coding information quickly. Because Find-A-Code maintains the most current coding data sets, it is considered one of the most reliable sources of coding information.  

Types of Pain

Pain can occur alone or arise from an underlying condition or injury. In order to select the correct code, it is important to first understand the terminology used to describe the type(s) of pain the patient is experiencing: 

• Acute: Comes on suddenly and resolves in a short period of time (e.g., usually less than 3 months) or is documented by the provider as acute pain. Note that payers may have their own definition of what is considered acute so pay close attention to payer policy
• Chronic: Continuing over a long period of time or recurring frequently. Generally, this means it lasts longer than three months, does not resolve with treatment, or is documented by the provider as chronic. 

• Traumatic: Caused by an injury (e.g., fall, motor vehicle, crush, fracture) 
• Psychological: Physical pain resulting from a psychiatric disorder or long-term, chronic pain that causes depression, anxiety, or another psychological factor 
• Postoperative: Pain resulting from a surgical procedure 
• Site Specific: Pain located in a specific anatomic region or site (e.g., lumbago, arm, eye, finger) 
• Pain as a Symptom: The pain is a symptom of a confirmed diagnosis (e.g., abdominal pain due to an ulcer; ulnar pain due to a fracture). Note that this type of pain is not reported unless the reason for the encounter is for pain management and not to treat the condition that is causing the pain. 

Sequencing Pain Codes

Codes that describe pain are reported and sequenced based on the encounter notes and the reason for the admission/encounter. Sometimes more than one code will need to be assigned to fully describe the type or cause of the pain documented. Beyond code assignment, sequencing of multiple codes may also be important to accurately describe the patient’s condition at the time of the encounter.

Pain Disorders — Psychological Factors

To better understand proper reporting of pain for each chapter, we will refer to the ICD-10-CM Official Guidelines for Coding and Reporting as follows:

Chapter 5: Pain disorders exclusively (F45.41) or with (F45.42) related psychological factors  In ICD-10-CM, Chapter 5: Mental, Behavioral, and Neurodevelopmental Disorders (F01-F99), there are two codes used to identify somatoform disorders associated with physical pain:   F45.41: Pain disorder exclusively related to psychological factors  Somatoform pain disorder (persistent)  Pain, not otherwise specified (NOS)  F45.42 Pain disorder with related psychological factors

F45.41 can refer to: 

• a pain disorder that is either a direct result of a psychiatric disorder.
• pain the patient is experiencing that is not identifiably linked to a physical injury, disease, or illness but is, nonetheless, very real, such as pain that is caused by emotional or mental distress in the absence of a physical injury or disease process (somatoform pain disorder). 

F45.42 is just the opposite, referring instead to pain that causes emotional or mental distress. Many patients who suffer from chronic pain due to a physical injury, disease, or following a complicated trauma or surgical procedure often experience anxiety and depression that accompany their physical pain. Patients diagnosed with serious illnesses, injuries, or genetic disorders that require surgical intervention or intense testing and/or painful healthcare encounters often develop a psychological disorder in light of their situation. 

To differentiate between these different types of pain look in the documentation for any behavioral health condition that the provider has linked to the patient’s pain disorder (e.g.,anxiety, depression) which would support the reporting of code F45.42. If noted/documented, consider also adding a code from Chapter 6 (G89.-) to more fully explain the type of pain the patient is experiencing (e.g., acute, chronic, due to trauma). However, if no medical condition is documented to support a physical condition causing the pain and the treatment is focused on psychotherapy, counseling, or medications specific to a psychological disorder then consider reporting F45.41 and add additional ICD-10-CM codes that would support any psychological condition the patient may also have. When the documentation is unclear, be sure to submit a query to the healthcare provider for clarification of any underlying disorder causing the pain diagnosis. 

NOTE: Sequencing of ICD-10-CM codes for pain is important. If the reason for the encounter is treatment for the pain, then it should be sequenced first followed by the code describing the underlying cause, unless specific instructional notations within the official ICD-10-CM guidelines direct otherwise.  

Pain as Described in Chapter 6 (G89)

Only pain that falls into one of the following categories should be reported with a code from category G89.

• acute 
• chronic 
• post-thoracotomy (incision into the chest cavity or thoracic cavity), 
• postprocedural 
• neoplasm-related pain 

Encounter for Pain Control or Pain Management 

When a patient presents for admission/encounter for pain management the pain diagnosis code is assigned and sequenced first (reported as the first diagnosis) in the following situations:

• refilling of pain medication
• a diagnostic or surgical procedure to manage pain from an known (or unknown) underlying condition, illness, or injury.

While the ICD-10-CM guidelines instruct coders to assign a symptom code only when the condition or cause of the symptom is unknown, it is important to understand that when the reason for the encounter or admission is specifically for pain management or pain control, it is correct (and fully expected) that the code(s) describing the patient’s pain are assigned and listed first. In this situation, the provider is treating the pain and not the condition causing it. 

To illustrate this concept, consider a patient with rheumatoid arthritis without rheumatoid factor of the cervical vertebrae. Inflammation in the cervical canal caused by bone overgrowth has caused significant pain and has begun to compress the spinal cord, causing the patient to lose grip strength among other symptoms. 

If this patient presented for an epidural steroid injection of the cervical spine to help control pain symptoms by reducing inflammation in the surrounding area, the diagnosis code describing pain in the cervical spine would be the primary code and would be sequenced first on the claim form. It must also be linked to the procedure performed. After that, the code(s) for the rheumatoid, intervertebral disc disorder, and spinal cord compression would then be reported (i.e., sequenced after the primary diagnosis code). 

If this patient underwent surgery to remove the osteophytes, open back up the cervical canal, and fuse the vertebrae together to decompress the spinal cord; the condition causing the pain would be reported and the pain code would NOT need to be assigned. 

Reminder: The primary or first-listed diagnosis code should be the one that most accurately describes the reason for the patient encounter. 

Surgical Encounter for Pain Control

Surgical encounters are assigned diagnosis codes following the same rules. For example, a patient may undergo surgical implantation of a neurostimulator or intrathecal pain pump for pain control. In this situation, the main reason for the encounter is for pain control and not for correction of a condition or disease. As such, the code(s) describing the patient’s pain should be assigned and sequenced first.

Pain due to Cancer/Tumor

When the patient presents for pain management services due to cancer, primary or secondary malignancy, or tumor, report the pain code (G89.3) first, followed by the code for the underlying neoplasm as an additional diagnosis. As noted in the full code description below, code G89.3 is reported for any of the following:  

G89.3 Neoplasm related pain (acute)(chronic)

            Cancer associated pain

            Pain due to malignancy (primary)(secondary)

            Tumor associated pain

Site-Specific Pain Codes

Pain codes may also refer to a specific anatomic site (e.g., left forearm pain, right ocular pain). Codes from category G89 may be reported along with site-specific pain codes to provide a more complete description of the type of pain the patient presents with. Some site specific pain codes may include the terms acute or chronic; but if they do not, assigning a code from G89 to clarify acute vs. chronic pain would help to clarify the type of pain. 

Example 1: 

Patient presents to obtain refills of his pain medications for acute eye pain due to contusion of the eyeball (injury).

G89.11 Acute pain due to trauma 

H57.11 Right ocular pain

S05.11XS Contusion of eyeball and orbital tissues, right eye, subsequent encounter

Example 2:

Patient presents with acute onset lower right quadrant abdominal pain. An abdominal ultrasound and lab tests were ordered to rule out an acute appendicitis. 

R10.31 Right lower quadrant abdominal pain

While code G89.11 describes acute pain due to trauma, in Example 2, it is not documented, therefore, symptoms are assumed to be acute until otherwise specified, so a code from category G89 is not applicable for that particular scenario. However, if the results of the lab work and ultrasound return as acute appendicitis, code R10.31 would be replaced with the applicable code for acute appendicitis, because the abdominal pain is considered a symptom of the confirmed diagnosis of appendicitis. 

Postoperative Pain 

There is a normal and expected degree of postoperative pain that accompanies every surgical procedure, but abnormal levels of postoperative pain may be indicative of something wrong such as an implanted device breaking or a wound reopening. Postoperative pain should be reported when it is specifically documented as such in the medical record. Normal postoperative pain immediately following surgery should not be coded. However, when it is documented as associated with a specific postoperative complication, assign a code for the appropriate type of postoperative pain from category G89. 

For example, a thoracotomy is an incision between the ribs that allows a surgeon to reach the lungs or other thoracic organs during surgery. Acute post-thoracotomy pain (G89.12) is reported when the document specifies it is acute, or when it fails to identify the type (acute or chronic) because acute is the default. 

Chronic Pain 

There is no defined period of time for when acute pain officially becomes chronic pain. Instead this is left to the professional opinion of the healthcare provider treating the patient and how it is documented in the medical record. When pain is documented as chronic it should be reported as chronic. 

Symptomatic Pain or Pain Related to an Underlying Condition

Symptom codes for pain (e.g., throat pain [R07.0], chest pain on breathing [R07.1]) are often assigned when the cause of the pain has not yet been identified or documented by the provider. For example, a patient with arm pain after a fall may be suspected to have a fracture, but to confirm this, imaging of the arm must be performed. Until the results of additional testing (e.g., x-ray of the arm) confirm a fracture, only the symptoms should be reported (e.g., pain in right arm [M79.601]). Once the imaging is completed, and if the report identifies the presence of a fracture, the imaging service along with any subsequent encounters related to the fracture would then be reported with the ICD-10-CM code for the fracture unless the encounter is specifically for the treatment of the pain caused by the fracture.  There are many coders who struggle with this concept of reporting pain in the presence of a previously identified and fully documented condition which explains the cause of the patient’s pain. This is because of the following ICD-10-CM guidelines that are constantly reiterated in forums, code books, and testing platforms:  

• “Codes that describe symptoms and signs, as opposed to diagnoses, are acceptable for reporting purposes when a related definitive diagnosis has not been established (confirmed) by the provider.” [ICD-10-CM Official Guidelines for Coding and Reporting; Section I (B)(4)] 

• “Signs and symptoms that are associated routinely with a disease process should not be assigned as additional codes, unless otherwise instructed by the classification.” [ICD-10-CM Official Guidelines for Coding and Reporting; Section I (B)(5)] 

• “If a definitive diagnosis has not been established by the end of the encounter, it is appropriate to report codes for sign(s) and/or symptom(s) in lieu of a definitive diagnosis.” [[ICD-10-CM Official Guidelines for Coding and Reporting; Section I (B)(18)]

When a diagnostic statement begins with “rule out, possible, or probable” it means the condition that follows has not yet been confirmed and the additional testing should help to confirm or eliminate the diagnosis being considered. In situations like these, do NOT report the diagnosis being considered but rather assign and report the codes that describe the symptom(s) the patient has identified as the reason for seeking evaluation. Once additional testing and evaluation have been completed and an actual  condition, illness, disease, or injury has been documented in the medical record by the provider, the code for that diagnosis may then be reported/assigned. 

For example, joint pain is a common symptom of Zika virus disease (A92.5), so if a patient presents with Zika symptoms, which includes joint pain, the symptom is coded until a diagnosis of Zika is confirmed. An additional code to consider would be Z20.821 “Contact with and (suspected) exposure to Zika virus” which would be sequenced second.

Coders must carefully review the documentation and identify the reason for the encounter and the rules that govern code assignment and sequencing to ensure accurate coding. These codes, especially when they pertain to risk adjusted plans (e.g., Medicare Advantage, ACA plans), can have a significant financial impact on plan funding and ultimately patient care. 

Pain Described by ICD-10-CM Combination Codes

There are many ICD-10-CM combination codes that reduce the number of codes reported by combining multiple, commonly reported diagnoses into a single code. New combination codes are added to the code set annually and should be reviewed to ensure proper code assignment occurs. For example, previously, a patient with intervertebral disc displacement (bulging vertebral disc) causing chronic low back pain seeking an encounter for refill of pain medications would be reported with these codes: 

G89.29 Other chronic pain

M54.5 Low back pain, unspecified (This will be M54.50 as of October 1, 2021)

M51.27 Other intervertebral disc displacement, lumbosacral region 

This combination code reduces the number of codes reported to: 

G89.29 Other chronic pain

M51.26 Lumbago due to intervertebral disc displacement of the lumbar spine  

FIND-A-CODE Subscriber Tip: From the main menu, select “codes,” then “diagnosis,” then “icd-10-cm” to see the main ICD-10-CM page. Look under “Information” to review the  codes within this data set that are new, changed, deleted, or reactivated for the current or past years. A quick review of the codes most reported for your organization will help to eliminate incorrect code assignment and potential claim denials.  

CODING TIP: Carefully review all Excludes1 codes to ensure the codes may be reported together or, if you are a Find-A-Code subscriber, use our simple, online ICD-10-CM Validator™ tool to quickly compare multiple ICD-10-CM codes for inclusions, exclusions, and age/gender edits. To see a demo of this tool, click ICD-10-CM Validator. 

Chronic Pain Syndrome (G89.4) vs Central Pain Syndrome (G89.0)

Chronic pain syndrome and central pain syndrome are very different from each other. As such, a careful review of the medical record should be performed prior to assigning either of these codes. These conditions are described as follows: 

• Chronic pain syndrome (CPS): Chronic physical pain associated with a psychological disorder such as depression or anxiety, poor sleep, suicidal thoughts, drug or alcohol abuse, etc. Treatment uses a combination of behavioral health experts and pain management physicians. Typically, only a  low percentage of chronic pain patients may go on to develop CPS.
• Central pain syndrome: A neurological condition caused by damage or injury to the central nervous system (consisting of the brain, brainstem, and/or spinal cord) which is causing pain that may be intermittent or constant and affects skin sensation in the face, arms, and/or legs, and creates a hypersensitivity to painful stimuli.  

If the documentation leaves questions about the correct code assignment, it is necessary to submit a provider query for clarification. 

Pain Due to Medical Devices

ICD-10-CM Chapter 19 contains codes that identify pain associated with medical devices that have been implanted or grafted into the patient’s body. Over time, medical devices may malfunction, fall apart, break, or simply continue to cause inflammation and pain as they are not a normal part of the human body. As discussed previously, when the encounter is for pain management (see “Encounter for Pain Control or Management” above) related to these devices, report the code for acute or chronic pain first, followed by a secondary code for the type of medical device causing the pain. 

Summary

As you can see, properly coding pain requires a thorough understanding of the different types as well as the code options. The provider’s documentation needs to provide the necessary information to ensure proper reporting. 

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