GERD ICD 10: K21.9, K21.00 and K21.01 Explained
The ICD-10 code for gastroesophageal reflux disease (GERD) without documented esophagitis is K21.9. For GERD with documented esophagitis without bleeding, use K21.00, and for GERD with documented esophagitis with bleeding, use K21.01. K21.0 is an incomplete subcategory and cannot be used as the final diagnostic code on a claim.
Although it may seem easy to assign an ICD-10 code when a patient has GERD and esophagitis, many providers have encountered a patient who has a list of complaints and a prolonged endoscopy report that does not support a reflux diagnosis. This document will help clarify which parts of the complaint or endoscopy report will determine code selection, when clarification may be necessary and which billing assumptions should not be made.
GERD codes at a glance
| Code | Meaning | Documentation that supports the choice |
|---|---|---|
| K21.9 | GERD without esophagitis | Established GERD or an indexed equivalent, without documented associated esophagitis |
| K21.00 | GERD with esophagitis, without bleeding | Reflux esophagitis or GERD with associated esophagitis; no bleeding identified in the documented diagnosis |
| K21.01 | GERD with esophagitis, with bleeding | The documented condition and applicable coding conventions support bleeding reflux esophagitis |
| K21 | GERD category | A classification heading, not a complete reportable diagnosis code |
| K21.0 | GERD with esophagitis subcategory | Requires selection of K21.00 or K21.01 |
This section cites terms, codes, and distinctions from the official ICD-10-CM Index and Tabular List. The three complete K21 codes are descriptive of documented findings; they do not ascribe a payment amount or define a level of office visit.
This resource is limited to U.S. ICD-10-CM. ICD-10 is published by the World Health Organization, while the U.S. Clinical Modification is maintained by the Centers for Disease Control and Prevention’s National Center for Health Statistics. A code shown in another country’s reference may have different reporting requirements.
Read the assessment before choosing a code
In the case of GERD, the reflux of stomach contents into the esophagus results in bothersome symptoms or complications. Heartburn and regurgitation are common symptoms of GERD, but the presence of either of these symptoms alone does not warrant a coding diagnosis.
Patients are often able to communicate the presence of heartburn, even if the patient has not formally been diagnosed with GERD. On the other hand, a clinician is able to make a diagnosis of GERD through an assessment, and an endoscopy is not always warranted.
According to NIDDK, clinicians are typically able to make a diagnosis of reflux disease based on the presence of symptoms and the patient’s medical history. Testing is often ordered to help identify complications of the disease, or if the patient’s symptoms remain unresolved or the diagnosis remains uncertain. Therefore, an endoscopy is not always necessary for K21.9 code assignment.
The responsible clinician is generally the one who made the final assessment. Context, including the patient’s symptom report, medication order and/or test orders, can help provide additional information. However, these do not give the coder the right to diagnose.
Using the examples above, if the clinician said: “heartburn, reflux disease possible”, then for outpatient coding, the condition is uncertain.
“GERD; treatment reviewed.” Provider has determined diagnosis, even in the absence of an endoscopy report.
Diagnostic certainty is the main distinction. A longer symptom list does not determine diagnostic certainty of an uncertain assessment.
There is an Index entry for acid reflux
The Alphabetic Index directs Esophageal and Gastroesophageal reflux to K21.9, unless additional information changes the choice.
This is important, because the exact term “GERD” is not required. A provider’s established diagnosis of Acid reflux supports K21.9, using the Index. A patient stating “food feels acidic” does not hold the same weight.
Read the term in context. If the assessment is vague, clarify. Replacing reflux with R12 across the record does not always appropriately reflect the patient record. Likewise converting all the symptoms to GERD does not always hold true to the record.
Choosing among K21.9, K21.00 and K21.01
K21.9: GERD Without Documented Esophagitis
K21.9 accommodates GERD without esophagitis, as well as esophageal reflux NOS (not otherwise specified). It uses inclusion terminology for both.
An assessment stating only GERD commonly follows the Index default to K21.9. The absence of an endoscopic finding negates the esophagitis diagnosis and therefore does not justify using K21.9.
K21.9 should not be used to validate the patient has mild symptoms. The code represents the absence of esophagitis, and should not be used to evaluate discomfort, treatment burden, or quality of life.
Consider this: does another part of the documentation establish the presence of esophagitis, or contradict the assessment? If so, resolve the contradiction and do not let the preselected diagnosis pass through unchanged.
K21.00: Reflux Esophagitis Without Bleeding
K21.00 captures GERD with esophagitis that has been demonstrated without bleeding. “Reflux esophagitis” is an inclusion term under this code.
The Index places “without bleeding” in parentheses in the relevant pathway. It is not necessary for a given diagnosis to include verbatim the phrase “without bleeding.” Therefore, a diagnosis of reflux esophagitis without bleeding follows the default pathway, and the absence of conflicting evidence justifies use of the code.
Esophagitis still must be documented. Isolated nonspecific esophageal mucosal erythema, or the prescription of an acid-suppressant, should not be a coder created diagnosis.
Also evaluate the type of esophagitis documented. Eosinophilic and medication-related esophagitis are not interchangeable terms with reflux esophagitis. Follow the documented term and its guidelines.
K21.01: reflux esophagitis with bleeding
K21.01 describes reflux esophagitis complicated by bleeding. The documentation needs to demonstrate the combined condition.
Bleeding reflux esophagitis can occur with other conditions that cause esophageal bleeding, and may be cited with other, unrelated, conditions, such as with an ulcer. The chart may not specify the source of the bleeding.
If reflux esophagitis is ruled out, and another bleeding condition is identified, for example, a bleeding lesion of the stomach, K21.01 is also warranted. Classification of each should be supported.
Multiple, sometimes contradictory, statements in the record may lead a coder to think a query is warranted. When there are contradictory statements, it is more productive to query the source of the bleeding rather than assume which statement is incorrect, or is more severe, and assign that code.
Use the “with” rule correctly
An association between conditions listed in the Index or Tabular List is generally assumed, unless documentation states they are unrelated, or other rules state they must be explicitly linked. Check the GERD pathway for linking rules before requesting a statement that conditions are unrelated.
This rule connects documented conditions, and does not convert a symptom to a diagnosis. It is productive to query the classification team regarding the actual, stated reason for a refusal to classify, rather than to demand a statement that does not fulfill classification requirements.
Heartburn, uncertain diagnoses and care settings
R12 identifies heartburn. It can be appropriate when heartburn is evaluated and the provider has not established GERD or another definitive explanation.
R12 is not a universal substitute for every reflux-like complaint. If the encounter documents dysphagia, abdominal discomfort or another symptom, investigate that documented term separately.
| Encounter situation | Coding approach |
|---|---|
| Office assessment says “possible GERD” | Report established symptoms or findings; do not code the uncertain disease as confirmed |
| Emergency department or observation assessment remains uncertain | Apply outpatient diagnosis-reporting rules |
| Qualifying hospital inpatient discharge diagnosis says “probable GERD” | Apply the hospital inpatient uncertain-diagnosis guideline |
| GERD is confirmed and heartburn is integral to it | Generally avoid separate reporting of the integral symptom |
The inpatient exception applies to the specified hospital inpatient reporting context. Being physically inside a hospital does not make an emergency department, observation or physician-office encounter an inpatient coding case.
A useful work-queue habit is to identify the claim setting before reviewing uncertain language. That keeps the same phrase from producing inconsistent decisions across different billing teams.
Excludes1 and Excludes2 notes that affect GERD coding
Describing only the codes provided can omit instructions tied to the category in which it is described. Refer to the hierarchical structure for completeness.
Excludes 1: reporting of newborn reflux and duplicate esophagitis
Excludes 1 note for newborn esophageal reflux states that this is coded as P78.83 rather than being coded with both classifications for the same condition. Similarly, K20 also states that reflux esophagitis and esophagitis associated with GERD will be excluded, when classified under K21.0-. Thus, adding an unspecified esophagitis code for a documented case of reflux esophagitis may be duplicative.
Per the guidance of an Excludes 1 note, in the majority of cases, it is not allowed to report the two codes together. There is an exception to this, which states that both codes may be reported when the conditions are clearly unrelated. Medical Billing and Coding Services team members should review the complete case record to determine if the exception applies. Team members may not report a condition more than once simply because there are multiple documents that state that condition. Newborn reflux requires special consideration and review of perinatal coding rules. It is suggested that an automatic age-related classification substitution be made in the billing system only when there is clear documentation by the Provider to support that reflux is present.
Excludes 2: hiatal hernia note is above K21
The section K20-K31, covering esophageal, stomach and duodenal diseases, has an Excludes 2 note for hiatus hernia, K44.-. This is an inherited section instruction relevant to K21.
Excludes 2 generally indicates the excluded condition is located elsewhere, and can coexist with the condition. Documented GERD and a separately reportable hiatal hernia, in case supported by the record, can be coded together. K21 doesn’t have a category-specific Excludes 2 note.
It should be noted that the presence of permission for both conditions does not mandate that the conditions be coded. The hernia should be documented, and should also meet the criteria for coding for the condition to be reported.
Related codes: use the condition actually documented
GERD does not explain every digestive finding. These related codes help distinguish symptoms, separate diagnoses and complications.
| Code | Condition | Practical distinction |
|---|---|---|
| R12 | Heartburn | A symptom code when appropriate; not a substitute for established GERD |
| R13.10 | Dysphagia, unspecified | Use the documented swallowing diagnosis; investigate greater specificity when available |
| R13.11 | Dysphagia, oral phase | Oral-phase difficulty is more specific than unspecified dysphagia |
| K20.90 | Unspecified esophagitis without bleeding | Follow the esophagitis pathway when reflux esophagitis is not the supported classification |
| K20.0 | Eosinophilic esophagitis | A distinct diagnosis that should not be inferred from reflux symptoms |
| K22.2 | Esophageal obstruction | Includes acquired esophageal stricture in the Tabular List |
| K22.70 | Barrett’s esophagus without dysplasia | Report the supported Barrett’s diagnosis separately when applicable |
| K22.710 | Barrett’s esophagus with low-grade dysplasia | Requires the low-grade dysplasia classification |
| K22.711 | Barrett’s esophagus with high-grade dysplasia | Distinct from low-grade dysplasia |
| K22.719 | Barrett’s esophagus with unspecified dysplasia | Dysplasia is documented, but its grade is unspecified |
| K44.9 | Diaphragmatic hernia without obstruction or gangrene | Often applies to an appropriately documented hiatal hernia |
| K30 | Functional dyspepsia | A separate diagnosis from GERD |
| K31.84 | Gastroparesis | Does not mean functional dyspepsia |
The descriptions of the codes and their hierarchical relationships are verified in the official Tabular List; CMS also lists many of these codes in their endoscopy billing resources.
Two distinctions should be made. First, K22.71 is a subcategory and is not the complete code to report low-grade dysplasia. Second, assigning a G code for complication of GERD for esophageal stricture is not correct.
Barrett’s esophagus is not interchangeable with GERD if both conditions are documented. The same is true for a hiatal hernia. Which diagnosis is listed first depends on what the primary concern of the visit was and what the standard conventions of the practice are.
Coding for pregnant patients also requires a review of the applicable obstetric coding and coding for GERD, especially if the patient is pregnant and has reflux. The general GERD table is not a substitute for that review.
Documentation that makes the coding decision clear
A note that summarizes the assessment and provides rationale for any tests ordered is very helpful to reviewers. This note will help the reviewer understand the encounter and why a particular test was ordered and what diagnosis was accepted.
For providers
Key elements to document include:
- Diagnostic conclusion: Established GERD, other diagnosis or symptom, or other diagnosis under consideration.
- Esophagitis: Type (e.g. Acid-related, non-acid-related, eosinophilic), if reflux is present, if there is association.
- Bleeding: if the source is determined, or if the source is unknown.
- Other conditions: Hernia, Barrett’s esophagus, stricture, or other relevant condition.
- Clinical judgment: Reason for the test ordered or change in management
- Plan: Interventions ordered or other management strategies
These are prompts and may or may not be applicable to a given situation. A “typical” outpatient office visit may require very little rationale as compared to an endoscopy.
Findings need to be documented and diagnoses need to be made. Descriptions of findings in a procedure report are separate from the final impression.
For coders
Read all pertinent documentation and procedure reports. Pick out pertinent information that changes the code, and check the instruction manuals.
Use the focused discrepancy list:
- Is the assessment supporting the selected diagnosis?
- Is a procedure impression reflecting a different condition?
- Is a problem list entry that was imported by the provider different from the provider’s assessment?
- Is additional information needed to describe a complication?
- Is the question really about diagnosis reporting, or more about coverage of the service?
If clarification is necessary, describe the conflicting clinical information in a neutral manner. Avoid asking the clinician to document esophagitis, for example, just because a payer accepts that diagnosis for a particular procedure.
An audit that helps to resolve an issue is the most effective type of audit. “Problem-list mismatch” is more helpful than “wrong code” because it identifies the area of the workflow in need of correction.
Practical coding examples
These examples are based on real world scenarios encountered by coders and are provided to illustrate the types of documentation decisions that are part of the normal routine review performed by a medical coding services organization. These examples are not derived from actual patient records.
Example 1: Established diagnosis without endoscopy
Assessment: “GERD. Acid regurgitation and heartburn discussed; medication plan reviewed.”
Coding decision: K21.9 is assigned, as the complete record does not document related esophagitis or a contradictory diagnosis.
Practical lesson: The absence of the endoscopy report does not permit removing an established diagnosis of GERD and replacing it with a V20.X symptom code. The assessment indicates the provider’s judgment, which goes beyond the nature of the presenting complaint.
Example 2: Procedure impression conflicts with coded diagnosis
Assessment: “GERD with reflux esophagitis, without bleeding.”
Charge entry: K21.9 is selected for this encounter.
Coding decision: The documented diagnosis supports K21.00. Correct the diagnosis selection in accordance with the authorized coding process of the organization and reconcile any conflicting chart statements.
Practical lesson: A populated diagnosis field does not always mean the code has been confirmed against the completed report. Review the clinical source of the field.
Example 3: Bleeding is documented elsewhere
Assessment: “GERD without esophagitis. Gastrointestinal bleeding attributed to a separate gastric lesion.”
Coding decision: The bleeding does not change the GERD diagnosis to K21.01. Code the other condition from its documented source and follow the pertinent sequencing rules.
Practical lesson: Just because a claim contains GERD and bleeding does not mean the bleeding is from reflux esophagitis. The relationship between the diagnosed conditions and the anatomical location are important.
Example 4: Heartburn is still under investigation
Assessment: “Heartburn; possible GERD. Additional evaluation planned.”
Coding decision: It is possible R12 represents the documented symptom. The uncertainty with the diagnosis of GERD in this case is outpatient, and so it would not be reported as confirmed.
Practical lesson: The work done does not determine the level of diagnostic certainty. An assessment may correctly end in a code for a symptom.
Connect the diagnosis to the billed service
ICD-10-CM identifies the condition or reason for care. Procedure codes describe the work performed. A supported diagnosis and a correctly selected procedure must each stand on their own documentation.
For upper endoscopy, two commonly encountered CPT codes are:
| CPT code | Plain-language description | Review point |
|---|---|---|
| 43235 | Diagnostic upper gastrointestinal endoscopy | Confirm the documented procedure |
| 43239 | Upper gastrointestinal endoscopy with biopsy | Confirm that the report documents tissue sampling |
Do not separately report the diagnostic endoscopy merely because visual inspection occurred as part of the biopsy procedure. CMS NCCI guidance treats the diagnostic component as included in the surgical endoscopy. 6
K21.9 does not necessarily contradict an endoscopy claim
A claim linking K21.9 to an endoscopy with a biopsy does not automatically contradict. A biopsy could be to help diagnose a condition that has not been established as esophagitis.
For example, in a CMS coverage article A57063, K21.9 is listed among other diagnoses in a procedure group that includes both 43235 and 43239. That is a particular contractor article, and not a universal coverage statement. The associated policy and coverage criteria, as well as clinical conditions, apply. 5
Review the indication, plan requirements, authorization and documentation of the procedure. Never change K21.9 to K21.00 to make a diagnosis fit a coverage listing.
Modifiers pertain to eligible services only
Don’t add modifiers to K21.9. Determine if a procedure or E/M service meets the requirements of modifier eligibility, and add the appropriate modifier according to billing rules.
The requirements for modifier 25 are met if a significant, separately identifiable E/M service is performed in addition to the diagnostic endoscopy. A second diagnosis alone, for example, does not justify the use of modifier 25. Adding modifier 59 or an X modifier to bypass a bundling edit is not justified either. 7
Make complex modifier decisions on a case-by-case basis. Generally, a GERD diagnosis does not justify a higher level of service for the E/M or for the procedure.
Common GERD coding and claim mistakes
Treating every incomplete field as a missing diagnosis
An assessment may support an Index default even if every descriptor isn’t fully documented. Identify legitimate defaults and distinguish them from contradictory documentation to minimize queries.
Coding the complication suggested by the procedure
Just because a biopsy was done to evaluate esophagitis doesn’t mean that esophagitis is diagnosed. Similarly, just because a dilation was done to treat a presumed stricture doesn’t mean esophageal stricture is diagnosed. Code the complication based on the procedure that was performed and the diagnosis that was established.
Adding every symptom to an established diagnosis
Adding more lines of diagnosis does not improve the description of the service provided. Determine if the symptom is needed for a diagnosis to be confirmed and if it’s independently reportable. Don’t copy an entire list of symptoms to the claim.
Using a denial as evidence that the diagnosis is wrong
Read the remittance advice before changing a code. X12 adjustment reasons distinguish different problems:
| CARC | Plain-language issue | Useful review |
|---|---|---|
| 4 | Procedure and modifier conflict | Check the modifier and service combination |
| 16 | Missing information or a submission error | Read the accompanying remark code |
| 50 | Payer medical-necessity determination | Compare the documentation with the applicable policy |
These adjustment reasons are not exclusive to GERD. In particular, CARC 4 is not a general label for a diagnosis-to-procedure mismatch. 8
Assign the follow-up work to the right person. Registration errors belong with the team that owns demographic data; unclear assessments belong with the provider-query process; coverage disputes require policy and appeal review. Repeatedly resubmitting an unchanged claim does not address the underlying issue.
A focused claim-review checklist
Use this checklist along with the clinical record:
- Confirm that the assessment meets the criteria for GERD or an equivalent.
- Documented esophagitis, and bleeding details, if any.
- Resolve conflicting diagnoses, rather than choosing from isolated phrases.
- Review the complete code and the instructional notes, if any.
- Review whether the other conditions meet the reporting threshold.
- Confirm that all the relevant diagnoses for each service are linked to that service.
- Review the details of the procedures, bundling and modifier requirements.
- Review coverage and the requested justification.
For an audit sample, separate selection of codes from coverage and claims format issues. Usually, distinguishing code-selection errors from coverage and payment-related issues yields the most useful findings to both the clinical and the billing staff.
Frequently asked questions
What is the ICD-10-CM code for GERD unspecified?
K21.9 is generally the Index default when the provider documents GERD without additional detail. Its descriptor is GERD without esophagitis, and it includes esophageal reflux NOS. Contradictory documentation still needs review.
Is K21.0 a billable GERD code?
K21.0 is an incomplete subcategory. Select K21.00 for GERD with esophagitis without bleeding or K21.01 for GERD with esophagitis with bleeding when supported.
Can GERD be coded without an endoscopy?
Yes. A clinician can establish GERD through an appropriate clinical assessment. A coder should not infer the diagnosis solely from medication use or patient-reported symptoms.
Can R12 and K21.9 be reported together?
Heartburn that is integral to established GERD is generally not separately reported. Check the documented circumstances and applicable rules rather than routinely adding R12 to a GERD claim.
Which code applies to GERD with esophagitis and bleeding?
K21.01 applies when the documented diagnosis and coding conventions support that combined condition. Bleeding from a separate gastrointestinal source does not automatically change the GERD code.
Can GERD and a hiatal hernia both be coded?
Yes, when both are documented and separately reportable. K44.9 may apply to a hiatal hernia without obstruction or gangrene. Select the GERD code independently and sequence the diagnoses according to the encounter and coding instructions.
Place the documentation and claim side by side
There are a few important distinctions to make when determining GERD code assignments. These include any established diagnosis, esophagitis, bleeding, and separately reportable conditions. Check your work against the service documentation and the complete code.
Look at a particular GERD encounter and assess whether it is appropriate for coding. If the assessment and/or the claim and/or procedure report do not agree with one another, resolve the disagreement or obtain a focused coding review before submitting your work.
