K21.0 — Gastro-esophageal reflux disease with esophagitis, without bleeding

Clinical Definition

Gastro-esophageal reflux disease (GERD) with esophagitis is a condition in which chronic retrograde flow of gastric acid and digestive enzymes into the esophagus causes visible mucosal inflammation, erosion, or ulceration of the esophageal lining. Unlike uncomplicated GERD, where reflux symptoms are present without endoscopically confirmed mucosal injury, K21.0 specifically denotes cases where esophagitis has been identified, typically via upper endoscopy (esophagogastroduodenoscopy). The inflammatory changes may range from mild erythema and edema to deep erosions, and the condition often presents with heartburn, regurgitation, dysphagia, odynophagia, and chest pain.

ICD-10-CM code K21.0 is used when the provider documents GERD with esophagitis in the absence of bleeding. This code is distinct from K21.9, which captures GERD without esophagitis (i.e., symptomatic reflux without endoscopic evidence of mucosal damage). It is also distinct from K21.01, which is assigned when GERD with esophagitis is accompanied by bleeding. The differentiation between K21.0 and K21.9 hinges entirely on whether esophagitis has been confirmed or documented by the treating provider; symptoms alone, without documentation of esophagitis, do not support assignment of K21.0.

The severity of reflux esophagitis is commonly graded using the Los Angeles (LA) classification system, which ranges from Grade A (one or more mucosal breaks no longer than 5 mm) through Grade D (mucosal breaks involving at least 75% of the esophageal circumference). While ICD-10-CM does not require a specific LA grade for code assignment, documenting the grade supports medical necessity for treatment intensity, particularly for long-term proton pump inhibitor (PPI) therapy, fundoplication referral, or advanced endoscopic interventions. Standard first-line treatment includes PPIs, H2 receptor antagonists, and lifestyle modifications, with surgical options such as Nissen fundoplication or magnetic sphincter augmentation reserved for refractory cases.

When to Use K21.0

• ✓The patient has undergone upper endoscopy (EGD) that reveals esophageal mucosal inflammation, erosion, or ulceration consistent with reflux esophagitis, and no bleeding is documented.
• ✓The provider documents a diagnosis of GERD with esophagitis or reflux esophagitis without any mention of associated gastrointestinal bleeding.
• ✓A patient with chronic GERD symptoms is found on biopsy to have histologic evidence of esophagitis attributable to acid reflux, without bleeding.
• ✓The clinician documents erosive esophagitis on endoscopy with a Los Angeles classification grade (A, B, C, or D) in the absence of bleeding.
• ✓The patient is being managed for known reflux esophagitis with proton pump inhibitor therapy, and the current encounter documents esophagitis without bleeding.
• ✓A follow-up endoscopy confirms persistent or recurrent esophagitis in a patient with GERD, with no evidence of hemorrhage or hematemesis.

Common Coding Mistakes

Related & Differential Codes

Documentation Requirements

• 1Presence of esophagitis: documentation must explicitly state esophagitis, erosive esophagitis, or reflux esophagitis to support K21.0 — symptoms of reflux alone are insufficient.
• 2Absence of bleeding: the record should indicate that there is no associated gastrointestinal bleeding (hematemesis, melena, or endoscopic hemorrhage); if bleeding is present, K21.01 applies.
• 3Diagnostic basis: document whether esophagitis was confirmed via upper endoscopy (EGD), biopsy with histologic findings, or clinical diagnosis by the treating provider.
• 4Severity grading: when endoscopy is performed, include the Los Angeles classification grade (A through D) or descriptive severity to support medical necessity for treatment.
• 5Associated symptoms: document relevant symptoms such as heartburn, regurgitation, dysphagia, odynophagia, chest pain, or chronic cough to establish the clinical picture.
• 6Treatment plan: document current and planned therapies including PPI therapy (drug, dose, duration), H2 receptor antagonists, lifestyle modifications, or surgical referral.
• 7Underlying risk factors: note contributing conditions such as hiatal hernia, obesity, tobacco use, or medications that reduce lower esophageal sphincter pressure.
• 8Follow-up plan: document the surveillance strategy including repeat endoscopy intervals, Barrett's esophagus screening if applicable, and criteria for escalation of care.

Reimbursement & Billing Notes

ICD-10-CM code K21.0 is a valid, billable code accepted by Medicare, Medicaid, and commercial payers for encounters related to GERD with esophagitis. It supports reimbursement for diagnostic services including upper endoscopy (CPT 43235-43259), esophageal pH monitoring, and esophageal manometry, as well as ongoing medical management. Payers generally consider K21.0 sufficient medical necessity for initial and surveillance EGD, particularly when documenting erosive esophagitis severity or screening for Barrett's esophagus. Claims submitted with K21.0 should be supported by documentation confirming the presence of esophagitis to withstand audit scrutiny.

For risk adjustment purposes under CMS-HCC models, K21.0 does not map to a hierarchical condition category and therefore does not directly impact RAF scores. However, accurate coding of GERD with esophagitis is important for quality measure reporting, appropriate resource utilization tracking, and supporting medical necessity for long-term PPI therapy and procedural interventions. Payers may deny claims for repeat endoscopy if the documented diagnosis is only K21.9 (GERD without esophagitis), so ensuring the correct code is assigned when esophagitis is present directly affects procedural reimbursement and reduces the risk of claim denials or downcoding.

Frequently Asked Questions