Understanding Gastroesophageal Reflux Disease and ICD-10-CM Coding

by  Aimee L. Wilcox, CPMA, CCS-P, CST, MA, MT
Aug 22nd, 2023

GERD stands for Gastroesophageal Reflux Disease, a chronic condition where stomach acid flows back into the esophagus, causing a range of symptoms, such as heartburn, regurgitation, chest pain, difficulty swallowing, and a chronic cough. GERD occurs when the lower esophageal sphincter (LES), a muscular ring that normally prevents the backflow of stomach acid, becomes weak or relaxes inappropriately, allowing the backward flow of stomach acid and contents into the esophagus. Stomach acid is a highly acidic fluid produced by the cells that line the stomach walls. It is primarily made up of hydrochloric acid (HCI), but contains other substances like enzymes, mucus, and electrolytes. 

It's important to note that millions of people suffer from the symptoms of GERD on a daily basis, signifying that GERD is a very common condition being reported in medical records each day, so understanding what to look for in the documentation to support code selection for this disease is important. 

GERD may be identified as the underlying cause of other conditions, such as Barretts esophagitis, among other conditions. Barretts esophagitis is a condition where the normal lining of the esophagus is replaced by abnormal cells, usually from exposure to long-term acid reflux from GERD. These abnormal esophageal cells, if left unmonitored alongside a chronic GERD condition, can lead to dysplastic or cancerous changes, requiring more aggressive treatment. 

The ICD-10-CM code set is a medical coding and classification system used to report diseases, illnesses, injuries, symptoms, and other related health problems. Within this coding system is category K21.- Gastro-esophageal reflux disease,” which is further broken down into the following code options: 

• K21.00 Gastro-esophageal reflux disease with esophagitis, without bleeding
• K21.01 Gastro-esophageal reflux disease with esophagitis, with bleeding
• K21.9 Gastro-esophageal reflux disease without esophagitis

GERD without esophagitis and without bleeding is the least severe stage of the disease reported with K21.9. If the medical record does not identify esophagitis (inflammation or irritation of the esophagus) or bleeding then K21.9 should be reported. 

Coders are aware that coding guidelines differ when coding records in inpatient versus  outpatient settings. According to the Official ICD-10-CM Coding Guidelines, when GERD is suspected, but not yet confirmed (e.g., differential diagnosis) in the inpatient setting, it may be reported as if it has been confirmed. However, in the outpatient setting, suspected, rule out, or differential diagnosis statements are not considered as confirmed diagnoses and cannot be assigned. When language is used to describe possible diagnoses in the outpatient setting, coders are instructed to report the patient’s symptoms instead; until a confirmed diagnosis is documented by the treating provider. 

To diagnose GERD, and of course rule out other conditions or associated conditions, healthcare providers may perform or order the following: 

• Medical history: This includes a detailed history of when the patient’s symptoms began, such as heartburn, regurgitation, chest pain, or chronic cough as well as identifying any remedies the patient may have used with some success (e.g., over-the-counter antacids, digestive enzymes). Identifying the makeup of the patient’s diet, such as processed or greasy foods, large amounts of caffeine, or even gluten, can assist the provider in identifying patterns that may help identify the likelihood of GERD.
• Physical examination: Examination of the throat, mouth, and dentition can provide additional evidence of GERD or rule out other causes of the patient’s symptoms.
  Esophagogastroduodenoscopy (EGD) or upper endoscopy: This procedure involves inserting a thin, flexible tube with a camera (endoscope) through the mouth and into the esophagus and stomach to visualize structures, mucosal linings, and possibly part of the small interesting where absorption occurs. It can help identify the presence of esophagitis, bleeding, ulcers, strictures, hiatal hernia, or other abnormalities.
• Esophageal pH monitoring: This is a test that measures the acidity (pH) levels in the esophagus over a 24-hour period. A thin tube is placed through the nose or mouth and into the esophagus and then connected to a portable device and over the following 24 hours, the patient will journal any symptoms, dietary intake, and activities performed while the device records the various pH levels.
• Esophageal manometry: This test measures the function and strength of the esophagus and LES by inserting a thin tube through the nose or mouth and into the esophagus. Once positioned in the esophagus, the patient is asked to swallow to allow it to measure the strength of the muscle contractions and coordination of the esophagus in its functionality.
• Upper GI or Barium swallow: This test involves drinking liquid barium a contrast or barium sulfate suspension, which is a radiopaque substance used in imaging procedures to enhance vizualization of structures that are difficult to see in the gastrointestinal tract. Once the barium coats the lining of the esophagus, stomach, and upper part of the small intestine, X-rays are taken to look for any abnormalities.

Understanding the disease and how it is diagnosed, along with the definitions of key words in the code description allow coders to better understand what to look for in the documentation in order to assign the correct ICD-10-CM code. Of note, it is best to set internal policies on what portions of the medical record should be used to locate information for reporting chronic conditions or the details that provide better options for higher-specificity coding. 

Problem lists that are not updated or chronic conditions that were not addressed during the patient’s encounter are not good sources for coding and can lead to incorrect coding and inappropriate reimbursement either to the provider or payer (e.g., risk adjustment). Educating providers on clearly documenting all problems addressed during the encounter or those chronic conditions that while not treated, did have an impact on the provider’s treatment decisions for the problems that were addressed, is vital in promoting documentation that supports medical necessity and high-specificity code assignment. 

About Aimee L. Wilcox, CPMA, CCS-P, CST, MA, MT

Aimee L. Wilcox is a medical coding, billing, and auditing consultant, author, and educator with more than 30 years of clinical and administrative experience in healthcare, coding, billing, and auditing. Medicine, including coding and billing, is a constantly changing field full of challenges and learning and she loves both. Aimee believes there are talented medical professionals who, with proper training and excellent information, can continue to practice the art of healing while feeling secure in their billing and reimbursement for such care.