Gastroenterology Coding Alert

Remember: Time is a factor when choosing between 91037 and 91038.

If your gastroenterologist performs impedance and pH testing on the same date of service, you simply apply the 9103x series and move on, right? Not so fast. Check out the following case study to determine when you have to take time into account and how you can select the most appropriate codes for every situation.

Scenario: The provider performs impedance and pH testing for over an hour. The patient, who complains of frequent and painful heartburn, leaves the office with the catheter in place until the next day.

The key to selecting the most appropriate code for this situation is to understand what each code entails, but don’t just base your choice on the obvious. You should give weight to National Correct Coding Initiative (NCCI) edits, too. These guidelines should keep you on the right track.

1. Turn to 91037-91038 For Impedance Catheter

When reporting esophageal function (impedance) tests, you have two main codes to peruse:

• 91037 (Esophageal function test, gastroesophageal reflux test with nasal catheter intraluminal impedance electrode(s) placement, recording, analysis and interpretation)
• 91038 (… prolonged (greater than 1 hour, up to 24 hours))

When reviewing these codes, you’ll note that the descriptors for 91037 and 91038 depict time measurements, which means you should apply 91037 for testing that lasts up to one hour. If the monitoring spans more than an hour, bill 91038 instead. However, you shouldn’t report both codes for the same test. You should apply only a single code to report the session.

What happens: During an impedance test, the catheter enters the patient’s body transnasally. This test measures bolus transit dynamics with either pH measurement or esophageal muscular function in the evaluation of symptoms including chest pain, swallowing difficulty, or chronic heartburn unresponsive to medication. Sometimes, physicians would perform these tests in combination with manometry or pH testing.

Both motility study (manometry) and esophageal function testing use a nasal catheter. However, the impedance probe is multipurpose and measures more things than the motility test (91010, Esophageal motility (manometric study of the esophagus and/or gastroesophageal junction) study with interpretation and report) or the gastroesophageal reflux test (91034, Esophagus, gastroesophageal reflux test; with nasal catheter pH electrode(s) placement, recording, analysis and interpretation).

2. Sole Code Describes Cather-Based pH Test

When a gastroenterologist provides an esophageal acid reflux test using either a disposable or a reusable nasal catheter, you would report 91034.

Pointer: Make 91034 your go-to code regardless of how long the nasal catheter remains in place. Typically, however, the physician will leave the catheter in place for about a day. In the past, you had to distinguish between standard and “extended” pH monitoring. Currently, only one code (91034) describes a catheter-based pH service.

On the other hand, if your gastroenterologist conducts pH testing using a Bravo capsule, you will turn to 91035 (Esophagus, gastroesophageal reflux test; with mucosal attached telemetry pH electrode placement, recording, analysis and interpretation) instead of 91034.

3. Beware What NCCI Edits Say

The scenario describes both impedance and pH tests being performed in one session. If you think coding it is as easy as billing 91038 and 91034, then you’re incorrect.

Dodge a potential audit by looking into another important factor: NCCI edits.

Edit alert: Codes 91038 and 91034 are bundled, according to NCCI version 28.0, which went into effect on Jan. 1, 2022. Check out the NCCI edits table and you’ll see 91034 described as the more extensive code. Since the 91038/91034 edit carries a modifier indicator of “0,” you cannot override the edit by using a modifier such as 59 (Distinct procedural service).

For that reason, you would bill the given scenario with only 91034. Link R12 (Heartburn) to 91034 to describe the patient’s condition.