Radiology Coding Alert

The key to success begins and ends with a knowledge of the terminology.

An overweight patient with hypertension presents for imaging complaining of severe pain, swelling, and heat in the joint of the big toe on his right foot. The indication reports excessive alcohol use and a diet rich in meat and high-fructose foods.

After reviewing the patient’s scans, the radiologist arrives at a diagnosis of gout. The next step in the process is arriving at the correct diagnosis code. But as you will see, that’s sometimes easier said than done.

Use these helpful tips and expert feedback to get you confidently coding any and all gout diagnoses that come your way.

Step 1: Know the Terminology

First, some background definitions to help get you started. Gout belongs to a class of diseases known as crystal-induced arthropathies. An arthropathy is a disease of a joint in the body, and this particular group of arthropathies is distinguished by inflammation in the joint, or the tissues around the joint, caused by a buildup of crystal deposits in the joint itself.

Coding caution:  One problem facing coders involves providers using numerous terms that describe similar, yet slightly different, conditions. “It is very common for providers to state gouty arthropathy, gouty arthritis, or pseudogout,” says Ruby O’Brochta-Woodward, BSN, CPC, CPMA, CPB, COSC, CSFAC,  coding and compliance manager at Suburban Imaging in Minneapolis, Minnesota.

“Gout is due to monosodium urate crystal deposition, while pseudogout is caused by calcium pyrophosphate crystals, a different crystalline deposition,” O’Brochta-Woodward continues. “Pseudogout should be coded to M11.2- [Other chondrocalcinosis] group, where you would look to the anatomical location of the patient’s condition for specificity.”

As for gouty arthropathy or gouty arthritis, “if the provider stated either of these in the dictation report, you would need more information to code them to a further degree of specificity. Otherwise you will use the unspecified code M10.9 [Gout, unspecified] instead,” says Melanie Witt, RN, CPC, MA, an independent coding expert based in Guadalupita, New Mexico.

Step 2: Know Acute or Chronic

The next piece of information you will need from your provider to help guide you to the right code choice will be a determination of the condition as either chronic or acute. For chronic gout, you’ll use the M1A (Chronic gout) group; for acute, the M10 (Gout) group.

Avoid 7thcharacter confusion: Aside from documenting the different manifestations of the condition, the other major difference between the M1A and M10 code groups is that only one — M1A — takes an additional seventh character, either 0 or 1, to mark the absence or presence of tophi, respectively. “This is because tophi, which are deposits of urate crystals in the joints, usually only appear with a patient with chronic gout,” says Witt. “In other words, the body can’t get rid of the number of urates produced over time. This leads to crystal formation. In the acute state, there has not been enough time for this to happen,” Witt notes.

So, to document drug-induced chronic gout in the patient’s left ankle and foot with tophi, you would report M1A.2721.

Step 3: Know Cause, Primary or Secondary

Both the M1A.- and M10.- code sets make a distinction between primary or secondary gout, which is gout caused by a medication or another medical condition. The codes are then broken down by etiology using the following fourth characters:

• MXX.0 — Idiopathic gout (meaning that the gout has occurred spontaneously, and the cause is unknown)
• MXX.1 — Lead-induced gout
• MXX.2 — Drug-induced gout
• MXX.3 — Gout due to renal impairment
• MXX.4 — Other secondary gout
• MXX.9 — Unspecified.

When your provider assigns a secondary gout code group, such as renal failure with MXX.3, make sure you obey the code first notes associated with the code groups. In the case of renal failure, for example, that note reads “code first associated renal disease.” For other secondary gout causes besides lead, drugs, and renal impairment, you will go to MXX.4 and follow the instructions to code the associated condition first. So, for a patient that has chronic gout without tophi in the right ankle and foot due to arthropathic psoriasis, you would code L40.5- (Arthropathic psoriasis) first, followed by M1A.4710 (Other secondary chronic gout, right ankle and foot, without tophus (tophi)).

Step 4: Know Anatomic Location

The last, and easiest, step in coding gout is to assign the correct anatomic location to the affected joint. You will simply assign one of the following fifth characters, such as 2 for the elbow or 7 for the ankle and foot, then indicate laterality (where applicable), following the usual ICD-10 convention, with a sixth character 1 (right), 2 (left), or 9 (unspecified).

One Final Piece of Advice

“Coders often have difficulty when providers do not specify the type of crystalline arthropathy patients have,” says O’Brochta-Woodward. “We have the option of hydroxyapatite deposition, calcium pyrophosphate, calcium oxylate, and other crystal deposition diseases. Without a specific type, we must default to unspecified, not other,” O’Brochta-Woodward concludes.

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