Primary Care Coding Alert

Hint: Gain some insight on medical necessity, too.

Injection encounters are easy to miscode for a variety of reasons. You can misrepresent billable units, not supply adequate support to prove medical necessity, and more.

We’ve compiled these three common injection myths to help you clear up any lingering confusion.

Myth 1: You Can’t Report Allergy Shots Without Supply Codes

It’s true that when patients come in for shots, you’re generally looking for codes to account for the injection as well as the product itself. However, that won’t be the case when the provider doesn’t supply the medication.

When the medication comes from another source, such as the patient supplying their own allergy immunotherapy agent, you’ll turn to injection-only codes that represent only the administration of the extract prepared by another physician or other source. Which code you use will depend on how many injections the provider performed.

If your physician provided only one injection, reach for CPT^® code 95115 (Professional services for allergen immunotherapy not including provision of allergenic extracts; single injection). If your physician provides more than one injection, use 95117 (Professional services for allergen immunotherapy not including provision of allergenic extracts; 2 or more injections) to report the allergy immunotherapy services that your physician performed. The code involves the observation service (to check for allergic reactions) that your physician or the clinical staff performed after the injection.

Reminder: If your physician administered the antigens sublingually (i.e., by placing drops under the patient’s tongue), then you cannot report the service using 95115 or 95117, since there is no injection involved. Note that antigen(s) administration is reported with 95115 or 95117 only if it is injected by your provider. For an encounter involving sublingual administration of an antigen, consider reporting the appropriate evaluation and management (E/M) service instead.

Myth 2: Dose is the Same as Volume when Billing Units

Dose is not the same as volume, but with the different units of measurement you’re looking at, it’s easy to understand the confusion.

When drugs are administered in a liquid form, the active drug is suspended in the liquid. When this happens, the drug concentration is often expressed in units of mg/mL, where the amount of the drug, measured in milligrams (mg), is expressed alongside the amount of the liquid, measured in milliliters (mL).

Two doses of the same amount of drug may involve different volumes if the concentration is different. For example, let’s say a physician wants to administer 10 mg of dexamethasone sodium phosphate to a patient. If the physician uses a 10 mg/ ml concentration, the volume will be 1 ml. However, if the physician uses a 4 mg/ml concentration, the volume will need to be 2.5 ml to equal the same 10 mg.

When choosing the correct number of billing units, look at the code descriptor for the drug administered. For dexamethasone sodium phosphate, the HCPCS Appendix 1 – Table of Drugs directs you to J1100 (Injection, dexamethasone sodium phosphate, 1 mg). The descriptor for J1100 not only tells you what the drug is, but it also tells you the units used to bill the drug — in this case, 1 mg.

In this example, the physician administers a 10 mg dose, so the calculation is easy: As the billing unit is 1 mg, you will bill for 10 units. This is true whether the volume is 1 ml or 2.5 ml. The descriptors for other drugs may define the billing unit in volume, so let the code descriptor guide how many units you report.

Myth 3: Injection Diagnosis Codes are Enough to Prove Medical Necessity

When a patient has a painful condition, such as osteoarthritis, that’s not necessarily enough to prove medical necessity for injection of medication.

Let’s say your provider diagnoses an older patient with primary osteoarthritis of the left knee, coded to M17.12 (Unilateral primary osteoarthritis, left knee), and decides to treat the condition by injecting the knee with hyaluronate, which you document with the appropriate number of units of J7325 (Hyaluronan or derivative, Synvisc or Synvisc-One, for intra-articular injection, 1 mg) and 20610 (Arthrocentesis, aspiration and/or injection, major joint or bursa (eg, shoulder, hip, knee, subacromial bursa); without ultrasound guidance).

On the surface, such treatment may meet the accepted standards and reasonable and necessary definitions of medical necessity. However, not all payers will agree. You may be

facing a payer who argues that the injection is only medically necessary if the patient has experienced the condition for six months or more; if the osteoarthritis was classified as grade II or III as confirmed by X-ray; and if the patient had already undergone other, more conservative treatment for the condition such as physical therapy, weight loss, and/or analgesic medication. The payer is not going to get any of that information from the diagnosis code.