Nearly 555,000 people in the United States are on dialysis, making dialysis billing key to a practice’s revenue success. However, dialysis billing is challenging to master, even for the most experienced billers. Why? Because often, situations arise where standard dialysis CPT codes cannot accurately describe the provided services. This makes fair reimbursement collection difficult because if providers don’t know what to bill for, the insurance payers will not be able to pay.
In these scenarios, billers must use unlisted codes, like CPT code 90999. So, how can you effectively use 90999 to tackle these ambiguous situations? Let’s find out.
CPT Code 90999 – Description
CPT code 90999 is defined as:
“Unlisted dialysis procedure, inpatient or outpatient.”
CPT 90999 is the last code in the dialysis code range 90935-90999. However, unlike other codes in this range, 90999 is unlisted. You may wonder what unlisted means. Well, this code serves as a catch-all for all dialysis services that don’t have specific CPT codes assigned to them. These situations happen more often than you think. However, not all of them will be valid for 90999.
You must use 90999 only as a last resort. It is not meant for routine use. If you can find a specific code that applies to your case, you must first consider that code. If you try to use 90999 irresponsibly, it can cause claim denials and even audits.
Additionally, the use of CPT code 90999 as an unlisted code becomes a little blurry when it comes to End-Stage Renal Disease (ESRD) billing. That is because, in the case of ESRD, the Centers for Medicare and Medicaid Services (CMS) requires you to use 90999 as the basic billing code, like any other ordinary code. This becomes especially important when the ESRD routine hemodialysis session exceeds the standard frequency of three times per week. This dual nature of use makes 90999 both a true “unlisted” code and a specific billing requirement, like other ordinary codes.
Scenarios Where CPT Code 90999 is Applicable
To make things even clearer and easier to understand, let’s look at a couple of real-world scenarios in which this code can be used.
Routine ESRD Hemodialysis
Let’s consider an example of a 58-year-old patient who is suffering from ESRD. After trying and failing at all possible treatments, the only option left is hemodialysis. The patient needs maintenance hemodialysis three times per week at an outpatient dialysis facility. The nephrologist prescribed him a standard treatment schedule of Monday, Wednesday, and Friday sessions.
Each session takes about 4 hours to complete. The facility will bill each session with CPT code 90999 for routine care without modifiers.
Ultrafiltration Procedures
CPT code 90999 can also be used for cardiac patients who need ultrafiltration for fluid management. This is required in cases of chronic heart failure. Ultrafiltration removes excess fluid without the whole dialysis process. This makes it different from regular dialysis, so code 90999 can be used.
When performed for cardiac fluid overload management, facilities may report this service using CPT 90999.
Applicable Modifiers for CPT Code 90999
The following modifiers are commonly appended to CPT code 90999 to explain to the insurance payer the special circumstances under which the procedure was performed.
| Modifier | Description | Usage Guidelines |
|---|---|---|
| KX | Requirements specified in the medical policy have been met | Used for medically necessary additional hemodialysis sessions beyond the standard three per week. |
| CG | Policy criteria applied | Explains to Medicare that more than 3 dialysis sessions per week were conducted, but supporting documentation has not been submitted. In this case, the facility attests that the additional dialysis sessions were medically unnecessary and are non-reimbursable. |
| G1 | Most recent URR reading of less than 60% | Required for adequacy reporting. Must be used with at least one 90999 line item when URR is below 60%. |
| G2 | Most recent URR reading of 60% to 64.9% | Required for adequacy reporting when URR falls within this range. |
| G3 | Most recent URR reading of 65% to 69.9% | Required for adequacy reporting when URR falls within this range. |
| G4 | Most recent URR reading of 70% to 74.9% | Required for adequacy reporting when URR falls within this range. |
| G5 | Most recent URR reading of 75% or greater | Required for adequacy reporting when URR meets or exceeds 75%. |
| G6 | An ESRD patient for whom fewer than seven dialysis sessions have been provided in a month | Used when the patient receives six or fewer treatments in a month due to hospitalization, travel, or other circumstances. |
Please note that billers must use the G modifiers (G1-G6) when filing claims for ESRD. They must be reported with at least one line of 90999 per claim.
CPT Code 90999 – Billing & Reimbursement Guidelines
Paying attention to the following factors when filing claims for the dialysis procedure (covered by CPT code 90999) will help ensure their accuracy and timely processing.
Documentation
Since CPT code 90999 is unlisted, providing the proper documentation becomes even more necessary. Without documentation, billers can not justify the medical necessity, and the insurance payer will deny the claims.
Always make sure to provide the following details with CPT 90999 claims:
- Patient’s Plan of Care (POC) with prescribed dialysis frequency
- Clinical rationale for any additional sessions beyond 3x weekly
- Urea Reduction Ration (URR) measurements and adequacy data
- Progress notes supporting medical necessity
- Physician orders for treatment modifications
Billing Frequency
Billing frequency is another essential thing to keep in mind. Different insurance payers might have different rules for this, but overall, they all have a set frequency for using CPT code 90999 for reimbursement collection. Since Medicare is the biggest and most crucial insurer, let’s discuss its details.
Medicare typically covers up to 13-14 monthly dialysis sessions, depending on calendar days. Sessions billed as 90999 without modifiers receive payment as routine dialysis within this limit.
For sessions exceeding the monthly maximum:
- Use modifier KX with supporting documentation for medically necessary treatments
- Use modifier CG for non-covered additional sessions
Many billers miss the critical point that the monthly billing cycles should reflect actual treatments provided, with each session reported on a separate line item. Facilities cannot bill for prescribed treatments that were not delivered, and any missed sessions should not appear on the claim.
Medical Necessity
Although 90999 is an unlisted code, you cannot use it for every other dialysis case. You must have a valid diagnosis to justify its medical necessity. There are tens of ICD-10 diagnosis codes that are valid for pairing with CPT code 90999. Some of these are:
- E83.30: Disorder of phosphorus metabolism, unspecified
- E83.39: Other disorders of phosphorus metabolism
- E87.21: Acute metabolic acidosis
- E87.22: Chronic metabolic acidosis
- E87.29: Other acidosis
- E87.5: Hyperkalemia
- E87.70: Fluid overload, unspecified
You can check the complete list of valid ICD-10 codes at the official CMS website.
Wrapping Up
That’s it! This guide has everything you need to submit claims with CPT code 90999 successfully. We know that 90999 can be hard to bill due to its unlisted nature, but we have tried to simplify it as much as possible.
If medical billing is a hassle for you or you face frequent denials despite multiple efforts, contact our consultants at MediBillMD for the best nephrology billing services.
