Watch Out--Diagnosis Details Can Bring You a Payment or a Denial

Betsy Nicoletti, MS


February 19, 2020

The Coding Expert Answers Your Questions

Betsy Nicoletti, MS, a nationally recognized coding expert, will take your coding questions via email and provide guidance on how to code properly to maximize reimbursement. Have a question about coding? Send it here.

In this column, Nicoletti details the proper order in which to bill a diagnosis to avoid a delay or denied payment, as well as the importance of sequencing in billing.

Getting Paid Properly Is All in the Details

Question: Why does the biller at our primary care office send charts back to me for a different diagnosis code when I use "fall" as a diagnosis? The patient comes in having fallen, and I indicate that in the record.

Answer: There are a lot of ICD-10 diagnosis codes that include the word "fall" in categories W00–W19. Unfortunately, none of them can be the first diagnosis you list on a claim form. When searching for a code in the electronic health record (EHR), you may find W19.xxxA, "unspecified fall, initial encounter" and be tempted to use it. If that is the first—or only—diagnosis code on the claim form, the insurance company will reject the claim. That's why your biller sends the chart back to you.

The first diagnosis must describe the injury that was the result of the fall. This will be a code that starts with the letter S. There are many codes in the chapter that describe injuries. They include minor injuries, such as contusions and sprains, all fractures and life-threatening injury; these codes are detailed and can be difficult to select. The type of injury is specific, and the biller in many practices will want the physician to select it.

Use a code that describes how the injury happened as the second diagnosis, such as "fall while walking," "ice-skating injury," or "fall from bed." These how-did-it-happen codes (external cause codes) are also very specific. Both the injury and the external cause codes require a seventh character extender, indicating whether the visit is the initial encounter, a subsequent encounter, or the sequela from an injury.

This also happens for bee stings or tick bites. A search in the EHR brings a code that starts with a W, such as W57 (bitten or stung by nonvenomous insect and other nonvenomous arthropods). This code is also an external cause code and can't be used as the first or only code. Instead, use a code such as S40.861A, insect bite (nonvenomous) or right upper arm, initial encounter.

When Services Change, Convert the Codes

Question: How do we bill when a patient at our surgery center is scheduled for a screening colonoscopy but at the time of the procedure an adenomatous polyp is removed?

Answer: Use the CPT code that describes the procedure that you performed. For example, if you removed one polyp using a snare, use code 45385.

If the patient is covered by original Medicare, add modifier PT to the CPT code (45385-PT). This informs the Medicare contractor that this was scheduled as a screening service but was converted to a therapeutic or diagnostic procedure. The deductible will be waived for this patient, but unlike a screening exam, the patient will still be charged coinsurance.

For other payers, add modifier -33 to the CPT code (45385-33). This tells the payer that the CDC US Preventive Services Task Force (USPSTF) has assigned an "A" or "B" rating to the service. The payer should pay it without charging a deductible to the patient.

It is important to use the correct diagnosis codes, in the correct sequence, on the claim form. Code first the screening diagnosis, Z12.11 (encounter for screening for malignant neoplasm). Then add the diagnosis for the polyp or other condition found during the colonoscopy. If there are additional risk factors, these are added after Z12.11. This can include family or personal history conditions.

Here are some frequently used diagnosis codes that may help:

Z12.11 Encounter for screening for malignant neoplasm

Z86.0 Family history of malignant neoplasm of digestive organs

Z86.010 Personal history of colonic polyps

Z85.0 Personal history of malignant neoplasm (use specific code)

K63.5 Polyp of the colon

Have a coding question? Send it in and it may be answered in a future column. (Please be sure to note your specialty in the text of the question.)

Betsy Nicoletti, MS, is a consultant, author, and speaker as well as the founder of, a wiki for physician reimbursement.

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