Gastroenterology Coding Alert

Question: In your last issue, you discussed coding for a screening colonoscopy turned diagnostic and mentioned the use of modifier PT (Colorectal cancer screening test converted to diagnostic test or other procedure). Can you explain specifically when modifier PT is necessary and when it isn't?

Codify Subscriber

Answer: Modifier PT tells the Medicare contractor that the service started as a screening procedure (e.g. G0105 [Colorectal cancer screening; colonoscopy on individual at high risk], G0121 [Colorectal cancer screening; colonoscopy on individual not meeting criteria for high risk]) but an abnormality was found and the procedure became diagnostic or therapeutic.

When appended to your procedure code, the modifier will indicate to Medicare to waive the deductible for a diagnostic procedure.

Once the physician indicates that the screening procedure has turned diagnostic, you'll bill only the diagnostic colonoscopy code, and not the screening code (G0104-G0106, G0120-G0121). Not only is this correct coding, but it's also the only way you can use modifier PT.

According to WPS Medicare:

• Modifier PT should only be appended when a service began as a colorectal cancer screening test and then was moved to therapeutic test due to findings during the screening
• Practitioners should append the modifier to the therapeutic procedure code that is reported instead of the screening colonoscopy or screening sigmoidoscopy HCPCS code

Therefore, you should not append modifier PT to G codes such as G0104-G0121.

For example: During a screening colonoscopy for an average risk Medicare patient, the physician discovers several polyps. He removes the polyps (which are later determined to be benign) during the same procedure using a snare technique. In this case, you should bill the colonoscopy with polyp removal via snare technique (such as 45385, Colonoscopy, flexible; with removal of tumor(s), polyp(s), or other lesion(s) by snare technique) with modifier PT appended to 45385.

Because your colonoscopy started out as a screening procedure, your diagnosis code should reflect both the screening nature of the visit and the actual condition that the physician treated.

For private payers, the modifier 33 (Preventive services) is used instead of PT, unless the payer directs otherwise. Note that the ICD-10 diagnosis codes used should first be the screening code to identify the initial/primary reason for the examination, and the second or subsequent diagnosis code(s) should identify findings.