Billing Stages for Mohs

Question:

I am very confused. I am new to coding for Mohs procedures. The Mohs surgeon performed a procedure on the patient’s scalp in 5 stages. I spoke with the Mohs surgeon about billing over 4 stages in one area using CPT code 17312. He billed 17311 for the first stage and 17312 with 4 units for a total of 5 stages. In each stage, the documentation states that 1 tissue block was mapped. I think we should bill CPT 17315 for the last stage instead of 17312 since it is the 5th stage. Can you clarify if this is the case or if 17312 with 4 units is correct.

Answer:

I agree with your Mohs surgeon. The only time you use 17315 is when there are more than 5 tissue blocks per stage. Based on the information you have provided each stage indicates 1 block. CPT code 17311 should be reported for stage 1 and 17312 is reported for each additional stage (4).

*This response is based on the best information available as of 2/27/25.