Otolaryngology Coding Alert

Question: A patient with vocal cord paralysis had a bilateral excision of arytenoid cartilage using forceps and microlaryngeal scissors. An operating microscope was also used. Next, the surgeon performed a laser ablation of subglottic stenosis. This was achieved using a CO2 laser on two large subglottic cysts affecting the right subglottic wall. What’s the CPT^® coding for these services?

Answer: The procedure involving the bilateral excision of the arytenoid cartilage is known as an arytenoidectomy. This procedure involves the use of a laryngoscope to surgically excise diseased arytenoid cartilage. While the coding may seem relatively straightforward, there are a few discrepancies between the CPT^® index and the code description that can be a source of confusion.

A laryngoscopy with an operating microscope, also known as a microlaryngoscopy, can be performed using a direct or flexible laryngoscope. Laryngoscopic subglottic excision procedures are typically performed using a direct laryngoscope. However, if you’re going to rely on the CPT^® index to reach the correct code, you’ve got to go the following route:

• Laryngoscopy/Flexible/Operative/31530-31561

In fact, if you have a look in the CPT^® index, you’ll actually need to bypass Laryngoscopy/Direct entirely, and look below to the Laryngoscopy/Flexible listing in order to reach the correct code for an arytenoidectomy, 31561 (Laryngoscopy, direct, operative, with arytenoidectomy; with operating microscope or telescope). While this may simply be an error on the part of the AMA in formulating the index routing, it offers a valuable lesson that the CPT^® index does not always yield optimal results.

Next, you’ve got to address the CO2 laser ablation of the subglottic cysts. Unfortunately, you won’t find any existing code within the CPT^® manual to cover this particular procedure. While code 31540 (Laryngoscopy, direct, operative, with excision of tumor and/or stripping of vocal cords or epiglottis) might seem to fit the bill, this code involves excision of the subglottic tissue using instrument such as rigid forceps. Instead, you’ll have to resort to reporting code 31599 (Unlisted procedure, larynx) on your CMS-1500 form. In Box 19, you’ll want to equate the procedure to the closest comparison code, 31540. You should discuss with the provider in determining the appropriate percentage of 31450 to equate to the surgeon’s work. Keep in mind that depending on the work involved, this can be a percentage estimation above 100 percent.