Mastering Mechanical Thrombectomy Coding for Success in 2023

Mechanical thrombectomy has a series of keys and nuances that coders must know for correct comprehension and accurate reimbursement. So, what is mechanical thrombectomy? This is a medical procedure that breaks up and removes the thrombus (blood clot) from an artery or vein using a balloon or another device. Note that mechanical thrombectomy is distinct from atherectomy, which is a procedure designed to cut and remove plaque from the sides of an artery. One of the continuing universal challenges is determining whether mechanical thrombectomy is primary or secondary. Let’s examine this problem along with the key components for successful coding in 2023 and beyond.

Breaking Down the Basics and Primary Understanding

Understand that the coronary artery mechanical thrombectomy code (92973) is specific to the use of a device such as AngioJet™. This device mechanically breaks up and removes the thrombus through a catheter. However, suction thrombectomy is not considered mechanical thrombectomy for the coding of procedures in the coronary arteries. However, in the peripheral vascular system, suction thrombectomy may be coded as mechanical thrombectomy.

Although it might be tempting to code diagnostic angiography and vascular catheterization together, these procedures must be coded separately. The one exception is when they are included in other procedures performed during the same session or when mechanical thrombectomy/thrombolysis is performed in intracranial arteries. So, what can be coded separately? These include other interventions such as:

• Angioplasty,
• stent placement,
• and/or thrombolysis infusions (except intracranially).

Note that injections of a thrombolytic agent during mechanical thrombectomy are included in the thrombectomy procedure and should not be coded as a thrombolysis infusion. The codes below include the mechanical thrombectomy procedure and imaging necessary to perform and complete the procedure. Do not assign a supervision and interpretation (S&I) code separately. Arterial mechanical thrombectomy codes apply to treatment in both native arteries and arterial bypass grafts. Note that you should not report these codes for intracranial mechanical thrombectomy; instead see code 61645.

Arterial mechanical thrombectomy is considered “primary” when the focus of planning and treatment. One questionable element occurs when arterial mechanical thrombectomy is considered “primary.” The procedure is considered primary when the focus of planning and treatment is removal of thrombus. Usually, the diagnosis of thrombus has been made prior to the procedure.

Understand that once the thrombectomy has been performed, an underlying lesion may be seen, and additional procedures such as angioplasty may be required. However, thrombectomy would still be considered the primary procedure, in other words, the original reason for the patient’s treatment. Primary mechanical thrombectomy is usually the first procedure performed, but that is not an absolute.

Arterial mechanical thrombectomy is reported per vascular family using 37184 for the initial vessel treated. 37185 should be reported for second or all subsequent vessels within the same vascular family. Be careful to assign code 37185 only once within a single vascular family.

What if the procedure involves treating arteries in multiple vascular families? If one or more arteries in a different vascular family are also treated with primary mechanical thrombectomy, assign 37184 and 37185 again, as appropriate, with modifier 59 or other modifiers, as specified by the payer. Check Appendix L of the CPT® manual for more information. Be careful: This chart assumes catheterization to the aorta and then out into one of the first-order or beyond vessels. If catheterization does not include the aorta, this chart could be incorrect.

Assessing Secondary Mechanical Thrombectomy

Understand that arterial mechanical thrombectomy is considered a “secondary” transcatheter procedure for removal or retrieval of short segments of the thrombus or embolus. This classification occurs when the procedure is performed either before or after another percutaneous intervention (e.g., percutaneous transluminal balloon angioplasty, stent placement).

Coders should note other terms that signal secondary mechanical thrombectomy. Secondary mechanical thrombectomy may be called a rescue or bailout thrombectomy. For example, a patient has had an angioplasty in the superior femoral artery (SFA), and the immediate post-procedure follow-up exam shows a clot in the previously open anterior tibial (AT) artery.

Suction removal of that clot is considered a secondary mechanical thrombectomy. Another type of secondary thrombectomy occurs when a patient is scheduled for angioplasty and/or stent placement, and the initial imaging shows a thrombus that must be removed before the angioplasty and stent placement can be performed.

When should these codes not be assigned? Do not assign 37184 or 37185 in addition to 37186 during the same session. If assigning the add-on code bilaterally, report in units; do not assign modifier 50 to the add-on code. It is often challenging for a coder to determine whether mechanical thrombectomy is primary or secondary. If it is unclear, clarify with the physician before coding.

To correct a misunderstanding about mechanical thrombectomy, the NCCI Manual 2023 (Ch. V, Sec. D, No. 25, pg. V-14) states the following:

“The ‘CPT Manual’ defines primary and secondary percutaneous transluminal arterial mechanical thrombectomies. The ‘CPT Manual’ contains an instruction which states: ‘Do not report 37184-37185 for mechanical thrombectomy performed for retrieval of short segments of thrombus or embolus evident during other percutaneous interventional procedures. See 37186 for these procedures.’ Based on this CPT instruction, the NCCI program contains edits bundling the primary percutaneous transluminal mechanical thrombectomy (CPT code 37184) into all percutaneous arterial interventional procedures. These edits allow use of NCCI–associated modifiers if a provider performs a primary percutaneous transluminal arterial mechanical thrombectomy rather than a secondary percutaneous transluminal arterial mechanical thrombectomy (CPT code 37186) in conjunction with the other percutaneous arterial procedure.”

Note that these are not all the necessary coding tips and rationale required for interventional radiology knowledge and mechanical thrombectomy coding. As service volumes rebound and every last dollar of reimbursement counts, now more than ever, it is imperative to make sure your CPT® coding is correct and compliant. Master more IR topics and break down the complexity with our expert-infused Lower Extremity Interventional Radiology Coding webcast. This webcast is an essential training tool for both audio and visual learners.