Upper extremity coding remains an area of complex and challenging coding, loaded with opportunities for errors. Misunderstood concepts, confusion around modifiers, and failure to understand services can undermine coding accuracy, leading to lost revenue. Mechanical thrombectomy remains one of the more serious and complex components of upper extremity coding, enough for our subject matter experts to identify it as an area prioritized for review. To unlock success in this area, we will review some of the fundamentals critical for accurate understanding.

Targeting The Basics of Mechanical Thrombectomy

Accurate reporting begins with comprehension of the service itself. Mechanical thrombectomy is a minimally invasive procedure used to break up and remove a thrombus (blood clot) from an artery or vein using a specialized device, such as a balloon or catheter-based thrombectomy system. Its purpose is to quickly restore blood flow by physically extracting the clot.

Be aware that this procedure is distinct from atherectomy, which is designed to cut and remove plaque that has built up along the walls of an artery rather than remove a blood clot.

When coding coronary artery procedures, it’s important to recognize that CPT code 92973 is reserved for true mechanical thrombectomy performed with a device such as the AngioJet, which mechanically fragments and removes thrombus through a catheter. To further complicate reporting, understand that suction thrombectomy alone does not meet the definition of mechanical thrombectomy for coronary artery coding and should not be reported with CPT code 92973.

The rules differ in the peripheral vascular system, where suction thrombectomy may be considered a form of mechanical thrombectomy for coding purposes. Understanding this distinction between coronary and peripheral procedures is vital to coding accuracy.

Coding Distinctions Dissected

When it comes to these services, what should be coded separately? What are the primary rules surrounding these services?

Diagnostic angiography and vascular catheterization should be coded separately unless they are included in other procedures performed during the same session or when mechanical thrombectomy/thrombolysis is performed in intracranial arteries.
Other interventions, such as angioplasty, stent placement, and/or thrombolysis infusions (except intracranially), may be coded separately.

On the other hand, strict rules apply to what cannot be coded separately:

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 code an S&I code separately.

Of special note, arterial mechanical thrombectomy codes apply to treatment in both native arteries and arterial bypass grafts. Do not report these codes for intracranial mechanical thrombectomy; instead, look to code 61645.

37184

+37185

Primary percutaneous transluminal mechanical thrombectomy, noncoronary, arterial or arterial bypass graft, including fluoroscopic guidance and intraprocedural pharmacological thrombolytic injection(s); second and all subsequent vessel(s) within the same vascular family (List separately in addition to code for primary mechanical thrombectomy procedure)

Primary vs. Secondary Procedures

Primary arterial mechanical thrombectomy is performed when the main objective of the procedure is the removal of a thrombus (blood clot). In most cases, the presence of the thrombus has already been confirmed before the procedure begins, making clot removal the primary reason for treatment. After the clot has been successfully removed, the physician may identify an underlying arterial narrowing or blockage that requires additional intervention, such as angioplasty. Although these secondary procedures may be necessary, the thrombectomy remains the primary procedure because it was the original focus of treatment. While primary mechanical thrombectomy is often the first procedure performed, this is not always the case.

From a coding perspective, primary arterial mechanical thrombectomy is reported by vascular family. CPT code 37184 is assigned for the initial vessel treated within a vascular family, while 37185 is used for the second and any additional vessels treated within that same vascular family. Code 37185 should only be reported once per vascular family, regardless of the number of additional vessels treated.

When primary mechanical thrombectomy is performed in arteries belonging to a different vascular family during the same session, CPT codes 37184 and 37185 may be reported again, as appropriate, with modifier 59 or another payer-required modifier to distinguish the separate vascular family. Coders should also refer to Appendix L of the CPT manual for guidance on vascular families. However, use caution when applying the appendix, as its illustrations assume catheterization extends through the aorta into a first-order or higher-order branch vessel. If the catheterization does not include the aorta, the appendix may not accurately reflect the vascular family relationships for coding purposes.

+37186

Secondary percutaneous transluminal thrombectomy (e.g., nonprimary mechanical, snare basket, suction technique), noncoronary, arterial or arterial bypass graft, including fluoroscopic guidance and intraprocedural pharmacological thrombolytic injections, provided in conjunction with another percutaneous intervention other than primary mechanical thrombectomy (List separately in addition to code for primary procedure)

Unlike primary mechanical thrombectomy, where the main goal of the procedure is to remove a known thrombus, secondary arterial mechanical thrombectomy is performed as an additional transcatheter procedure during another intervention. It is used to remove or retrieve a short segment of thrombus or embolus that occurs before or after a separate percutaneous treatment, such as percutaneous transluminal balloon angioplasty or stent placement.

Because this type of thrombectomy is performed to address an unexpected clot or embolic complication during an existing procedure, it is often referred to as a rescue thrombectomy or bailout thrombectomy. The thrombectomy is not the original reason for treatment but rather a necessary step to restore blood flow, manage a procedural complication, or improve the outcome of the primary intervention.

Understanding the difference between primary and secondary mechanical thrombectomy is essential for accurate coding. While primary thrombectomy represents the main therapeutic objective, secondary thrombectomy is an adjunct procedure performed in conjunction with another vascular intervention. Arterial mechanical thrombectomy is considered a “secondary” transcatheter procedure for the removal or retrieval of short segments of thrombus or embolus when performed either before or after another percutaneous intervention (e.g., percutaneous transluminal balloon angioplasty or stent placement). Note that secondary mechanical thrombectomy may be called a rescue or bailout thrombectomy.

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