CPT Codes 37184–37188: Thrombectomy and Thrombolysis Billing Guide
An interventionalist clears a clotted graft, then places a stent to finish the job. The report mentions thrombectomy twice. Was it a primary thrombectomy or a secondary one? The answer decides between 37184 and 37186, and the wrong choice creates a claim that the edits will not forgive.
CPT codes 37184–37188 look similar but depend on arterial versus venous anatomy, whether thrombectomy was the main event, the vessel count, and the treatment day. This guide explains each code, separates thrombectomy from thrombolysis, and shows what to document and check before you submit. Descriptors are paraphrased, so confirm them in the current CPT manual.
Understanding CPT Codes 37184–37188
CPT | Procedure type | Territory | Key billing distinction | Documentation focus |
37184 | Primary mechanical thrombectomy | Arterial | Initial vessel, per vascular family | Primary procedure and vessel |
+37185 | Additional primary thrombectomy | Arterial | Second and later vessels, same family | Vessel identification |
+37186 | Secondary thrombectomy | Arterial | With another percutaneous intervention | Technique and associated procedure |
37187 | Mechanical thrombectomy | Venous | Initial treatment day | Vein and thrombectomy details |
37188 | Repeat mechanical thrombectomy | Venous | Subsequent day during thrombolytic therapy | Treatment timeline |
Code selection depends on the actual procedure, vascular territory, treatment sequence, and current CPT instructions. The arterial codes apply to noncoronary, nonintracranial arteries or arterial bypass grafts, with coronary thrombectomy reported elsewhere (92973) and intracranial in a different code (61645), per vendor coding guides.
CPT 37184: Primary Arterial Mechanical Thrombectomy
Reports primary percutaneous mechanical thrombectomy of the initial vessel in a vascular family, including fluoroscopic guidance and intraprocedural pharmacological thrombolytic injections. Document the treated vessel and that thrombectomy was the intended primary procedure. See AAPC guidance.
CPT +37185: Additional Arterial Vessel
An add-on for the second and all subsequent vessels in the same vascular family, reported with 37184. Coding references indicate it is reported once for all additional vessels in that family, per CPT Assistant as cited by Medtronic. Document each additional vessel and the family. A different family treated through a separate access site is handled differently, and sources conflict on the modifier (59 or 51), so verify with CPT and the payer.
CPT +37186: Secondary Arterial Thrombectomy
An add-on for nonprimary mechanical techniques, such as snare, basket, or suction, performed with another percutaneous intervention other than primary mechanical thrombectomy. It is typically used for smaller amounts of thrombus around angioplasty or stenting. It is never reported with 37184 or 37185, and AAPC notes the edit between primary and secondary thrombectomy cannot be bypassed with a modifier.
CPT 37187: Venous Mechanical Thrombectomy
Reports percutaneous mechanical thrombectomy of veins on the initial treatment day, including intraprocedural pharmacological thrombolytic injections and fluoroscopic guidance. Document the vein, thrombus location, technique, and date.
CPT 37188: Repeat Venous Thrombectomy
Reports repeat venous mechanical thrombectomy on a subsequent day during a course of thrombolytic therapy. Document dates, the ongoing thrombolytic course, and why repeat treatment was needed. Without a documented subsequent-day treatment, 37188 should not be reported.
Thrombectomy vs. thrombolysis Mechanical thrombectomy physically removes or macerates clot. Catheter-directed thrombolysis infuses a drug over time and has its own codes, including 37211 (arterial infusion, initial treatment day) and 37212 (venous infusion, initial treatment day), per AAPC. Subsequent-day and cessation services have separate codes in the same family. Not every combination is separately reportable, so check the CPT parentheticals and NCCI edits. |
Primary vs. Secondary Thrombectomy
| Primary (37184, +37185) | Secondary (+37186) |
Role | Thrombectomy is the intended main procedure | Performed with another percutaneous intervention |
Typical context | Clot burden is the target | Small thrombus around angioplasty, stenting, or similar |
Billing note | 37185 follows 37184 in the same family | Not reported with 37184 or 37185 |
Documentation | Primary intent, vessel, technique | Technique, associated intervention, thrombus extent |
Do not treat any example as universal. Review the full operative report.
Arterial vs. Venous Thrombectomy
Element | Arterial | Venous |
Relevant codes | 37184, +37185, +37186 | 37187, 37188 |
Initial treatment | 37184 per vascular family | 37187 on the initial day |
Additional vessels | +37185 for same family | Not applicable in this code set |
Secondary thrombectomy | +37186 with another intervention | No equivalent add-on |
Subsequent-day treatment | Not applicable | 37188 during thrombolytic therapy |
Documentation differences | Vessel, family, primary vs. secondary | Vein, treatment day, thrombolytic course |
Arterial and venous procedures are not interchangeable when selecting codes.
Documentation Requirements for CPT 37184–37188
The checklist supports, but does not replace, the full operative report and official coding guidance.
☐ Clinical indication
☐ Target vessel and territory
☐ Arterial versus venous anatomy
☐ Thrombus presence and location
☐ Primary versus secondary thrombectomy
☐ Mechanical technique used
☐ Additional vessels treated
☐ Other percutaneous interventions performed
☐ Pharmacological thrombolytic injections, if any
☐ Procedure date and treatment sequence
☐ Subsequent-day treatment when reporting 37188
☐ Medical necessity and findings
8 Common Billing Mistakes in Thrombectomy and Thrombolysis
Mistake | What goes wrong and why | How to prevent it |
Confusing primary and secondary | Wrong code and a conflicting edit pair | Establish whether thrombectomy was the intended primary procedure |
37185 without the same family | Add-on lacks support | Confirm the vascular family |
Incorrect additional-vessel reporting | Over- or under-reporting vessels | Count by family, per CPT instructions |
Confusing arterial and venous | Wrong code set | Verify the territory |
37188 without subsequent-day support | No documented repeat treatment | Document dates and the thrombolytic course |
Reporting included services | Guidance and thrombolytic injections are included | Review code descriptors and parentheticals |
Overlooking NCCI edits | Possible denials or adjustments | Check current edit files |
Thin procedural documentation | Support may be questioned | Validate reports before billing |
These errors do not automatically cause denials, but each raises review risk.
NCCI Edits and Bundling Considerations
The Medicare NCCI Policy Manual and procedure-to-procedure (PTP) edits define which code pairs are bundled. PTP edits flag pairs that should not be reported together. Medically unlikely edits cap units of service. Practitioner and hospital outpatient edit sets differ. Edit files update quarterly, so review the current quarter for your date of service. Add-on codes are reported only with their primary codes. Modifiers are for distinct, documented circumstances, never to bypass an edit, and some edit pairs allow no modifier at all.
Before Submitting a Thrombectomy Claim: 10-Point Review
☐ Correct CPT code selected
☐ Arterial or venous territory verified
☐ Initial versus additional vessel established
☐ Same vascular family confirmed when applicable
☐ Primary versus secondary procedure established
☐ Procedure details documented
☐ Other interventions reviewed for bundling
☐ Add-on code requirements checked
☐ Current NCCI edits reviewed
☐ Medical necessity and documentation confirmed
Real-World Billing Scenarios
Educational illustrations, not coding advice for every case or payment guarantees.
Scenario | What matters | Review and avoid |
1. Primary arterial thrombectomy of an initial vessel and another vessel in the same family | Initial vessel versus additional vessel in one family | Review vessel and family documentation. Avoid reporting 37184 for the second vessel. |
2. Secondary thrombectomy with another percutaneous intervention | Primary versus secondary intent | Review technique and the associated procedure. Avoid pairing 37186 with 37184 or 37185. |
3. Initial venous thrombectomy, then repeat treatment the next day during thrombolytic therapy | Initial day versus subsequent day | Review dates and the thrombolytic course. Avoid 37188 without a documented subsequent-day treatment. |
Revenue Cycle Management Challenges
RCM challenge | Potential impact | Recommended billing response |
Incorrect code selection | Claim accuracy problems | Specialty coding review |
Missing documentation | Medical necessity or coding issues | Documentation validation |
Bundling errors | Payment delays or denials | NCCI review |
Payer-specific requirements | Claim rework | Payer policy verification |
Unresolved denials | Delayed reimbursement | Structured denial follow-up |
Aging A/R | Cash flow pressure | A/R prioritization |
How Sirius Solutions Global Supports Complex Medical Billing and RCM
You focus on patient care. We’ll handle the rest. Sirius Solutions Global combines AI-powered technology with human-verified billing workflows across medical coding, claims management, advanced eligibility verification, denial management, prior authorization, credentialing and re-credentialing, A/R follow-up, billing audits, revenue leakage assessment, and RCM reporting. Complex thrombectomy claims need documentation review, correct code selection, payer awareness, and claim-level quality control. Technology supports that work, but people make final coding decisions. We do not claim vascular specialty clients, certifications, or results.
How Strong Is Your Vascular Billing Workflow?
Mark Yes or No, then count your Yes answers.
Question | Yes | No |
Are operative reports reviewed before coding? | ☐ | ☐ |
Are arterial and venous procedures distinguished? | ☐ | ☐ |
Are primary and secondary thrombectomies reviewed separately? | ☐ | ☐ |
Are additional vessel requirements checked? | ☐ | ☐ |
Are NCCI edits reviewed regularly? | ☐ | ☐ |
Are denials tracked by root cause? | ☐ | ☐ |
Is A/R aging monitored? | ☐ | ☐ |
Are payer-specific requirements reviewed? | ☐ | ☐ |
Yes answers | Educational recommendation |
0–2 | Several workflow areas may need attention |
3–5 | Consider reviewing specific processes |
6–8 | Maintain regular monitoring and reassess as rules change |
Educational workflow assessment only, not a compliance certification.
Frequently Asked Questions
▸ What are CPT codes 37184–37188 used for?
Percutaneous mechanical thrombectomy: arterial (37184–37186) and venous (37187–37188).
▸ What is the difference between 37184 and 37186?
37184 is primary thrombectomy. 37186 is a secondary add-on with another percutaneous intervention.
▸ When is CPT 37185 reported?
For second and subsequent vessels in the same vascular family, with 37184.
▸ What does CPT 37187 represent?
Venous mechanical thrombectomy on the initial treatment day.
▸ When can CPT 37188 be used?
For repeat venous thrombectomy on a subsequent day during thrombolytic therapy.
▸ What is the difference between thrombectomy and thrombolysis?
Thrombectomy mechanically removes clot. Thrombolysis infuses a clot-dissolving drug.
▸ Does CPT 37184 include fluoroscopic guidance?
Yes. It also includes intraprocedural pharmacological thrombolytic injections.
▸ What documentation is needed?
The vessel, territory, technique, intent, additional vessels, dates, and medical necessity.
▸ How do NCCI edits affect claims?
They bundle certain pairs and limit units. Modifiers must be supported, never used to bypass.
▸ Why is specialized IR billing important?
Small documentation distinctions change the code, so careful review reduces rework.
Disclaimer: This article is educational, published by Sirius Solutions Global, and is not a substitute for the current CPT manual, official coding guidance, payer policies, or individualized coding advice. CPT® is a registered trademark of the American Medical Association, and descriptors are paraphrased. Sirius Solutions Global is not affiliated with CMS or the AMA. Nothing here guarantees coverage, reimbursement, or audit outcomes.
