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CPT 61645: Intracranial Mechanical Thrombectomy

CPT code 61645 represents percutaneous intracranial mechanical thrombectomy, with or without intra-arterial thrombolytic infusion, performed under fluoroscopic guidance. This endovascular procedure is a critical intervention for acute ischemic stroke caused by intracranial arterial occlusion and has significant implications for national stroke care protocols, hospital stroke workflows, and payer coverage policies. The code captures both mechanical clot retrieval and catheter-directed thrombolysis, and includes catheter placement and diagnostic angiography.

Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of clinical context for use of the code, typical sites of service, and what to expect in claims and billing for acute stroke interventions. The publication highlights common billing considerations and related service definitions, and provides benchmarking and policy-oriented context where available. Data not available in the input is noted where applicable.

This summary is intended for national audiences including hospital administrators, billing and coding professionals, and policy analysts seeking clarity on clinical scope, payer coverage landscape, and the role of CPT code 61645 in acute stroke management.

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Billing Code Overview

CPT code 61645 describes a percutaneous intracranial mechanical thrombectomy with or without intra-arterial thrombolytic infusion performed under fluoroscopic guidance. The procedure involves inserting a catheter through a small skin incision into an intracranial artery (a branch of the carotid artery) to remove or dissolve an occlusive clot. The service includes catheter placement, administration of thrombolytic medication via catheter, and diagnostic angiography using contrast-enhanced imaging displayed on a video monitor.

Service type: Interventional neuroradiology/ endovascular mechanical thrombectomy with possible intra-arterial thrombolysis
Typical site of service: Hospital inpatient or hospital-based interventional radiology/neuroradiology suite, often performed in an acute care setting such as an emergency department or stroke center

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CPT 61645: Intracranial Mechanical Thrombectomy

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Billing Code Overview

Service type: Interventional neuroradiology/ endovascular mechanical thrombectomy with possible intra-arterial thrombolysis
Typical site of service: Hospital inpatient or hospital-based interventional radiology/neuroradiology suite, often performed in an acute care setting such as an emergency department or stroke center

Clinical & Coding Specifications

Clinical Context

A 68-year-old male with atrial fibrillation presents to the emergency department with sudden onset right-sided weakness and aphasia 90 minutes after symptom onset. Noncontrast CT excludes hemorrhage and CT angiography demonstrates an occlusion of the left middle cerebral artery (M1 segment). The stroke team activates an endovascular thrombectomy pathway. Under conscious sedation in the interventional neuroradiology suite, the neurointerventionalist obtains femoral arterial access, advances a guide catheter into the left internal carotid artery under fluoroscopic guidance, performs diagnostic cerebral angiography, then navigates a microcatheter to the occlusion and deploys a stent retriever and/or aspiration device to remove the clot. Thrombolytic infusion through the catheter may be administered if indicated. Post‑procedure angiography confirms revascularization and the patient is transferred to the neurological intensive care unit for monitoring.

Typical clinical workflow steps:

Pre-procedure neurologic assessment, imaging (CT/CTA) and IV thrombolysis decision-making
Informed consent and transfer to angiography suite
Vascular access, diagnostic cerebral angiography, catheterization of the intracranial artery
Mechanical thrombectomy with or without intra-arterial thrombolytic infusion
Completion angiography, hemostasis at access site, and post-procedural monitoring

Typical site of service: hospital-based interventional radiology or neuroradiology angiography suite, often as an emergent inpatient or same‑day procedure.

Coding Specifications

Modifier	Description	When to Use
`00`	Default — no special modifier	General reporting when no modifier applies
`11`	Office or other outpatient visit — primary care HCPCS use (institution-specific)	Rarely used; not typically appended to interventional procedures but present in the modifier set provided
`22`	Increased procedural services	Use when work, time, or complexity significantly exceeds typical for `61645` (document rationale)
`26`	Professional component	Use when billing only the physician professional component separate from technical component (rare for bundled endovascular procedures)
`50`	Bilateral procedures	Applicable if bilateral intracranial interventions performed during same session (rare)
`51`	Multiple procedures	Append when multiple CPT procedures are reported the same day; highest‑value code is primary and others may have `51` per payer rules
`52`	Reduced services	Use when procedure is partially reduced or not fully completed (document reason)
`53`	Discontinued procedure	Use when procedure is started but discontinued due to extenuating circumstances after meaningful work performed
`59`	Distinct procedural service	Use to indicate a separate and distinct service from another procedure on same day (e.g., unrelated diagnostic procedure)
`62`	Two surgeons — same specialty	Use when two surgeons of same specialty share responsibility for a single procedure
`78`	Return to OR for a related procedure during postoperative period	Use if patient returns emergently to angiography suite for reintervention during global period
`79`	Unrelated procedure or service during postoperative period	Use if an unrelated procedure is performed during the postoperative period
`80`	Assistant surgeon	Use when an assistant surgeon participates in the procedure
`AS`	Physician assistant, nurse practitioner, or clinical nurse specialist services for assistant	Use when an advanced practice provider performs assistant duties per payer rules

Taxonomy Code	Specialty	Notes
2084P0800X	Neurology/Interventional Neurology	Physicians who perform endovascular stroke interventions and stroke care coordination
207T00000X	Radiology/Interventional Radiology	Interventional radiologists performing mechanical thrombectomy and endovascular procedures
2086S0102X	Surgery/Neurosurgery	Neurosurgeons trained in endovascular techniques and open cerebrovascular surgery
363L00000X	Emergency Medicine	Emergency physicians involved in stroke activation and triage (not primary operators)
367A00000X	Critical Care Medicine	Intensivists providing post-procedure ICU management

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`I63.9`	Cerebral infarction, unspecified	General code for ischemic stroke when occlusion site unspecified; indicates an ischemic event potentially treated with thrombectomy
`I63.3`	Cerebral infarction due to thrombosis of cerebral arteries	Directly relates to large vessel occlusion amenable to mechanical thrombectomy
`I63.1`	Cerebral infarction due to embolism of cerebral arteries	Embolic large vessel occlusions are common indications for catheter thrombectomy
`I63.8`	Other cerebral infarction	For specified ischemic infarctions not classified elsewhere; may be used when infarct characteristics vary
`I61.9`	Intracerebral hemorrhage, unspecified	Important to document as a contraindication; must be excluded prior to performing `61645`
`G45.9`	Transient cerebral ischemic attack, unspecified	TIAs are part of the differential but typically not treated with thrombectomy unless evolving to sustained large vessel occlusion
`I67.89`	Other cerebrovascular disease	Used for associated cerebrovascular pathologies that may affect procedure planning

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`61645`	Percutaneous intracranial mechanical thrombectomy/thrombolysis with catheter placement and diagnostic angiography	Primary endovascular thrombectomy code describing catheter-directed clot retrieval and/or thrombolytic infusion with angiography
`36245`	Selective catheter placement, cerebral arterial system; initial vessel	Often reported for selective catheter placement into the cervical or cerebral vessel when coded separately from thrombectomy in some payer policies
`36246`	Selective catheter placement, each additional second order or more selective catheterization	Used for additional selective catheterizations during diagnostic angiography or treatment of multiple intracranial branches
`75898`	Injection procedure for cerebrovascular angiography with non-selective or selective catheter	Related diagnostic angiographic contrast injection codes sometimes billed in conjunction with angiography components
`92928`	Percutaneous transluminal coronary revascularization (for reference)	Not typically used for cerebral procedures but sometimes shows in differential coding audits; include for coder awareness

CPT 61650: Image-Guided Intracranial Endovascular Catheter Placement

CPT-61651-INTRACRANIAL-ENDOVASCULAR-CATHETER-ADDITIONAL-ARTERY

CPT 61651: Intracranial Endovascular Catheter Placement, Additional Artery

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.

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Clinical & Coding Specifications

Clinical Context

Typical clinical workflow steps:

Pre-procedure neurologic assessment, imaging (CT/CTA) and IV thrombolysis decision-making
Informed consent and transfer to angiography suite
Vascular access, diagnostic cerebral angiography, catheterization of the intracranial artery
Mechanical thrombectomy with or without intra-arterial thrombolytic infusion
Completion angiography, hemostasis at access site, and post-procedural monitoring

Typical site of service: hospital-based interventional radiology or neuroradiology angiography suite, often as an emergent inpatient or same‑day procedure.

Coding Specifications

Modifier	Description	When to Use
`00`	Default — no special modifier	General reporting when no modifier applies
`11`	Office or other outpatient visit — primary care HCPCS use (institution-specific)	Rarely used; not typically appended to interventional procedures but present in the modifier set provided
`22`	Increased procedural services	Use when work, time, or complexity significantly exceeds typical for `61645` (document rationale)
`26`	Professional component	Use when billing only the physician professional component separate from technical component (rare for bundled endovascular procedures)
`50`	Bilateral procedures	Applicable if bilateral intracranial interventions performed during same session (rare)
`51`	Multiple procedures	Append when multiple CPT procedures are reported the same day; highest‑value code is primary and others may have `51` per payer rules
`52`	Reduced services	Use when procedure is partially reduced or not fully completed (document reason)
`53`	Discontinued procedure	Use when procedure is started but discontinued due to extenuating circumstances after meaningful work performed
`59`	Distinct procedural service	Use to indicate a separate and distinct service from another procedure on same day (e.g., unrelated diagnostic procedure)
`62`	Two surgeons — same specialty	Use when two surgeons of same specialty share responsibility for a single procedure
`78`	Return to OR for a related procedure during postoperative period	Use if patient returns emergently to angiography suite for reintervention during global period
`79`	Unrelated procedure or service during postoperative period	Use if an unrelated procedure is performed during the postoperative period
`80`	Assistant surgeon	Use when an assistant surgeon participates in the procedure
`AS`	Physician assistant, nurse practitioner, or clinical nurse specialist services for assistant	Use when an advanced practice provider performs assistant duties per payer rules

Taxonomy Code	Specialty	Notes
2084P0800X	Neurology/Interventional Neurology	Physicians who perform endovascular stroke interventions and stroke care coordination
207T00000X	Radiology/Interventional Radiology	Interventional radiologists performing mechanical thrombectomy and endovascular procedures
2086S0102X	Surgery/Neurosurgery	Neurosurgeons trained in endovascular techniques and open cerebrovascular surgery
363L00000X	Emergency Medicine	Emergency physicians involved in stroke activation and triage (not primary operators)
367A00000X	Critical Care Medicine	Intensivists providing post-procedure ICU management

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`I63.9`	Cerebral infarction, unspecified	General code for ischemic stroke when occlusion site unspecified; indicates an ischemic event potentially treated with thrombectomy
`I63.3`	Cerebral infarction due to thrombosis of cerebral arteries	Directly relates to large vessel occlusion amenable to mechanical thrombectomy
`I63.1`	Cerebral infarction due to embolism of cerebral arteries	Embolic large vessel occlusions are common indications for catheter thrombectomy
`I63.8`	Other cerebral infarction	For specified ischemic infarctions not classified elsewhere; may be used when infarct characteristics vary
`I61.9`	Intracerebral hemorrhage, unspecified	Important to document as a contraindication; must be excluded prior to performing `61645`
`G45.9`	Transient cerebral ischemic attack, unspecified	TIAs are part of the differential but typically not treated with thrombectomy unless evolving to sustained large vessel occlusion
`I67.89`	Other cerebrovascular disease	Used for associated cerebrovascular pathologies that may affect procedure planning

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`61645`	Percutaneous intracranial mechanical thrombectomy/thrombolysis with catheter placement and diagnostic angiography	Primary endovascular thrombectomy code describing catheter-directed clot retrieval and/or thrombolytic infusion with angiography
`36245`	Selective catheter placement, cerebral arterial system; initial vessel	Often reported for selective catheter placement into the cervical or cerebral vessel when coded separately from thrombectomy in some payer policies
`36246`	Selective catheter placement, each additional second order or more selective catheterization	Used for additional selective catheterizations during diagnostic angiography or treatment of multiple intracranial branches
`75898`	Injection procedure for cerebrovascular angiography with non-selective or selective catheter	Related diagnostic angiographic contrast injection codes sometimes billed in conjunction with angiography components
`92928`	Percutaneous transluminal coronary revascularization (for reference)	Not typically used for cerebral procedures but sometimes shows in differential coding audits; include for coder awareness

CPT 61650: Image-Guided Intracranial Endovascular Catheter Placement

CPT-61651-INTRACRANIAL-ENDOVASCULAR-CATHETER-ADDITIONAL-ARTERY

CPT 61651: Intracranial Endovascular Catheter Placement, Additional Artery

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.

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CPT 61645: Intracranial Mechanical Thrombectomy

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Billing Code Overview

OpenPayer

CPT 61645: Intracranial Mechanical Thrombectomy

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Billing Code Overview

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Related Diagnoses

Related CPT Codes

Related Codes

References

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Related Diagnoses

Related CPT Codes

Related Codes

References