Thrombin injection for the treatment of worsening brachiocephalic fistula pseudoaneurysm

Abstract

An 86-year-old woman with end-stage renal disease was being dialyzed via a left brachiocephalic arteriovenous fistula. She developed a pseudoaneurysm at one of the angioaccess sites that did not resolve spontaneously. She developed significant pain and discomfort and presented for treatment. Ultrasound evaluation identified and characterized the pseudoaneurysm. Thrombin injection with ultrasound guidance successfully resolved the pseudoaneurysm, and at her follow-up her symptoms has resolved. Although off-label, thrombin injection remains an important tool in the management of pseudoaneurysms, no matter the location.

Patients with end-stage renal disease (ESRD) often develop vascular access-related complications, including the formation of pseudoaneurysms at arteriovenous fistula (AVF) access sites, which can present with pain, swelling, and potential risk of rupture.¹ This case report describes an 86-year-old female patient with ESRD on maintenance hemodialysis who presented with a progressively enlarging pulsatile mass at the site of her left brachiocephalic AVF.

The patient opted for a minimally invasive thrombin injection procedure, which successfully resolved the pseudoaneurysm without compromising the patency of the AVF, allowing continued use for dialysis. This report highlights a successful treatment approach for a common complication in ESRD patients undergoing hemodialysis.

Full publication consent was obtained from the patient before the publication of this case report.

Case report

An 86-year-old female patient with ESRD on maintenance hemodialysis presented with a progressively enlarging mass at the site of her left brachiocephalic AVF (Fig 1). She had the AVF placed 6 months before reporting increasing pain and swelling at the site for 1 month. Physical examination revealed a pulsatile mass with a bruit at the area of concern. Her medications included aspirin but no other anticoagulant or antiplatelet medications. Her medical history otherwise included COVID-19 infection remotely, dyslipidemia, hyperparathyroidism, hypertension, hypothyroidism, macular degeneration, and prior transient ischemic attack.

Fig 1.

Preprocedural image of the left upper arm demonstrating a prominent mass at the site of the brachiocephalic arteriovenous fistula (AVF), consistent with pseudoaneurysm.

Ultrasound evaluation confirmed the presence of a pseudoaneurysm measuring 4.5 × 3.3 × 4.4 cm with a neck which measured 0.3 cm (Fig 2, A-C). There was no evidence of proximal or downstream obstruction contributing to the development of the pseudoaneurysm. Given the patient's symptoms and the pseudoaneurysm size, the patient was provided with the options of surgical revision, endovascular revision, or thrombin injection. She opted for thrombin injection given the minimally invasive nature of the procedure and her advanced age, understanding the off-label use. The patient was advised that although the thrombin injection would convert the pseudoaneurysm to a hematoma, it would take time for her body to reabsorb the hematoma.

Fig 2.

(A) Color Doppler ultrasound image demonstrating turbulent flow external to the fistula consistent with pseudoaneurysm. (B) Grayscale longitudinal ultrasound image showing the size and heterogeneous nature of the pseudoaneurysm. (C) Additional color Doppler view showing bidirectional flow within the pseudoaneurysm.

Ultrasound visualization of the pseudoaneurysm with adjacent fistula was performed with a similar approach as in femoral pseudoaneurysm treatment. A total of 500 U of thrombin (0.5 mL of a solution of 5000 U thrombin in 5 mL normal saline) were injected at the superficial-most aspect of the pseudoaneurysm to avoid inadvertent injection into the fistula with real-time color Doppler guidance. The fistula thrill remained palpable before and after the procedure. A completion duplex ultrasound examination revealed pseudoaneurysm thrombosis with persistent patency of the fistula itself.

Follow-up ultrasound examination at 1 week confirmed thrombosis of the pseudoaneurysm with no recurrence. By 1 month, symptoms, including the lump on her upper arm, had resolved completely. The fistula remained patent and was being used for hemodialysis without further issues.

Discussion

This was the first time the authors attempted this technique, and this case highlights the effectiveness of percutaneous thrombin injection for the treatment of dialysis fistula pseudoaneurysms. Pseudoaneurysm formation is a recognized complication at AVF sites in patients undergoing hemodialysis, often resulting from repeated cannulation, vessel wall degeneration, or localized trauma.¹ Although surgical and endovascular interventions remain standard treatment options, minimally invasive techniques such as ultrasound-guided thrombin injection have emerged as viable alternatives, particularly in patients with high surgical risk or advanced age.²

There are no clearly established indications for the treatment of vascular access pseudoaneurysms and so we used criteria similar to those used for treatment of femoral artery pseudoaneurysms. For femoral artery pseudoaneurysms in particular, the American College of Cardiology recommends that patients with large and/or symptomatic pseudoaneurysms be treated, with initial therapy consisting of ultrasound-guided compression or thrombin injection. Surgical repair is considered reasonable for pseudoaneurysms 2.0 cm or more in diameter that persist or recur after initial nonsurgical treatment.³ For asymptomatic pseudoaneurysms less than 2.0 cm, observation with repeat ultrasound examination at 1 month is appropriate. The rationale for these recommendations is to prevent complications such as rupture, expansion, pain, skin ischemia, or infection, which are more likely with larger or symptomatic lesions.³

Endovascular approaches to pseudoaneurysms are also available. Covered stents are frequently used to treat AVF stenosis and thrombosis and can be used to treat dialysis access pseudoaneurysms; however, their success is short lived. A 2025 study found that covered stents achieved a target lesion primary patency of 78.7% at 6 months and 47.9% at 12 months in patients with dysfunctional upper extremity AVFs.⁴

Thrombin injection is most commonly used in the treatment of iatrogenic femoral artery pseudoaneurysms after catheterization procedures.^5,6 Thrombin injection is also indicated for pseudoaneurysms of the brachial, radial, subclavian, posterior tibial, and superficial femoral arteries, particularly when these arise from arterial access, trauma, or surgical interventions and are accessible to ultrasound guidance.⁷ Their use in treating AVF-related pseudoaneurysms is less well-established but growing in clinical relevance. It is generally well-tolerated, can be performed on an outpatient basis, and is effective in patients on anticoagulation.⁸ Certainly, thrombin injection also could potentially be applied to pseudoaneurysms in arteriovenous prosthetic grafts.

Although thrombin injection for AVF pseudoaneurysms is considered off-label by the Food and Drug Administration, several case reports have demonstrated its efficacy and safety.9, 10, 11 Although the Food and Drug Administration advises against injection of the thrombin, this is understood to mean intravascular injection, and pseudoaneurysm treatment with thrombin injection does not fall under this definition. Complications of thrombin injection, although rare, can include embolization, allergic reactions, or thrombosis of the parent vessel.⁶ The most reported embolic complication is distal arterial embolism, with rates of arterial microembolization of up to 15% and rare cases of pulmonary embolism (0.3%) documented in large prospective series of postcatheterization femoral pseudoaneurysms treated with ultrasound-guided thrombin injection.12, 13, 14 Central venous embolism is not a typical complication, but isolated case reports describe femoral vein thrombosis or pulmonary embolism, particularly in the setting of direct communication between the pseudoaneurysm and the venous system or when the pseudoaneurysm compresses the femoral vein.12, 13, 14 For cases in which there is compromise of the overlying skin in the setting of infection or necrosis, surgical intervention is preferred.⁶

Thrombin injection has historically been avoided in cases with infection, rapidly expanding hematoma, or when there is a high risk of thrombin entering the systemic circulation, such as with wide-necked or AVF-associated pseudoaneurysms.¹⁵ In arteriovenous dialysis access, thrombin injection can be paired with balloon occlusion to help prevent embolization of the thrombin into the systemic circulation. As such, patient selection and meticulous technique (with ultrasound guidance and with consideration of balloon occlusion) are critical to minimizing risk.

Conclusions

This case adds to the growing body of evidence supporting thrombin injection as a practical and effective treatment for AVF-associated pseudoaneurysms in selected patients. It also underscores the importance of individualized care, balancing procedural risks with patient-specific factors such as age, comorbidities, and access site preservation. Further studies and standardized protocols are warranted to define the long-term outcomes and optimal use of thrombin injection in this unique patient population.

Funding

None.

Disclosures

None.