Interventional Radiology Imaging

What Is the Best Next Step for a Malfunctioning Dialysis Fistula?

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What Is the Best Next Step for a Malfunctioning Dialysis Fistula?

A nephrologist calls you about a 68-year-old patient with a left brachiocephalic arteriovenous fistula. For the past two months, his dialysis sessions have been problematic. The access flow rates measured at the dialysis unit have dropped from a stable 700 mL/min to under 450 mL/min, and the venous pressures are steadily climbing. The patient still has a palpable thrill, but it feels weaker. You are now faced with a common but critical decision: how to evaluate and treat this failing access to prevent thrombosis and preserve it for long-term hemodialysis. This article outlines the clinical workflow for this specific scenario, guided by the American College of Radiology (ACR) Appropriateness Criteria, which rates Fluoroscopy fistulography hemodialysis access with intervention as Usually Appropriate.

Who Fits This Clinical Scenario for Dialysis Access Dysfunction?

This guidance applies to patients with a mature, previously well-functioning arteriovenous (AV) fistula or graft who now present with objective evidence of dysfunction. The key is that the access is still patent—a thrill and bruit are present—but its performance is degrading.

Inclusion criteria for this workflow include:

  • A mature AV fistula or graft currently in use for hemodialysis.
  • Objective signs of dysfunction, such as:
  • Decreased blood flow rates measured during dialysis (e.g., via ultrasound dilution, thermal dilution).
  • A significant drop in dialysis clearance (Kt/V or urea reduction ratio).
  • Consistently elevated static or dynamic venous pressures.
  • Prolonged bleeding from cannulation sites after needle removal.
  • Difficulty with cannulation or aspiration of clots.

This workflow does NOT apply to several similar-sounding but distinct clinical situations:

  • Acute Thrombosis: If the patient presents with a sudden absence of the thrill and bruit, this is an access emergency. That scenario routes to the ACR variant for suspected thrombosis, which has a different and more urgent management pathway.
  • Failure to Mature: This guidance is not for a newly created fistula that has never developed adequate flow or size for cannulation. That situation is covered under the “Failure of an upper or lower extremity arteriovenous fistula to mature” ACR topic.
  • Primary Arm Swelling: If the patient’s chief complaint is significant edema of the access extremity, face, or chest, the primary concern is central venous stenosis. While this can cause access dysfunction, the workup is anchored on the “Clinical suspicion of central venous stenosis or occlusion” scenario.

What Diagnoses Are You Working Up in Suspected Fistula Dysfunction?

When a dialysis access begins to fail, the underlying cause is almost always a hemodynamically significant stenosis somewhere in the circuit. The goal of the workup is to identify the location and severity of the narrowing.

The most common cause of dysfunction in an AV fistula is a juxta-anastomotic stenosis. This refers to a narrowing in the outflow vein within the first few centimeters of the arteriovenous anastomosis. This area experiences high flow and turbulent shear stress, which stimulates the growth of neointimal hyperplasia, a process similar to scar tissue formation that progressively narrows the vessel lumen. This is the classic failure point for many fistulas.

Another frequent culprit is an outflow vein stenosis located further downstream from the anastomosis. These stenoses can occur anywhere along the draining vein up to the central veins. They are often associated with repeated needle cannulation, which can cause vessel wall trauma and subsequent scarring. These are sometimes referred to as “needle-site” stenoses.

Central venous stenosis is a less common but highly consequential cause of access dysfunction. This involves narrowing of the large veins in the chest (subclavian, brachiocephalic, or superior vena cava). It is most often a long-term complication of previously placed central venous catheters, which damage the vein wall and lead to fibrosis. While often presenting with arm swelling, it can also manifest solely as high venous pressures and poor flow within the access circuit.

Finally, an inflow artery stenosis can limit the amount of blood entering the fistula. This is the least common cause of access failure but should be considered, especially in patients with known peripheral arterial disease. An atherosclerotic plaque in the feeding artery (e.g., brachial or radial artery) can restrict flow, effectively starving the access circuit.

Why Is Fluoroscopic Fistulography with Intervention the Recommended First Step?

For a patient with clear signs of access dysfunction requiring treatment, the ACR designates Fluoroscopy fistulography hemodialysis access with intervention as a Usually Appropriate procedure. This approach is favored because it combines definitive diagnosis with immediate therapeutic capability in a single session.

A fistulogram provides a complete, real-time “road map” of the entire vascular access circuit. By injecting iodinated contrast under fluoroscopy, the interventionalist can visualize the inflow artery, the anastomosis, the entire outflow vein, and the central veins. This allows for the precise identification of the number, location, and severity of any stenoses.

The key advantage is the “with intervention” component. If a hemodynamically significant lesion is identified, it can be treated on the spot. The standard treatment is percutaneous transluminal angioplasty (PTA), where a balloon catheter is inflated across the stenosis to widen the vessel lumen. In some cases, a stent may be placed to hold the vessel open. This “see and treat” strategy is highly efficient, restoring access function immediately and allowing the patient to continue their scheduled dialysis without interruption.

Comparing Alternatives:

  • US Duplex Doppler is also rated Usually Appropriate. It is an excellent non-invasive tool for screening and surveillance. It uses sound waves to visualize the access and measure blood flow velocities, which can identify areas of stenosis. However, it is a purely diagnostic study. If it identifies a problem, the patient must still be referred for a fistulogram and intervention. Therefore, in a patient with clear, progressive dysfunction who will almost certainly require treatment, proceeding directly to fistulography can be the most direct and efficient pathway.
  • Surgical Consultation is rated May be appropriate. Surgery is a crucial option for complex problems not amenable to endovascular repair, such as long-segment stenoses, aneurysmal degeneration, or complete access failure. However, for the common focal stenoses that cause progressive dysfunction, a less-invasive endovascular approach is typically the preferred first-line treatment.

Fluoroscopic fistulography involves ionizing radiation and iodinated contrast, which should be considered in patients with significant residual renal function, though this is uncommon in this population.

Once you’ve decided on this procedure, understanding the technical aspects is key. While a detailed fistulogram protocol is distinct, our guide on related techniques can be helpful. For principles of venous access and intervention, see our protocol guide: IR Central Venous Access (PICC, Tunneled, Port).

What’s Next After Fluoroscopy Fistulography? Downstream Workflow

The results of the fistulogram and intervention directly guide the next steps in the patient’s care. The post-procedure workflow is a clear decision tree based on the findings.

  • If the study is positive for a treatable stenosis: The most common outcome is successful angioplasty (with or without stenting) of the identified lesion(s). The access function is typically restored immediately. The patient can often use the access for their next scheduled dialysis session. The referring physician should be notified of the successful intervention, and the patient should continue routine surveillance at their dialysis unit.
  • If the study is negative: In the rare case that a comprehensive fistulogram reveals no significant stenosis, the cause of the dysfunction may be functional rather than anatomical. This could include inadequate cardiac output or systemic hypotension. The next step is a clinical re-evaluation in collaboration with the nephrology and cardiology teams to investigate other potential causes for poor access flow.
  • If the study shows a lesion not amenable to endovascular treatment: The interventionalist may encounter a stenosis that cannot be successfully treated with a balloon or stent. This can occur with long, elastic, or recurrent stenoses (“recoil”), or with complex central venous occlusions. In this case, the next step is a Surgical Consultation, which the ACR rates as May be appropriate. The surgeon will evaluate the patient for options such as a surgical revision of the access (e.g., a patch angioplasty or an interposition graft) or the creation of an entirely new fistula or graft at a different site.

Pitfalls to Avoid (and When to Get Help)

Navigating the workup of a failing dialysis access requires avoiding several common pitfalls to ensure timely and effective treatment.

First, avoid the pitfall of “watchful waiting” when objective data shows progressive decline. A drop in flow rates or a steady rise in venous pressures is a clear warning sign of an impending thrombosis. Intervening before the access clots completely yields better long-term outcomes.

Second, ensure the entire access circuit is evaluated. A fistulogram should always include imaging of the central veins. Failing to identify a central stenosis while treating a more peripheral lesion will lead to a poor outcome and rapid recurrence of the problem.

Third, do not mistake a high-flow state with central stenosis for a well-functioning access. High flow numbers at the anastomosis can be misleading if there is a significant blockage downstream, which will be reflected in high venous pressures.

If a patient develops acute signs like a suddenly absent thrill, severe pain, or coldness in the hand (suggesting steal syndrome), escalate immediately. An absent thrill requires urgent evaluation for thrombosis, while ischemic symptoms warrant an immediate vascular surgery consultation.

Related ACR Topics and Tools

For a comprehensive understanding of this clinical area and related scenarios, the following resources are valuable. They provide the broader context for the specific workflow detailed in this article and offer tools to aid in clinical decision-making.

Frequently Asked Questions

Why not just get a Duplex Ultrasound first on every patient with suspected fistula dysfunction?

Duplex ultrasound is an excellent, non-invasive first step and is also rated ‘Usually Appropriate’ by the ACR. Many centers use it for surveillance. However, if a patient has clear, progressive, and clinically significant dysfunction (e.g., flow rates too low to support adequate dialysis), they will almost certainly need an intervention. In these cases, proceeding directly to fistulography is a more efficient strategy because it combines diagnosis and treatment in one procedure, avoiding delays in care.

What is the difference between this scenario and ‘suspected thrombosis’?

The key difference is the presence or absence of a thrill and bruit. In this scenario (dysfunction), the access is still patent and flowing, but poorly. A thrill is still palpable. In ‘suspected thrombosis,’ the access has clotted off, and there is a sudden absence of the thrill and bruit. Thrombosis is an acute event requiring more urgent intervention, whereas dysfunction is a subacute, progressive problem.

Can a fistulogram be performed if the patient has a contrast allergy?

Yes. For patients with a known allergy to iodinated contrast, a fistulogram can be performed using carbon dioxide (CO2) as the contrast agent. CO2 is a safe and effective alternative for visualizing the venous side of the access circuit. Pre-medication with steroids and antihistamines is another option for patients with mild to moderate allergies to iodinated contrast.

What if the fistulogram shows multiple stenoses? Can they all be treated at once?

Yes, it is common to find and treat multiple stenoses during a single procedure. An interventionalist will typically treat all hemodynamically significant lesions identified in the circuit, from the anastomosis to the central veins, to restore normal flow dynamics throughout the entire access.

How soon after a successful angioplasty can the patient use their fistula for dialysis?

In most cases, the access can be used for the very next scheduled dialysis session, often the same day or the following day. The angioplasty sites are typically small punctures that heal quickly. The interventional radiologist will provide specific post-procedure instructions, but the goal is to minimize any interruption to the patient’s dialysis schedule.

Reviewed by Pouyan Golshani, MD, Interventional Radiologist — May 30, 2026