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Dialysis Vascular Access Evaluation

The access determines how your years on dialysis go — evaluated, monitored, and planned early. Assessment and coordination at Remix Medical in Houston, TX.

Your access is the thing that determines how well your years on dialysis go. It is also the thing patients hear about last.

The hierarchy is not close

An arteriovenous fistula — your own artery joined to your own vein. Lowest infection rate, lowest thrombosis rate, longest survival. It requires three to six months to mature before it can be used.

A graft — a synthetic tube between artery and vein. Usable in weeks. Clots and infects more often. Shorter lifespan.

A tunneled catheter — a line in a central vein. Works immediately, and is the worst option by a wide margin. Infection rates are several times higher. Central veins stenose and occlude, foreclosing future access on that side.

The entire argument for planning early reduces to this: a fistula placed six months before you need it means you never require a catheter.

What we assess

Whether the access is working. Bruit and thrill on examination. A fistula that has lost its thrill has clotted, and that is an emergency — hours matter.

Whether it is maturing. Six weeks after creation we look for adequate diameter, adequate flow, and sufficient depth beneath the skin to cannulate. Roughly a third of fistulas never mature. Catching that early means salvaging it or moving to plan B rather than discovering the problem when someone tries to needle it.

Whether it is failing. Difficulty cannulating. Prolonged bleeding after needle removal. Rising venous pressures during dialysis. Falling delivered dose. Arm swelling, which points to central venous stenosis. A pulsatile access with no thrill.

Whether it is stealing. A hand that is cold, pale, painful, or weak means the access is diverting blood from the distal circulation. This can progress to tissue loss and needs urgent attention.

Whether it is infected. Redness, tenderness, drainage, fever.

Whether the vessels support a new one. Vein mapping by ultrasound before any access is created.

What Remix Medical does, and does not do

We evaluate. We examine the access, order and interpret duplex ultrasound and vein mapping, monitor maturation, recognize dysfunction early, and determine which access strategy fits your anatomy and your timeline.

We do not place accesses and we do not perform interventions. Fistula and graft creation is done by a vascular surgeon. Angioplasty, stenting, and declotting are done by an interventional radiologist or vascular surgeon. We coordinate those referrals and we manage everything around them.

That division matters, and stating it plainly is more useful than implying otherwise.

Protecting the arm

Once an arm is designated for access, protect it. No blood draws. No intravenous lines. No blood pressure cuffs.

This should be told to every patient with an eGFR under 30, well before dialysis is on the horizon. It usually is not, and by the time it is, both arms have been used for years.

Timing, again

A fistula needs three to six months. Vein mapping and surgical referral precede that. Maturation surveillance follows it.

A patient who begins at an eGFR of 20 has a mature fistula waiting. A patient who arrives in an emergency room at an eGFR of 6 gets a catheter in the neck, and carries its risks for months while a fistula is built.

The difference between those two patients is a conversation held early.

How it's performed

The nephrologist examines the access for bruit, thrill, pulsatility, aneurysmal change, and signs of infection, and assesses the distal limb for evidence of steal. Duplex ultrasound evaluates arterial inflow, the body of the access, and venous outflow, measuring flow volume and identifying stenosis. Maturation is assessed approximately six weeks after fistula creation against criteria for diameter, flow, and depth. Preoperative vein mapping evaluates arterial and venous anatomy before any access is created. Findings of dysfunction, stenosis, thrombosis, steal, or infection prompt referral. Access creation is performed by a vascular surgeon; angioplasty, stenting, and thrombectomy are performed by an interventional radiologist or vascular surgeon. Remix Medical performs evaluation and coordination only, not placement or intervention.

How to prepare

Wear short sleeves or clothing that exposes the access arm. Do not allow blood draws, intravenous lines, or blood pressure measurement on the access arm, before or after creation. Report any difficulty with cannulation, prolonged bleeding after needle removal, arm swelling, or a cold or painful hand. A fistula that has lost its thrill is an emergency and should not wait for a scheduled appointment.

Outcome

Early identification of failing maturation, stenosis, thrombosis, steal syndrome, and infection, permitting timely referral for surgical or interventional salvage. Approximately a third of fistulas fail to mature; surveillance detects this before a failed cannulation. Vein mapping before access creation improves the likelihood that the chosen site succeeds. Planning at an eGFR of 30 to 20 allows a fistula to mature and avoids tunneled catheter placement entirely.

Ready to see a nephrologist in Houston?

Book your first visit, or call us to verify your insurance and ask any questions about nephrology care.

Your physician

Your nephrology at Remix Medical.

Every clinician at Remix Medical is board-certified and owns the practice — so the physician in your exam room is the one making decisions about your care.

  • Uday Khosla, MD

    Nephrologist

    Montrose — Upper Kirby · Limestone County — Groesbeck · Katy — Grand Parkway · East Houston — Woodforest

    Board certifiedAccepting newBook
Specialty
Nephrology & Hypertension
Type
Diagnostic test
CPT code
93990 (duplex scan of hemodialysis access); 93985, 93986 (duplex scan for preoperative vessel assessment prior to hemodialysis access creation, bilateral and unilateral); G0365 (vessel mapping prior to hemodialysis access creation). Access creation (36818–36833) and endovascular intervention (36901–36909) are performed by a vascular surgeon or interventional radiologist.

Also known as: AV Fistula Evaluation, Arteriovenous Fistula Assessment, Dialysis Access Surveillance, Vein Mapping, Fistula Maturation Study, AV Graft Evaluation, Access Duplex Ultrasound

This page is for general education and is not a substitute for medical advice. Whether a given procedure is appropriate depends on your individual evaluation. Contact a Remix Medical clinician to discuss your care.

Updated July 9, 2026.

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