What Is A Fistulogram And How Is The Procedure Done?

A fistulogram is an imaging test that uses X-rays and a contrast dye to create detailed pictures of an abnormal tunnel, called a fistula, that has formed between two body structures. The procedure involves injecting contrast material into the fistula opening so a radiologist can map its exact path, length, and connections. This test is most commonly used to evaluate fistulas related to dialysis access, but it is also used for fistulas in the digestive tract and other areas of the body.

Why Would a Doctor Order a Fistulogram?

Doctors order this test for two main reasons: to diagnose a problem or to guide a treatment. When a fistula is not working correctly, or when doctors need to understand its structure before surgery, a fistulogram provides the clearest picture available.

For people on hemodialysis, a fistula is a surgically created connection between an artery and a vein, usually in the arm. This connection allows high volumes of blood to flow through a needle during dialysis sessions. Over time, these fistulas can narrow, clot, or develop aneurysms. A fistulogram identifies exactly where and why the flow is blocked.

Outside of dialysis, fistulas can develop between organs, such as between the bowel and the bladder, or between the rectum and the skin. In these cases, the test maps the tunnel so a surgeon knows precisely what needs to be repaired.

What Is A Fistulogram And How Is The Procedure Done: Step by Step

The procedure is performed by an interventional radiologist, a doctor who uses imaging to perform minimally invasive procedures. You will lie on an X-ray table, and the area around the fistula will be cleaned and numbed with a local anesthetic. You remain awake during the test, but you should not feel sharp pain—only pressure or a brief sting from the numbing medicine.

The radiologist inserts a thin plastic tube called a sheath into the fistula, then guides a smaller catheter through it. Contrast dye is injected through the catheter while a series of X-ray images, called fluoroscopy, are taken in real time. The dye makes the inside of the fistula visible on the screen, revealing any narrowing, blockages, or abnormal connections.

If the test is being done for dialysis access and a narrowing is found, the radiologist can often treat it immediately. A small balloon may be inflated inside the narrowed area to widen it, a procedure called angioplasty. In some cases, a small metal mesh tube called a stent is placed to keep the vessel open. This means a diagnostic test and a treatment can happen in a single session.

The entire procedure typically takes 30 to 60 minutes. Afterward, the catheter is removed, and pressure is applied to the insertion site to stop any bleeding. You will be asked to lie still for a few hours before going home.

Are There Different Types of Fistulograms?

Yes. The specific approach depends entirely on where the fistula is located. The most common type is a dialysis fistulogram, which examines the arm vessels used for hemodialysis. This is performed on an outpatient basis and rarely requires an overnight stay.

A gastrointestinal fistulogram, sometimes called a fistulogram through a sinus tract, is used when a fistula connects the bowel to the skin or to another organ. Contrast dye is injected through the external opening of the tract on the skin. The images show whether the tunnel connects to the intestine, bladder, or another structure. Surgeons use these images to plan the repair.

Some fistulas are internal and have no external opening, such as one between the rectum and vagina. In these cases, contrast may be injected through a catheter placed during an exam, or MRI may be used instead because it provides better detail of soft tissues without radiation.

What Are the Risks and Side Effects?

A fistulogram is a low-risk procedure, but it is not risk-free. The most common side effects are minor bruising, bleeding, or infection at the catheter insertion site. These occur in a small percentage of cases and are usually managed easily.

Contrast dye carries its own risks. Some people experience a warm flush or a metallic taste in the mouth when the dye is injected—this is normal and passes quickly. A more serious concern is an allergic reaction to the dye, which can range from mild hives to a severe drop in blood pressure. Tell your doctor beforehand if you have had a reaction to contrast dye in the past or if you have allergies to any medications.

Kidney function is another consideration. The dye is filtered by the kidneys, and in people with pre-existing kidney disease, it can cause further damage. Your doctor will likely check your kidney function with a blood test before the procedure. For dialysis patients, this is less of a concern because their blood is already being filtered by the dialysis machine.

Radiation exposure from fluoroscopy is real but modest. The amount of radiation is comparable to several hundred chest X-rays, depending on the complexity of the case. For a single diagnostic procedure, the risk from this exposure is very small. Pregnant women should not undergo this test unless it is absolutely necessary, as radiation can harm a developing fetus.

What Happens After the Procedure?

After the test, you will be monitored for a short period to ensure there is no bleeding from the insertion site. Most people go home the same day. You should avoid heavy lifting and strenuous activity for about 24 hours.

Drink plenty of water unless your doctor tells you otherwise. This helps flush the contrast dye out of your system through your kidneys. If you are on dialysis, your regular schedule will continue as normal unless your doctor gives different instructions.

If angioplasty or stenting was performed during the fistulogram, you may notice the fistula feels stronger or has a better “thrill”—the vibration you can feel over a working fistula. This improvement is often immediate. However, narrowed areas can recur, which is why dialysis fistulas are monitored regularly.

How Do Fistulograms Compare to Other Imaging Tests?

Doctors have several imaging options for evaluating fistulas, and each has strengths and limitations. The choice depends on the location of the fistula, the question being asked, and whether treatment is needed at the same time.

Ultrasound is often the first test because it is quick and involves no radiation. But it cannot treat a problem it finds. An MRI provides excellent detail of soft tissue but cannot be used in people with certain metal implants and takes longer. A fistulogram is unique because it combines diagnosis with the ability to treat immediately during the same procedure.

How Should You Prepare for a Fistulogram?

Preparation is straightforward. Your doctor will tell you whether to stop taking any blood-thinning medications such as warfarin, apixaban, or aspirin. Do not stop these on your own—always follow your doctor’s specific instructions, as stopping some blood thinners can increase your risk of blood clots.

You will need to fast for several hours before the procedure, usually nothing to eat or drink for six to eight hours. This is because sedation is sometimes used, and having food in your stomach increases the risk of complications if you vomit while sedated.

Arrange for someone to drive you home. Even though you may only receive local anesthesia, the sedation given to help you relax can impair your judgment and reaction time for several hours.

Wear comfortable clothing and leave jewelry at home. You will change into a hospital gown for the procedure.

When Are the Results Available?

The radiologist can often give you preliminary results immediately after the procedure. If a narrowing was found and treated with angioplasty, you will know right away. A full written report is usually sent to your referring doctor within a few days.

Your doctor will discuss what the images show and what the findings mean for your treatment plan. If the fistulogram was done for dialysis access, the results will help determine whether your fistula can continue to be used or whether a new access site is needed.