Adrenal Venous Sampling (AVS): A Guide to Diagnosis and Treatment

Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: September 2026

TL;DR

Adrenal Venous Sampling (AVS) is a specialized diagnostic procedure used to determine which adrenal gland is overproducing aldosterone in patients with primary aldosteronism. By collecting blood directly from the adrenal veins, healthcare providers can distinguish between one-sided and two-sided hormone excess, which is essential for deciding between surgical removal or medical management.

Quick Answer Adrenal Venous Sampling (AVS) is an outpatient interventional radiology procedure performed to locate the source of excess aldosterone production. During the test, a radiologist inserts a catheter through the groin to collect blood samples from both the left and right adrenal veins. These samples are compared to see if the hormone imbalance originates from one gland (unilateral) or both (bilateral), directly informing whether surgery or medication is the most effective treatment for conditions like primary aldosteronism.

Overview of Adrenal Venous Sampling

Adrenal Venous Sampling (AVS) is primarily performed when a patient has been diagnosed with primary aldosteronism, also known as Conn’s syndrome. This condition occurs when the adrenal glands (small, triangle-shaped organs located on top of the kidneys) produce too much aldosterone. This hormone plays a critical role in regulating blood pressure and maintaining the body’s balance of electrolytes, such as sodium and potassium. To learn more about how these glands are built and what they do, see our guide to adrenal gland anatomy and function.

While imaging tests like CT scans or MRIs can show physical abnormalities, they often cannot confirm which gland is actually overproducing hormones. AVS is considered the “gold standard” because it provides functional data by measuring hormone levels directly at the source.

Purpose	Description
Primary Diagnosis	Identifies if one or both adrenal glands are overproducing aldosterone.
Treatment Direction	Determines if a patient is a candidate for surgery (adrenalectomy) or needs lifelong medication.
Rare Tumor Location	Occasionally used to locate rare tumors like pheochromocytomas.
Hormonal Mapping	Maps the venous system of the adrenal glands using contrast dye for precise sampling.

The AVS Procedure: What to Expect

AVS is an outpatient procedure typically performed in a hospital or specialized surgical center by an interventional radiologist. The process is designed to be painless, utilizing local anesthetics and, in some cases, light sedation to ensure patient comfort.

Preparation and Timing

Patients are generally required to fast (avoid eating or drinking) on the morning of the procedure. Additionally, healthcare providers may request that certain medications be paused in the days leading up to the test to ensure the results are not skewed. The procedure itself usually takes about two hours, followed by a recovery period of two to four hours for monitoring.

Step-by-Step Process

1. Stimulation: Medication is administered through an IV to stimulate the adrenal glands, ensuring they are actively producing hormones during the test.

2. Numbing: A local anesthetic is applied to the groin area to numb the site where the catheter will be inserted.

3. Catheterization: A small incision is made in the groin, and a thin tube (catheter) is passed into the vein. Radiologists use ultrasound and X-ray guidance to navigate the catheter.

4. Contrast Mapping: A contrast dye is injected to help the radiologist clearly see the adrenal veins on the X-ray.

5. Sampling: Blood samples are carefully collected from both the right and left adrenal veins.

6. Completion: The catheter is removed, and a simple bandage is applied to the incision site.

Interpreting Your Results

Once the blood samples are collected, they are sent to a laboratory where a technician measures the concentration of aldosterone in each sample. The comparison between the two sides is the most critical part of the diagnosis.

• Unilateral Overproduction: If only one adrenal gland is producing excess hormone, the condition is considered one-sided. In these cases, the surgical removal of the affected gland (adrenalectomy) is often the recommended treatment, which can potentially cure high blood pressure.

• Bilateral Overproduction: If both glands are overproducing aldosterone, the condition is two-sided. Surgery is typically not an option for these patients, and long-term management with specialized medications is the standard course of action.

Risks and Recovery

Adrenal Venous Sampling is widely regarded as a safe and effective procedure. However, like any invasive test involving catheters and contrast dye, there are minor risks that patients should be aware of.

Potential Risk	Frequency and Management
Bleeding	Very rare; typically managed at the incision site with pressure.
Infection	Small risk at the groin incision site; prevented with sterile techniques.
Allergic Reaction	Rare reactions to contrast dye; medical teams are equipped to treat these immediately.
Kidney Impact	Contrast material can affect those with pre-existing kidney conditions.
Vein Issues	Rare instances of vein rupture or difficulty accessing the small adrenal veins.

Post-Procedure Care

Recovery from AVS is relatively quick, but patients should plan to rest for 24 to 72 hours. During the first three days following the procedure, it is important to avoid strenuous activities, including heavy lifting, driving, or soaking the incision site in water (such as bathing or swimming). Tenderness in the groin and slight fatigue from sedation are normal and should resolve within a few days.

Conclusion

Adrenal Venous Sampling is a vital diagnostic tool for anyone suffering from primary aldosteronism. While the procedure may seem complex, its ability to pinpoint the exact source of hormone overproduction is unmatched by standard imaging. By providing a clear roadmap for treatment, whether through curative surgery or targeted medication, AVS ensures that patients receive the most effective care for their specific condition, ultimately helping to manage blood pressure and long-term health.

Next Steps for Your Health

If you have been diagnosed with primary aldosteronism or have persistent high blood pressure that is difficult to control, speak with your healthcare provider about whether Adrenal Venous Sampling is right for you. Early and accurate diagnosis is the first step toward effective treatment. Contact your medical team immediately if you experience worsening pain, fever, or bleeding following your procedure.

Frequently Asked Questions

Why do I need AVS if I already had a CT scan?

A CT scan shows the shape of your glands, but AVS shows how they are functioning. A scan might show a tumor that isn’t actually making hormones, or it might miss a small, overactive area.

Is AVS a painful procedure?

No, you should not feel pain. The area is numbed with local anesthetic, and you may receive light sedation to help you relax.

How long does it take to get the results?

Results are usually available after the lab analyzes the blood samples, which can take several days depending on the facility.

Can AVS cure my high blood pressure?

AVS itself is a diagnostic test, but it identifies if you are a candidate for surgery, which can potentially cure high blood pressure caused by primary aldosteronism.

What is primary aldosteronism?

It is a condition where your adrenal glands make too much aldosterone, leading to high blood pressure and low potassium levels.

Do I have to stay in the hospital overnight?

No, AVS is typically an outpatient procedure, meaning you can go home the same day after a few hours of observation.

What is contrast dye used for in AVS?

The dye helps the radiologist see your veins clearly on the X-ray so they can accurately place the catheter.

Are there any alternatives to AVS?

While imaging exists, AVS is the only test that can reliably distinguish between one-sided and two-sided hormone production.

Can I drive myself home after the procedure?

No, if you receive sedation, you must have someone else drive you home.

What happens if the radiologist can’t find the veins?

In some cases, the adrenal veins are difficult to access. If this happens, the procedure may need to be rescheduled or repeated.

What is an interventional radiologist?

A doctor who uses medical imaging to perform minimally invasive procedures like AVS.

Is there a risk of kidney damage?

There is a small risk for people who already have kidney disease because of the contrast dye used.

How long should I wait to exercise after AVS?

You should avoid strenuous physical activity for at least three days following the procedure.

What are the signs of a complication?

Call your doctor if you experience heavy bleeding from the groin, a high fever, or worsening pain at the incision site.

What is an adrenalectomy?

It is the surgical removal of one or both adrenal glands, often recommended if AVS shows only one side is overproducing hormones.

Medical Disclaimer: This content is for educational purposes and does not replace professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified healthcare provider with any questions regarding a medical condition.