Adrenal Vein Sampling (AVS) is a specialized medical procedure used in diagnosing certain conditions related to the adrenal glands. This minimally invasive test helps healthcare providers gather specific information about hormone production within these small glands located atop the kidneys. It serves as a focused diagnostic tool to guide appropriate medical management.
What is Adrenal Vein Sampling
Adrenal Vein Sampling (AVS) is an interventional radiology procedure that measures hormone levels directly from the veins draining the adrenal glands. It determines if one or both adrenal glands are overproducing hormones, most commonly aldosterone. Aldosterone is a hormone that regulates blood pressure and electrolyte balance.
Blood samples are collected from the adrenal veins and a peripheral vein for comparison. This allows for an individual assessment of hormone secretion from each gland.
Why AVS is Performed
AVS is primarily performed to diagnose and differentiate subtypes of primary aldosteronism. This condition involves excessive aldosterone production, which can lead to high blood pressure and low potassium levels. While imaging tests like CT scans can show tumors or enlarged glands, they cannot definitively confirm which gland is overproducing hormones.
The procedure helps distinguish between unilateral aldosteronism, where one adrenal gland is responsible for the excess hormone, and bilateral aldosteronism, where both glands are involved. This distinction is significant because the treatment approach differs. If a single gland is overactive, surgical removal of that gland (adrenalectomy) can potentially cure the condition. For bilateral overproduction, medical management with aldosterone-blocking medications is recommended.
AVS is considered the most reliable method for making this distinction, guiding whether surgery is an appropriate treatment option. AVS may also be performed to locate a pheochromocytoma, a rare tumor on the adrenal gland, or for other less common hormonal imbalances.
The AVS Procedure Steps
Preparation for AVS involves adjusting certain medications, such as blood pressure medications or diuretics, that might interfere with test results. Patients are instructed to fast from food and drink for about 6 hours prior to the procedure. Blood tests may be conducted beforehand to check electrolyte levels and kidney function.
On the day of the procedure, a small needle is inserted into an arm vein for medication. The procedure is performed in a hospital or specialized clinic by an interventional radiologist. Local anesthetic is injected into the groin to numb it, and light sedation may be administered to help the patient relax.
A small incision is made in the groin, and a thin catheter is inserted into the femoral vein. It is then guided through the veins to reach the adrenal veins. A contrast dye is often injected, allowing the radiologist to visualize the veins using X-ray imaging (venography) and confirm catheter placement. Blood samples are collected from each adrenal vein and a peripheral vein. After samples are obtained, the catheter is removed, and pressure is applied to the incision site to prevent bleeding.
Potential Considerations and Recovery
Adrenal Vein Sampling is generally safe, but risks exist. These include bleeding or bruising at the catheter insertion site in the groin, a small risk of infection, or an allergic reaction to the contrast dye. More serious complications can include adrenal hemorrhage, adrenal vein thrombosis, or damage to blood vessels.
After the procedure, patients are monitored in a recovery room for a few hours, with vital signs checked. Patients are advised to lie flat for a period to help prevent bleeding at the access site. Recovery involves resting for 24 to 72 hours, avoiding strenuous activities, lifting heavy objects, or activities that could put strain on the groin area.
Discomfort or tenderness at the puncture site is common for a day or two. If sedation was administered, patients should not drive, operate machinery, or make important decisions for at least 24 hours. Patients should seek medical attention if they experience excessive bleeding, severe pain, fever, or other concerning symptoms after returning home. The analysis of the collected blood samples can take several days to weeks, after which the results are discussed with their healthcare provider.