Venous sampling

Venous sampling is a procedure that involves inserting a catheter (thin tube) into a specific vein or veins, taking blood samples from them and sending them to the laboratory for testing. The results can help the doctors looking after you to make decisions about any future treatment.

The doctors in charge of your case are trying to find if there are any abnormalities in your blood results to decide which treatment you require. For example:

• Adrenal Venous Sampling (AVS) is when blood samples are taken from the veins of the adrenal glands. This is usually done for patients with a particular form of high blood pressure.
• Parathyroid Venous Sampling (AVS) is when blood samples are taken from the veins in the area of the parathyroid glands to help determine any abnormality.

The Consultant in charge of your case, and the Interventional Radiologist (the doctor who specialises in Imaging Procedures) who will be carrying out the venous sampling will have discussed the situation, and feel that this is the best option. However, you will also have the opportunity for your opinion to be taken into account and if, after discussion with your doctors, you do not want the procedure carried out, then you can decide against it.

A specialist doctor called an Interventional Radiologist. Interventional Radiologists have special expertise in using X-ray equipment and in microsurgical techniques.

In the Imaging Department, in a special Interventional Radiology (IR) Procedure Room which is designed for these specialised procedures. You will be checked into the department by a nurse, who will ask some medical questions and fill out some paperwork. The Interventional Radiologist will then talk to you about the procedure, and you will have the opportunity to ask any questions or raise any concerns. Only if you are happy to continue with the procedure will you be asked to sign the consent form.

It is performed in the IR procedure room. You will lie on a special x-ray table on your back and be covered with sterile drapes.

• Your groin or neck area will be cleaned with an antiseptic solution. The Interventional Radiologist will talk with you about which area he or she plans to use when you sign the consent form before the procedure starts.
• Local anaesthetic will be injected to numb the area and stop you feeling pain. When the groin or neck is numb, a thin tube (catheter) is positioned into the vein/veins using x-ray guidance.
• Contrast (x-ray dye) is injected into the catheter and viewed on an x-ray screen. This confirms that it is in the right position.
• When the catheter is in the right position the radiologist will begin to take the blood samples that are required. Once the blood samples have been taken, the radiologist removes the catheter and will press gently on the entry site. This prevents bleeding. The procedure usually takes around one hour.

Sometimes it can be difficult to insert the catheter into narrow veins or difficult to locate certain veins. This makes it difficult to get adequate blood samples. Occasionally the test may need to be repeated, or it may not be possible in all patients due to medical and/or technical issues.

To prepare for the procedure you will need to make sure you do the following:

Please let us know if you are taking any antiplatelet medicines (for example, Aspirin, Clopidogrel) or any medicines that thin the blood (for example, Warfarin), as these may need to be withheld temporarily before the procedure. Call the IR department for advice as soon as you get your appointment letter on 01273 696955 Ext. 4240/4278 and ask to speak to one of the IR nursing team.

If you are taking medicines for diabetes (for example metformin) or using insulin, then these may need to be altered around the time of the procedure. Call the IR department on the numbers above for advice as soon as you get your appointment letter.

For these procedures there are certain drugs that you may need to stop taking so they don’t affect the results of the blood samples. If your doctor has not told you about this please call us to confirm what you can and can’t take.

You cannot eat or drink anything (except water) for four hours before your procedure. You can drink water up to two hours before your procedure.

You will need a responsible adult to take you home.