Up until the invention of venous duplex ultrasound scanning there were several different tests for varicose veins.
As you will see from the NICE guidelines, venous duplex ultrasound scanning has now become the gold standard test for the investigation of varicose veins. However there are some things that the venous duplex ultrasound scan do not show – and more importantly the venous duplex ultrasound scan is only as good as the person using it.
To get optimum results from venous duplex ultrasound scanning, the scan should be performed by a vascular technologist who scans veins every day. It is a very specialised and detailed process which should take between 30 to 45 minutes per scan.
Scans that are undertaken using small machines, taking just 5 to 10 minutes, will often miss important underlying causes of varicose veins. These scans are often performed by doctors or other professionals who only scan occasionally and do multiple other things during the day.
This has been studied and internationally presented research suggests that these quick scans may well record venous duplex ultrasound scans but the more in-depth and more accurate scans, that are performed by specialists should be called ‘extended venous duplex ultrasound scans’. It is this scan that is performed by Vascular Technologists at The Whiteley Clinic.
At The Whiteley Clinic we do not believe that a patient should be treated on the basis of anything but a full venous duplex ultrasound scan which has been performed by a specialist and therefore that should be the standard rather than be called ‘extended’.
It is essential that patients are aware that if their varicose veins are treated following a quick scan which has been performed by someone who does not specialise in doing venous ultrasound scans daily, there is evidence that they are probably not getting a full diagnosis and hence underlying causes for their vein problems may well be missed.
For completeness, we will now look at some of the available tests for veins that have been used in the past or currently used.
The Trendelenburg or ‘tourniquet’ test to check the source of varicose veins was used for years before Doppler ultrasound was available and before we understood the underlying mechanisms of varicose vein development.
Nowadays it should never be used, not even in medical school examinations as it has been shown to be completely inaccurate when assessed against duplex ultrasound examination.
Doppler ultrasound was invented in the mid 1950’s. By the 1980’s, small hand held Dopplers or ‘pencil Dopplers’ were common in every hospital and venous practice.
These are often still found around clinics and hospitals as they are quite useful in measuring arterial pressure.
A simple plastic probe is held at an angle to the skin and an electronic box emits a sound if blood flow is found. There is no television monitor and the entire scanning device can fit into a pocket.
Although many papers were written on the use of such a device in varicose vein surgery in the 1980s and 1990s, by the turn of the last century it was clear that this test was totally inadequate for the investigation of varicose veins and venous reflux.
Although it is possible to hear blood flow if the Doppler beam is directed at a blood vessel, there is no way of knowing which blood vessel is actually being heard. As such, one can either misdiagnose reflux or be lulled into a false sense of security by inadvertently listening to a signal from a vein in front of, behind or to the side of the vein that we think we are listening to.
Since the advent of venous duplex ultrasound scanning where the vein can be seen on a TV monitor and the blood-flow measured within it, the hand held Doppler should have disappeared from modern venous practice.
A venogram (or venography) is the injection of a contrast solution into a vein and then a series of x-rays to watch the contrast flow up inside the vein, are taken.
The idea being that the contrast will act like venous blood and show the flow and the vein wall.
Unfortunately this is not the case. The contrast is more dense and is usually cold and the blood does not behave like venous blood.
In addition the contrast might not flow into a vein that is there and so might mislead the doctor into thinking there is no vein present at that point.
Venograms are very poor at showing venous reflux whereas venous duplex ultrasound scanning will show this very clearly.
There are some indications for venograms but these are few and far between in normal venous practice. Occasionally we use them to help diagnose males with pelvic vein problems and more commonly we use them to guide treatment catheters for pelvic vein embolisation. However in this case the venogram is not being used to diagnose the condition as transvaginal duplex ultrasound scanning has been shown to be superior in our research. In this case venography is used as part of the treatment to make sure any coil embolisation or foam embolisation is positioned exactly as required.
CT and MRI technology are excellent scans for a great many areas of medicine.
They are virtually never needed in varicose vein surgery but they can be useful in deep vein thrombosis or in people with severe venous disease such as in post thrombotic syndrome (PTS).
However in normal varicose vein surgery they should never be required.
This is a fantastic new technology in which a small ultrasound probe can be passed into a vein on the end of the catheter.
It is very useful for looking at veins that are narrowed or being compressed and so as with CT and MRI, may be useful in post thrombotic syndrome (PTS).
However in normal varicose veins, IVUS is not required.
Plethysmography is a technique that measures the changes in volume of a limb. There are several different ways of doing this.
In photo plethysmography (PPG) an infrared light probe shines infrared light into the capillaries and measures the reflection. As the venous pressure rises and the veins dilate, the speed of dilatation can be measured.
In a plethysmography and strain gauge plethysmography, the volume of the leg (usually the calf) is measured. The leg is then usually elevated and dropped to see how the movement of blood in the veins changes the volume of the limb.
From these results, we are able to observe the function of veins as a whole rather than just which way the blood is flowing as with venous duplex ultrasound.
As such, the information provided by plethysmography adds to the information that can be gleaned from venous duplex ultrasound scanning and so quite often we perform both venous duplex ultrasound scanning and PPG together to get a full assessment of the limb.
As research progresses, it is becoming more apparent that to get a full understanding of venous disease in a leg, it is beneficial to have the information from plethysmography in addition to the map created by the venous duplex ultrasound scanning to fully understand what a patient needs to get the best result.
Although this has been mentioned before, it is well worth an explanation in this section by itself.
The words ‘duplex’ means there are two different parts to the scan. In reality there are actually three parts and so in some areas of the world it is called ‘triplex scanning’, ‘colour-coded duplex scanning’ or even ‘colour flow duplex scanning’.
To understand venous duplex ultrasound scanning, it is easiest to think of the basic technology as being ultrasound scan. Medically this is called either greyscale or B-mode ultrasound. This is the standard sort of ultrasound scan used to look at babies in the womb in pregnant mothers or at gallbladders in people with abdominal pain. Most people have seen this sort of scan.
Ultrasound scanners do not produce any radiation like x-rays or use any needles or injections. They merely use gel on the skin to get a good contact and then probe over the area to get a good view.
The second modality is the Doppler ultrasound. Again this is ultrasound that is beamed into one specific area of the body and this area can be determined by the ultrasound picture. Hence, if a vein is seen on the picture, the Doppler ultrasound can be directed inside the vein.
Doppler has a very special ability to be able to measure flow. Hence by using both the ultrasound picture and the Doppler waveform, flow in the vein can be measured.
Finally, the third modality is called ‘colour flow’ Doppler or ‘colour-coded’ Doppler. Computers these days are so fast that any movement on the black and white ultrasound picture can be picked up and coded as either blue or red depending on the direction of flow, enabling blood flow to be seen in a vein in real time. In addition we can see when blood flows up the vein normally and when it flows down the vein abnormally if the valves are not working.
It is this ability of the duplex ultrasound scan to actually see the flow in real life, that makes it such an incredibly powerful technique to understand varicose veins and to know exactly which of the different treatments, or combination of treatments, are best for each individual patient.