Hand held Doppler has now been superseded by duplex ultrasound scanning
In the 1980s and 1990s, a hand held Doppler was regarded as essential in varicose vein surgery.
Now with the duplex ultrasound scanner being available in all reputable vein clinics, no one should ever need to use a hand held Doppler to assess varicose veins or recurrent varicose veins ever again.
A hand held Doppler is a small box that can be held in the hand or put in the pocket. It has a wire coming from it leading into a small cylindrical probe, often called a pencil probe.
The end of this probe emits a beam of ultrasound and then listens for the reflected beam.
When the probe is placed on the skin, contact gel is used to make a good connection and then the ultrasound beam is projected directly into the skin and to the underlying structures.
If nothing is moving, the ultrasound beam that is reflected is the same as the one that was projected and nothing happens.
However, if there is blood moving in a vein or artery under the skin, then the ultrasound beam is changed by the Doppler effect. The reflected beam is different from the projected beam and the hand held Doppler machine is calibrated to pick up this change.
In most hand held Doppler machines, this change is converted into a noise that sounds like a ‘wooosh’.
You will often see a hand held Doppler being used by district nurses or nurses on the ward in hospitals. They are very useful to find pulses in arteries particularly at the ankles in the foot where they can be hard to feel.
However, when it comes to veins, the hand held Doppler is now rarely use.
In the 1980s and 1990s, when duplex ultrasound scanners were very rare, the hand held Doppler was seen to be magical. A patient could be stood up, a hand held Doppler placed over a vein and when the vein was squeezed, blood flow could be heard.
If a wooosh was heard on squeezing, then this meant that the vein was being examined and blood flow going up the vein was being heard. On release of the vein, if the valves were working nothing would be heard. If, however, the valves were not working, then a second wooosh could be heard as blood fell back down the vein.
Since duplex ultrasound scan has now become more available, it has become much clearer that hand held Dopplers can give the wrong information.
The biggest problem with the hand held Doppler is that you do not know which vein is being examined. If the Doppler probe is being pointed into the groin, there are several veins that might be at that point under the skin. If only one wooosh is heard, it might make the doctor or nurse think that the vein is normal. However this would be wrong if the Doppler had slipped and the second wooosh was missed simply due to bad positioning. Alternatively, the Doppler may be examining a completely different vein that is working whilst a big varicose vein slips passed unnoticed.
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