An ultrasound gel is a medium that is applied directly onto the skin before performing an ultrasound imaging or therapeutic procedure.
The purpose of the gel is to increase the conductivity between the skin of the patient and the transducer of the ultrasound device in use.It also helps the transducer glide smoothly along the surface of the skin, with minimal patient discomfort.
In this article , we examine a few questions that may be asked by patients who are encountering an ultrasound gel for the first time.
How Does Ultrasound Technology Work?
Ultrasound technology is used to send pulsing sound waves deep into your skin using a specially designed “probe” also known as a transducer. The transducer also receives sound waves reflected back to it from within the body. The reflected waves are translated into images that can be viewed on a computer screen.
How Does The Ultrasound Gel Help?
Unfortunately, the sound waves transmitted into the body do not travel well through the air.
To solve this problem, the gel is used to reduce the amount of air bubbles between the transducer and the skin. This improves the conductivity of sound waves both to and from the transducer. It therefore helps ensure that the image to be produced is of sufficiently high quality for an accurate medical diagnosis.
Another important function of an ultrasound gel is to reduce the amount of static electricity between the transducer and the patient’s skin. Static electricity can reduce the quality of the images produced by the procedure.
Propylene glycol is a synthetically manufactured product with a thick and sticky consistency. This texture is important for it to be effective as an ultrasound medium. It ensures that the ultrasound gel will stay on the patient’s skin long enough for completion of the procedure.
Why Do Gels Have Different Formulations?
If you look at the range of ultrasound gels offered by a vendor, you will likely notice that there are gels with many different degrees of thickness. Another name for this thickness is viscosity.
The more viscous a gel, the thicker it is and the greater its resistance to flowing freely. On the other hand, the less viscous the gel, the more “runny” it is. Water, for example,has a very low viscosity.
The more viscous gels are used for longer lasting procedures, as they have to stay in place for longer. A runny gel will not maintain a thick layer against the skin for very long, and conductivity will therefore suffer.
A high viscosity gel will also perform better on a highly contoured body area. Its viscosity helps it to cling to the contours better and maintain a uniform conductive medium that will result in sharper images.
A low viscosity gel is easier to use over a larger body area. This is because it will be less resistant to spreading over such an area.
Clear vs. Tinted
Ultrasound gels come in both clear (transparent) and tinted forms. Some patients may have sensitive skin or allergies. For these patients, a clear gel presents less risk of an allergic reaction and is therefore a preferable choice.
What About The Gels Used For TENS or NMES Therapies?
TENS or NMES therapies involve sending electrical energy into the body to reduce pain or rehabilitate atrophied muscles.
Just as with ultrasound, these therapies rely on the use of a highly conductive medium between the TENS/NMES electrodes and the skin. Air bubbles between the electrode and the skin compromise conductivity and reduce the effectiveness of the therapy.
Ultrasound gels,because they contain water, are highly conductive to electricity. As a result, use of these gels for TENS/NMES therapies is widespread. However, because some TENS/NMES therapies are much longer than the typical ultrasound session, the gels used tend to be of high viscosity.
What About Ultrasound Lotions?
Ultrasound lotions are also in widespread use. They serve the same purpose as ultrasound gels, i.e. to improve conductivity between the transducer and the patient’s skin.
However, unlike ultrasound gels, lotions are easily absorbed into the skin. They can therefore be simply rubbed into the patient’s skin at the end of the ultrasound procedure. This reduces the annoyance and distraction some patients may experience from a sticky gel residue on the skin.
Many lotions contain skin health nutrients like aloe vera and vitamin E for this reason. They can therefore provide added value to the patient by helping to improve skin health and moisturization.
Lotions tend to have medium viscosity. This allows them to be general purpose in nature and be suitable for a wide range of procedures.