What is the "jelly-like substance" that doctors apply during color ultrasound?

During color Doppler ultrasound examination

Have you ever wondered

The transparent, sticky "jelly" smeared on the body

What is it?

In fact, this substance is called "medical ultrasonic coupling agent". It looks ordinary, but it actually contains profound scientific principles.

During the ultrasound diagnosis and treatment process, the coupling agent is applied between the probe (or treatment head) and the human tissue to act as an intermediary medium for transmitting (transmitting) sound waves to ensure clear images during the examination.

Medical coupling agent is a medical product composed of a new generation of water-based polymer gel (mainly composed of propylene glycol, glycerol, triethanolamine, carbomer, trichlorohydroxydiphenyl ether, etc.), with a neutral pH value, non-toxic and harmless to the human body, not easy to dry, not easy to become rancid, and non-greasy. The probe is easy to slide, can moisten the skin, eliminate air on the skin surface, and reduce the acoustic impedance difference between the probe and the skin, thereby making the ultrasound imaging clear.

Image source: Made by myself

● In order to obtain high-quality images, the coupling agent can reduce the acoustic impedance difference between the probe and the skin, reduce ultrasonic energy loss, and make the image clearer.

● The coupling agent can also act as a lubricant, reducing the friction between the probe and the skin and alleviating pain.

● It is thermally stable and has acoustic transmission and electrical insulation properties.

● It can maintain stickiness and adhesion for a longer period of time, so that the probe can slide smoothly along the skin.

Since the main components of the coupling agent are water and gel , after the examination, the doctor will provide a tissue for simple wiping to remove the sticky residue on the surface. It can actually be cleaned without washing with water.

Image source: Made by myself

The coupling agent is harmless to the skin.

Because the coupling agent is water-soluble and dries quickly , it will not stay on the skin for a long time. If you are allergic to the coupling agent, you should inform your doctor before the examination.

In general, medical coupling agents have become an indispensable auxiliary tool in ultrasonic diagnosis due to their excellent performance and stability.

Image source: Made by myself

Image source: Made by myself

In winter, by heating the medical ultrasonic coupling agent, it will feel warm and comfortable when applied to the human body surface, which can effectively alleviate the strong cold stimulation caused by the cold coupling agent on the human body.

Statement: This article is a medical-related educational popular science article. It does not involve specific treatment methods or medical behaviors and cannot replace hospital visits.

Author

References

[1] Tai Qiru, Zhou Fangping, Feng Bo, Dong Shunfu, Li Wenliang. Development of antibacterial medical ultrasound coupling agent[J]. Journal of Jilin Medical College, 2016, 37(03): 217-219. DOI: 10.13845/j.cnki.issn1673-2995.2016.03.024.

[2] Li Ping, Wu Dan, Xiong Lei, et al. Technical review focus of medical ultrasound coupling agents[J]. Drug Evaluation, 2023, 20(6): 665-667. DOI: 10.19939/j.cnki.1672-2809.2023.06.04.

[3] Niu Fengqi, Zhu Chenggang, Cheng Yang. Medical ultrasound coupling agent: knowledge and information that ultrasound physicians should know [J]. Chinese Journal of Medical Imaging Technology, 2009, 25(4): 715-717. DOI: 10.3321/j.issn:1003-3289.2009.04.057.

[4] Zhang Liubo, Yang Huaming (eds.). Latest progress in medical disinfection[M]. 2015

[5] Li Baolin. Analysis on the quality management of medical ultrasonic coupling agent[J]. China Medical Device Information, 2021, 27(7): 6-7, 38. DOI: 10.3969/j.issn.1006-6586.2021.07.003.

[6] Niu Fengqi, Zhang Di, Zhu Chenggang, et al. The use of medical ultrasound coupling agent needs to be formulated [J]. Chinese Journal of Medical Imaging Technology, 2020, 36(11): 1706-1708. DOI: 10.13929/j.issn.1003-3289.2020.11.027.

[7] Hong Fanzong, Zhou Jinsheng. Research and development of coupling agent warmer[J]. Chinese Journal of Medical Equipment, 2008, 23(10):88-88. DOI:10.3969/j.issn.1674-1633.2008.10.037.

Content Production

Editor: Zhang Fuyao

Map: Eastern Zhou Dynasty