Whenever I talk to others about my work, I always say “a glimpse of the leopard through the tube can reveal a part of it” (Part 1)

Produced by: Science Popularization China

Author: Xue Yadi (Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences) Ran Yue (Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences)

Producer: China Science Expo

Editor's note: In order to unveil the mystery of scientific work, the China Science Popularization Frontier Science Project launched a series of articles called "Me and My Research", inviting scientists to write articles themselves, share their scientific research experiences, and create a scientific world. Let us follow the explorers at the forefront of science and technology and embark on a journey full of passion, challenges, and surprises.

In the world of minimally invasive surgery, the medical endoscope is the undisputed star. With its small size, it can easily shuttle through our complex body structure, providing doctors with an unprecedented field of vision, making surgery more precise and greatly reducing the pain of patients.

Have you ever wondered how doctors examined internal organs before the invention of endoscopes? How did endoscopes help doctors see the target clearly and even accurately guide surgery in a narrow and lightless body?

To this end, we have specially planned a series on medical endoscopes, which is divided into two parts to take you to understand the past and present of medical endoscopes and explore the scientific principles and amazing achievements behind them. This is the first part of the series.

From observation, listening, questioning and palpation to clinical medicine

Ancient doctors did not have advanced diagnostic equipment. How did they diagnose the symptoms of their patients?

Traditional Chinese medicine, represented by Chinese medicine, attempts to peek into the mysteries of the human body through the patient's external manifestations, which can be mainly summarized into the four major diagnostic methods of "observation, auscultation, questioning and palpation": observation is to observe the patient's body shape, mental state, complexion, tongue, excretion, etc. with the eyes; auscultation includes listening to sounds and smells, diagnosing the patient's breathing, voice, cough, bowel sounds and other sounds; questioning is to listen to the patient's own description of discomfort; palpation is to use fingers to feel the changes in the pulse and identify the functions of the internal organs.

Tumors are one of the problems in modern medicine, and the profession of "Yang Yi" was already recorded in the "Zhou Li" of the pre-Qin period. The so-called "Yang Yi" refers to doctors in ancient times who specialize in treating various diseases including tumors.

As time goes by and medical technology continues to develop, people begin to look for more intuitive and accurate ways to observe the patient's internal conditions. As a result, the endoscope came into being. It is like a magic key that opens the door to the inside of the human body, allowing doctors to see the secrets hidden under the skin with their own eyes.

A wide variety of endoscopes with different characteristics

An endoscope is an instrument that can penetrate deep into the human body to help doctors observe what is happening inside the body. It was originally invented to allow doctors to directly observe the internal organs of patients without having to rely on surgery to open the patient's body. This technology has completely changed the medical field, especially in the diagnosis of diseases of internal organs, where endoscopes have provided great help to doctors.

In daily life, many people may have heard of endoscopy. The most common application scenario includes gastrointestinal endoscopy.

For example, many people go to the hospital for long-term stomach pain, acid reflux or indigestion. Doctors usually recommend gastroscopy, which is a type of endoscopy. Through this small, soft fiber optic device, doctors can slowly insert the endoscope from the mouth into the stomach to observe the condition of the gastric mucosa and find out whether there are ulcers, inflammation or other problems.

Similarly, colonoscopy is performed by entering through the anus to observe the health of the large intestine and to check for problems such as colon cancer and polyps. In addition, there are also examination equipment for other parts such as the ear, nose, and throat. For example, patients with rhinitis often need nasal endoscopy to observe the inflammation inside the nasal cavity.

Overall, endoscopy allows doctors to quickly and non-invasively or minimally invasively examine many conditions, greatly reducing the risks of traditional surgery.

From gastroscopes to arthroscopy, each type of endoscope has its own unique channels and characteristics, which together constitute an important means of diagnosis and treatment in modern medicine. Endoscopes can enter the human body through a variety of "channels". For example, a gastroscope is inserted into the esophagus through the mouth and directly reaches the stomach; a colonoscope enters the large intestine through the anus; a cystoscope reaches the bladder through the urethra; a hysteroscope enters the uterine cavity through the vagina; and a laparoscope, thoracoscope, etc. need to enter the corresponding body cavity through a small incision in the abdomen or chest wall.

The selection of these channels depends on the purpose of the endoscope and the needs of examination and treatment.

Laparoscopic clinical surgery

(Photo source: Veer Gallery)

Different "channels" have their own unique characteristics. The use of natural orifices such as the mouth, anus, and urethra reduces invasiveness to the body and has a relatively short recovery period. However, these channels are usually narrower, placing higher demands on the size and shape of the endoscope. Small incisions in the abdomen or chest wall are slightly more invasive, but provide a larger operating space and are suitable for more complex operations.

The design of the endoscope must be combined with these characteristics and adjusted. For endoscopes that enter through natural orifices, their size is usually smaller and their shape is more slender to facilitate flexible operation in narrow channels. At the same time, in order to reduce patient discomfort, the surface of these endoscopes is usually specially treated to make them smoother. For endoscopes that need to enter through small incisions, their size can be slightly larger to provide a better field of view and operating space. In addition, these endoscopes also need to have good lighting and imaging systems to ensure that doctors can clearly observe the situation inside the body.

From simple lighting tubes to cell-level microscopic observation

**The history of endoscopes can be traced back to the 19th century. The earliest endoscopes were actually just a thin metal tube with a light source, which was used to peek into the body. **This early endoscope had many problems, such as insufficient light, blurry images, and poor patient experience. It was also inconvenient for doctors to use. In many cases, they could only see blurry images and could not penetrate into more complex organs. They were more like a "peeping tool" rather than a real medical instrument.

Laryngoscopy

(Photo source: Veer Gallery)

Endoscopes have gone through many iterations over time. The introduction of fiber optic technology in the mid-20th century revolutionized the field. This new type of endoscope used optical fibers to transmit images, allowing doctors to see clearer, brighter images of the body. However, fiber optic endoscopes still have certain limitations, such as image quality is limited by the number and arrangement of optical fibers, and complex surgical procedures cannot be performed.

In the late 20th century, the emergence of electronic endoscopes completely changed this situation. This endoscope uses advanced CCD or CMOS sensors to capture high-definition images and transmit them to the display screen via digital signals. Doctors can not only clearly see the situation inside the body, but also perform precise surgical operations.

Gastrointestinal examination under flexible endoscopy

(Photo source: Veer Gallery)

Endoscopic technology is like a joint adventure of science and medicine. From the initial simple peep device to today's minimally invasive instrument, endoscopy technology has undergone a rapid "evolutionary journey".

Today’s endoscopes are no longer just “peeping tools”, but have evolved into sophisticated “scouts” that can penetrate deep into the human body in a variety of ways to reveal lesions that are difficult to detect with the naked eye. From high-definition images to microscopic observations at the tissue cell level, endoscopy technology has ushered in a new era for medical diagnosis and treatment.

In the next article, let us learn about the various advanced imaging technologies behind endoscopes!