Endoscope

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Drawing of an endoscope for fetal detection, or "fetoscope" Fetal-endoscope.gif
Drawing of an endoscope for fetal detection, or "fetoscope"

An endoscope is an inspection instrument composed of image sensor, optical lens, light source and mechanical device, which is used to look deep into the body by way of openings such as the mouth or anus. A typical endoscope applies several modern technologies including optics, ergonomics, precision mechanics, electronics, and software engineering. With an endoscope, it is possible to observe lesions that cannot be detected by X-ray, making it useful in medical diagnosis. An endoscope uses tubes only a few millimeters thick to transfer illumination in one direction and high-resolution video in the other, allowing minimally invasive surgeries. [1] It is used to examine the internal organs like the throat or esophagus. Specialized instruments are named after their target organ. Examples include the cystoscope (bladder), nephroscope (kidney), bronchoscope (bronchus), arthroscope (joints) and colonoscope (colon), and laparoscope (abdomen or pelvis). [2] They can be used to examine visually and diagnose, or assist in surgery such as an arthroscopy.

Contents

Etymology

"Endo-" is a scientific Latin prefix derived from Ancient Greek ἐνδο- (endo-) meaning "within", and "-scope" comes from the modern Latin "-scopium", from the Greek σκοπεῖν (skopein) meaning to "look at" or "to examine". [3]

History

Drawings of Bozzini's "Lichtleiter", an early endoscope Bozzini's Lichtleiter.svg
Drawings of Bozzini's "Lichtleiter", an early endoscope

The first endoscope was developed in 1806 by German physician Philipp Bozzini with his introduction of a "Lichtleiter" (light conductor) "for the examinations of the canals and cavities of the human body". [4] However, the College of Physicians in Vienna disapproved of such curiosity. [5] The first effective open-tube endoscope was developed by French physician Antonin Jean Desormeaux. [6] He was also the first one to use an endoscope in a successful operation. [7]

After the invention of Thomas Edison, the use of electric light was a major step in the improvement of endoscope. The first such lights were external although sufficiently capable of illumination to allow cystoscopy, hysteroscopy and sigmoidoscopy as well as examination of the nasal (and later thoracic) cavities as was being performed routinely in human patients by Sir Francis Cruise (using his own commercially available endoscope) by 1865 in the Mater Misericordiae Hospital in Dublin, Ireland. [8] Later, smaller bulbs became available making internal light possible, for instance in a hysteroscope by Charles David in 1908. [9]

Hans Christian Jacobaeus has been given credit for the first large published series of endoscopic explorations of the abdomen and the thorax with laparoscope (1912) and thoracoscope (1910) [10] although the first reported thoracoscopic examination in a human was also by Cruise. [11]

Laparoscope was used in the diagnosis of liver and gallbladder disease by Heinz Kalk in the 1930s. [12] Hope reported in 1937 on the use of laparoscopy to diagnose ectopic pregnancy. [13] In 1944, Raoul Palmer placed his patients in the Trendelenburg position after gaseous distention of the abdomen and thus was able to reliably perform gynecologic laparoscope. [14]

Georg Wolf, a Berlin manufacturer of rigid endoscopes established in 1906, produced the Sussmann flexible gastroscope in 1911. [15] [16] Karl Storz began producing instruments for ENT specialists in 1945 through his company, Karl Storz GmbH. [17]

Fiber optics

A Storz endoscopy unit used for laryngoscopy exams of the vocal folds and the glottis Storz Endoscopy Unit.png
A Storz endoscopy unit used for laryngoscopy exams of the vocal folds and the glottis

Basil Hirschowitz, Larry Curtiss, and Wilbur Peters invented the first fiber optic endoscope in 1957. [18] Earlier in the 1950s Harold Hopkins had designed a "fibroscope" consisting of a bundle of flexible glass fibres able to coherently transmit an image. This proved useful both medically and industrially, and subsequent research led to further improvements in image quality.

The previous practice of a small filament lamp on the tip of the endoscope had left the choice of either viewing in a dim red light or increasing the light output – which carried the risk of burning the inside of the patient. Alongside the advances to the optics, the ability to 'steer' the tip was developed, as well as innovations in remotely operated surgical instruments contained within the body of the endoscope itself. This was the beginning of "key-hole surgery" as we know it today. [19]

Rod-lens endoscopes

There were physical limits to the image quality of a fibroscope. A bundle of 50,000 fibers would only give a 50,000-pixel image, and continued flexing from use breaks fibers and progressively loses pixels. Eventually, so many are lost that the whole bundle must be replaced at a considerable expense) . Harold Hopkins realised that any further optical improvement would require a different approach. Previous rigid endoscopes suffered from low light transmittance and poor image quality. The surgical requirement of passing surgical tools as well as the illumination system within the endoscope's tube which itself is limited in dimensions by the human body left very little room for the imaging optics.[ citation needed ] The tiny lenses of a conventional system required supporting rings that would obscure the bulk of the lens' area. They were also hard to manufacture and assemble and optically nearly useless.[ citation needed ]

The elegant solution that Hopkins invented was to fill the air-spaces between the 'little lenses' with rods of glass. These rods fitted exactly the endoscope's tube making them self-aligning and requiring of no other support.[ citation needed ] They were much easier to handle and utilised the maximum possible diameter available.

With the appropriate curvature and coatings to the rod ends and optimal choices of glass-types, all calculated and specified by Hopkins, the image quality was transformed even with tubes of only 1mm in diameter. With a high quality 'telescope' of such small diameter the tools and illumination system could be comfortably housed within an outer tube. Once again, it was Karl Storz who produced the first of these new endoscopes as part of a long and productive partnership between the two men. [20]

Whilst there are regions of the body that will always require flexible endoscopes (principally the gastrointestinal tract), the rigid rod-lens endoscopes have such exceptional performance that they are still the preferred instrument and have enabled modern key-hole surgery.[ citation needed ] (Harold Hopkins was recognized and honoured for his advancement of medical-optic by the medical community worldwide. It formed a major part of the citation when he was awarded the Rumford Medal by the Royal Society in 1984.)

Composition

The insertion tip of an endoscope Insertion tip of endoscope.jpg
The insertion tip of an endoscope

A typical endoscope is composed of following parts:

Besides, patients undergoing endoscopy procedure may be offered sedation in order to avoid discomfort.

Laparoscopic surgery Laparoscopic stomach surgery.jpg
Laparoscopic surgery

Clinical application

An endoscopy room in a hospital Endoscopy room.jpg
An endoscopy room in a hospital

Endoscopes may be used to investigate symptoms in the digestive system including nausea, vomiting, abdominal pain, difficulty swallowing, and gastrointestinal bleeding. [21] It is also used in diagnosis, most commonly by performing a biopsy to check for conditions such as anemia, bleeding, inflammation, and cancers of the digestive system. The procedure may also be used for treatment such as cauterization of a bleeding vessel, widening a narrow esophagus, clipping off a polyp or removing a foreign object.

Health care workers can use endoscopes to review the following body parts:

Classification

A rigid endoscope Rigid endoscope.jpg
A rigid endoscope
A flexible endoscope PENTAX Colonoscope001.jpg
A flexible endoscope

There are many different types of endoscopes for medical examination, so are their classification methods. Generally speaking, the following three classifications are more common:

Recent developments

Robot assisted surgery

A capsule endoscope CapsuleEndoscope.jpg
A capsule endoscope

With the development and application of robotic systems, especially surgical robotics, remote surgery has been introduced, in which the surgeon could be at a site far away from the patient. The first remote surgery was called the Lindbergh Operation. [22] And a wireless oesophageal pH measuring devices can now be placed endoscopically, to record ph trends in an area remotely. [23]

Endoscopy VR simulators

Virtual reality simulators are being developed for training doctors on various endoscopy skills. [24]

Disposable endoscopy

Disposable endoscopy is an emerging category of endoscopic instruments. Recent developments [25] have allowed the manufacture of endoscopes inexpensive enough to be used on a single patient only. It is meeting a growing demand to lessen the risk of cross contamination and hospital acquired diseases. A European consortium of the SME is working on the DUET (disposable use of endoscopy tool) project to build a disposable endoscope. [26]

Capsule endoscopy Capsule endoscopes are pill-sized imaging devices that are swallowed by a patient and then record images of the gastrointestinal tract as they pass through naturally. Images are typically retrieved via wireless data transfer to an external receiver. [27]

Augmented reality

The endoscopic images can be combined with other image sources to provide the surgeon with additional information. For instance, the position of an anatomical structure or tumor might be shown in the endoscopic video. [28]

Image enhancement

Emerging endoscope technologies measure additional properties of light such as optical polarization, [29] optical phase, [30] and additional wavelengths of light to improve contrast. [31]

A low-cost waterproof USB endoscope for non-medical use Endoscope, USB, 2015-05-30.jpg
A low-cost waterproof USB endoscope for non-medical use

Non-medical use

Industrial endoscopic nondestructive testing technology

The above is mainly about the application of endoscopes in medical inspection. In fact, endoscopes are also widely used in industrial field, especially in non-destructive testing and hole exploration. If internal visual inspection of pipes, boilers, cylinders, motors, reactors, heat exchangers, turbines, and other products with narrow, inaccessible cavities and/or channels is to be performed, then the endoscope is an important, if not an indispensable instrument. [32] In such applications they are commonly known as borescopes.

See also

Related Research Articles

<span class="mw-page-title-main">Laparoscopy</span> Minimally invasive operation within the abdominal or pelvic cavities

Laparoscopy is an operation performed in the abdomen or pelvis using small incisions with the aid of a camera. The laparoscope aids diagnosis or therapeutic interventions with a few small cuts in the abdomen.

<span class="mw-page-title-main">Endoscopy</span> Procedure used in medicine to look inside the body

An endoscopy is a procedure used in medicine to look inside the body. The endoscopy procedure uses an endoscope to examine the interior of a hollow organ or cavity of the body. Unlike many other medical imaging techniques, endoscopes are inserted directly into the organ.

<span class="mw-page-title-main">Fiberscope</span> Flexible optical fiber bundle with an eyepiece on one end and a lens on the other

A fiberscope is a flexible optical fiber bundle with a lens on one end and an eyepiece or camera on the other. It is used to examine and inspect small, difficult-to-reach places such as the insides of machines, locks, and the human body.

<span class="mw-page-title-main">Borescope</span> Optical instrument

A borescope is an optical instrument designed to assist visual inspection of narrow, difficult-to-reach cavities, consisting of a rigid or flexible tube with an eyepiece or display on one end, an objective lens or camera on the other, linked together by an optical or electrical system in between. The optical system in some instances is accompanied by illumination to enhance brightness and contrast. An internal image of the illuminated object is formed by the objective lens and magnified by the eyepiece which presents it to the viewer's eye.

<span class="mw-page-title-main">Esophagogastroduodenoscopy</span> Diagnostic endoscopic procedure

Esophagogastroduodenoscopy (EGD) or oesophagogastroduodenoscopy (OGD), also called by various other names, is a diagnostic endoscopic procedure that visualizes the upper part of the gastrointestinal tract down to the duodenum. It is considered a minimally invasive procedure since it does not require an incision into one of the major body cavities and does not require any significant recovery after the procedure. However, a sore throat is common.

<span class="mw-page-title-main">Endoscopic retrograde cholangiopancreatography</span> Use of endoscopy and fluoroscopy to treat and diagnose digestive issues

Endoscopic retrograde cholangiopancreatography (ERCP) is a technique that combines the use of endoscopy and fluoroscopy to diagnose and treat certain problems of the biliary or pancreatic ductal systems. It is primarily performed by highly skilled and specialty trained gastroenterologists. Through the endoscope, the physician can see the inside of the stomach and duodenum, and inject a contrast medium into the ducts in the biliary tree and/or pancreas so they can be seen on radiographs.

<span class="mw-page-title-main">Endoscopic ultrasound</span> Medical imaging procedure

Endoscopic ultrasound (EUS) or echo-endoscopy is a medical procedure in which endoscopy is combined with ultrasound to obtain images of the internal organs in the chest, abdomen and colon. It can be used to visualize the walls of these organs, or to look at adjacent structures. Combined with Doppler imaging, nearby blood vessels can also be evaluated.

<span class="mw-page-title-main">Endoscopic foreign body retrieval</span> Medical intervention

Endoscopic foreign body retrieval refers to the removal of ingested objects from the esophagus, stomach and duodenum by endoscopic techniques. It does not involve surgery, but rather encompasses a variety of techniques employed through the gastroscope for grasping foreign bodies, manipulating them, and removing them while protecting the esophagus and trachea. It is of particular importance with children, people with mental illness, and prison inmates as these groups have a high rate of foreign body ingestion.

<span class="mw-page-title-main">Self-expandable metallic stent</span> Medical intervention

A self-expandable metallic stent is a metallic tube, or stent that holds open a structure in the gastrointestinal tract to allow the passage of food, chyme, stool, or other secretions related to digestion. Surgeons insert SEMS by endoscopy, inserting a fibre optic camera—either through the mouth or colon—to reach an area of narrowing. As such, it is termed an endoprosthesis. SEMS can also be inserted using fluoroscopy where the surgeon uses an X-ray image to guide insertion, or as an adjunct to endoscopy.

<span class="mw-page-title-main">Endoclip</span>

An endoclip is a metallic mechanical device used in endoscopy in order to close two mucosal surfaces without the need for surgery and suturing. Its function is similar to a suture in gross surgical applications, as it is used to join together two disjointed surfaces, but, can be applied through the channel of an endoscope under direct visualization. Endoclips have found use in treating gastrointestinal bleeding, in preventing bleeding after therapeutic procedures such as polypectomy, and in closing gastrointestinal perforations. Many forms of endoclips exist of different shapes and sizes, including two and three prong devices, which can be administered using single use and reloadable systems, and may or may not open and close to facilitate placement.

<span class="mw-page-title-main">Capsule endoscopy</span> Medical imaging procedure

Capsule endoscopy is a medical procedure used to record internal images of the gastrointestinal tract for use in disease diagnosis. Newer developments are also able to take biopsies and release medication at specific locations of the entire gastrointestinal tract. Unlike the more widely used endoscope, capsule endoscopy provides the ability to see the middle portion of the small intestine. It can be applied to the detection of various gastrointestinal cancers, digestive diseases, ulcers, unexplained bleedings, and general abdominal pains. After a patient swallows the capsule, it passes along the gastrointestinal tract, taking a number of images per second which are transmitted wirelessly to an array of receivers connected to a portable recording device carried by the patient. General advantages of capsule endoscopy over standard endoscopy include the minimally invasive procedure setup, ability to visualize more of the gastrointestinal tract, and lower cost of the procedure.

<span class="mw-page-title-main">Harold Hopkins (physicist)</span> British physicist (1918–1994)

Harold Horace Hopkins FRS was a British physicist. His Wave Theory of Aberrations,, is central to all modern optical design and provides the mathematical analysis which enables the use of computers to create the highest quality lenses. In addition to his theoretical work, his many inventions are in daily use throughout the world. These include zoom lenses, coherent fibre-optics and more recently the rod-lens endoscopes which 'opened the door' to modern key-hole surgery. He was the recipient of many of the world's most prestigious awards and was twice nominated for a Nobel Prize. His citation on receiving the Rumford Medal from the Royal Society in 1984 stated: "In recognition of his many contributions to the theory and design of optical instruments, especially of a wide variety of important new medical instruments which have made a major contribution to clinical diagnosis and surgery."

Therapeutic endoscopy is the medical term for an endoscopic procedure during which treatment is carried out via the endoscope. This contrasts with diagnostic endoscopy, where the aim of the procedure is purely to visualize a part of the gastrointestinal, respiratory or urinary tract in order to aid diagnosis. In practice, a procedure which starts as a diagnostic endoscopy may become a therapeutic endoscopy depending on the findings, such as in cases of upper gastrointestinal bleeding, or the finding of polyps during colonoscopy.

The Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) is a 501c6 non-profit professional organization providing education on gastrointestinal minimally invasive surgery. It describes itself thus: The mission of the Society of American Gastrointestinal and Endoscopic Surgeons is to innovate, educate and collaborate to improve patient care.

Narrow-band imaging is an imaging technique for endoscopic diagnostic medical tests, where light of specific blue and green wavelengths is used to enhance the detail of certain aspects of the surface of the mucosa. A special filter is electronically activated by a switch in the endoscope leading to the use of ambient light of wavelengths of 415 nm (blue) and 540 nm (green). Because the peak light absorption of hemoglobin occurs at these wavelengths, blood vessels will appear very dark, allowing for their improved visibility and in the improved identification of other surface structures.

Endomicroscopy is a technique for obtaining histology-like images from inside the human body in real-time, a process known as ‘optical biopsy’. It generally refers to fluorescence confocal microscopy, although multi-photon microscopy and optical coherence tomography have also been adapted for endoscopic use. Commercially available clinical and pre-clinical endomicroscopes can achieve a resolution on the order of a micrometre, have a field-of-view of several hundred μm, and are compatible with fluorophores which are excitable using 488 nm laser light. The main clinical applications are currently in imaging of the tumour margins of the brain and gastro-intestinal tract, particularly for the diagnosis and characterisation of Barrett’s Esophagus, pancreatic cysts and colorectal lesions. A number of pre-clinical and transnational applications have been developed for endomicroscopy as it enables researchers to perform live animal imaging. Major pre-clinical applications are in gastro-intestinal tract, toumour margin detection, uterine complications, ischaemia, live imaging of cartilage and tendon and organoid imaging.

Fluorescence guided surgery (FGS), also called fluorescence image-guided surgery, or in the specific case of tumor resection, fluorescence guided resection, is a medical imaging technique used to detect fluorescently labelled structures during surgery. Similarly to standard image-guided surgery, FGS has the purpose of guiding the surgical procedure and providing the surgeon of real time visualization of the operating field. When compared to other medical imaging modalities, FGS is cheaper and superior in terms of resolution and number of molecules detectable. As a drawback, penetration depth is usually very poor in the visible wavelengths, but it can reach up to 1–2 cm when excitation wavelengths in the near infrared are used.

Endoscopic endonasal surgery is a minimally invasive technique used mainly in neurosurgery and otolaryngology. A neurosurgeon or an otolaryngologist, using an endoscope that is entered through the nose, fixes or removes brain defects or tumors in the anterior skull base. Normally an otolaryngologist performs the initial stage of surgery through the nasal cavity and sphenoid bone; a neurosurgeon performs the rest of the surgery involving drilling into any cavities containing a neural organ such as the pituitary gland. The use of endoscope was first introduced in Transsphenoidal Pituitary Surgery by R Jankowsky, J Auque, C Simon et al. in 1992 G.

A scanning fiber endoscope is a technology that uses a flexible, small peripheral or coronary catheter to provide wide-field, high-quality, full-color, laser-based video imaging. These differences distinguish SFE applications from current imaging approaches such as IVUS and Intracoronary OCT. Applications for the device, are expected to include medical diagnosis and support in determining interventional treatments such as surgery or biopsy. Providing both full-color images and a wide-field, real-time surgical view into the inner depths of arteries, enables physicians to circumnavigate hard to reach internal tissues to assess for potential disease.

The per-oral endoscopic myotomy, or POEM, is a minimally invasive surgical procedure for the treatment of achalasia wherein the inner circular muscle layer of the lower esophageal sphincter is divided through a submucosal tunnel. This enables food and liquids to pass into the stomach, a process that is impaired in achalasia. The tunnel is created, and the myotomy performed, using a flexible endoscope, meaning the entire procedure can be done without external incisions.

References

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  3. ↑ "endoscope". Oxford English Dictionary. Oxford Press.
  4. ↑ Bozzini, Philipp (1806). "Lichtleiter, eine Erfindung zur Anschauung innerer Teile und Krankheiten, nebst der Abbildung" [Light conductor, an invention for examining internal parts and diseases, together with illustrations]. Journal der Practischen Arzneykunde und Wundarzneykunst (in German). 24: 107–24.
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  16. ↑ "Endoscope Biopsy channels". Richard Wolf Medical Instruments.
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