Welcome back to another post diving into the common procedures we perform in internal medicine. And we would not be talking about internal medicine if we didn’t mention endoscopy!

What is endoscopy?

Endoscopy is probably the most common procedure we perform in medicine, and it is used to examine body cavities or hollow organs such as the airway, nasal cavity, lower urinary tract, oesophagus, stomach, small and/or large intestines. 

This is achieved through the use of an endoscope – a hollow tube which contains either fibre-optics or video technology in order to visualize mucosal surfaces, and guide the passage of instruments. 

A number of different endoscopes exist, depending on the area being examined. We can classify these as either flexible or rigid endoscopes, based on how they are designed.

Flexible endoscopes

Flexible scopes use either fibreoptics or video technology to generate an image and are referred to as fibrescopes or videoscopes, respectively. 

Fibrescopes contain thin bundles of fibreoptic cables, which transmit the image to an eyepiece; a camera is then attached to the eyepiece in order to transmit the image to the viewing screen. 

Videoscopes contain a video chip which converts the image to a digital signal. This is then transmitted through wires within the endoscope to a video processor, then to a viewing screen. An external camera does not need to be connected to a videoscope, but a special cable which transmits the video signal from the endoscope to the endoscope tower is required.

What is a flexible endoscope made up of?

There are several key components which make up a flexible endoscope, and it’s important that the veterinary nurse is familiar with what these are, and what they do, in order to properly handle, prepare and use the scope.

The body of the endoscope is the main area which houses the endoscope controls. It is the area held and used by the clinician throughout the procedure. The angulation controls, brake, air and water button (if applicable), suction button, instrument channel access port and the eyepiece & focussing dial (if you’re using a fibrescope) are all located on the body of the scope. 

The insertion tube is connected to the distal aspect of the endoscope body. This is the working end of the scope (i.e. the tube which will enter the patient). It usually has pre-marked 5-10cm measurements on the outside of the tube, so the clinician can easily identify how far in they are. The insertion tube is incredibly delicate and contains the instrument channel, air/water and suction channels, angulation wires and fibreoptic bundles.

The distal end of the insertion tube contains the bending section and the distal tip. The bending section is where tip deflection (moving the insertion tube, in order to drive through body channels) occurs. Steel wires move the end of the tube in line with the angulation dials on the scope body. These wires can stretch and break over time and so the angulation should always be operated carefully.

The distal tip is the very end of the insertion tube. This is where all of the channels exit the endoscope and the fibreoptic bundles end (or a video chip is present if a videoscope) protected by a lens cap. The distal tip is extremely fragile and prone to damage. Particular care should be taken to avoid knock or swing injuries to this portion of the scope.

Some endoscopes also have an umbilical tube. This is an additional, wider tube which does not enter the patient, but carries light, air, water and suction to the endoscope body and insertion tube. The umbilical tube ends in a light guide plug, which contains the light guide, air pipe, water bottle attachment, suction port and pressure compensation valve. The light guide plug plugs into the endoscopy tower, water source, and suction unit. The pressure compensation valve is used to leak test the endoscope; this must be performed prior to each use, and prior to cleaning. If you are using an endoscope which does not have an umbilical tube, the pressure compensation valve will be located on the endoscope body.

Several different types of flexible endoscope are used in practice, depending on the procedure being performed. 

A gastroscope is generally the largest, longest endoscope used in practice. This has an umbilical tube as well as an insertion tube, contains an air/water channel, larger instrument channel (usually 1.8-2.3mm across), and has 4-way angulation (the bending section can move left and right, as well as up and down). This function is unique to gastrointestinal endoscopes, as other flexible scopes have 2-way (up and down) angulation only. The gastroscope is used to examine the oesophagus, stomach, duodenum, ileum and colon. Some practices have a colonoscope, which has exactly the same functions as a gastroscope but has a slightly longer insertion tube.

A bronchoscope is a narrow endoscope, with a shorter insertion tube. They often do not have an umbilical tube and have a narrower instrument channel (1-1.8mm across). Most have suction facilities, but air and water channels are not necessary. This is used to image the nasopharynx, larynx and lower airways.

The smallest flexible endoscope used in practice is the cystoscope. This is similar in structure to a bronchoscope but has a narrower insertion tube. This is used to examine the urethra and urinary bladder in male dogs.

Rigid endoscopes

Rigid endoscopes or telescopes are narrow, hollow tubes containing a number of glass rod lenses to magnify images back to an eyepiece, to which a camera attaches. Light is transmitted through the scope through a remote light source.

Rigid endoscopes are incredibly delicate and need to be housed within an outer working sheath during use, and stored within a plastic protective cover whenever they are not in use (including during cleaning). 

The working sheath contains ports for the introduction of instruments and the administration of irrigation fluid. Fluid administration is often necessary during the use of rigid endoscopes, as the image quality is greatly improved when visualizing through a column of fluid.

The working end of the telescope may be angled, depending on the intended use; the angle will change the clinician’s field of view.

The operator end of the telescope contains an eyepiece (to which a camera is usually attached), and light guidepost (to which the light source is attached).

In internal medicine, rigid endoscopes are used to image the rostral aspect of the nose, and the female lower urinary tract. Rigid scopes are also used surgically for arthroscopic and laparoscopic procedures (the minimally invasive examination of joints, and the abdominal/thoracic cavity).

The endoscope tower

In order for the endoscope to function, a number of external components are required. These may be housed together in one unit (e.g. a unit containing a viewing screen, air pump, light source and video processor) or be separate units combined to make up an endoscopy tower. These contain a light source, air pump, video processing unit, image capture device and viewing screen. If your tower is also used for surgical endoscopy (laparoscopy/arthroscopy), a carbon dioxide insufflator and an arthroscopic fluid pump may also be present. In addition to the equipment listed above, an endoscope water bottle and a suction unit will be required.

Handling the endoscope

As we know, endoscopes are delicate and that can make handling them a little fear-inducing! However, as long as we handle them safely and carefully, we’ll minimise the risk of any damage.  Here are a few of my top tips for handling endoscopes:

1. When handling a rigid endoscope, make sure it is in either a protective cover or working sheath at all times. When switching between the two, handle the eyepiece end of the scope only, and do not touch the insertion tube.

2. When carrying a flexible endoscope, coil the insertion and umbilical tubes, ensuring that the light guide plug and distal tip are not swinging freely. Hold the body of the scope in one hand, and the coiled tubes in the other.

3. Avoid handling areas of flexible endoscopes where relief cones are present. These are covering joins (e.g. where the umbilical and insertion tubes attach to the body of the scope), so will be weaker areas.

4. Always store your endoscopes hanging up, on a rack or wall holder. Most endoscopy trolleys either come with a holder, or one can be added to them. Once the endoscope is set up and ready for use, it should be stored hanging vertically, rather than on a table or work surface. This minimises the risk of drop/fall injuries, as well as things coming in to contact with the scope.

Preparing the endoscope

Endoscopes require careful preparation in order to be used correctly, and the veterinary nurse plays a key role in this process. When setting up for an endoscopic procedure, the following steps should be followed:

1. Prior to use, visually inspect the endoscope for signs of damage. If you are using a flexible endoscope, perform a leak test at this stage too. If this shows evidence of a leak, do not use the endoscope, as irreversible damage may occur. 

2. Appropriately position your endoscopy tower, connect your endoscope, camera and light cable (if required depending on the type of endoscope being used).

3. Connect any additional equipment required, such as a suction unit and tubing, and a distilled water bottle if using a gastrointestinal endoscope.

4. Turn the endoscopy tower on, attach a storage device (CD/USB) and enter the patient’s details.

5. Perform a white balance test (this ensures the colours appear realistic when viewing the screen), focus the endoscope (if a fibrescope is being used), and check the function of any attached suction, air and water. Ensure you do this before your patient is anaesthetised in case there is a problem with your endoscope!

After you’ve prepared your endoscope, you’ll need to go ahead and prepare all of your anaesthetic monitoring equipment and consumables for the procedure being performed. If you’ve not checked them out yet, be sure to head to our resource library for access to a free bundle of consumables lists for every common endoscopic procedure!

So that’s an introduction to endoscopy! How many endoscopies do you do in practice? Let me know below!

In the next few posts, we’ll be diving into endoscopy in lots more detail, including how to clean and maintain your endoscopes, what we do in each endoscopic procedure, and what our nursing considerations should be for these patients!

References and further reading:

1. Cox, S. 2016. Endoscopy for the Veterinary Technician. Iowa: Wiley-Blackwell.

2. Merrill, L. 2012. Small Animal Internal Medicine for Veterinary Technicians and Nurses. Iowa: Wiley-Blackwell.

Disclaimer: Individual endoscope use and maintenance protocols may vary depending on your practice, the endoscopes you use, and the cleaning/disinfectant products used. The above information is intended as a guide only. Veterinary Internal Medicine Nursing is not responsible for any issues which may arise as a result of their use. Any photographs within this post are for reference only and are not product endorsements or recommendations.