1.1 Coupled charge device (CCD)

A CCD is composed of a silicon semiconductor with an insulating oxide coating to which aluminum electrodes known as MOS (metal oxide semiconductors) are attached. MOS are photosensitive, and convert light to electricity in accordance with the brightness of the light. The atoms of the MOS photosensitive surface store an electric charge when exposed to light. The accumulated electrical charge is proportional to the intensity of the incident light.

The photosensitive surface of a CCD is divided into a large number of photodiodes. This image element is often incorrectly referred to as a pixel. However, the photodiode that captures the light is actually part of the pixel, which is also the charge transmission channel. Thus a pixel actually refers to a device’s resolution, not the number of photosensitive cells (photodiodes) it combines.

If a digital camera is said to have a resolution amounting to 6.2 million pixels, this means that the CCD comprises 3.3 photodiodes. However, this artificially widens the scope of the definition, since additional pixels are produced by means of a software process known as interpolation. Interpolation involves inserting a new pixel into an image via a calculation between a number of existing pixels. It degrades the quality of the original image, which is why it is necessary to speak in terms of photodiodes rather than pixels.

Division of the target allows each photodiode to respond independently to the amount of light reflected by the tissue.

Photodiodes are discharged during the reading process before a new charge acquisition cycle begins. The reading process is extremely rapid, but during it, the electrical charges continue to accumulate on the image that is being transmitted. These additional (thermal) charges accumulate even in the absence of light. This signal is stronger for lines that are read last, i.e. the lines at the top of the image. This results in a problem known as image smearing, which can be resolved by transferring the useful portion of the frame to an area that is shielded from the light source.

This transfer process, which occurs extremely rapidly, occurs in various ways depending on the type of CCD used.

1.2 CCD frame transfer (Fig. 4)

CCD frame transfer provides optimal resolution and sensitivity. The image zone that gathers the electrons is transferred to a memory zone of the same size that is shielded from the light source. This separation increases sensitivity, thus providing maximum image-surface efficiency. The drawback of this solution is that it involves the use of a relatively large CCD.

Figure 4 Frame transfer.

1.3 CCD interline transfer (Fig. 5)

This configuration contains, alternatively, an image element area, as well as an electron transfer area that is shielded from the light source. These frames thus integrate a memory adjacent to each sensitive line and engender substantial dead areas in the final images. This is why relatively small CCDs exhibit limited sensitivity, despite their good resolution.

Figure 5 Interline transfer.

1.4 Full frame read-out CCD (Fig. 6)

This technology is identical to frame transfer CCD, but lacks a storage area that is shielded from the light source. Hence, these CCDs are small. Their drawback is that the lighting is not available throughout the reading process, as it is desirable to alternate between luminance at the charge creation locus and dark periods during which these charges are transferred.

Figure 6 Full-frame read-out.

Color is not a physical reality. It is an impression generated in our brain, via our eyes, by luminous radiation from objects. In 1676, Isaac Newton showed that sunlight can be broken down into the colors of the spectrum by passing light through a prism (Fig. 7).

Figure 7 White-light decomposition through a prism.

Light is composed of electromagnetic waves. Visible light comprises a continuous spectrum, the wavelengths of which range from 380 to 780 nanometers (nm). Each element of white light has a refraction coefficient that varies according to the element’s wavelength.

1.5 Color system selection

1.5.2 CCD colors: a mosaic system

A CCD combines a mosaic filter that is transparent to one of the primary colors (red, green, or blue) or their complements (cyan, magenta, or yellow). Each photodiode captures a color and then reconstitutes a pixel using four photodiodes. Inasmuch as cyan is composed of blue and green, and yellow is composed of red and green, the color green has more potential luminance, i.e. red and blue have only 25% as much luminance as green (Fig. 8).

Figure 8 CCD colors.

2.1 Blooming

The capacity of each CCD pixel to store electrons is limited. If there is too much light, the electrons jump to the adjacent pixels, resulting in image distortion, as well as a phenomenon known as blooming (color dissociation at the edge of the object). Integration of an anti-blooming system changes the sensitivity via a loss of some of the photosensitive surface of a pixel.

2.1 Resolution

A light sensor comprises a fixed number of pixels. A lens’s resolution allows it to separate the image details. Resolution patterns make it possible to take real-time measurements in practice. The theoretical limit is reached when a pair of black and white lines is projected onto a pair of pixels.

The best videoendoscope is one whose CCD contains the most pixels, depending on the type of transfer system used. Some CCDs only use a portion of the image elements, while reserving the others for the transfer process.

Today, owing to improvements in image stability, color CCDs are gaining ground on their black and white counterparts and manufacturers are currently focusing on the following developments:

Completely digital electronic videoendoscope systems (i.e. from the endoscope to the screen) open up (a) a major field of investigation by virtue of the wealth of information that is captured by the CCD; and (b) new image processing options.

Endoscopic imaging is making major advances thanks to the migration to digital technology.

Once the pixel count, lens, and field of exploration have been improved, the range of structures amenable to examination can be expanded by greatly improving the peripheral contrast of a lesion and enhancing its relief.

Addition of a zoom function may represent a major advance, but must nonetheless be validated scientifically. The following types of zooms are currently in use:

2.1 The role of automatic regulation of the electric current

When, for example, 100 W of current pass through the tungsten filament of an electric light bulb, there is a substantial thermal effect that turns the filament white, thus generating light, which is in fact a secondary effect. In the copper wire that provides the electricity for the light bulb, this same electric current engenders little or no heat. Hence, various types of biological tissue exhibit differing levels of current impedance (resistance). In order to obtain a stable effect in tissue, the level of electric current administered to the tissue must be commensurate with the tissue’s impedance, which, if elevated, requires relatively little voltage. Conversely, low-impedance tissue needs considerable voltage to achieve the same effect.

2.2 Sectioning may inadvertently result in tissue coagulation

This can occur if too little current is applied to the target contact surface (Fig. 4). Sectioning a 1 mm² contact surface requires a high level of current density. This same current applied to a 1 cm² surface will be unduly low and will induce coagulation. New electrosurgical generators avoid this problem by automatically adjusting the instrument’s output current to the characteristics of the tissue being sectioned, within the limits of the maximum-current setting, which must be high enough to allow sectioning, as otherwise the tissue will be coagulated.

Figure 4 The heat generated increases exponentially as tissue surface area decreases.

2.3 Consequences of using unsuitable settings for electrosurgical generators

The device settings must be defined in such a way as to (a) prevent the generator from peaking out; and (b) ensure that the device’s power is sufficient to perform the section and does not induce coagulation and accidents.

3.1 The Power Peak System and Endocut

At the beginning of the process, the Power Peak System (PPS) delivers power exceeding the configured threshold for a few milliseconds (ms) so as to allow rapid initiation of resection.

Following this, in endocut mode, sectioning occurs for 50 ms, followed by low-intensity coagulation for 750 ms. Sectioning and coagulation alternate automatically until the tissue has been completely resected. When using ‘endo-cut’ mode, the operator should avoid pulling too hard on the snare, or closing it too tightly; it should be in gentle contact with the tissue at all times. This results in a slow cutting process that alternates with coagulation. The risk of hemorrhaging is greatly reduced if the operator does not section mechanically by pulling hard on the snare. By the same token, the risk of secondary perforation and excessive coagulation is reduced if the resection begins immediately on application of current.

3.2 What to do if the resection does not start immediately

There are two possible scenarios in this case:

The high power generated by an automatically regulated electrosurgical generator poses no risk for the operator for the simple reason that the device only generates the amount of power that is needed for sectioning.

3.3 Endocut for sphincterotomies

Endocut is used frequently for sphincterotomies with lower settings in some cases and identical settings in others, and using less coagulation than for polypectomies (endo-cut I mode in ERBE VIO). The use of an electrosurgical generator for sphincterotomies gives the operator better control over the sectioning process, without provoking bleeding, and this in turn avoids abrupt sectioning, perforations and secondary hemorrhaging. A randomized study comparing an Erbotom T175 (classic electrosurgical generator) with an ERBE ICC 200 (which has an endoscopic diathermy or ‘endo-cut’ function) revealed a significant difference in terms of reducing secondary bleeding.

3.4 Starting endocut

To start (‘endo-cut’) mode, press the yellow foot pedal, whereupon the cutting/coagulation cycle will take place automatically. All you need to define is the sectioning power threshold, in accordance with the diameter of the polyp that is being resected (if in doubt, use the 120 W default setting with effect level 3 or 2 hemostasis) and set the coagulation (blue pedal) to ‘low’ (60 W) to avoid an undesired result in the event of accidentally pressing the wrong pedal.

The low-coagulation power in endo-cut mode is set by default to from 0 to 60 W, which automatically overrides any manual setting on the electrosurgical generator.

4.1 Low-intensity coagulation

The low-intensity coagulation provided by using the blue pedal occurs without an electric arc or tissue coagulation. This type of coagulation is slow, penetrating, and provokes no bleeding.

4.2 Forced coagulation

Forced coagulation is obtained using 1300 V resulting in an electric arc and tissue carbonization. This type of coagulation is quicker and less penetrating than low-intensity coagulation.

4.3 Spray-mode coagulation

Spray-mode coagulation is only used in gastrointestinal endoscopy in conjunction with an argon plasma coagulator and requires >4000 V of electricity. In this process, ionized argon gas is applied via flexible probes that do not come into contact with the tissue. The gas acts as an electrical conductor between the probe and tissue. Argon plasma distributes heat evenly across a very large surface. The coagulation is very rapid and does not penetrate nearly as deeply as with laser coagulation. However, the coagulation depth is determined by the preset power and particularly by the target-surface application time (there is no automatic regulation in Argon spray mode). For endoscopic procedures, APC is superior to laser coagulation for all indications other than destruction of bulky tumors, where laser still has a role.

5.1 Monopolar current (Fig. 6)

Monopolar current circulates between the active electrode (diathermy snare, hot biopsy forceps, sphincterotome), and the patient grounding pad.

Figure 6 Monopolar current.

5.2 Bipolar current (Fig. 7)

Here, the second electrical pole is located in very close proximity to the active element, and the current circulates between the two ends. If a bipolar snare was used with an electrosurgical generator for a bipolar section, the electric arc (and hence the resection) would occur on one side of the snare only, where there is less contact with the tissue. The other side would assume the function of a neutral electrode and would coagulate rather than section. No bipolar instrument is available for endoscopic sphincterotomy and for polypectomy. Bipolar current is used solely for coagulation with specific bipolar probes. The coagulation depth obtained with bipolar current is less than with monopolar current owing to the fact that the current is recovered immediately.

Figure 7 Bipolar current (returns to the electrosurgical generator).

9.1 General tips

9.2 Standard settings for an ERBE ICC 200 electrosurgical generator

The endoscopic diathermy (‘endo-cut’) function can only be obtained using the yellow pedal, in which case cutting and coagulation will alternate automatically (Fig. 9).

Figure 9 ICC 200 electrosurgical scalpel with a regulated endo-cut function for polypectomies.

9.3 Polypectomy

9.4 Sphincterotomy

To avoid the problems caused by excessive contact surface between the sphincterotome and tissue, insert only the distal third of the cutting wire into the papilla. The endoscopic diathermy (endo-cut) function is adjusted for hemostasis and using the same amount of power as for a polypectomy (120 W). Low-intensity coagulation is performed using 60 W.

9.5 Endoscopic mucosal resection (EMR)

There are small but significant differences with the newest range of ERBE electrosurgical generators (VIO 200 or 300) (Fig. 10). Two different endo-cut functions (Q and I) exist: ‘endo-cut Q’ is designed for polypectomy and functions much as described above with slow cutting and more coagulation. The standard setting for a polypectomy is 120 W, effect level 3 (the effect level can be reduced to 2 if less coagulation is desired). There are, however, many adjustable settings and general recommendations are outlined in Tables 1 and 2. ‘Endo-cut I’ is designed for sphincterotomy with a different cutting-coagulation cycle, designed for quick cutting and less coagulation, although it can be adjusted.

Figure 10 (A) ESD for superficial gastric cancer. (B) Argon plasma coagulation for recurrence of esophageal cancer. (C) VIO ERBE 300 D with ERBE JET.

Table 1 Manufacturer’s recommended settings for ERBE VIO series electrosurgical generators

Table 2 Manufacturer’s recommended settings for ERBE VIO series electrosurgical generators when performing endoscopic submucosal dissection (ESD)

1.1 Endoscopy rooms

The number of endoscopy rooms should be appropriate for the number of procedures that are performed annually. These rooms should be equipped for upper and low GI tract procedures, as well as for endoscopic ultrasound.

1.1.2 Endoscopy room equipment

• The center of the room (Fig. 2) should contain a 60 cm wide trolley that can be oriented in any direction necessary and that has removable side-restraints. This trolley should be placed at a distance from the examination table so as to prevent patients from tampering with it.

• The endoscopy stack accommodates the screen, light source, video processor, electrosurgical generator, DVD/VCR, and photo printer.

• An instrument table containing the equipment that the nurses will need to have at their disposal, including the following: gloves; local anesthesia; lubricant; biopsy fixative jars; forceps; polypectomy snares; sterile brushes in individual pouches (for a multilevel table). The table should also have dedicated spot lighting that is trained directly at it.

• Distribution arm for fluids, electricity, and video/data cabling, located above the video console.

• X-ray film viewer; work surface for patient records.

• A trolley or distribution arm for anesthesia/emergency procedures, equipped and meeting agreed resuscitation standards.

• Under the technical window, on the side containing the cleaning and disinfection surface, a work surface covered with a material that is atraumatic for endoscopes. Trolleys containing the endoscopes and their clean field (outbound) and the endoscope submersion container (inbound) are used in settings where the disinfecting room does not adjoin the endoscopy rooms.

• A washbasin with an automatic control that allows staff members to wash and disinfect their hands.

• A cabinet that is large enough to store all necessary supplies.

• The electrical equipment must comply with all applicable standards and regulations, and must be compatible with the room’s specific equipment. Having numerous power cords on the floor of the room should be avoided, and towards this end, the distributing arm should house a sufficient number of outlets (five at a minimum).

• Wall-mounted vacuum suction: two separate connections are needed: one for the endoscope and the other for upper GI tract aspiration.

• Oxygen, supplied under constant pressure, should be available via the distributing arm if any examinations are to be undertaken under sedation or anesthesia.

• Audio/video and data line: the distribution arm should contain at least one audio and video input and output port, and two data ports.

• An endoscopist’s desk for computer and dictation equipment.

Figure 2 Gastrointestinal endoscopy room.

1.2 Postoperative monitoring room and recovery room

All endoscopy units that administer general anesthesia or IV sedation should have a postoperative monitoring room where each patient’s vital signs are monitored by a nurse (cardiac activity, pulse, blood pressure, and oxygen saturation). When the patient fully awakens they should be taken to the recovery room, where they remain until the doctor in charge authorizes their discharge. In some countries, nurse-led discharge policies exist, allowing them to discharge patients who meet key safety criteria, e.g. mobile, pain-free, normal observations. The postoperative monitoring room must comply with national safety standards (Fig. 3).

Figure 3 Postoperative monitoring room.

1.3 Cleaning room

The disinfecting room (Fig. 4) should be a separate, self-enclosed space that communicates with each endoscopy room via a technical window, or preferably a door that opens automatically. This room is used to clean and disinfect endoscopes. Medical supplies should not be sterilized in the disinfecting room. This should be done in a central sterilization facility that is used for the operating rooms, if the endoscopy unit is part of a hospital. Cleaning and disinfecting rooms for medical equipment must comply with legal regulations pertaining to design, methodology, and personnel training.

Figure 4 Endoscope disinfecting room.

There should be one or more work surfaces for non-sterile items. Each surface should be cushioned and covered with a material that is not traumatic for endoscopes. There should be 4–6 cleaning sinks of adjustable height in which the endoscopes can be immersed in water. Each basin must have its own tap and drain.

The use of gluteraldehyde is illegal in many countries, as are other aldehyde disinfectants. In some countries it is mandatory to establish a wastewater disposal contract with the municipal authorities in charge of sewage treatment. A separate circuit can be established that allows wastewater to be channeled into a tank if necessary.

In most countries, manual disinfection has been replaced by the use of automated endoscope reprocessors (AERs), but the steps of manual cleaning are described here. There must be separate washing and rinsing basins for each stage of the washing process. A hot and cold water mixer tap must be available for one or two of the basins. In some countries, it is law that the basins used for disinfectant and for the final rinse should contain a 0.22 µm microbiological filter that is autoclaved daily and changed regularly in accordance with the manufacturer’s instructions (after every 40–60 autoclave cycles). Basins used for detergent and disinfectant should be equipped with lids.

The microbiological and physical quality of the tap water used must meet the criteria of local health and safety regulations or infection control policies. However, in both treatment and disinfection rooms, so-called ‘water for standard medical treatment’ is sufficient if the quality of the water used by the unit is under active management. If not, so-called ‘bacteriologically managed’ water is to be used for the final rinse, as is done in washer-disinfectors.

Basins used for detergent and disinfectant should have a suction connection at the height of the basin and an extraction hood with an absorbent filter. The air recirculation system must have separate extraction and fresh air pipes. The fresh-air intake element should be located more than 8 meters away from the air extraction outlet element, and the air in the room should be exchanged at a rate of more than 10 volumes per hour. The room must be depressurized at all times. Endoscopes must be transported in covered plastic containers that are color coded: one color for contaminated endoscopes (e.g. red) and a second color for clean ones (e.g. green). These containers must be disinfected in a basin that is used for this purpose only.

1.4 Endoscope storage room

The endoscope storage room (Fig. 5) must be separate from the disinfecting room and should contain vented cabinets to store endoscopes, endoscope accessories, and small implements. Endoscopes should be stored vertically. The utility of cabinets with high efficiency particulate air filtration (HEPA) systems, and their location, have yet to be clearly established but they may allow clean endoscopes to be stored for up to 72 hours without the need for reprocessing prior to use.

Figure 5 Endoscopes stored vertically.

1.5 Spaces for patients

An endoscopy unit must contain the following dedicated spaces for patients:

1.6 Waiting area and reception desk

This area must be located at the entrance of the endoscopy unit and should be the place where patient records are stored. At endoscopy units that have a large number of patients, there should be one reception desk for appointments and preparing patient records and taking information confidentially from patients, and a second desk where reports are prepared and records are archived.

1.7 Consultation rooms

A consultation room allows a doctor to provide patients with the relevant information prior to and following an endoscopy examination. In endoscopy units that administer general anesthesia and handle large numbers of patients, there should also be an anesthesia-team station that adjoins the recovery area.

1.8 Office for the chief endoscopy nurse

This office allows management of the staff (nurses and doctors) and equipment in an endoscopy unit that handles a large number of patients.

2.1 Endoscopes

Ideally, each endoscopy room should be equipped with at least four gastroscopes and four colonoscopes so that sufficient time is available for cleaning/disinfection and upkeep without the need to borrow instruments or reduce the unit’s activities.

2.2 Medical instruments

This includes all items that are needed for endoscopy and that enhance its diagnostic and therapeutic efficacy. All of the following must be available at all times: biopsy forceps; washing or spray catheters; injection sclerotherapy needles; variceal ligation devices; thermal hemostasis probes; diathermy snares; hemostatic or perforation closure clips; and all necessary pancreaticobiliary endotherapy accessories, if the center performs ERCP. Centers performing EUS must keep a supply of different caliber needles for EUS-guided fine-needle aspiration (19–25 gauge).

3.1 Endoscopists

Gastrointestinal endoscopy involves diagnostic and therapeutic procedures for which the operator must possess an extremely high skill level and must be thoroughly conversant with gastrointestinal pathologies. Quality can only be maintained if the operators and their teams are highly experienced and competent. Operators must receive thorough endoscopy training from both a theoretical and a practical standpoint, based on structured training programs. It should begin during the initial months of a gastroenterology training program. The endoscopy trainee’s competence should be objectively assessed before certification of competence can be issued.

3.2 Endoscopy nurse assistants

The training program for an endoscopy assistant is demanding and needs to include the following diverse topics:

It is essential for endoscopy assistants to continue with their training throughout their careers to keep abreast of new equipment and techniques. In many countries endoscopy nurses have their own societies or are officially part of the national society representing endoscopists and membership of such a body should be encouraged.

3.3 Medical secretaries

Endoscopy unit medical secretaries need specific training. Their main tasks involve scheduling appointments and providing operators with information regarding procedures and anesthesiology protocols. Medical secretaries must be sufficiently familiar with endoscopic procedures to provide patients with support in the form of information and encouragement. Endoscopy unit medical secretaries also type up medical reports and manage medical records.

All secretaries should have the same credentials and skill sets and should be interchangeable.

3.4 Endoscopy center administrator

An endoscopy unit requires a dedicated administrator who is in charge of ensuring that the unit functions smoothly. This should not be left to the general administrative department of the hospital. They should be conversant with all diagnostic and therapeutic procedures and the equipment used; and also the applicable regulations and policies regarding endoscope and accessory disinfection. They should also have basic knowledge of equipment management, as well as medical and paramedical personnel management.

2.1 Plastic models

The Tübingen model is a plastic dummy which allows a number of different pathologies to be assessed. However, the model is not ideal, as it conducts electricity poorly, which affects the ability to perform hemostasis techniques.

2.2 Animal models

Pigs have been used as models, as the digestive system of pigs is similar to that of humans. However, this type of model has a number of drawbacks, including high cost, and the pigs must be sacrificed after two or three procedures due to the fragility of their bile ducts.

2.3 Digital simulators

The Simbionix GI Mentor robot is a computer simulator which consists of an endoscope with sensors at its distal end. Moving the endoscope in a cylinder generates a virtual image. Software applications that integrate diagnostic and therapeutic cases have been developed for the robot, and the graphics are of high quality. Programs available include: investigation of upper and lower GI tract; hemorrhage; polypectomy; EUS and ERCP. However, the mechanical constraints in terms of loops and instruments are not very realistic.

2.4 Erlangen active simulator for interventional endoscopy (EASIE)

EASIE uses resected stomachs of adult pigs which have been washed, and frozen (Figs 1–4). The stomachs are fastened to a board at six points, with the distal end of the esophagus attached to a tube that simulates the gastrointestinal tract. ERCP training can also be performed, in which case the stomach-duodenum-liver is preserved to allow for access to the bile ducts via the papilla. Current EASIE models include: hemostasis; polypectomy; APC; dilation; stent placement and ERCP. Endotrainer uses the same models, with some improvements.

Figure 3 EASIE training model. This model uses pig organs. A trainee is learning how to place esophageal stents.

Figure 1 Hemostasis model. (A) A trainee is taught how to perform hemostasis by injection. (B) Hemostasis model with clips placed.

Figure 2 A student is being taught how to perform endoscopic mucosal resection on a model.

Figure 4 (A) Room at IRCAD in Strasbourg, containing various stations to allow for in-vivo work on an animal model. (B) Expert practitioners at a training session.

1.1 Dealing with patient needs

An endoscopy nurse must have the ability to admit and prepare patients, provide the patient with the information needed for their examination, ensure their comfort and safety, and give the patient instructions regarding post-procedural aftercare. An endoscopy nurse must also act competently and professionally during emergencies, to ensure that care is given properly and that important tasks are prioritized. To this end, the endoscopy unit should be part of a healthcare system to ensure that these objectives are fulfilled. Endoscopy nurses ensure that patients are properly settled in, that the relevant equipment is available, and conduct pre-procedure instrument checks. They also counsel the patient regarding the endoscopy procedure and the period thereafter.

1.2 Technical knowledge

An endoscopy nurse must have the following technical attributes:

1.3 Management of endoscopes and endoscopic accessories

Management of endoscopy equipment is a highly responsible role, in light of the capital costs involved. These management processes are the responsibility of the endoscopy nurses, in collaboration with decontamination staff, infection control teams and the hospital’s technical or medical physics department (a unit’s endoscope inventory may cost $500 000–$1.5 m, or even more). Endoscopy nurses are also in charge of ensuring the traceability of endoscopic devices and disinfection processes. An endoscopy nurse is also in charge of inventory management and stock requisition, sterilization of reusable medical devices, and sterilization of linens, biomedical and maintenance equipment.

1.4 Infection control

Endoscopy nurses are also in charge of unit environmental hygiene and endoscopy disinfection processes (see Ch. 1.10).

1.5 Training

Endoscopy nurses play a number of key training roles in terms of induction and knowledge transfer for new staff members and trainees. They are also involved in appraisal, staff development and clinical research. In the UK, the national ‘GIN’ training program has been developed to train endoscopy nurses to be local facilitators who run regular nurse training courses. In the USA, the Society of Gastrointestinal Nurses and Associates (SGNA) is an important forum for nurse training in endoscopy and gastroenterology. The European Society of Gastroenterology and Endoscopy Nurses and Associates (ESGENA) is similar, and runs regular training and update courses (Table 1).

Table 1 Endoscopy nurses – societies and training links

3.1 Patient information

This is discussed in Chapter 1.8 and should include as much information as is reasonable to allow patients to make an informed decision. It must be easy to understand, and patients must have adequate time to read and contemplate the information before making their decision. It is generally not acceptable for patients to be presented with information and/or a consent form for signature immediately prior to the proposed procedure. Knowing how much information to provide to patients without causing undue concern is not easy, but a description of the procedure, alternatives, the need for sedation and potential risks is essential. All common complications (occurring with a frequency of 1% or more) should be discussed, as should rare complications, if they are potentially serious or fatal, or may lead to long-term disability (e.g. perforation, pancreatitis). The principle is that serious complications, no matter how rare, might influence a patient’s decision to proceed, and therefore needs to be discussed beforehand.

3.2 Refusal of treatment and withdrawal of consent

Competent adults may refuse treatment or withdraw consent at any time, and no matter how much the endoscopist may disagree with this, the patient’s autonomy must be respected. If an unsedated patient withdraws consent during a procedure, the procedure should stop immediately. If a sedated patient indicates that they are in distress or wishes the procedure to stop, the endoscopist must act in the patient’s best interests. Sometimes, discussion with the patient and the offer of additional sedation may allow the procedure to proceed and be completed successfully, but if the patient is clear that they wish the procedure to stop, or the patient is combative and safety is jeopardized, the procedure should stop.

3.3 Adults lacking capacity to give consent

The legal situation varies from country to country, but, in general, no one else can give consent on behalf of an incompetent adult, unless they have been appointed by a court of law as a legal guardian or ‘power of attorney’. If an endoscopist is in doubt about how to proceed, the hospital’s legal department should be consulted for advice beforehand. This may also pertain to patients with ‘advanced directives’ about life-sustaining treatment.

3.4 Retention and storage of tissue

Specific consent should be obtained for the retention of tissue samples including biopsies. Tissues are useful in teaching and research but patients must be given the opportunity to refuse permission for the use of their tissues for such purposes. If additional tissue samples are to be taken for research purposes, this can only be done with explicit approval from the local Ethics Committee and the patient’s written consent.

3.5 Photography and/or videorecording

These may be made for clinical management as part of the patient’s medical record but use of imaging for teaching, publication or research requires the patient’s formal consent and they must understand that the material may appear in the public domain.

3.6 Patients lacking capacity to give consent

When patients lack capacity to give consent, endoscopists must ensure that they have made every effort to discuss treatment in a way that the patient is best able to understand. Patients should be offered the option of having a relative or carer present to help them make an informed decision. Providing them with a written record of the conversation is sometimes helpful. These situations may arise with patients with mental health problems, brain injury, learning disabilities or dementia, and in those with alcohol or drug misuse. At all times, the endoscopist must act with the patient’s best interests at heart and their dignity must be respected. Endoscopists must remain objective and not allow their personal feelings or views to influence them. All available options for treatment should be carefully considered, and the one that is least restrictive to the patient considered. Any previously expressed preferences by the patient must be considered, as should the views of their relatives or partners, etc. Wherever possible, the aim should be to reach a consensus about patient management, but in complex cases, it may be helpful to hold a multidisciplinary meeting to review the clinical and ethical aspects of the patient’s case. Only in rare cases is it necessary to seek a formal judicial review. Finally, it is wise to remember always to act in a patient’s ‘best interests’, and to avoid making assumptions or being judgmental.

1.1 Cleaning

Refers to the removal of biological, organic and liquid particles and other debris using a procedure that is compatible with the characteristics of the surface being treated, and using the following factors in combination with each other: a combination of chemical action, mechanical action and heat, all for an adequate duration.

According to ISO 15883-1, the term ‘cleaning’ means removing contamination from an object up to the level necessary for the use for which the object is intended. This cleaning phase may include two or more washing phases. Contamination here means debris.

1.2 Disinfection

Disinfection is defined as a procedure, the result of which is transient and that eliminates or kills microorganisms and/or deactivates undesirable viruses that are carried by inert contaminated environments. Such operations, which are carried out in accordance with defined objectives, relate solely to the microorganisms that are present at the time the procedure is carried out.

Disinfection is a generic term that refers to any antimicrobial measure (regardless of the level of the outcome attained), using a product that exhibits in-vitro properties that meet the criteria of a disinfectant or antiseptic agent. The name of each disinfection procedure should indicate its application domain, for example, medical device disinfection, floor disinfection, and hand disinfection.

1.3 Disinfectant

A product that is used for disinfecting under defined conditions. If the procedure is selective, this must be specified. A disinfectant is a product that contains one or more active ingredients that exhibit antimicrobial properties and the activity of which is determined by a recognized standard system.

1.4 Sterilization

A thermal operation, the purpose of which is to eliminate all living microorganisms of any kind whatsoever. Items that undergo sterilization are disinfected beforehand and remain so as long as their protective packaging remains intact. Sterilization is used for autoclavable instruments and not for flexible endoscopes.

1.5 Traceability

The purpose of medical device traceability is to enable the relevant agencies to determine how and where a specific medical device was used, based on a registered ID number in accordance with ISO 9000: 2000.

The traceability of disinfection and sterilization procedures is part of the quality control process. In the present context, traceability refers to documentation of all stages of the processing undergone by a medical device so as to allow for certification that the relevant steps were carried out properly. Such documentation, either paper or electronic, relates to all human, technical, and material resources deployed, as well as all procedures used.

1.6 Medical device

A medical device is any instrument, apparatus, material, or product of non-human origin, or any item used alone or in association with such items, including accessories and software, that is intended by the vendor for human medical applications and whose primary effect is not obtained by pharmacological, immunological or metabolic means.

Endoscopes, endoscopic accessories and supplies, disinfectants, and reprocessing machines all count as medical devices and are subject to the CE mark or equivalent.

2.1 Preliminary cleaning

The purpose of this phase is to remove visible debris. Preliminary cleaning, which is performed immediately following the procedure, comprises the following:

The device is then taken to the disinfection room where subsequent steps are carried out. In the interest of preventing the endoscope from drying out if it is not disinfected immediately or if the disinfection room is far from the endoscopy room, the endoscope should be immersed in a cleaning and decontaminating fluid.

However, before an endoscope is immersed, it must undergo a leakage test.

2.2 Initial cleaning (basin 1)

An adequate number of basins must be available for manual cleaning steps. The purpose of this phase is to reduce the endoscope’s contamination level and remove any debris by physicochemical means, as well as a mechanical process during which force is applied.

Manual cleaning is undertaken by completely immersing the endoscope in a basin containing an enzymatic detergent solution.

The initial cleaning phase must include the following actions and a minimum of 10 min should be spent on this phase:

2.3 First rinsing (basin 2)

2.4 Second cleaning (basin 1)

A minimum of 5 min should be spent on this phase.

2.5 Intermediate rinsing (basin 2)

2.6 Disinfection (basin 3)

This phase is efficient only if the cleaning before is well done.

In most countries, manual disinfection is now unacceptable and the use of automated endoscope reprocessing machines (AER) is required. For countries where AERs are not mandatory or widely available, the process for manual cleaning is described below but this practice will have the desired effect only if the previous two phases were carried out properly, and is strongly discouraged.

This operation is composed of the following steps:

2.7 Final rinse (basin 4)

The purpose of the final rinse is to reduce toxic risk by eliminating all traces of disinfectant on the device without changing the level of cleanliness and antisepsis that was attained in the previous phases.

The quality of the final rinsing water will be determined by the level of disinfection obtained previously. Bacterial sampling of the final rinse water must be undertaken regularly.

The water quality for gastrointestinal endoscopy must meet either of the following criteria:

Purge the channels, which is the final step in this phase.

Change the final rinsing water after each endoscopy procedure.

2.8 Drying

2.9 Storage

Store endoscopes in a clean and dry place, protected from any source of microbial contamination, and preferably in an enclosure whose efficacy has been evaluated. Purpose-built storage cabinets using filtered air have been shown to prevent colonization for up to 72 h and may obviate the need for endoscope reprocessing before every list.

Do not store endoscopes in cases.

2.10 Post-storage disinfection

If an endoscope has been stored for >3 h, it must be disinfected via a procedure comprising, at a minimum, a disinfection and final rinsing phase, in such a way that: (a) the manufacturer’s recommended time for soaking the endoscope in disinfectant is observed; and (b) water is circulated in the endoscope’s channels.

4.1 Steam-sterilizable instruments

This type of procedure is used less frequently nowadays, as single use disposable accessories are widely used in many countries. Reusable instruments should only be used where no equivalent disposable device exists and in these situations, full traceability is essential. In some countries, economic considerations mean that reusable accessories are still used, in which case, the following procedures should be followed:

4.2 Non-steam-sterilizable instruments

These types of instruments are rarely used nowadays.

The cleaning procedure is the same as for flexible endoscopes, and should be carried out in such a way that all five phases are followed. It is particularly important that the procedure be carried out immediately following use of the instruments, and that a preliminary cleaning phase occurs.

The instruments must be stored in specialized disposable packaging, the appearance of which is noticeably different from that of sterilization packaging. Stored instruments must undergo a disinfection and rinsing phase prior to use.

4.3 Basin maintenance

The following must be performed after each use:

5.1 Endoscope cleaning room equipment and layout

The equipment and layout of this room (see also Ch. 1.5) must be specifically intended for the cleaning and maintenance of medical devices. It should designed in accordance with the ‘forward movement’ principle, i.e. equipment flow is one-way from dirty to clean.

The room must meet the following criteria:

5.2 Personnel

Each patient is a potential source of infection and endoscopy unit staff should take the following precautions:

2.1 Biopsies

After being labeled, biopsy specimens are checked against the bottles, as well as the specified biopsy sites, and are then desiccated, incorporated into paraffin, cut into 2 µm slices, and stained using hematoxylin and eosin (H&E). Specific stains can be used if required. Those most frequently requested are: Masson trichrome (stains connective tissue, vascular walls, basal membrane); Perl’s (excess iron); PAS (Whipple’s disease); Congo red for amyloidosis (homogenous appearance, with green birefringence under polarized light); and Alcian blue for mucin. The lamina propria is seen with silver impregnation (for reticulin) or Giemsa (for lympho-plasmocytotic cells).

Immunohistochemistry can be performed using specific antibodies which can be used to assess undifferentiated tumors. Markers which can be assessed include:

2.2 Cytological smears

The endoscopist performs the smear, following aspiration, or brushing. However, a biopsy is always preferable to a cytology smear, regardless of the quality of the specimen or the pathologist’s competence. Cytology smear results are only conclusive in the presence of a previously diagnosed tumor.

2.3 Bile or pancreatic juice

This is performed using a dry tube containing at least one drop of formaldehyde. If the specimen is not analyzed immediately, it should be refrigerated at 4°C. The analysis can be performed using the classic method or the so-called monolayer technique, depending on the equipment available. Any contrast material can be used, with Papanicolaou and May-Grünwald-Giemsa (MGG) the most frequently used.

Biliary or pancreatic brush specimens are spread on glass slides, air dried, and then sent to the pathologist for MGG staining. The monolayer technique allows for dilution of the material collected on the brush in a specific liquid, whereupon the cells are spread more evenly so that they form a ‘single’ layer. This technique allows for better cell visualization as it eliminates cell clumping and superimposition.

3.1 The esophagus

The esophagus consists of the mucosa, submucosa, and muscularis propria (Fig. 1). The mucosa contains non-keratinized stratified squamous epithelium, lamina propria, and muscularis mucosae. The submucosa contains small aciniform cells that secret mucins and connective fibers (papillas), which extend far into the mucosa. The muscularis propria consists of striated muscle in the upper third, both striated and smooth muscle in the middle, and smooth muscle in the lower third. The esophagus contains no serous membrane.

Figure 1 Structure of the GI tract, from the esophagus to the colon.

3.1.2 Barrett’s esophagus

Four quadrant biopsies should be taken every 2 cm from the Barrett’s mucosa. Advanced imaging techniques (Figs 2, 3) can be used to screen for Barrett’s esophagus (see Chs 6.1 and 6.2). The gastroesophageal junction can be visualized using confocal endomicroscopy (Fig. 2), as can Barrett’s esophagus (Fig. 3B) and dysplasia (Fig. 3C), which correlate with the pathological findings (Fig. 3A). Biopsies should be submitted to pathology in separate containers to permit focusing of subsequent biopsies, should dysplasia be detected. Depending on whether high-grade, low-grade or no dysplasia is found, this determines management and endoscopic screening intervals (for screening intervals for Barrett’s esophagus, see Ch. 3).

Figure 2 Gastroesophageal junction seen with confocal endomicroscopy.

Figure 3 Barrett’s esophagus. Seen on (A) histology and (B) endomicroscopy. (C) Dysplasia in Barrett’s esophagus on endomicroscopy.

3.2 The stomach

The cardia is a 5–30 mm area composed of individual or interlinked cardiac glands, which contain identical mucus secreting cells. The fundus (Fig. 4A,B) contains two regions. The first is delineated by furrows containing vessels with thick mucosa. Its crypts are round and regular and are surrounded by a vascular web (Fig. 4D), with numerous narrow, rectangular glands, which are perpendicular to the surface. The second region is composed of mucus and parietal cells. The body of the fundic gland is mainly composed of parietal cells, but also contains larger cells that are rich in pepsin or zymogens. The antrum (Fig. 4C) contains a thinner mucosa that is 200–1000 µm thick. Its epithelium is more irregular than the fundus. The antrum’s crypts are elongated and contain smaller glands that are mainly composed of mucus cells that occur around primary or secondary crypts. Cells producing gastrin and serotonin are also found here.

Figure 4 Gastric histology. (A,B) Histology of the fundus. (C) Gastric antrum. (D) Vascular network of the fundus (×60).

3.2.1 Helicobacter pylori infection

This initially provokes acute gastritis, accompanied by a polynuclear infiltration, followed by chronic gastritis accompanied by a lympho-plasmocyte infiltration (Fig. 5), which provokes lymphoid follicles. The latter occurs mainly in the antrum, but also extends to the fundus. An endoscopic examination may reveal mini- or macro-nodules that constitute submucosal lymphoid nodules. Micro-ulceration can be seen with zoom magnification (Fig. 6). Helicobacter pylori infection is initially accompanied by elevated acid secretion, which induces chronic duodenitis, which in turn is associated with gastric metaplasia and colonization by bacteria. Chronic Helicobacter pylori infection is associated with atrophy, which can be associated with reduced acid secretion and should be investigated during screening for intestinal metaplasia (Fig. 7).

Figure 5 Chronic gastritis with lymphocyte infiltrations on histology.

Figure 6 Antral micro-ulcerations (×60).

Figure 7 Atrophic gastritis with intestinal metaplasia (×50).

Helicobacter pylori is detected via direct examination, culture, or a urease test (CLO test). Culture is considered the gold standard, and allows assessment of antibiotic sensitivity. CAG A+ strains tend to activate inflammatory cells. Specimens should be collected from the antrum (2 cm around the pylorus) and fundus, in accordance with the Sydney classification system (two antral and two fundic specimens). Helicobacter pylori distribution is heterogeneous in the stomach, but predominates in the antrum.

3.2.2 Linitis plastica

In cases of gastric linitis plastica (Fig. 8), where there is invasion of the gastric wall by small signet-ring cells, biopsies sometimes yield false negative results and have to be repeated. Endoscopic ultrasound should be used where doubt exists.

Figure 8 Linitis plastica. Note the submucosal infiltration accompanied by small, signet-ring cells.

3.3 Duodenum and jejunum

The duodenum and jejunum contain villi, which are covered with absorbent cells (enterocytes with microvillous, brush border) as well as a very small number of goblet cells, with crypts of Lieberkühn between the villi.

 Clinical Tip

Duodenal biopsies should be taken in the distal duodenum below the ampulla of Vater, as the villi in the first part of the duodenum are only three-quarters of the height of the villi below the papilla (Fig. 9).

Figure 9 Normal duodenal villi (×120).

Duodenal biopsies should be performed in cases of anemia secondary to iron or folic acid deficiency (or any other nutritional deficiency), chronic diarrhea accompanied by exudative enteropathy or malabsorption, particularly for the diagnosis or monitoring of celiac disease. Duodenal biopsies are also recommended in cases of suspected amebiasis, strongyloidoses, or bacterial overgrowth. Immunohistochemical staining should be performed on biopsies in patients in whom lymphoma is suspected.

3.4 Rectum, colon, and ileum

The ileal mucosa is composed of long villi that are identical to those in the jejunum; goblet cells outnumber absorbent cells by a ratio of 5 : 1 (Fig. 10).

Figure 10 Ileal lymphoid follicle.

The colonic mucosa, which is mainly composed of goblet, absorbant and endocrine cells, and varies in thickness from 500–1000 µm (owing to the absence of Paneth cells) (Figs 11–13). Small numbers of intraepithelial lymphocytes (<5% of the epithelial cells) are observed in normal colic mucosa. The basal membrane is <5 µm thick, and the crypts (1700/cm²), are rectangular, and terminate with parallel intestinal glands. The goblet cells are more numerous in the upper part of the gland. Endocrine cells occur in the lower segment. The lamina propria is composed of fibroblasts, smooth mucosal fibers, macrophages, capillaries and small lymphocytes containing a few lymphoid follicles. The muscularis mucosae is 20–40 µm thick, and the submucosa is composed of loose connective tissue that is rich in arterioles and mini-veins and contains the Meissner plexus. The terminal vascularization is web-like and contains glandular crypts. Peri-cryptic micro-arches are more numerous in the caecum than in the sigmoid colon, whereas colonic mucosa thickness varies inversely.

Figure 11 Normal colonic mucosa with regular glands rich in goblet cells. Two axes with perpendicular slices.

Figure 12 Normal colonic mucosa with a regular pit pattern (×120).

Figure 13 Endomicroscopy (×1000). (A) Sunflower-like colonic mucosa with mucin-rich cells. (B,C) Vascular arches. (D) 150 µm deep.

3.4.1 Benign polyps

Benign polyps include hyperplasic, inflammatory, and juvenile hamartomatous polyps.

• Hyperplastic polyps exhibit a saw-tooth appearance. The epithelium is characterized by elongation of the glandular crypts; the muscularis mucosa is thickened. Hyperplastic polyps are typically located in the recto-sigmoid and are <5 mm in diameter. If multiple, they can be associated with hyperplastic polyposis syndrome (Box 4)

• Inflammatory polyp containing numerous inflammatory cells and a regenerative basal membrane

• Juvenile hamartomatous polyps occur where the epithelium is replaced by tissue composed of pseudocystic crypts, with central thickened fibromuscular stroma and eosinophilic infiltration. If multiple, they can be associated with familial juvenile polyposis syndrome (Box 4).

Box 4 Hereditary polyposis syndromes

• Hyperplastic polyposis syndrome (HPS).

This is characterized by multiple, large/proximal hyperplastic polyps and occasionally a smaller number of serrated adenomas. Unlike sporadic hyperplastic polyps, HPS is associated with an increased risk of colorectal cancer. The diagnosis of HPS requires:

At least five hyperplastic polyps proximal to the sigmoid colon, with two >1 cm in size or

Any number of hyperplastic polyps proximal to the sigmoid colon in a person with a 1st-degree relative with HPS or

>30 hyperplastic polyps throughout the colon.

• Familial adenomatous polyposis (FAP).

FAP is an autosomal dominant disease involving >100 polyps in the colorectal region with chromosomal mutation 5q21. In addition to developing colorectal cancer at an early age, FAP is associated with duodenal ampullary cancers, gastric cancer, follicular or papillary thyroid cancer, hepatoblastoma and medulloblastomas.

• Familial juvenile polyposis syndrome (FJP).

Associated with multiple juvenile polyps and inherited in an autosomal dominant fashion. It is associated with an increased risk of developing colorectal cancer, and in some families, gastric cancer.

• Hereditary non-polyposis colorectal cancer (HNPCC).

HNPCC is due to a mutation in mismatch repair genes, and is associated with gastrointestinal and extraintestinal cancer. HNPCC is associated with the development of colorectal cancer occurring at a younger age (mean 45), which classically occurs in the right colon. The diagnosis can be made using the Amsterdam II criteria (below) or the Bethesda guidelines. FAP must be excluded. The Amsterdam II criteria are:

Three members of the same family present with a malignancy associated with HNPCC (colorectal cancer, endometrial cancer, small intestine cancer, transitional cell carcinoma of the ureter or renal pelvis)

One individual is a 1st-degree relative of the other two (parent, sibling or child)

Two or more successive generations are affected

One person developed cancer before the age of 50.

• Peutz–Jeghers syndrome.

Hamartomatous polyps are found in the colon and small intestine. These consist of a proliferation of smooth muscle extending into the lamina propria with normal overlying epithelium. Associated with an increased risk of gastric, small bowel, colon and pancreatic cancer, as well as non-gastrointestinal cancers.

• Cowden’s disease.

This is associated with multiple hamartomas is accompanied by multiple hamartomas.

• Cronkhite–Canada syndrome.

This is a non-familal disorder associated with multiple hamartomatous polyps. In addition, patients exhibit alopecia, cutaneous hyperpigmentation, onychodystrophy. Patients present with diarrhea, bleeding, and sepsis.