Endoscopy Necessities Decrease Gastrointestinal Endoscopy Sequence Half 2: Decrease Gastrointestinal Endoscopy Methods

Welcome to Endoscopy Necessities, a column that discusses endoscopic analysis of particular physique techniques, reviewing indications, illness abnormalities, and correct endoscopic strategies. Go to to learn the primary 4 Endoscopy Necessities articles:

  • Overview of Higher Gastrointestinal Endoscopy (November/December 2014)
  • Higher Gastrointestinal Endoscopy Methods (March/April 2015)
  • Endoscopic Overseas Physique Retrieval (November/December 2015)
  • Overview of Decrease Gastrointestinal Endoscopy (July/August 2016).

Decrease gastrointestinal (GI) endoscopy is a minimally invasive diagnostic method that permits the clinician to guage the mucosal surfaces of the rectum, colon, ileocolic sphincter, cecum, and distal small gut (ileum).

The primary article on this collection—Half 1: Overview of Decrease Gastrointestinal Endoscopy (July/August 2016)—reviewed indications for decrease GI endoscopy, look of the traditional decrease GI tract, and customary ailments. This text discusses affected person preparation, instrumentation, and directions on performing decrease GI endoscopy.


Colonic Lavage

Thorough analysis of the mucosal surfaces of the decrease GI tract requires enough affected person preparation to take away feces from the colon (Determine 1).

  1. Withhold meals from the affected person for 24 to 48 hours earlier than colonoscopy.
  2. Roughly 12 hours previous to the process, place an orogastric or nasoesophageal (NE) tube for administration of the lavage answer; NE tubes are indicated in cats and any canines which can be illiberal of orogastric tubes.
  3. After placement of the NE tube, take radiographs to verify right placement of the tube to be able to keep away from deadly aspiration.
  4. As soon as placement is confirmed, administer a high-volume colonic lavage answer (eg, polyethylene glycol answer with electrolytes [PEG 3350-E]) in 2 doses of 40 to 60 mL/kg in canines or 30 mL/kg in cats over 2 H, repeated 2 to Four H later.
  5. Alternatively, your entire quantity could be delivered as a continuing price infusion through NE tube over 6 to eight H. Not often, essentially the most enthusiastic canines could also be inspired to devour the PEG 3350-E flavored with broth, ice cream, or small quantities of canned pet food.
  6. Be certain to clamp or kink off the tube throughout extubation to stop inadvertent and doubtlessly deadly aspiration of colonic lavage answer.

FIGURE 1. Colonoscopic images of 2 dogs demonstrating poor (A) and excellent (B) colon preparation. Poor colon preparation limits the ability to visualize the mucosal surface for lesions and the lumen for safe scope passage.

FIGURE 1. Colonoscopic photos of two canines demonstrating poor (A) and glorious (B) colon preparation. Poor colon preparation limits the flexibility to visualise the mucosal floor for lesions and the lumen for secure scope passage.


Along with the lavage answer, all sufferers ought to obtain a number of heat water enemas.

  1. Administer an enema 30 to 60 minutes after every profitable administration of PEG 3350-E and repeat 1 to 2 H earlier than the process.
  2. Insert a well-lubricated purple rubber catheter into the rectum and advance it to the extent of the final rib.
  3. Instill 20 to 30 mL/kg heat water.
  4. In cats, administer the enema slowly as a result of fast administration could trigger vomiting and potential aspiration of colonic lavage answer.


For full decrease GI endoscopy, normal anesthesia is really helpful. If a focal lesion of curiosity exists within the distal descending colon or rectum, sedation could also be used for inflexible colonoscopy. Nonetheless, if important insufflation is used (versatile endoscopy), analysis of the transverse or ascending colon or ileum is desired, or deep biopsies are carried out, normal anesthesia is really helpful to enhance affected person consolation and cooperation.


Relying on the objectives of decrease GI endoscopy and the realm of curiosity, inflexible or versatile endoscopes could also be used.

Inflexible Colonoscopy

Inflexible endoscopy can be utilized to guage the descending colon and rectum, and is primarily carried out with human sigmoidoscopes or proctoscopes (Determine 2).

FIGURE 2. Welch Allyn 19-mm × 15-cm standard sigmoidoscope with obturator and insufflation bulb (

FIGURE 2. Welch Allyn 19-mm × 15-cm normal sigmoidoscope with obturator and insufflation bulb (

These scopes can be found in pediatric (9–15 mm) and grownup (19–23 mm) diameters, and their lengths vary from 10 to 35 cm. As a rule, the most important scope that allows profitable analysis of the realm of curiosity needs to be chosen. If devices are used, they must be longer than the endoscope’s speculum.

In contrast with versatile endoscopy, magnification and detailed examination of the mucosal floor are poor; nonetheless, proctoscopes and sigmoidoscopes are comparatively cheap and permit for big biopsy samples.

Versatile Colonoscopy

Versatile endoscopy can be utilized to guage the rectum, colon, cecum, and distal ileum. Whereas versatile endoscopy permits a extra thorough analysis of the mucosa than inflexible endoscopy, biopsy samples are typically restricted by the dimensions of the working channel. Some clinicians really feel that inflexible endoscopy permits a greater examination of the rectum however, with correct method and enough insufflation, the rectum is properly visualized even in sufferers through which retroflex protocscopy can’t be carried out.

A gastroscope or a colonoscope could also be used (Determine 3), and the largest-diameter endoscope that allows analysis of the areas of curiosity is really helpful. Subsequently, number of a versatile endoscope depends upon affected person measurement. With developments in video endoscopy, versatile endoscopes for colonoscopy can have an insertion tube as small as 5.9 mm in diameter. This typically permits intubation of the ileocolic junction and analysis of the distal ileum even in small canines and cats.

FIGURE 3. Fujinon EC-530-LS 11.5-mm × 160-cm videoscope with 3.8-mm operating channel and forward water jet function for irrigation (

FIGURE 3. Fujinon EC-530-LS 11.5-mm × 160-cm videoscope with 3.8-mm working channel and ahead water jet operate for irrigation (

An working channel of not less than 2.Eight mm is really helpful for enough biopsy pattern measurement and is probably not obtainable on smaller diameter scopes. Gastroscopes or colonoscopes typically have a working size between 100 cm and 170 cm. For big- or giant-breed canines, an endoscope with a working size of not less than 140 cm could also be wanted to guage the ascending colon, cecum, or ileum.

Further Instrumentation

  • If the preparation is insufficient, colonic lavage pumps could also be used to advertise visualization of the colonic mucosa (Determine 4).

FIGURE 4. Erbe EIP2 irrigation pump (

FIGURE 4. Erbe EIP2 irrigation pump (

  • For inflexible colonoscopy, mare uterine biopsy forceps could also be used to acquire giant biopsy samples of intraluminal lots. Alternatively, inflexible biopsy devices can be utilized to biopsy extra discrete mucosal lesions.
  • For versatile endoscopy, a wide selection of biopsy forceps is on the market, and choice relies upon totally on the working channel of the endoscope and operator choice.
  • If a rectal polyp or a pedunculated mass is recognized, a snare could also be used to take away it at its stalk. Notice: This system will not be really helpful for the novice endoscopist; inadequate coaching could end in substantial hemorrhage and/or colonic perforation.
  • Balloon dilators in quite a lot of sizes can be utilized to sequentially balloon-open rectal strictures.


No matter whether or not inflexible or versatile endoscopy is used, clinicians ought to observe a number of necessary tips to keep away from potential issues.

  • Frequent insufflation is crucial to keep up a visible discipline throughout GI endoscopy, however keep away from overinsufflation as a result of it may result in affected person discomfort or elevated threat for GI rupture.
  • The anesthetist or an assistant ought to monitor the stomach continuously for proof of distension.
  • Solely advance the insertion tube when a transparent luminal view is current (besides when utilizing blind “slide-by” method, see Step 5). If the lumen can’t be visualized, don’t advance the scope till the lumen is centered once more.
  • If visualization turns into impaired from feces or mucus, use irrigation to scrub the distal tip. If that is unsuccessful, clear the distal tip by touching it to a transparent space of mucosa.

Inflexible Colonoscopy

Navigating the Anatomy

  1. Inflexible colonoscopy could be carried out with the animal in any recumbency, however proper lateral recumbency is most popular to reduce the angle of the rectocolic junction.
  2. Earlier than inserting the endoscope into the rectum, make certain the obturator and finish of the endoscope are properly lubricated.
  3. Take away the obturator as soon as it’s superior into the rectum; then rotate the viewing lens into place. Closure of the lens permits insufflation and visualization of the colonic mucosa.
  4. Advance the endoscope, with continuous insufflation, making certain clear luminal view is maintained.

Accumulating Biopsy Samples

  1. If biopsy specimens must be obtained, advance the endoscope to inside a centimeter of the specified space.
  2. Open the viewing lens and advance the inflexible biopsy forceps by way of the speculum to the mucosa.
  3. Open the jaws of the biopsy forceps, advance into the specified tissue, shut, and take away the pattern.
  4. Be certain there may be 1 cm between sampled areas to keep away from repeated biopsy in the identical location. This helps guarantee enough illustration of illness and reduces the chance for perforation.

Versatile Colonoscopy

Navigating the Anatomy

1. Versatile colonoscopy is carried out with the affected person in left lateral recumbency.

2. Earlier than inserting the endoscope into the rectum, make certain the distal tip of the scope is properly lubricated, with care taken to keep away from the target lens.

3. As soon as the endoscope is inserted into the rectum, have an assistant maintain the anus closed to stop air from escaping. After a seal has been shaped, insufflate the rectum, offering visualization.

4. Rectocolic junction: Because the scope is superior orally, the primary flexure is encountered on the rectocolic junction, the place the colon begins to deviate from midline to the left aspect of the animal’s physique (Determine 5). In most animals, this flexure is well navigated with insufflation and deflection of the scope tip towards the lumen. As soon as the rectocolic junction is handed, consider the rest of the descending colon.

FIGURE 5. Anatomy of the canine large intestine. Courtesy Savannah Mauragis

FIGURE 5. Anatomy of the canine giant gut. Courtesty Savannah Mauragis

5. Splenic flexure: The subsequent flip is on the splenic flexure, the place the descending and transverse colon meet at a close to 90-degree angle. To cross the splenic flexure, advance the endoscope to the far wall of the descending colon. Then deflect the bending part upward (to the animal’s proper) and apply strain whereas insufflating. A “purple out” is often seen because the distal tip brushes in opposition to the colonic mucosa, however the endoscope ought to transfer ahead with minimal resistance. The mucosa needs to be seen “sliding by” the tip of the scope till the lumen is once more visualized (view a video demonstrating this method at If important resistance is encountered, withdraw the scope and try the maneuver once more. As soon as the splenic flexure is handed, re-establish the luminal view and consider the transverse colon.

6. Hepatic flexure: After the brief transverse colon is evaluated, advance the endoscope to the hepatic flexure. The hepatic flexure is handed similarly as with the splenic flexure to achieve entry into the ascending colon. The ascending colon may be very brief in canines and cats and terminates within the ileocolic and cecocolic junctions. If the scope is handed with out visualization of the lumen of the ascending colon, it’s straightforward to inadvertently advance the endoscope into the cecum, because the cecocolic valve is commonly open. The cecum is a blind sac, and aggressive development of the scope may end up in rupture of the cecum. The cecum within the canine is commonly recognized by its spiral course to the distal tip. If the hepatic flexure is handed and an open lumen can’t be recognized, withdraw the scope slowly till the ileocolic valve is seen or the transverse colon is visualized. If the cecocolic junction is closed, it seems as a flat mucosal fold.

7. Cecocolic & ileocolic junctions: To enter the cecum, middle the distal tip of the endoscope on the sphincter, whereas making use of fixed light ahead strain with intermittent insufflation. As soon as the cecum is entered, advance the endoscope and consider the cecum. Then withdraw the endoscope to the extent of the ascending colon and enter the ileocolic junction similarly. If a number of unsuccessful makes an attempt are made to enter the ileum, cross closed biopsy forceps by way of the ileocolic junction to behave as a stylet, facilitating the endoscope’s entry into the ileum, however take care to keep away from perforating the gut.

Accumulating Biopsy Samples

  1. To gather biopsy samples, advance the closed biopsy instrument by way of the working channel into the lumen of the gut, open it, after which retract it to the tip of the endoscope.
  2. Angle the endoscope towards the mucosa and advance the biopsy instrument into the wall as near a perpendicular angle as attainable.
  3. Shut the biopsy instrument and permit the distal bending part to loosen up earlier than swiftly retracting the instrument. Eradicating some air from the lumen will help enhance buy of the biopsy instrument on the mucosa.
  4. If the ileocolic valve can’t be intubated, blind biopsies of the ileum could also be carried out. To perform this, cross closed biopsy forceps by way of the ileocolic junction, open after which advance the forceps till resistance is encountered. Shut the biopsy instrument; then retract.
  5. As soon as the ileum has been biopsied, slowly withdraw the endoscope. Further biopsy samples needs to be taken from the cecum; the ascending, transverse, and descending colon; and the rectum. Focus biopsy samples on irregular areas but additionally get hold of samples from all sections of the big gut, no matter look. A minimal of two to three samples from every area needs to be obtained—extra if the samples aren’t good high quality.

Inspecting the Rectum

As soon as the biopsy samples are collected, the aboral-most portion of the rectum could also be evaluated in some bigger canines. To perform this:

  1. Withdraw the endoscope in order that the distal tip is 10 to 20 cm from the anus; then deflect the endoscope upward to attain an approximate 90-degree angle within the distal bending part.
  2. Seat the distal tip in opposition to the colonic mucosa and advance the insertion tube as extra upward deflection is utilized. This allows the distal bending part to “roll over” itself to attain full retroflexion.
  3. Withdraw the insertion tube till the terminal rectum could be evaluated (Determine 6) and rotate the scope clockwise and counterclockwise in order that the mucosa hidden behind the insertion tube could be evaluated.
  4. As soon as completed, advance the scope into the proximal rectum/descending colon and carry out the reverse maneuver to straighten the scope tip earlier than withdrawal.

FIGURE 6. Retroflex colonoscopic view of the rectocolic junction. The insertion tube (black) should be rotated clockwise and counterclockwise to ensure the mucosa behind the endoscope is visualized.


Decrease GI endoscopy is a minimally invasive diagnostic method that allows the clinician to guage the rectum, colon, cecum, and ileum for all kinds of lesions. Relying on the realm of curiosity and the objectives of endoscopy, both a inflexible or versatile endoscope could also be used. No matter the kind of endoscope used, it’s important to organize the affected person adequately, and use acceptable tools and method to maximise diagnostic and therapeutic worth in addition to guarantee affected person security.

GI = gastrointestinal; NE = nasoesophageal

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