GI Endoscopy

Question 1

how does transmission work in endoscopy?

Answer 1

light source transmits light into body cavity

resulting image is transmitted to eyepiece/monitor

Question 2

what are the overall roles of endscopy?

Answer 2

diagnostic and therapeutic

Question 3

how can endoscopy aid diagnostics?

Answer 3

observation and sampling

Question 4

what types of sampling can be done via endoscopy?

Answer 4

fluid (BAL)

brush cytology (cells from lining)

FNA

biopsies

Question 5

how can endoscopy be therapeutic?

Answer 5

foreign body removal

stricture dilation

feeding (gastrotomy) tube placement

Question 6

what are the benefits of endoscopy?

Answer 6

minimally invasive

low morbidity/mortality (mainly GA related)

no convalescence required

Question 7

why is it advantageous that there is no significant convalescence required after endoscopy?

Answer 7

commonly used for diagnosis of chronic inflammatory enteropathies (immune-mediated) - no need to delay to start steroids like there would be with surgical biopsy

Question 8

what are the limitations of endoscopy?

Answer 8

cannot visualise whole GI tract

assesses appearance, not function

mucosal evaluation only (visual and histopathological)

cannot evaluate extra-GI disease

Question 9

why can’t the whole GI tract be visualised?

Answer 9

GI tract 12ft long, can only access proximal and distal 3 feet

Question 10

how can the entire GI tract be visualised?

Answer 10

capsule endoscopy - cannot visualise

Question 11

what are the contraindications to endoscopy?

Answer 11

known GI surgical disease (perforation, mass lesion)

inadequate investigation of other causes

unsuitable for anaesthesia (CP/hepatic/renal function impaired)

coagulopathy

inadequate preparation - gut not cleansed properly

Question 12

how does gastric distension affect the endoscopist?

Answer 12

challenging pyloric intubation due to increased angle of lesser curvature

increased antro-pyloric motility

Question 13

how does gastric overdistension affect the anaesthesia?

Answer 13

caudal vena compression –> reduced venous return –> reduced CO –> reduced BP

diaphragmatic splinting –> decreased tidal volume

Question 14

what are the possible complications during endoscopy?

Answer 14

acute bradycardia +/- AV block due to vagal reflex

aspiration (inc during recovery)

bacteraemia (transient during colonoscopy)

GI perforation

haemorrhage - mucosal or laceration of major vessels

Question 15

how can acute bradycardia +/- AV block be reduced during endoscopy?

Answer 15

abolish with atropine or glycopyrrolate

Question 16

how can risk of bacteraemia be reduced?

Answer 16

prophylactic abs if at risk e.g. patients with pacemaker

Question 17

why might GI perforation occur during endoscopy?

Answer 17

usually if pre-existing ulcer/severe pathology

Question 18

does haemorrhage commonly occur from mucosal biopsy?

Answer 18

rare unless underlying coagulopathy

Question 19

when might laceration of a major vessel happen during endoscopy?

Answer 19

FB removal (fish hook)

stricture dilation

Question 20

what are the different parts of the endoscopy system>

Answer 20

light source

air/water insufflator

suction pump

endoscope + insertion tube

forceps/other biopsy equipment

Question 21

why isn’t tungsten halogen light used for endoscopy any more?

Answer 21

cheap but not bright, red hue

Question 22

what light is commonly used in endoscopes today?

Answer 22

xenon arc - brighter, white light, long-lasting

Question 23

what is housed by the light source?

Answer 23

air pump for insufflation

separate suction pump for deflation

water reservoir for washing lens

Question 24

what type of illumination is fibre-optic?

Answer 24

non-coherent

Question 25

what are the fibre optics made of?

Answer 25

individual glass fibre, coated in lower optical density glass 'cladding'

Question 26

how is light transmitted in fibre optics?

Answer 26

by total internal reflection

Question 27

how are the fibres arranged in fibre optic light transmission?

Answer 27

coherent bundles

Question 28

how is the image transmitted in video endoscopy?

Answer 28

via wire, from video chip (CCD) behind lens

Question 29

what are the advantages of fibre optic endoscopes?

Answer 29

portable wide range of sizes moderate cost

Question 30

what are the disadvantages of fibre optic endoscopes?

Answer 30

faceted image (appears as 'honeycomb') fragile size of endoscope dictates image quality eye piece vs video

Question 31

is video endoscopy any different to fibre optic mechanically?

Answer 31

identical

Question 32

what type of illumination does video endoscopy utilise?

Answer 32

non-coherent

Question 33

how is the image transmitted in video endoscopy?

Answer 33

CCD detects image and transmits it to screen

Question 34

what is the advantage of not having an eyepiece on an endoscope?

Answer 34

more hygienic

Question 35

what are the advantages of video endoscopy?

Answer 35

excellent image obtained image control buttons available

Question 36

what are the drawback of video endoscopy?

Answer 36

expensive not portable smallest diameter not possible

Question 37

what diameter insertion tubes are used for gastroscopy?

Answer 37

5.5 - 9.5mm diameter / 1 - 1.5m length

Question 38

what diameter insertion tubes are used for colonoscopy?

Answer 38

10-13mm

Question 39

what variations can be seen between insertion tubes?

Answer 39

diameter and length viewing direction/angle steering - uni-planar vs multi-planar accessory channel

Question 40

why is tip retroflexion important?

Answer 40

allows visualisation of the cardia and entering duodenum useful in foreign body retrieval

Question 41

how does size of channel affect biopsy quality?

Answer 41

smaller channel = poorer quality biopsies

Question 42

what size channel are typically used for gastroscopes?

Answer 42

2.2-2.8mm

Question 43

what endoscopy accessories might be used?

Answer 43

cytology brush biopsy forceps sheathed needles for FNA lavage tubes

Question 44

what are the different types of biopsy forceps available?

Answer 44

reusable / disposable ellipsoid / round fenestrated / whole no spike / spike alligator / smooth swing jaw / fixed angle rotatable / non-rotatable

Question 45

what are the key factors determining biopsy quality

Answer 45

cup size and pressure

Question 46

how can we confirm endoscopy is indicated for a patient?

Answer 46

exclude extra-GI causes of signs exclude surgical disease consider contraindications

Question 47

how long should patients be fasted for gastroscopy?

Answer 47

12 hours for visualisation/manoeuvrability - food clogs channels

Question 48

why should we wait 24 hours after barium to perform a gastroscopy?

Answer 48

barium damages the scope

Question 49

why might 12 hours fasting not be sufficient for some patients?

Answer 49

many GI diseases cause reduced GI motility stress impairs motility

Question 50

what is involved in patient pre for colonoscopy?

Answer 50

fast 24-36 hours oral lavage multiple 'high' enemas

Question 51

what is a 'high' enema?

Answer 51

enema performed as far up the colon as safe and sensible to perform

Question 52

what is used for oral lavage?

Answer 52

poly ethylene glycol (PEG) electrolyte solutions (klean-prep)

Question 53

when is klean-prep given?

Answer 53

day prior to endoscopy

Question 54

how much klean-prep is given?

Answer 54

25-30ml/kg x 3 doses (dogs) 20ml/kg x 2 doses (cats) 2-4 hours apart

Question 55

how is klean-prep administered?

Answer 55

can be orally vs NO tube (usually cats)

Question 56

what are the risks of oral lavage?

Answer 56

tracheal intubation - likely obvious aspiration - contraindicated if significant pre-existing aspiration risks e.g. brachy, laryngeal paralysis trauma (rare)

Question 57

what is used for 'high' enemas?

Answer 57

warm water

Question 58

why shouldn't phosphate enemas be given?

Answer 58

can result in marked hyperphosphataemia

Question 59

how are multiple 'high' enemas administered?

Answer 59

higginson pump or enema bucket

Question 60

how much water should be used for enema?

Answer 60

1L/30kg dogs /until clear 20ml/kg cats

Question 61

when should enema be performed?

Answer 61

1-2hrs before colonoscopy - sometimes not tolerated and must be done under GA

Question 62

what are the general GA considerations for endoscopy?

Answer 62

avoid atropine impact on GI motility and tone smooth induction (avoid aerophagia) familiar routine cuffed ET tube in dogs avoid nitrous care with gastric dilation and reflux/aspiration on recovery

Question 63

why should nitrous oxide be avoided during GI scopes?

Answer 63

accumulates in gas-filled organs

Question 64

is it ok to give opioids for endoscopy?

Answer 64

fine to give - allegedly affect sphincter tone but this is actually more dependent on endoscopist skill

Question 65

which position should a patient be in for GI endoscopy?

Answer 65

left lateral

Question 66

why is left lateral the best position for endoscopy?

Answer 66

pylorus and ascending colon air-filled - will sit dorsally and be easier to intubate

Question 67

why might we have a patient in right lateral recumbency for GI endoscopy?

Answer 67

g-tube placement FB removal - sometimes useful to try multiple orientations

Question 68

why should spring-loaded mouth gags not be used in cats?

Answer 68

contraindicated as potential for reduced blood supply to brain and central blindness afterwards

Question 69

why should the ET tube be secured to the mandible/maxilla?

Answer 69

scope will move tube if tied to back of head

Question 70

why should endoscopic examination reports be filled out?

Answer 70

for record keeping, consistency and completeness

Question 71

how should endoscopes be cleaned/disinfected/sterilised after use?

Answer 71

ensure channels clear - blow air and water through immediately post-scope ethylene oxide gas sterilisation approved disinfectant

Question 72

why shouldn't endoscopes be autoclaved?

Answer 72

will melt scope