Colonoscopy technique

Positioning

• Left lateral decubitus
• Inspect anus and do PR
• Liberal lube
• Rectosigmoid junction @15-20cm
• Caecum 60-80cm

Variable stiffness

• Twist on shaft
• The top 30cm is left floppy at all times
• Useful to increase stiffness after a looping section of the colon has been passed

Pre-scope checks

• Insufflation
  • Check light source - is air pump switched on?
  • Are umbilical and water-bottle connections pushed in fully and water bottle screwed on?
  • Is rubber O-ring in place on the water-bottle connection?
  • Is air/water valve in good condition and sealed properly?
  • If in doubt, put a rubber glove over the tip and re-test
• Lens washing
• Water wash
  • Empty water bottle?
  • Faulty air/water valve?
• Suction
  • Valve blockage
  • Debris blocking suction channel - water syringe through biopsy port

Insertion

• PR exam with generous amount of lubricant
• Grip shaft 25-30cm from anus
• Relax posture
• Often see a 'red-out' initially - up against rectal mucosa
  • Insufflate to distend rectum
  • Pull back and angulate/rotate slightly, to find the lumen
  • Rotate so that any fluid lies inferiorly
  • Aspirate the fluid to avoid anal leakage later
  • Push in
• Use torque-steer to get around the first few bends

Rectal retroversion

• Go to widest part of distal rectum
• Angulate both controls fully
• Twist shaft vigorously and simultaneously
• Push inward to invert the tip towards anal verge

Looping

• Clues that a loop has formed:
  • Loss of one to one relationship
  • Paradoxical movement
  • Controls feel jammed up - not working properly
• Sigmoid looping
  • Abdominal pressure can be helpful if the sigmoid loops anteriorly, close to the abdo wall
  • Don't ignore pain
  • Alpha looping
    • Suspect this if insertion is very easy through to descending colon
    • Push on to descending/splenic flexure before trying to straighten (don't want to straighten half way round an alpha loop - wait until fully formed then pull back)
  • The 'N' loop
    • Steps:
      • Use some water and gentle pressure, but don't push through blanching
      • Pull back and deflate to shorten the sigmoid. This should allow direct passage into descending colon.
      • Pull back with clockwise shaft twist
      • Change to slimmer/paediatric scope
      • Abdominal pressure
      • Change patient to supine or right lateral
    • Stop it from forming in the first place by using less air and less push in the sigmoid
  • Spiral loop
    • Actually a good thing because it means no acute angle at sigmo-descending junction
    • The 'alpha maneuvre' (counter clockwise torsion in the sigmoid) can be used to create a spiral loop
    • Need to remove it at some stage - mostly at splenic flexure. Often, once you get to about 90cm with a spiral loop, you can pull back to about 50cm to straighten it.
    • Straighten via pull back and strong clockwise twist (twist alone would just change it into an N loop. If you pull back and just move back without releasing loop, apply more twist.
  • S loop
    • This occurs in the setting of a long sigmoid. A flat S shaped loop may form with no spiral configuration. Need to get past the splenic flexure, angulate the tip and then pull back.
• Splenic flexure
  • Aim to reduce scope to 50cm after hooking around splenic flexure (it can go back as far as 40cm if there is a lax phrenicocolic ligament). If proximal colon is hard, it's probably because the splenic flexure hasn't been reduced to 50cm.
  • Hand pressure does not help here due to depth of colon
  • Variable fixation due to phrenicocolic ligament
  • After going around splenic flexure:
    • Reduce scope to 50cm
    • Stiffen scope to stop sigmoid re-looping
    • De-angulate scope a little to allow it to smoothly run around the outside of the bend
    • Deflate colon
    • If still getting resistance, hand-pressure at sigmoid
    • Clockwise torque to stop sigmoid loop
    • Slow push
    • Change position (if stuck for about 60 seconds)
  • Reversed splenic loop can occur - needs to be de-rotated first (counterclockwise)
• Transverse mesocolon
  • To reach hepatic flexure:
    • Pull back to lift up transverse loop
    • Deflate
    • Try counterclockwise twist - changes splenic flexure path more medially
    • Try hand pressure in the upper abdomen or over sigmoid
  • Gamma loop
    • Forms in a long redundant transverse colon
    • Hard to remove due to size and because there are no anchoring points to angulate the tip
    • Generally necessary to push on to caecum with the loop in place
    • Can sometimes be removed with combined withdrawal and very strong twist (usually anticlockwise)
• Hepatic flexure
• Ascending colon
  • Looping preventing reaching caecum - try sigmoid pressure, then repositioning onto back
  • Try fully reducing loops by withdrawing back to splenic flexure at ~50cm

Options for polyp removal:

Snare polypectomy

• Needs adequate margins
• Aim for 2mm margins with pedunculated polyps

Endoscopic mucosal resection (EMR)

• Define margins clearly and estimate size and degree of invasion
• Raise a submucosal cushion with fluid to allow excision of more tissue, also acts as thermal cushion. Start with the proximal side, as this can be hard to reach once the distal side is lifted.
• Failure to lift raises concern for malignancy (unless a previous polypectomy attempt could have fixed it to the submucosa)
• Usually use Gelofusine mixed with methylene blue and maybe also adrenaline
• Use hot snare to resect
• Polyps >2cm should be resected piecemeal to reduce the perforation rate
• Must tattoo - preferably at least 3cm away on the opposite wall, since if it spreads to the polypectomy site, subsequent identification of recurrence will be harder

Endoscopic submucosal dissection (ESD)

• Used when a polyp >2cm should be resected en bloc
• Much less useful in the colon than upper GIT - polyps are less likely to be malignant

Polypectomy:

• <10mm colorectal polyps: cold snare
• Pedunculated stalk >10mm: mechanically ligate the stalk with a clip or polyloop
• Only pulsatile bleeding requires intervention (Resolution clip)

Risk factors for difficult polypectomy

Tattoo