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Anorectal investigation
a
c
Imaging in faecal incontinence
AES has revealed that many patients who were
thought to have idiopathic faecal incontinence in
fact have a surgically remediable sphincter defect. It
has also been shown that a much higher proportion
of women sustain sphincter damage during
childbirth than is suspected by clinical assessment
alone. While the true incidence of sphincter tears
may be lower than initially thought,
sustain important morphological changes to the
sphincter following delivery.
diagnose and correctly assess the extent of external
sphincter damage has been validated by comparison
with EMG studies and findings at surgery.
superior in the differentiation between those patients
with idiopathic faecal incontinence and those with a
sphincter defect when compared with either simple
manometric assessment or vector volume studies.
70
many women
71
The ability of AES to
72
AES is
b
Figure1.7 • Examples of complex perirectal sepsis as
shown by the endoanal magnetic resonance probe.
(a,b) T1-weighted images of an intersphincteric collection
prior to and following gadolinium–DTPA contrast (arrow).
(c) Short tau inversion recovery (STIR) image of the
abscess cavity showing a central gas-containing cavity
(long arrow) and a fistula at the 7 o'clock position (short
arrow).
MRI is also used to assess patients with faecal
incontinence and the diagnosis of sphincter
defects using endocoil MRI has been validated
with surgical confirmation of defect presence and
extent. Endocoil MRI may be superior to AES in
the detection and assessment of external sphincter
defects because of better sphincter definition
using MRI, although it is more important that the
clinician is familiar with the imaging technique
73
used.
MRI has multiplanar capability (i.e. axial, sagittal
and coronal images can be acquired), whereas
standard AES provides only axially oriented images.
The acquisition of volume ultrasound data has
overcome this problem, and using three-dimensional
AES has led to a better understanding of sphincter
injury. A direct correlation exists between the length
of a defect and the arc of displacement of the two
ends of the sphincter.
74
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11
Chapter 1
The use of endocoil MRI has shown that
incontinence in the absence of a sphincter defect
may be due to atrophy, where the sphincter has been
replaced by fat and fibrous tissue.
53,75
The presence
of external anal sphincter atrophy on endocoil MRI
has been associated with poor results from anterior
sphincteroplasty.
Summary
A wide variety of physiological and morphological
tests is available for the assessment of the anus
and rectum. Although there is no clear correlation
between manometric/neurophysiological testing
and clinical symptomatology in patients with
idiopathic faecal incontinence, there is considerable
value in performing these tests before surgery to
predict long-term outcome. Anorectal investigation
has revealed a large group of parous women who
have occult sphincter trauma that may have a
clinical impact as the women get older.
Anorectal physiological assessment is essential
as an objective measure in patients with faecal
incontinence and for the diagnosis of Hirschsprung's
disease, and may help select those patients who will
Key points
have acceptable function after coloanal anastomosis
or an ileoanal pouch.
Endoanal imaging is becoming the gold standard
in the preoperative determination of sphincter
integrity and defines those patients most likely
to benefit from surgical intervention. Endorectal
imaging of early rectal tumours correlates well
with histological assessment of tumour depth. MRI
is the imaging modality of choice to assess the
circumferential resection margin and is accurate
for the diagnosis of recurrent tumour after previous
resection.
In patients with primary evacuatory disorders,
neurophysiological testing and defecography assist
in the demonstration of unsuspected rectoanal
intussusception or rectocele in patients who may
benefit from surgery and those who may be suitable
candidates for biofeedback therapy.
Anorectal investigation continues to have a major
role in clinical research and has helped outline the
anatomy of the component parts of the sphincter
complex as well as to define the physiology of both
defecation and anal continence. The understanding
of these processes is vital to the correct management
of patients with anorectal disorders.
• Normal pelvic floor function relies on a complex interplay between various mechanisms.
• Sphincter function may be assessed using anal manometry and electrophysiology.
• Sphincter anatomy may be assessed using AES and MRI, the former being the standard for the
diagnosis of sphincter trauma.
• Dynamic MRI evacuation proctography and dynamic pelvic floor scans are useful in the assessment
of patients with evacuatory disorders.
• Pelvic MRI or three-dimensional AES may be used to assess anorectal sepsis and can predict
recurrence of anal fistulas after surgery.
• MRI is the preferred modality for the staging of rectal cancer with more accurate circumferential
resection margin prediction. Preoperative staging of early T1 rectal cancer is superior with EUS.
Full references available at http://expertconsult.
inkling.com
Key references
18. Bharucha AE, Fletcher JG, Harper CM, et al.
Relationship between symptoms and disordered
continence mechanisms in women with
idiopathic faecal incontinence. Gut 2005;54(4):
546–55. PMID: 15753542.
In this study 35% of patients with faecal incontinence
had reduced resting pressure and 73% had reduced
squeeze pressures, higher percentages than the
control group. This study also found that volume and
pressure thresholds for defecatory desire were lower in
faecal incontinence patients.
19. McHugh SM, Diamant NE. Effect of age, gender,
and parity on anal canal pressures. Contribution of
impaired anal sphincter function to fecal incontinence.
Dig Dis Sci 1987;32(7):726–36. PMID: 3595385.
McHugh and Diamant found that in faecally incontinent
patients, 39% of women and 44% of men had normal
resting and squeeze pressures, and 9% of asymptomatic
normal individuals were unable to generate an appreciable
pressure on maximal squeeze.
61. LahayeMJ, EngelenSM, NelemansPJ, etal. Imaging
for predicting the risk factors – the circumferential
resection margin and nodal disease – of local recurrence
12
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Anorectal investigation
in rectal cancer: a meta-analysis. Semin Ultrasound CT
MR 2005;26(4):259–68. PMID: 16152740.
This meta-analysis of the accuracy of preoperative
imaging included studies between 1985 and 2004. It
showed that MRI was the only investigation accurate
at predicting circumferential resection margin. EUS was
slightly but not significantly superior at predicting nodal
status.
63. Bipat S, GlasAS, SlorsFJ, etal. Rectal cancer:
local staging and assessment of lymph node
involvement with endoluminal US, CT, and MR
imaging – a meta-analysis. Radiology 2004;232(3):
773–83. PMID: 15273331.
A meta-analysis of 90 articles showed that for
muscularis propria invasion, EUS and MRI had
similar sensitivities but the specificity of EUS (86%)
was significantly higher than that of MRI (69%). For
perirectal tissue invasion, sensitivity of EUS (90%)
was significantly higher than that of CT (79%) and MRI
(82%). EUS was more accurate than CT and MRI at
diagnosing perirectal tissue invasion and there was no
difference in diagnosis of lymph node involvement.
68. Buchanan GN, Halligan S, Bartram CI, et al.
Clinical examination, endosonography, and MR
imaging in preoperative assessment of fistula in ano:
comparison with outcome-based reference standard.
Radiology 2004;233(3):674–81. PMID: 15498901.
This prospective trial of 104 patients with anal fistulas
showed that AES with a high-frequency transducer is
superior to digital examination but MRI is superior to AES.
69. SiddiquiMR, AshrafianH, TozerP, etal. A diagnostic
accuracy meta-analysis of endoanal ultrasound and
MRI for perianal fistula assessment. Dis Colon
Rectum 2012;55(5):576–85. PMID: 22513437.
This meta-analysis reviewed published papers for
EAS and MRI between 1970 and 2010. The sensitivity
of both techniques was good but the specificity was
poor. Due to the significant variations between the
studies, the authors suggested further work is required
to advise on clinical use.
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13
2
2
Colonoscopy and flexible sigmoidoscopy
Siwan Thomas-Gibson
Adam Haycock
Introduction
Since flexible endoscopy of the colon was
introduced in 1963 it has become the gold-standard
diagnostic test for evaluation of colonic disease.
Improvements in technique and technology have
also led to advances in therapeutic procedures, and
the boundary between endoscopic, laparoscopic and
open procedures is becoming increasingly blurred.
A good understanding of both the technique
and technology is essential for an endoscopist to
perform high-quality, safe endoscopy. This chapter
gives an insight into how colonoscopy is influencing
the practice of colorectal surgery.
Indications and
contraindications
Flexible sigmoidoscopy vs
colonoscopy
Indications for colonoscopy or flexible
sigmoidoscopy must be weighed against the risk/
benefit profile. Diagnostic colonoscopy has a
significantly higher risk of complications relating
to sedation and bowel preparation than flexible
sigmoidoscopy. Flexible sigmoidoscopy is also
quicker, cheaper and easier to perform, and detection
of distal pathology is now considered a marker for
possible proximal pathology; for example in the
English Bowel Scope Screening Programme, finding
two or more tubular adenomas, a large adenoma, or
a tubulovillous adenoma prompts full colonoscopy.
Contraindications
The only absolute contraindications to endoscopic
examination of the colon are a competent patient who
is unwilling to give consent or a known free colonic
perforation. Relative contraindications include:
acute diverticulitis, immediately postoperative
patients, patients with a recent myocardial
infarction (within 30 days), pulmonary embolism,
severe coagulopathy (particularly for therapeutic
procedures) or haemodynamic instability. In
fulminant colitis, a limited examination with
flexible sigmoidoscopy to ascertain extent of disease
and acquire confirmatory biopsies is often helpful.
In general, colonoscopy or flexible sigmoidoscopy
is considered to be safe in pregnancy, but should
only be performed for strong indications and after
careful consent and liaison with an obstetrician.
1
Sedation
Sedation during colonoscopy continues to be the
subject of much debate and research. A recent
large multicentre European audit of current
practice2 showed that most colonoscopies were
done using moderate (conscious) sedation and that
although deep sedation was associated with shorter
procedure times and fewer technical difficulties, it
was also more resource-intensive and required more
hospitalisations for complications. American Society
of Gastrointestinal Endoscopy recommendations
are that routine use of deep sedation in average-risk
patients cannot be endorsed. Flexible sigmoidoscopy
is most often performed unsedated as the use of
14
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Colonoscopy and flexible sigmoidoscopy
intravenous sedation would negate many of the
potential benefits of the procedure. Unsedated
colonoscopy is certainly possible and practical in a
subset of patients with few complications and good
acceptability.
As the practice and evidence varies widely,
current recommendations are to use the minimum
amount of drugs within the manufacturers' guidelines
to ensure patient comfort and the success of the
endoscopy.
3
4
Insertion technique
Insertion technique varies greatly even amongst
expert colonoscopists. Technique will depend on the
local circumstances, sedation practice, endoscopist
preference and equipment available. However, there
are some basic principles that are recognised to
contribute to safe, efficient colonoscopy.
Handling and scope control
Most skilled colonoscopists now adopt the oneperson, single-handed approach where the right
hand is used to manipulate the shaft and the left
hand operates the angulation controls. Tip control
is gained by a combination of up/down angulation
with the large wheel and clockwise/anticlockwise
torque applied with the right hand. The left/
right angulation using the small wheel is used for
maintaining the luminal view while torque is being
applied with the right hand.
Insertion and steering
and improves the view. In contrast, excessive
pushing of the scope often results in formation
of large loops, excessive pain, loss of one-to-one
tip control and increases the risk of iatrogenic
perforation.
5
• Insufflate little and suction frequently. Pain or
discomfort during colonoscopy can often be due
to stretching of the bowel wall by excessive gas
insufflation. Pneumatic perforation of the right
colon from over-insufflation has been reported.6
Frequent suctioning of gas prevents this and may
often allow progression of the tip through the
colon by the concertina effect. The use of carbon
dioxide rather than air has been shown to cause
less discomfort and is widely recommended.7
The use of water-aided (either water-immersion
[WI] or water-exchange [WE]) colonoscopy is
also now advocated to improve comfort scores
and may improve adenoma detection rate.
8
• Use torque frequently. Twisting clockwise or
counter-clockwise with the right hand applies
torque to the shaft of the scope. With a straight
shaft and bent tip, use of torque will provide
lateral movement at the tip and help to stiffen the
scope to prevent looping during advancement.
Application of torque is also essential for
loop resolution. Without the use of an image
guidance device, the application of torque will be
determined both by frequency of loop type and
‘feel’ of the instrument. The majority of sigmoid
loops (N-loops, 80%; alpha loops, 10%) require
clockwise torque and pull-back to resolve;
atypical loops (reverse sigmoid N-spiral, 1%;
reverse-alpha, 5%) require anticlockwise torque.
A digital rectal examination should be performed
to lubricate the anal canal and detect any anal and
distal rectal pathology prior to insertion. The initial
view is often a ‘red-out’ due to the lens pressing
against the rectal mucosa. Gentle insufflation, slow
withdrawal and small amounts of tip angulation are
used to gain a view of the lumen.
Tips for insertion and steering
• Pull back more, push in less. The first rule
of expert colonoscopy is to keep the shaft
straight. This allows for accurate tip control,
prevents stretching of the mesentery, minimises
discomfort and shortens the colon by a
‘concertina’ effect of telescoping the bowel wall
over the shaft. Pulling back often reduces acute
angles of bends, disimpacts the tip of the scope
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Patient position change
Moving the patient's position from the left lateral
position during both insertion and withdrawal
can shift both fluid away from and air into
the uppermost segment of bowel, preventing
unnecessary suctioning of fluid and insufflation of
gas. It can provide mechanical advantage by opening
up acute bends, especially at the rectosigmoid
junction, splenic and hepatic flexures. The effective
use of gravity to assist the passage of the endoscope
is a simple, cost-neutral, effective technique that is
easily learnt. It has been shown to be effective in
promoting endoscope tip advancement in twothirds of cases9 but it does require cooperation from
the patient and can be difficult if heavy sedation or
general anaesthesia is used (Fig.2.1).
15
Chapter 2
lateral
lateral
Supine
Left
Figure2.1 • Schema for optimal patient position
change.
Right
Abdominal hand pressure
The use of abdominal hand pressure aims to prevent
the shaft of the endoscope looping by opposing
pressure close to the anterior abdominal wall.
Pressure is best used to prevent a loop from forming
rather than applying it to an already formed loop,
which is unlikely to be successful and may increase
the discomfort felt by the patient. Specific pressure
on anterior-protruding loops is more likely to be
helpful as intubation progresses than non-specific
pressure.10 Magnetic imaging devices can help with
guided pressure, although efficacy in promoting tip
advancement is less than for patient position change,9
as many loops do not protrude anteriorly. The use
of deep inspiration can also be used to splint the
diaphragm and provide pressure on the splenic and
hepatic flexures if external pressure is unsuccessful.
Three-dimensional imager
Magnetic imaging systems (ScopeGuide, Olympus
Optical Company; ScopePilot, Pentax Medical) use
low-voltage magnetic fields to produce a real-time,
three-dimensional image of the entire colonoscope
shaft in both anteroposterior and lateral views, allowing
the colonoscopist to visualise the configuration of
the scope within the patient (see Fig. 2.2). This can
help determine if there is an anterior component to
the loop and so assist with loop resolution, as well as
aiding accurate tip location. A sensor can assist with
accurate hand-pressure placement.
Meta-analysis of eight randomised controlled
trials has shown real-time magnetic imaging to be of
benefit in training and educating inexperienced
endoscopists and improves the caecal intubation rate
for experienced and inexperienced endoscopists.
11
Withdrawal technique
It should be remembered that the aim of colonoscopy
is to visualise the whole of the colonic mucosa in
order to identify pathology. A systematic review
of back-to-back studies12 has shown a polyp miss
rate at colonoscopy of 22% even in expert hands,
although most missed polyps were small (<1 cm).
All studies investigating miss rates have shown a
variation in performance between endoscopists,
but this can be wide even with expert examiners
(>10 000 procedures), with sensitivities ranging
from 17% to 48% in one large study.13 This implies
that there is a link between individual technical skill
and outcome measures.
Withdrawal time
Recent publications have stressed the importance
of spending sufficient time inspecting the colonic
mucosa on withdrawal as a key marker for the
adequacy of the examination.
The current recommendation is that
colonoscopists should spend more than 6 minutes
during withdrawal inspecting the colonic mucosa in
colonoscopies with normal results.14 A landmark
study15 looking specifically at withdrawal time found
that endoscopists who spent longer than 6 minutes
on withdrawal in a negative colonoscopy had
significantly higher adenoma detection rates (ADR)
than their quicker colleagues.
Optimal examination technique
It seems logical that those colonoscopists who
take longer to withdraw also use techniques
that increase visualisation of abnormalities. In
one study looking at differences in technique
between two colonoscopists with different polyp
miss rates,16 a lower miss rate was judged by
independent experts to be associated with superior
withdrawal technique for each of the following
examination criteria: (1) examining the proximal
sides of flexures, folds and valves; (2) cleaning
and suctioning; (3) adequacy of distension; and
(4) adequacy of time spent viewing. A study
looking at the quality of inspection at flexible
sigmoidoscopy17 has included similar criteria: (1)
time spent viewing the mucosa; (2) re-examination
of poorly viewed areas; (3) suctioning of fluid
pools; (4) distension of the lumen; and (5) lower
rectal examination.
The following continuous quality improvement
targets regarding withdrawal (adapted from Rex
16
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Colonoscopy and flexible sigmoidoscopy
a b c
ed
Figure2.2 • ScopeGuide images of: (a) sigmoid N-loop; (b) alpha loop; (c) reverse alpha loop; (d) deep transverse
loop; (e) gamma loop.
etal.16) aim to standardise withdrawal technique to
maximise detection rates:
1. Mean examination times during withdrawal
studies have looked at the effectiveness of various
bowel preparations for clearing the colon prior to
colonoscopy.
should average at least 6–10 minutes.
2. Adenoma prevalence rates detected during
colonoscopy in persons over 50years of age
undergoing first-time examination should be
≥25% in men and ≥15% in women.
3. Documentation of quality of bowel preparation in
all cases.
A recent publication has suggested that the
implementation of systematic monitoring of
withdrawal time and other quality indicators may,
in itself, increase the performance of endoscopists.
18
Bowel preparation
Evidence-based recommendations on bowel
preparation for colonoscopy are available from many
national societies.
19,20
It has been shown that better quality preparation
at flexible sigmoidoscopy results in a higher ADR,21
but crucially important, endoscopists with a higher
ADR are more likely to be critical of the quality of
bowel preparation.
Position change
The use of position change has been shown in a
randomised controlled trial to improve luminal
It is self-evident that pools of fluid or faeces will
obscure good visualisation of the mucosa, and many
distension between the hepatic flexure and
sigmoid-descending junction during colonoscope
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17
Chapter 2
withdrawal.22 The same schema can be used for
each segment as previously illustrated for insertion
(see Fig.2.1). Although four cross-over trials have
shown that the improved visualisation that results
can also improve polyp and adenoma detection
rates, three parallel trials did not, and a meta-analysis
concluded that the effectiveness is uncertain.
23
Antispasmodics
Premedication with an antispasmodic such as
hyoscine N-butyl bromide (Buscopan) has been
used for colonoscopy to decrease the amount
of muscular spasm caused by peristalsis. Small
randomised studies have shown that this can
shorten the total procedure time for flexible
sigmoidoscopy as compared with placebo, and that
it may be beneficial in terms of ease of insertion
and the time required for caecal intubation, total
procedure time, adequacy of sedation and scales
of patient comfort during colonoscopy. However,
a meta-analysis of the current studies concluded
that the improvements may be marginal.24 Caution
must be exercised in patients with known cardiac
history as there is a risk of sinus tachycardia. Other
antispasmodics such as glucagon and the use of
warm water irrigation may be used in patients
in whom anticholinergics are contraindicated,
although currently there are no data showing any
significant benefit.
25
Rectal and caecal retroflexion
Colorectal cancer is most common distally, and
most experts routinely perform retroflexion in the
rectum. Although the evidence that this significantly
improves detection rates is still being debated,
probably allows clearer views of the proximal sides
of rectal valves and the top of the anal canal. There
is a risk of iatrogenic perforation if the rectal lumen
is narrow, in which case a paediatric colonoscope
or thin upper gastrointestinal (GI) endoscope can
be used. Recent publications have looked at the
value of retroflexion in the proximal colon, but
currently the data do not support this in routine
practice.
28,29
A quality improvement study has shown that a
training bundle consisting of routine use of hyoscine,
rectal retroflexion and minimum withdrawal time
can improve global ADR, driven by improvements
among the poorest performing colonoscopists.
26,27
30
it
indicators, measurable outcomes and minimum
standards.
14,31,32
These aim to ensure a high-quality,
effective and patient-centred service by setting
benchmarks for both individual endoscopists and unit
performance. Development of these guidelines has in
a large measure been driven by the implementation of
bowel cancer screening programmes, which involve
asymptomatic individuals choosing to undergo
invasive investigations. It is imperative to minimise
risk for this group by provision of a safe, high-quality
service. This has had the benefit of improving quality
assurance standards for the whole of endoscopy.
33
Endoscopy training
Guidelines on training have been published both in
the UK and USA to improve access to and quality of
endoscopy training.
in endoscopy have been developed to provide
more readily available and structured training,
and have now become essential components of
gastroenterology training. Focus has also been
placed on ensuring that those endoscopists
responsible for training or performing screening
procedures on healthy populations are themselves
competent to do so. ‘Training the Trainers’ courses
teach experienced endoscopists adult education
theory and its application to skills training in
endoscopy. Accreditation for colonoscopists wishing
to undertake colorectal cancer screening is now
mandatory in England and Wales. Both initiatives
are aimed at maximising the provision of highquality endoscopy and training on a national basis
and not just in teaching centres. A national audit
in 2011 of all colonoscopies done in England has
demonstrated improvements in virtually all aspects
of colonoscopy,33 including training, validating the
rigorous quality assurance process undertaken in
recent years.
The use of both computer and animal endoscopic
simulation has now been shown to be of value in the
early phase of colonoscopy training,36 with transfer
of skills to live patients. The importance of nontechnical skills and teamwork is now considered
to be vital to the performance of high-quality
endoscopy. Training can improve safety-related
knowledge and attitudes,37 and observation of
behavioural markers relating to these non-technical
skills now forms part of the UK assessment and
credentialing process.
34,35
Accredited national courses
38
Quality assurance
There are now detailed guidelines for quality standards
in colonoscopy, which include key performance
Current European recommendations are that
endoscopy simulators, where available, should be
used to allow training to occur in a safe, controlled
environment.
39
18
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New techniques in
endoscopic mucosal
visualisation
There are many new developments in colonoscopic
technique and technology that may improve polyp
detection and identification of pathology.
Assisted-viewing devices
Cuffs, caps and rings have been developed that
attach to the distal tip of a colonoscope and aim
to improve the view by flattening the folds of the
colon during withdrawal, allowing for improved
visibility behind folds. They have all been shown
to increase the polyp and adenoma detection rates,
particularly for small proximal polyps, and there
may also be additional benefit of rings and cuffs
in improved caecal intubation rates and decreased
pain scores.40 Retrograde (Third-Eye RetroScope)
and 360-degree viewing endoscopes (Third-Eye
Panoramic, Fuse FullSpectrum Endoscopy, Ewave)
have shown some efficacy in improving adenoma
detection rates,41 but research is still ongoing and
none has yet shown benefit when incorporated into
routine practice.
42
Colonoscopy and flexible sigmoidoscopy
a
Chromoendoscopy
Chromoendoscopy is a technique that uses a surface
dye such as indigo carmine to make irregularities
in the colonic mucosa more readily apparent to the
endoscopist (Fig.2.3).
The use of chromoendoscopy has been
shown to significantly improve adenoma detection
during surveillance of high-risk groups such as
ulcerative colitis
syndromes.
It has also been shown to aid identification of
flat or depressed adenomas, which are much more
prevalent than was previously thought and have
a high risk of malignant transformation. It can,
however, be time-consuming and currently there is
no substantive evidence for its use during routine
colonoscopy.
Optical enhancement (electronic chromoendoscopy
or electronic chromoendoscopy) uses optical filters to
narrow the bandwidth of white light (narrow-band
imaging, NBI), or spectral emission processing of
white light (I-scan, Flexible Spectrum Imaging Colour
43–45
46
and familial colorectal cancer
b
Figure2.3 • (a) Polyp in white light. (b) With indigo
carmine dye-spray.
Enhancement, FICE) to enhance the visualisation of
the capillary network or microsurface pattern of
colonic adenomas47 (Fig.2.4). These technologies are
activated by the push of a button on enabled scopes,
which has clear advantages over the use of dye-spray.
They are recommended for use in high-risk groups
such as Lynch syndrome patients where spotting
even diminutive adenomas is crucial, but randomised
trials have not shown significant benefit in routine
endoscopy.
48,49
Confocal laser endomicroscopy
combines a standard video endoscope with a
miniaturised laser microscope. Using intravenous
sodium fluorescein as a contrast agent, ‘virtual
histology’ can be created, allowing visualisation of
both the surface epithelium and some of the lamina
propria, including the microvasculature. This can
potentially provide accurate identification of colonic
intra-epithelial neoplasia and carcinoma, although
many barriers have so far prevented uptake in
routine use.
50
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19
Chapter 2
Type I
inflammatory
Type II
Type III
Type III
Type IV
Villous adenoma
Type V
a
Figure2.4 • (a) Polyp in white light. (b) With narrow band imaging.
High-magnification endoscopy
b
current evidence does not support a 'resect-anddiscard' approach.
High-magnification endoscopes can magnify the
image up to 100 times, and newer high-definition
scopes have a much greater pixel density and ability
to improve detail discrimination. In conjunction
with dye-spray or electronic chromoendoscopy,
their use permits identification of a polyp's surface
‘pit pattern’ to assist in distinguishing between
cancerous, adenomatous and non-adenomatous
polyps. A classification system devised by Kudo
Endoscopic therapy
One of the exciting benefits of improving endoscopic
skills and technology is the increasingly successful
application of novel therapeutic techniques. Therapy
that previously required open surgical procedures
can now be performed in a minimally invasive way.
etal. in 199451 has been shown to have a reasonable
diagnostic accuracy (overall 86.1%, sensitivity
90.8%, specificity 72.7%) when compared to
Basic therapy
histological findings52 (Fig.2.5). There is a learning
curve in identification of the patterns, however, so for
inexperienced endoscopists it does not significantly
reduce the number of histological samples taken.
Further work has resulted in a simple classification
system, the Narrow-band Imaging International
Colorectal Endoscopic (NICE) Classification,53 but
studies have yet to confirm its real-world utility, and
Polypectomy
The ability to remove abnormal tissue endoscopically
forms the basis of all cancer prevention and
surveillance programmes. The resectability of
a polyp depends on its size, characteristics and
accessibility. Polyps that are unlikely to be removable
endoscopically are those with submucosal invasion,
54
L
Round pits
Normal/post
Figure2.5 • Classification of pit pattern at high-magnification chromoendoscopy (after Kudo etal.).
Stellate pits
Hyperplastic
Large tubular or
roundish pits
Adenoma
Small tubular or
roundish pits
Adenoma
s
Gyral or
sulcal pits
Adenoma/
20
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Non-
structured
Cancer
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