Expert Review The Digital Rectal Examination

Expert Review The Digital Rectal Examination
Anna Shirley* and Simon Brewster#
……………………………………………………………………………………………………………………………………..
The Journal of Clinical Examination 2011 (11): 1-12
Abstract Digital rectal examination is an important skill for medical students and doctors. This article presents a
comprehensive, concise and evidence-based approach to examination of the rectum which is consistent with The
Principles of Clinical Examination [1]. We describe the signs of common and important diseases of the rectum and,
based on a review of the literature, the precision and accuracy of these signs is discussed. Word Count: 2893
Key Words: digital rectal examination, rectum, anus
Address for Correspondence: [email protected]
Author affiliations: *Foundation Year 1 Doctor, Charring Cross Hospital, London. #Clinical Director of Urology,
Oxford Radcliffe Hospitals NHS Trust.
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Introduction
The importance of performing a digital rectal
examination (DRE) in the appropriate setting is
captured by the phrase, “If you don’t put your finger
in it, you put your foot in it.” – H. Bailey 1973 [2].
Anorectal or urogenital symptoms account for 510% of all general practice consultations [3] and the
DRE is part of the assessment of these. In addition,
statistics from 2008 show that colorectal and
prostate cancer were the third and forth most
commonly
diagnosed cancers in the UK
respectively (excluding non-melanoma skin cancer),
[4] and 22% of colorectal cancers occur in the rectum
[5]. DRE is an essential component of a complete
abdominal examination (See The JCE Expert
Review: Examination of the Gastrointestinal System
[6]), a urological, and sometimes a gynaecological
examination.
The DRE is frequently cited by medical students as
a way of completing the abdominal examination but
it is often not performed in practice. However, it is
essential that this skill is learned, as it is an
important part of clinical examination for Foundation
Doctors and beyond. A study of final year medical
students at one UK medical school revealed that
42% had performed fewer than five DREs before
qualifying, and lack of confidence in the skill was
commonly reported [7]. The same study recorded
that junior doctors perform DREs regularly, and this
highlights the need for proficiency in this physical
examination early in a medical career. The value of
learning how to perform the DRE is increasingly
being recognised across UK medical schools, and
rectal examination mannequins are now used in
student training and beyond. They may also be
used to assess the skill in Objective Structured
Clinical Examinations.
The Context of the DRE
There are many circumstances in which a DRE is
considered to be appropriate. It has even been
suggested that a DRE should be considered in all
patients aged over 40 years who are admitted to
hospital, unless there is a specific contraindication
[8]. The most common presentations in which a DRE
may be appropriate as part of their assessment are
listed in Table 1.
Anatomy of the Rectum and Anus
Interpretation of findings on DRE requires
knowledge of the anatomy of the rectum and anus,
and of the surrounding structures. The rectum is
approximately 12 cm long. It begins at the
termination of the sigmoid colon and is continuous
with the anal canal distally [5]. Anteriorly, the upper
two-thirds of the rectum are covered with
peritoneum. The anal canal is approximately 3-4cm
long [9], and its skin merges with the perianal skin at
the anal verge. There are two muscular anal
sphincters: the internal anal sphincter, which is
involuntary; and the external anal sphincter, which
1 is under voluntary control. The function of the
rectum is to permit voluntary defaecation [5]. It is
important to consider the anatomy of the rectum in
relation to surrounding structures, which can be
assessed when performing a DRE. In a male, the
base of the bladder, prostate and urethra are
situated anteriorly to the rectum, and in the female
the cervix and vagina lie anteriorly.
System
Gastrointestinal
Urological
Other
Symptoms/presentation
Acute abdomen
Change in bowel habit, faecal
incontinence
Rectal symptoms: bleeding,
tenesmus
Unexplained iron deficiency
anaemia
Unexplained weight loss
Lower urinary tract symptoms
Unexplained bone pain in
males
Gynaecological symptoms
Trauma: secondary survey
Neurological: suspected
spinal cord pathology
Table 1 Clinical presentations for which digital
rectal examination should be considered.
A clock face is traditionally used to describe the
location of any lesions found during the DRE, as
viewed in the lithotomy position (see Figure 1). 12 o’
clock is considered to be anterior, 3 o’ clock on the
patient’s left, 6 o’ clock posteriorly and 9 o’ clock on
the patient’s right. The distance of the lesion from
the anus is also reported. The anal canal is lined
with highly vascular anal cushions, which help with
the maintenance of continence. Their arterial supply
is from the rectal arteries, and they drain via the
superior rectal vein. Haemorrhoids, one of the
commonest pathologies of the anorectal region, are
abnormal anal cushions with congested vasculature
and dilated venous components. They typically
occur at 3, 7 and 11 o clock. They are not palpable
on DRE unless they are thrombosed, in which case
a tense, tender swelling may be palpated. First
degree haemorrhoids remain inside the anus,
second degree haemorrhoids prolapse on straining
but spontaneously return, and third degree
haemorrhoids remain prolapsed unless manually
returned. Prolapsed haemorrhoids may be visible on
inspection during the DRE [10].
Figure 1 Describing the location of pathology of
the rectum [13] Reproduced with permission.
Literature Search
The following textbooks of clinical examination were
reviewed:
Clinical Examination: A Systematic Guide to
Physical Diagnosis [8]
The Ultimate Guide to Passing Surgical Clinical
Finals [9]
Macleod’s Clinical Examination [11]
Introduction to Clinical Examination [12]
Clinical Examination [13]
The PubMed database was searched using the
following Medical Subject Headings (MeSH) terms
alone or in combination: digital rectal examination,
physical examination, rectum, sensitivity and
specificity, statistics & numerical information,
predictive value of tests.
The free text terms: rectal, rectal cancer, prostate
cancer, appendicitis, acute abdomen, trauma,
examination, faecal incontinence were combined
with the MeSH terms.
Clinical prediction rules were searched for the
rectum. The Rational Clinical Examination Series of
the Journal of the American Medical Association;
clinicalevidence.bmj.com and Evidence Based
Medicine Online were searched with the terms
‘rectum’ and ‘digital rectal examination [14,15,16].
Related articles were also evaluated. Relevant
articles available through Oxford University eresources were selected.
2 Preparation
Ensure the examination environment is appropriate
in terms of privacy. Wash your hands and introduce
yourself to the patient. Check the patient’s identity,
explain what you wish to do, and obtain consent for
the procedure. Advise the patient that the
examination should not feel painful, but that there
may be some mild discomfort. The patient may also
experience the desire to defaecate, and should be
warned of this. A study of 269 patients investigating
the acceptability of the DRE as part of prostate
cancer screening found that 59.4% of patients
considered this to be an acceptable examination,
with the figure rising significantly to 91.5% after the
examination [17]. This highlights the importance of
explanation and reassurance before the
examination.
The DRE is considered an intimate examination, so
it is important to offer a chaperone, as advised by
the Medical Defence Union [18]. The name and role
of the chaperone, or “chaperone was offered but
declined”, should be documented in the notes.
Gather the equipment needed, see Table 2.
Equipment Needed for Digital Rectal
Examination
Non-sterile gloves
Lubricant Jelly
Cotton wool
Tissue
considered in the gynaecological setting for
assessment of the pelvic organs [5].
Put on non-sterile gloves.
Figure 2 Position of the patient when
performing a digital rectal examination Initial
Inspection
The examination begins with an inspection of the
natal cleft (the groove between the buttocks) and
the anus and perianal skin. Part the buttocks gently
and inspect the skin of the natal cleft from the
sacrum to the perineum, and the anus (see Figure
3). Refer to Table 3 for a description of lesions that
may be visible on initial inspection. In the presence
of an anal fissure, the DRE may be exquisitely
tender, so it may be appropriate to anaesthetise the
area with lidocaine gel beforehand [12].
Table 2 Equipment needed for a digital rectal
examination
Position of the patient
Ask the patient to undress from the waist
downwards, including undergarments. He/she
should be allowed to do this in private and a gown
used to preserve modesty until the examination is
performed. The patient should be positioned lying
on the couch in the left lateral position, facing away
from the examiner (see Figure 2). Ask the patient to
draw his/her legs up towards the body.
An alternative, but less favoured approach, is to ask
the patient to stand over the examining couch in a
bent over position with his/her elbows resting on the
couch. Although useful for assessing the prostate, it
is inadequate for assessing the rectum as a whole
[19]. However, this position may be more suitable for
the elderly or those with reduced mobility. The
lithotomy position is another alternative and may be
Figure 3 Initial inspection of the natal cleft
The patient should then be asked to strain, or ‘bear
down’. Observe the descent of the perineum.
Excessive descent suggests a laxity of the
perineum. Look for any sign of rectal prolapse
(which in the early stages is just mucosal) or
prolapse of haemorrhoids. Rectal prolapse
originates from the rectum, higher than the origin of
haemorrhoids, and appears as a mass with
3 concentric rings of mucosa, whereas haemorrhoids
exhibit radial folds. However, it is not always easy to
tell them apart; they may coexist, and a contrast
defecogram (a radiological study) may be required
to diagnose rectal prolapse. Look also for a
patulous anus, which appears wide open and is due
to reduced tone in the sphincter muscles, and for
any sign of faecal incontinence [19].
Pathology of the
Natal Cleft and
Anus
Viral warts
Skin tags
Anal fissures
Fistulae
External
Haemorrhoids
Rectal Prolapse
Crohn’s disease
Dermatitis
Anal Carcinoma
Description
Papillomata with a rough,
white surface surrounding
the anus
Pedunculated,
fleshcoloured perianal skin
growths
Tear in the anal wall,
commonly posteriorly in the
midline.
The opening may be visible
as a red, pouting structure
near the anus
Bluish swellings protruding
from the anus
Folds of red mucosa
protruding from the anus
Blue-tinged perianal skin,
fistulae, fissures, skin tags
Red, inflamed skin
Mass may be visible at the
anal verge
Palpation
Lubricate the index finger of your gloved right hand
with a water-based lubricant such as K-Y Jelly.
Kneel down bedside the examination couch. Warn
the patient that you are about to examine the
rectum. Place the gloved finger on the anal margin
and gently apply pressure to enter the anal canal
and rectum. To begin with, the pulp of the
examining finger should be facing the 6 o clock
position (see Figure 5a). Aim your finger slightly
posteriorly, following the curve of the sacrum [8].
Figure 4 Testing perianal sensation:
dermatomes S2,S3,S4. Adapted from reference
13 [13].
Table 3 Pathology of the Natal Cleft and Anus.
Adapted from References 8 and 13 [8,13].
Sensation and the Perineal Reflex
The sensory dermatomes of the perianal region are
S2, S3 and S4. To test sensation, use cotton wool
to stroke lightly the areas that correspond to these
dermatomes (see Figure 4) and ask the patient if
he/she can feel the cotton wool in each of these
areas. To test the perineal reflex (anal reflex, anal
wink), use cotton wool to stroke the skin
immediately around the anus, and observe for
contraction of the anus (by the anal sphincter
muscles). Impaired perianal sensation and an
absent or reduced perineal reflex may indicate S2-4
nerve root or spinal cord pathology, for example
cauda equina syndrome, in which the sacral nerve
roots may be compressed. A more detailed
neurological examination may be then be required
Figure 5a Palpation of the rectum in the 6
o’clock position
Assessment of Anal Tone
On entering the anal canal, an initial judgment of the
anal tone at rest can be made. Then ask the patient
to ‘bear down’ and squeeze your finger, to assess
the anal sphincter further in terms of strength and
symmetry. Reduced or absent tone may indicate
4 spinal cord injury. DRE has traditionally been
considered a part of the secondary survey of the
Advanced Trauma Life Support protocol to examine
for this [20], as well as to detect a “high-riding”
prostate (the prostate is difficult to feel or only its
base is palpable) in males with urethral injury, and
to determine if a pelvic fracture is open (to the
gastrointestinal tract), or closed. Few studies have
assessed how useful the DRE is for detecting spinal
cord injury, but there is evidence to suggest that its
findings must be considered in the context of other
clinical signs, and in the absence of reduced anal
tone, spinal cord injury cannot be excluded (see
Evidence Box 1). Assessment of anal tone is also
used in the evaluation of faecal incontinence, and
findings on DRE have been shown to correlate well
with recordings from anal manometry [22,23].
Palpation of the Rectum
Normally, the coccyx and sacrum can be felt
posteriorly. Different authors disagree about the
direction in which to palpate the circumference of
the rectum, though the most important point is that
the entire rectum must be palpated [8,9,11-13]. A
popular way is described here. From the 6 o’clock
position, supinate your arm to examine the right
posterolateral rectal wall, until the 9 o’ clock position
is reached. Return to the 6 o clock position, and
pronate your arm 90° to the 3 o’ clock position to
examine the left posterolateral rectal wall. Continue
pronating your arm round to the 12 o’clock position,
and beyond this to the 9 o’clock position, to
examine the anterolateral rectal walls. Return to the
12 o’clock position (see Figure 5b). The entire
rectum is therefore assessed for tenderness and
any palpable masses. This may detect a rectal
carcinoma, which feels hard and irregular, however
there are many causes of a palpable rectal mass
(see Table 4). There is little evidence available as to
how useful the DRE is for detecting rectal
carcinoma, but one study in the setting of general
practice concluded that it should not be relied upon
alone (see Evidence Box [24].
The rectum may be loaded with faeces, which is a
common finding in patients with constipation. These
are typically moveable and indentable [11]. In the
presence of a palpable rectal mass, it may be
appropriate to repeat the examination after the
patient has defaecated, to exclude faeces as a
cause. Note that haemorrhoids are not palpable on
DRE unless they are thrombosed. In addition to
palpable masses, stenosis of the anal canal or
rectum can be felt as a tight, narrow region and may
indicate anal, rectal or prostate carcinoma.
Figure 5b Palpation of the rectum in the 12
o’clock position
Site of origin
of pathology
Rectum
Sigmoid colon
Pelvis
Prostate
Mass
Faeces
Rectal carcinoma
Rectal polyp
Foreign body
Prolapsed sigmoid carcinoma
Pelvic metastases
Uterine malignancy
Ovarian Malignancy
Cervical carcinoma
Endometriosis
Pelvic Abscess
Prostate carcinoma
Benign Prostatic Hypertrophy
Prostatic Abscess
Table 4 Causes of a palpable mass on digital
rectal examination. Adapted from Reference 8[8].
The DRE is performed on nearly all patients
presenting with an acute abdomen, and the
presence of tenderness has been reported to be
one of the more useful signs identified during this
examination [5]. It may indicate the presence of
inflammatory bowel disease, prostatitis, ovarian
abscesses and cysts, and appendicitis. However,
the evidence for the latter is variable, and suggests
that the DRE is not very sensitive for detecting
appendicitis, and provides additional useful
information only if the diagnosis is in doubt following
history taking and examination of the abdomen, in
which case other pathology should be suspected
(see Evidence Box 3) [25,26,27]
5 Prostate examination
The prostate is examined in males at the end of the
rectal examination when the examining finger is in
the 12 o’ clock position. One small study using a
DRE simulator found that a higher magnitude of
finger pressure led to the detection of smaller
prostate abnormalities, so it is important to ensure
adequate pressure when palpating the prostate [28].
The prostate should be assessed for consistency,
nodularity, size and symmetry. The normal prostate
feels firm with a smooth, regular surface and is
symmetrical [29]. It is approximately 3.5cm wide and
protrudes approximately 1cm into the rectal lumen.
There are two lobes separated by a palpable
longitudinal sulcus. It is not always possible to feel
the base of the gland but if it is small one can easily
get above it.
Enlargement of the prostate gland occurs in benign
prostatic hypertrophy, and its smooth, symmetrical
properties are typically maintained. Prostate size
determined by digital rectal examination has been
found to correlate significantly with transrectal
ultrasound measurements, though gives a slight
underestimate for larger sizes [30] Prostate cancer is
suggested by a hard, irregular asymmetrical
prostate, with the sulcus not palpable between the
lobes. A number of meta-analyses have evaluated
the role of the DRE in detecting prostate cancer,
and though the DRE is considered a vital part of the
work up for a patient with suspected prostate
pathology, evidence suggests its findings must be
considered in the context of investigations such as
the prostate specific antigen (PSA) measurement
and ultrasound scan (see Evidence Box 4) [31,32,33].
DRE has also been found to detect prostate cancer
in the presence of PSA levels that are not raised [34].
However the majority of cancers currently
diagnosed are in the early stages and are not
palpable. The prostate gland is typically not tender,
and tenderness may suggest acute prostatitis or a
prostatic abscess.
Further tests
There is also the option of testing for pelvic floor
dyssynergia, in which the external anal sphincter
contracts instead of relaxes when the patient strains
to defaecate. This is a common cause of chronic
constipation. To test for this, ask the patient to strain
trying to push your finger out. Paradoxical tightening
of the musculature suggests dyssynergia. The DRE
has been shown to be a very useful test for
identifying this (see Evidence Box 5) [35].
Completing the Examination
Always inspect the gloved finger for the nature and
colour of the stool, and note the presence of any
blood or mucus. Black tarry stools may represent
melaena, which occurs as the breakdown product of
blood, indicating an upper gastrointestinal bleed.
The stool may also appear dark if the patient is
taking oral iron supplements. Pale, offensive stools
occur in situations of malabsorption. Pale stools
may also be found in patients with obstructive
jaundice, along with dark urine. Fresh blood on the
surface of, or mixed in with stool suggests bleeding
from the large bowel, rectum or anus.
There is also the option for performing a faecal
occult blood test (FOBT) at this stage, as part of a
screening process for colorectal cancer. A single
sample of the stool obtained during DRE on the
gloved finger is smeared on to a faecal occult blood
test card. However, this is less commonly performed
now as it is considered inferior to the recommended
sampling practice using the guaiac smear method,
which tests 3 naturally passed stools on
consecutive days (see Evidence Box 6) [36].
Once the DRE is complete, wipe away the lubricant
jelly and direct the patient to redress. Remove your
gloves and wash your hands.
Conflicts of Interest None declared.
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8 Question. Does this patient have spinal cord injury based on findings from the DRE? Reference. Guldner
and Brzenski (2006) [20]. Population. 1032 patients over 15 years of age with blunt trauma. Incidence. 5.2%
Details of Study. Retrospective review. Comparator. Diagnosis of Spinal Cord Injury on discharge,
according to the International Classification of Diseases, Ninth Revision (ICD-9). Sensitivity. See Table
Specificity. See Table. Conclusion. The DRE is insensitive to spinal cord injury, but highly specific. A
negative DRE cannot rule out spinal cord injury. Reduced or absent rectal tone on DRE should be interpreted
in the context of the pre-test probability of spinal cord injury.
Question. Does this patient have spinal cord injury based on findings from the DRE? Reference. Shlamovitz
et al (2007) [21]. Population. 1401 Incidence. 3% Details of Study. Retrospective medical record review.
Comparator. Spinal cord injury on imaging or operation reports, or new parapleagia/quagriplegia/spinal injury
diagnosis. Sensitivity. See Table Specificity. See Table. Conclusion. Due to its poor sensitivity for
detecting spinal cord injury, the DRE should not be used as a screening tool in trauma cases. The DRE
cannot rule out spinal cord injury.
Author
Guldner GT 2006 [20]
Schlamovitz GZ 2007[21]
N
1032
1401
Sensitivity (%)
50
37
Specificity (%)
93
96
Evidence Box 1 The digital rectal examination in spinal cord injury.
Question. Does this patient have a rectal tumour on DRE by the general practitioner? Reference. Ang et al
(2008) [24]. Population. 1069 patients referred to the colorectal cancer referral service by GPs. Incidence.
3.93% Details of Study. Retrospective review of hospital data. Comparator. DRE performed in the specialist
clinic. Sensitivity. 76.2% Specificity. 91.7% Conclusion. In the primary care setting, although the specificity
and sensitivity of DRE for detecting rectal tumours are high, there was a high false positive rate, so DRE
should not be used alone in the diagnosis of a rectal tumour, but in the context of other findings.
Evidence Box 2 Identifying a rectal tumour on digital rectal examination.
9 Question. Does this patient have appendicitis based on DRE? Reference. Dickson et al (1985) [25].
Population. 328 patients aged 14 and under with suspected appendicitis. Incidence. 31.4% Details of
Study. Prospective study. Comparator. Histology of resected appendix Sensitivity. See table. Specificity.
See table. Conclusion. More than 90% were correctly diagnosed with appendicitis based on history and
abdominal signs alone, without information from DRE. DRE may therefore be more useful if the diagnosis
remains uncertain after this initial assessment and other pelvic pathology is suspected.
Question. Does this patient have appendicitis based on DRE? Reference. Dixon et al (1991) [26]. Population.
1028 patients with right lower quadrant pain who underwent DRE. Incidence. 37.3 Details of Study.
Prospective study. Comparator. Histology of resected appendix. Sensitivity. See table. Specificity. See
table. Conclusion. Although tenderness on DRE was more common in patients with appendicitis than other
diagnosed conditions, if rebound tenderness was present, the DRE provided no further useful information.
Question. Does this patient have appendicitis based on DRE? Reference. Sedlak et al (2007) [27].
Population. 577 patients aged over 16 with right lower quadrant pain who underwent DRE Incidence. 40.4%
Details of Study. Retrospective review of medical records. Comparator. Histology of resected appendix
Sensitivity. See table. Specificity. See table. Conclusion. The DRE is not helpful in making the diagnosis of
appendicitis or in guiding the decision whether to proceed to surgery.
Author
Dickson 1985 [25]
Dixon 1991 [26]
Sedlak 2007 [27]
N
328
1401
577
Sensitivity(%)
9
34
36.5
Specificity(%)
88
72
61.5
Evidence Box 3 Identifying appendicitis on digital rectal examination.
10 Question. Does this patient have prostate cancer on DRE? Reference. Hoogendam et al (1999) [30].
Population. ~22,000 men from unselected populations. Incidence. 1.2 – 7.3% Details of Study. Metaanalysis of 14 studies, 5 considered ‘good quality’. Comparator. Prostate biopsy or surgery. Sensitivity. See
Table. Specificity. See Table. Conclusion. DRE is highly specific for the detection of prostate cancer but the
sensitivity is low. It should not be used alone to diagnose or exclude prostate cancer.
Question. Does this patient have prostate cancer on DRE? Reference. Mistry and Cable (2003) [31].
Population. 47,791 men. Most studies included asymptomatic men aged over 50 years. Incidence 1.8%
Details of Study. Meta-analysis of 13 studies. Comparator. Prostate biopsy. Sensitivity. See Table.
Specificity. See Table. Conclusion. Prostate specific antigen measurement had a higher sensitivity and
specificity for detecting cancer than did DRE. PSA and DRE together detected 83.4% of early, localised
prostate cancer.
Question. Does this patient have prostate cancer on DRE? Reference. Song et al (2005) [32]. Population.
2029 men with lower urinary tract symptoms or benign prostatic hyperplasia. Incidence. 25.4% (13.5-41.5%).
Details of Study. Meta-analysis of 13 studies. Comparator. Prostate biopsy. Sensitivity. See Table.
Specificity. See Table. Conclusion. The findings on DRE are best considered as part of a triad along with
Prostate Specific Antigen measurement and Transrectal Ultrasound scanning.
Author
Hoogendam A 1999[30]
Hoogendam A 1999[30]
Mistry K 2003[31]
Song JM 2005[32]
Studies
14
5 good quality
13
13
Sensitivity(%)
59
64
53.2
68.4
Specificity(%)
94
97
83.6
71.5
Evidence Box 4 Identifying prostate cancer on digital rectal examination.
Question. Does this patient have dyssynergia? Reference. Tantiphlachiva et al (2010) [35]. Population. 209
consecutive patients with Rome III criteria for chronic constipation Incidence. 87% Details of Study.
Prospective study. Comparator. Physiological test results Sensitivity. 75% Specificity. 87% Conclusion.
The DRE is a useful tool in identifying patients with dyssynergia, and could help select patients for further
investigation and treatment.
Evidence Box 5 Identifying dyssynergia on digital rectal examination.
11 Question. Is a stool sample obtained by DRE as accurate as naturally passed stool for faecal occult blood
test (FOBT) sampling when screening for colorectal cancer? Reference. Collins et al (2005) [36]. Population.
2665 asymptomatic patients aged 50-75. Incidence. 10.7% Details of Study. Prospective cohort study.
Comparator. Colonoscopy. Sensitivity. See table. Specificity. See table. Conclusion. Digital FOBT is a
poor screening tool for colorectal cancer, and a negative result cannot exclude advanced disease. Alternative
tests such as the at-home 6 sample FOBT are preferred, and the digital FOBT should not be used alone.
Method of FOBT
Digital FOBT
At-home 6 sample FOBT
Sensitivity (%)
4.9
23.9
Specificity (%)
97.5
93.9
Evidence Box 6 Comparing methods of obtaining stool sample for faecal occult blood testing
12