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4. Physiologic Testing 69
high negative predictive values. Therefore, EMG alone is not
optimal for diagnosing the presence of nonrelaxing puborectalis. Surface electrodes avoid the pain of needle EMG.
• Biofeedback training is often done using surface electrodes. This
may be done for fecal incontinence or for diffi culties with evacuation, particularly if paradoxical sphincter contraction is present.
• Normal patients demonstrated no evidence of paradoxical activity.
Pudendal Nerve Terminal Motor Latency
• The pudendal nerve originates from S2, S3, S4 nerve roots and
travels along the lateral pelvic wall down to near the ischial spine
where it exits the pelvis to supply the external anal sphincter and
the periurethral muscles through its terminal perineal branch.
• Prolongation in the pudendal nerve conduction indicates injury
to the pudendal nerve sheath that results in focal demyelination
with resultant slowing of conduction.
• A normal PNTML does not exclude partial damage. However,
when unilaterally or bilaterally severely prolonged, PNTML
has been shown to affect results after sphincter repair.
H. Evaluation of Transit
• The time it takes for food to travel through the digestive tract
is known as bowel transit time. Gastric emptying, small bowel
transit, and colonic transit may be studied.
• Transit is dependent on diet and varies greatly from person to
person. For this reason, a dietary history and bowel evacuation
history should be obtained in conjunction with any transit testing.
Dietary history can be evaluated for fi ber, fat, and calorie intake.
Colonic Transit
• Evaluation of constipation and pelvic problems may require
determination of colonic transit times in order to assist in treatment. Transit may be measured by radiopaque markers or radionucleotide techniques.
• Colonic transit is most easily measured by use of a marker test. The
patient ingests a capsule containing radiopaque markers, which
are then followed through the colon by abdominal radiographs.
70 The ASCRS Manual of Colon and Rectal Surgery
• In the most simplifi ed colon transit technique, the patient takes
one marker capsule which contains 24 markers on day 0. On
day 5, a supine abdominal fi lm is taken to determine the number
and position of remaining markers. If fi ve or fewer markers are
remaining, the patient has normal colonic transit. If more than
fi ve markers are present, then the pattern of residual markers
is noted. Diffuse scattering throughout the colon would suggest colonic inertia or decreased motility. If the markers are
present in the rectosigmoid region, then the presence of pelvic
outlet problems should be considered. Variations of the test use
x-rays on day 1–5, 1, 3, and 5, and 3 and 5.
• Average normal transit is 11.3 h, 11.3 h, and 12.4 h for the
right, left, and rectosigmoid colon, respectively. Normal total
transit averages 35 h.
• Stool weight has been shown to correlate with transit time in
constipated patients.
Radionuclide Transit
• Transit may be measured by radionuclide gamma scintigraphic
techniques. Radiographic and scintigraphic methods correlate
well. The major advantage of scintigraphy is that 24–48 h of
scanning is needed compared with 5–7 days for marker test
completion.
Small Bowel Transit
• Small intestinal transit should be evaluated before surgical
treatment of constipation because the patient may have a global motility problem.
• Small bowel transit may be measured by breath hydrogen
analysis. Hydrogen breath analysis depends on the presence
of bacteria in the large intestine to metabolize lactulose. Up
to 25% of the population cannot metabolize the sugar because
they lack certain bacterial strains in the colon.
• A meal of lactulose and beans is ingested and hydrogen breath
analysis is undertaken. Fermentation of the meal occurs when
the substrate reaches the colon. The fermentation process
releases hydrogen gas that is absorbed and excreted by the
lungs. Time to a 20-ppm increase in hydrogen in the breath
correlates with small bowel transit. Some conditions such as
4. Physiologic Testing 71
low colonic pH, bacterial overgrowth, or antibiotic administration may interfere with the use of this test for small bowel
transit.
• Small bowel transit may also be determined by scintigraphic techniques. These techniques have the advantage of also measuring
gastric emptying. Scintigraphy has a tendency toward slightly
shorter transit times, but this is probably not clinically signifi cant.
• Radiation exposure with scintigraphy is highest for the colon
and can be reduced by the administration of laxatives after the
procedure.
5. Diagnostic Evaluations: Endoscopy:
Rigid, Flexible Complications
A. Anoscopy
• Anoscopy is the examination of the anal canal. The lower part
of the rectal mucosa, upper anal mucosa, anoderm, dentate line,
internal and external hemorrhoids can be seen through this
examination.
• There are basically two types of anoscopes: beveled type such
as the Buie or Hirschman scope (Fig. 5.1 ) and the lighted
Welch–Allen scope (Fig 5.2 ) that uses the same light source as
the rigid proctosigmoidoscope.
• Another type is the side-opening Vernon-David scope with
Hirschman handle (Fig. 5.3 ).
• The Hinkel–James anoscope (Fig. 5.4 ) is much longer than the
Vernon-David scope and is suitable for patients with deep buttock cheeks.
Indications
• Any anal and perianal diseases or conditions require a full examination of the anal canal. These include anal fi ssures, anal fi stulas,
anal Crohn’s disease, anal tumors, hemorrhoids, anal condyloma,
bright red rectal bleeding, and pruritus ani.
• Anoscopy is frequently used in conjunction with colonoscopy,
fl exible sigmoidoscopy, and rigid proctosigmoidoscopy as part
of the examination.
D.E. Beck et al. (eds.), The ASCRS Manual of Colon and Rectal Surgery, 73
DOI: 10.1007/978-0-387-73440-8_5, © Springer Science + Business Media, LLC 2009
74 The ASCRS Manual of Colon and Rectal Surgery
Fig. 5.1. Buie anoscope.
Fig. 5.2. Lighted Welch – Allen anoscope.
5. Diagnostic Evaluations: Endoscopy: Rigid, Flexible Complications 75
Fig. 5.3. Vernon-David with Hirschman handle anoscope.
Fig. 5.4. Hinkel – James anoscope.
76 The ASCRS Manual of Colon and Rectal Surgery
Contraindications
• Patients who have severe anal pain such as an acute anal fi ssure
or a perianal or intersphincteric abscess may not tolerate the
examination. In general, if a patient can tolerate a digital examination, anoscopy can usually be done. A 2% lidocaine jelly should
be used in patients with anal pain. Anal stricture or severe anal
stenosis is another contraindication.
Preparation
• No preparation is required.
Positioning
• A prone jackknife position gives the best exposure. An alternative is a left lateral recumbent position.
Technique
• Inspection of the anal area should always precede any other
examination and, for this, good lighting is essential.
• Skin tags, excoriation, and change in color or thickness of the
anal verge and perianal skin can be detected quickly.
• A scarred, patulous, or irregularly shaped anus may give clues
to the cause of anal incontinence. Particularly in multiparous
women, the anal verge may be pushed down quite far during
straining – a feature of the descending perineum syndrome.
• The next step is to do a digital examination. The index fi nger
should be well lubricated with a lubricant jelly, and the fi nger
pressed on the anal aperture to “warn” the patient. Then the fi nger should be gradually inserted and swept all around the anal
canal to detect any mass or induration. In men, the prostate
should be felt. In women, the posterior vaginal wall should be
pushed anteriorly to detect any evidence of a rectocele.
• Anal tone, whether tight or loose, can be easily estimated.
A stricture or narrowing from scarring or a defect in the internal
or external sphincters from a previous operation can be felt.
• A fi brous cord or induration in the anal area and the anal canal
may indicate a fi stulous tract.
5. Diagnostic Evaluations: Endoscopy: Rigid, Flexible Complications 77
• Persistence of a gaping anus indicates an abnormal refl ex
pathway in the thoracolumbar region frequently seen in paraplegic patients.
• In persons with good anal function voluntary contraction of
the muscles produces a squeeze of the muscle on the examining
fi nger and the fi nger is pulled forward by the puborectalis muscle.
• Insertion of the anoscope should always be done with the obturator in place. The obturator is removed during examination and reinserted to rotate the instrument to another area. However, if the
beveled type of endoscope is used, the endoscope can be rotated
all around without having to reinsert the obturator.
• The examination table need not be tipped down more than
10–15° if an inverted (jackknife) position is used.
• During examination, the patient is asked to strain with the anoscope sliding out to detect any prolapse of the rectal mucosa
and the anal cushion. Excoriation, metaplastic changes, and
friable mucosa indicate a prolapsed hemorrhoid.
• A biopsy of the anal canal can be performed with an anoscope
or a rigid proctosigmoidoscope.
Complications
• Anal tear, especially at the posterior midline, can occur in patients
with anal stenosis.
Fig. 5.5. Rigid proctosigmoidoscope. To p , 19 mm × 25 cm; middle , 15 mm × 25
cm; bottom , 11 mm × 25 cm.
78 The ASCRS Manual of Colon and Rectal Surgery
B. Rigid Proctosigmoidoscope
• Three sizes of rigid proctosigmoidoscope are available (Fig. 5.5 ).
• A 19mm × 25cm scope is the standard size for a general examination and for polypectomy or electrocoagulation.
• A 15mm × 25cm endoscope is a good size for general examinations. It is much better tolerated by the patient, causing less spasm
of the rectum and, thus, minimal air insuffl ation, yet enables as
adequate an examination as the standard-size endoscope.
• An 11mm × 25cm endoscope should be available for examining the patient who has anal or rectal stricture, such as Crohn’s
disease.
• Some physicians and surgeons prefer a disposable standardsize rigid proctosigmoidoscope for routine examination.
Indications
• Rigid proctosigmoidoscopy has largely been replaced by
flexible sigmoidoscopy, but remains useful. One advantage is
that blood clots or stool can easily be washed out. In a patient with
massive gastrointestinal bleeding, a rigid proctosigmoidoscopy
is the fi rst line of examination to rule out an anorectal source of
bleeding.
• A rigid proctosigmoidoscopy is used when an abnormality
of the anal canal and rectum is suspected such as nonspecifi c
proctitis, radiation proctitis, anorectal ulcer, anorectal neoplasm, infectious proctitis, and anorectal Crohn’s disease.
• Rigid proctosigmoidoscopy is also useful to identify the precise site and size of rectal neoplasm.
Contraindications
• Patients with severe anal pain from an acute fi ssure, thrombosed external hemorrhoids, and perianal abscess may not
allow an examination. The examination should be postponed
until the area is healed or sedation is available.
• Anal stricture that will not allow the passage of the smallest
size rigid proctosigmoidoscope.
• Patients with acute abdomen or a rectal or sigmoid anastomosis
less than 2 weeks postoperatively requires special judgement.
5. Diagnostic Evaluations: Endoscopy: Rigid, Flexible Complications 79
Preparation
• Two phosphate enemas should be given within 2h of the examination. This is not necessary in a patient who has diarrhea or
active bleeding. Sedation is unnecessary.
Positioning
• A prone jackknife is the position of choice. However, a left
lateral position also gives an adequate examination and should
be used in conditions such as pregnancy, severe hypertension,
retinal detachment or postoperative eye surgery, apprehensive
patients or if moveable examination table is not available.
Technique
• Although a standard proctosigmoidoscope is 25cm in length,
the average distance that the scope can be passed is 20 cm.
In men, the scope can be passed to 21–25cm half of the time, and
in women, it can be passed that distance one-third of the time.
• Rigid proctosigmoidoscopy is suitable to examine the rectum
and, in some patients, the distal sigmoid colon.
• When properly performed, rigid proctosigmoidoscopy should
produce no pain or only mild discomfort. Most patients are
fearful of the examination because of past bad experience with
the procedure or from what they have heard. A few words of
reassurance are often helpful.
• Air insuffl ation is limited to the amount necessary to open the
lumen.
• It is usually necessary to insuffl ate a small amount of air for
good visualization of the lumen.
• The length of insertion should be measured from the anal verge
without stretching the bowel wall.
• If a lesion is seen, the size, appearance, location, and level
must be recorded. If a biopsy is performed, the location, level,
number of biopsies, and whether electrocoagulation is necessary should be noted.
• During the entire procedure, suction and water irrigation should
be available.
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