Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_1185_Библиотеки_им_академика_М_И_Перельмана
.pdf
50 L.E. Smith and G.J. Blatchford
Anismus
Anismus is a nonrelaxing puborectalis or levator muscle complex, which is seen as a fixed anorectal angle with a puborectalis
indentation in the face of straining down or evacuation.
17–19,22
Normally the puborectalis relaxes, and the anorectal angle opens
up. The patient with anismus complains of severe straining to
evacuate, and sometimes pain. If the act of defecation is timed,
patients with anismus take >30 seconds to empty, starting
when the anal canal begins to open. Normally evacuation takes
10 seconds after the anal canal starts to open. In addition, the
anal canal width is narrow.
Intussusception/Prolapse
FIGURE 4-13. Defecography. A rectocele. R is the rectocele; A is the
margin of the distal anus.
Bowel can be seen to indent the upper rectum or, if a space is
present in front of the rectum, to herniate down toward the
perineum. It is abnormal for bowel to descend below the
upper rectum, and it is abnormal for a space to be present of
>2 cm between the rectum and vagina. The postevacuation
film may show the abnormal movement of bowel into the
deep cul-de-sac. It is not necessary for viscera to enter the
space to be abnormal. The best way to detect the depth of
the pouch of Douglas is to introduce water-soluble contrast
into the peritoneal cavity.
20,21
This finding is suspected in only
half of the cases.
The rectum may be seen to prolapse or intussuscept during
straining or evacuation (Figure 4-15A–C).
17–19
The intussusception or prolapse can be characterized as upper, mid, or
lower rectal, and the origin can be described as anterior or
posterior. The intussusception usually begins at 6–8 cm
above the anus. Generally the upper rectum should remain
attached to the sacrum and the retrorectal (presacral) space
should not vary. The distal part of the rectum may be in either
a vertical or horizontal plane and still be normal.
Radiologists have some difficulty deciding whether the
enfolding is a full-thickness intussusception or a normal
rectal fold. Measurement of the thickness of the enfolding
rectal wall will be twice as thick as the rectal wall or a normal fold of the rectum, because it represents two adjacent
layers of the wall.
23
Megarectum
This diagnosis is a combination of a large measurement of the
diameter of the rectum and incomplete emptying. The measurement of the width of the rectum at the level of the distal
sacrum >9 cm suggests megarectum.
Incontinence
During the procedure, incontinent patients may not be able
to hold the barium in the rectum, and it can be seen to
run out of the anal canal before the instruction to defecate
is given. Incontinence is often associated with other
pathology.
FIGURE 4-14. Defecography. An enterocele. V is the vagina; E is the
enterocele descending between the vagina and rectum.
Balloon Expulsion Test
The balloon expulsion test measures the ability of the patient
to expel a balloon inflated with 50–60 mL of water.
Condoms and Foley catheter balloons have been used for this
24
test.
Patients with outlet obstruction are not able to pass this
balloon readily. The problem is that some patients may pass
the balloon, but have undetected outlet obstruction.
Conversely, patients with outlet obstruction may call upon
compensatory mechanisms to pass the balloon.
2
4. Physiologic Testing 51
Indication
If a defect in the sphincter mechanism is suspected, ultrasound is the diagnostic technique of choice.
25
It is most useful in the work-up of incontinence. The obstetric injury is
readily seen, and the ability to find the defect approaches
100%.
Equipment
The most often used ultrasound machine displays a 360degree image made possible by a mechanically rotating transducer on a hand probe. The 10-MHz transducer provides the
clearest images. The transducer is covered by a plastic cap.
25,26
Technique
The only preparation is a small enema. Sedation is not necessary. The patient is placed in the left decubitus position. The
ultrasound system is assembled, and water is introduced to fill
the cap covering the transducer. Air bubbles must be
removed, because they cause an artifact. A digital examination is performed to find abnormality, but also to define the
direction for insertion of the probe. The probe is introduced
blindly to the point where the transducer is in the rectum.
Images are made in the upper, middle, and distal anus, which
is the distal 4–5 cm.
FIGURE 4-15. A–C Defecography. Intussusception of the rectum. R is
the rectum; A is the margin of the distal anus. The arrows show the
progressive infolding of the rectum.
Anal Ultrasound
Anal ultrasound is used to look for anatomic abnormality of
the anal sphincters. See the chapter on Endoluminal
Ultrasound, to see images of anal ultrasounds. Ultrasound has
replaced EMG as the best means to define an injury.
Interpretation
Bartram
canal: l) a hyperechoic layer that is the interface of the cone
with the tissues; 2) a hypoechoic layer that represents the
mucosa; 3) a hyperechoic layer that represents the submucosa; 4) a hypoechoic layer that is the internal anal sphincter;
5) a hyperechoic layer that represents the intersphincteric
plane and the longitudinal muscle; and 6) a layer of mixed
echogenicity representing the external anal sphincter.
loop around the upper anus. In the middle anus, both the internal and external sphincters may be seen. In the distal anus, the
subcutaneous portion of the external sphincter is visualized, but
the internal sphincter does not extend this far. The thickness of
the internal sphincter stands out in the middle of the anus. The
normal adult sphincter is 2–3 mm thick. A neonate may have a
sphincter of 1 mm, and in the elderly 3–4 mm thick.
Incontinence
A thin muscle suggests primary degeneration of the internal
sphincter. After lateral internal sphincterotomy, a distal defect
can be seen in the internal sphincter. Obstetric trauma may
extend into the transverse perineus muscle, the external
sphincter, or completely down through the internal sphincter.
The injury blurs out portions of the normal rings of tissue
described above.
26,27
describes six ultrasonographic layers in the anal
In the upper anal canal, the puborectalis muscle is seen to
28
52 L.E. Smith and G.J. Blatchford
Magnetic Resonance Imaging
MRI of pelvic floor function is developing rapidly. Dynamic
studies have yielded additional information compared with
static examinations alone. Identification of the anal and rectal
structures is fairly easy on MRI because the perirectal fat
shows a high degree of contrast when compared with the
musculature. Indications for MRI examination are primarily
sepsis, trauma, congenital abnormalities, and tumor.
There is a significant change in T1 and T2 weighted imaging associated with infection. This change produces high soft
tissue contrast and enables abscess and fistulous tracks to be
demonstrated. Sensitivity of MRI using the body coil can be
as high as 89% in identifying fistulas, but demonstration of
site of internal opening and differentiation of various muscle
layers is not always possible.
cordance between MRI and surgical findings for the primary
tract and secondary tracts of 86% and 93%, respectively.
Muscular anatomy is seen so well that MRI has become
useful in the evaluation of anal trauma. When compared with
endorectal ultrasound, endoanal coil MRI is superior in identifying the outer aspect of the external sphincter muscle.
Concordance between MRI and surgical findings has been
shown with regard to location of sphincter tears after obstetric
30
trauma.
Studies have shown endoanal MRI to be comparable
to endoanal ultrasound for identifying defects and/or thinning
of the internal sphincter. MRI, however, may also show thinning of the external sphincter and puborectalis, which are not
easily seen on endoanal ultrasound. This may represent atrophy in the pelvic musculature. Atrophy may correlate with a
poor result after sphincter repair. Determination of atrophy on
endoanal MRI may help in predicting the outcome after
sphincteroplasty.
31
Atrophy on MRI has been shown to correlate with single fiber needle EMG which confirms denervation
at the level of the muscle.
even in the presence of external anal sphincter atrophy.
Prolongation of the PNTML reflects damage to only the large
heavily myelinated nerve fibers and does not reflect the nerve
function at the muscle level.
Congenital abnormalities of the anus and rectum can be
delineated by MRI examination.
tify sphincter involvement by rectal tumors. Distance from the
distal aspect of the tumor to the levator muscle can be accurately assessed before surgical planning. Because of the
length of the endorectal coil, visualization of the musculature
of the sphincter up to 2 cm above the levator ani only is
34
seen.
Visualization of depth of invasion by tumor can be
done by manipulation of contrast with the use of T2 weighted
images.
Defecatory problems may also be evaluated by MRI.
Dynamic pelvic MRI (or MRI proctography) is now possible
since techniques for rapid MRI acquisition have been developed. This allows pelvic floor motion to be visualized in real
time during defecation. Generally this does not require addition
of contrast although some limitations with motion artifact can
29
In this study, there was con-
32
However, PNTML may be normal
33
MRI can be used to iden-
be seen. It has been suggested that examination in the supine
position (MRI) compared with the study in a seated position
(balloon proctography) shows minimal and probably clinically
insignificant differences in pelvic organ prolapse between these
two techniques.
35
MRI is able to demonstrate peritoneoceles,
cystoceles, perineal descent, and prolapse during evacuation.
Evidence of obstruction defecation may be seen with the
anorectal angle becoming more acute with straining, suggesting
paradoxical contraction of the puborectalis.
EMG of the Anal Sphincter
EMG is used primarily in evaluating fecal incontinence. EMG
is a means of assessing the motor unit. The integrity of the muscle may be assessed as well as its nerve supply. The integrity of
external anal sphincter innervation after sphincter injury can be
demonstrated. Sphincter reinnervation secondary to pelvic neuropathy can be demonstrated. EMG may also be used to “map”
specific anatomic sphincter defects. This mapping technique
has largely been replaced by anal ultrasonography, which is
simple, accurate, and painless. Anal EMG may also be used to
demonstrate appropriate relaxation and contraction of the anal
muscle and can be used in biofeedback therapy.
Concentric Needle EMG
Concentric needle EMG focuses on different motor unit characteristics. A concentric needle electrode will record muscle
contractions as motor unit potentials (MUPs). A single MUP
is caused by depolarization of the muscle from a single motor
unit. Three variables are noted within a MUP: amplitude,
duration, and shape. Amplitude is dependent on the number
of muscle fibers discharging. The larger the number of fibers,
the greater is the amplitude of the MUP. Generally only the
fibers lying within 1 mm of the electrode (typically less than
20) contribute to the spike of the MUP. Distance may also
influence amplitude to some degree. Duration of the MUP is
a result of dispersion of the action potentials originating from
the different muscle fibers of a motor unit. Duration of MUPs
increases with age. Denervation also causes a prolongation of
duration and polyphasic potentials. Shape of the MUP results
from summation of the single fiber action potentials in the
motor unit. Most normal MUPs are bi- or triphasic.
Polyphasic potentials (four or more phases) have been
reported in up to 25% of normal external anal sphincter muscles. Polyphasic potentials of short duration occur in myopathic disorders and those with long duration correlate with
histologic evidence of regeneration in denervated muscle.
Concentric needle EMG can be of particular value in the diagnosis of specific neurologic problems, including conditions of
the cone and cauda equina, sacral roots, pudendal nerve, and
for differential diagnosis of the various types of multisystemic
atrophy.
duration is <6 ms.
36
Normal amplitude of the MUP is <600 μV and
37
4. Physiologic Testing 53
Single Fiber EMG
Single fiber EMG electrodes are used because the area of
measurement is so small each fiber generates a single spike.
In normal circumstances, only a few muscle fibers from a single motor unit are within the recording area of a single fiber
electrode. In reinnervated muscle, the numbers of fibers
belonging to a single motor unit increase, thereby increasing
action potentials are recorded at the electrode. The number of
spikes can be recorded from separate potentials and fiber density can be calculated. Fiber density is the measurement of the
mean number of muscle fibers innervated by one alpha-motor
unit. This is usually an average from numerous separate
potentials. Technique of single fiber EMG involves placing a
sterilized fine needle (single fiber electrode) with a recording
surface of 25 μm into the external anal sphincter just outside
the anal verge. Readings are taken in both the left and right
lateral areas with 20 needle positions or more done for calculation of fiber density. A value >1.7 is considered abnormal.
Criteria for pudendal nerve damage in single fiber EMG are
the presence of an increased fiber density, increase of MUP
duration and amplitude at rest, decrease of the number of
MUPs during maximum contraction, and presence of “jitter
and blocking” phenomena.
39
amplitude from 8–10 μV, endurance (maintenance of sustained contraction) of 30–40 seconds. Normal patients
demonstrated no evidence of paradoxical activity.
37
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. Testing is usually done with a St. Mark’s electrode
with a stimulating electrode mounted at the fingertip portion
and a recording electrode mounted at the finger base portion.
The electrode has a constant distance of 50 mm between stimulation of the nerve and recording of the external anal sphinc-
38
ter response. Latency between stimulation and response can
then be recorded (Figure 4-16). This latency reflects the
myelin function of the peripheral nerve. Therefore, 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.
39,42,43
Surface Electrodes
Surface EMG electrodes are generally used to document anal
sphincter activity at rest, strain, and squeeze. Documentation
of paradoxical sphincter contraction may improve assessment
of patients with defecation disorders. When compared with
proctography, both needle EMG and surface EMG have a low
positive predictive value, but they have high negative predictive values.
nosing 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 difficulties with evacuation, particularly if paradoxical sphincter
contraction is present. A plug electrode may be used within
the anal canal or surface electrodes may be placed near the
anus in a lateral position. Surface electrodes are easy and
painless to apply and therefore well tolerated by patients.
They come with self-adhesive or can be secured with tape.
They should be placed over the subcutaneous part of the
external anal sphincter 1 cm from the anal verge in right and
left lateral positions. A grounding electrode is then placed on
the patient’s buttock. EMG recordings from the external anal
sphincter during straining using surface electrodes applied to
the skin correlate well with the result from needle electrodes
inserted into the muscle.
anal plug electrodes correlate well with anal manometry and
with wire electrodes during rest, squeezing, and straining.
Normal values for surface EMG show short contraction
(3-second) amplitude from 8–10 μV, 10-second contraction
40
Therefore, EMG alone is not optimal for diag-
41
Other studies have shown that the
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 fiber, fat, and calorie intake.
Patients who believe they eat a high fiber diet may be shown
to have a very modest fiber intake. Stool history will further
delineate the extent of the patient’s problem. In patients complaining of chronic constipation who believed that they had
less than or equal to three stools per week for more than
6 months, a 4-week stool diary revealed that only 49% actually met this criteria. The remaining 51% of patients had, on
average, six stools per week.
history of psychiatric illness was five times more frequent
among those whose bowel symptoms correlated poorly with
objective evidence of constipation.
Colonic Transit
The rate at which fecal residue moves through the colon is
important in determining whether the stool is liquid, semiformed, or hard. 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.
44
This study also showed that a
54 L.E. Smith and G.J. Blatchford
Pudendal
R
Right P - Recturn
Left P - Right P
MNCV Curves
Right Pudendal
Right P-Rectum
Left P-Rectum
2.0
2.4
0.5
0.1 −88
Stim
10mA
10mA
0.1mV
2ms
FIGURE 4-16. PNTML curves showing a latency of the right nerve of 2.0 msD and the left nerve of 2.4 msD.
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. Markers consist of a capsule containing radiopaque markers, which are commercially available
(Sitz-Mark, Konsyl Pharmaceuticals, Fort Worth, TX) or can
be individually created by filling gel capsules with small circles cut from radiopaque tubing. In the most simplified colon
transit technique, the patient takes one marker tablet which
of markers present in each section is counted on both the 4and 7-day films. A table can then be made with the values
(Table 4-1). Average normal transit is 11.3 hours, 11.3 hours,
and 12.4 hours for the right, left, and rectosigmoid colon,
respectively. Normal total transit averages 35 hours.
Segmental colectomy is not indicated for constipation even in
the face of markedly abnormal segmental transit time. Stool
weight has been shown to correlate with transit time in constipated patients.
44
contains 24 markers on day 0. On day 5, a supine abdominal
film is taken to determine the number and position of remaining markers. If five or fewer markers are remaining, the
patient has normal colonic transit. If more than five 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
Radionuclide Transit
Transit may be measured by radionuclide gamma scintigraphic techniques.
ods correlate well. The major advantage of scintigraphy is
that 24–48 hours of scanning is needed compared with 5–7
days for marker test completion.
46
Radiographic and scintigraphic meth-
outlet problems should be considered. Segmental transit may
be calculated as described by Metcalf et al.
and day 2, the patient takes one marker capsule for a total of
three capsules. On day 4, an abdominal film is taken. If there
are more than a total of 50 markers remaining, transit time is
abnormal and an additional abdominal radiograph is taken on
day 7 to determine the location and number of residual markers. The abdominal radiograph is divided into the following
sections: right colon, left colon, and rectosigmoid. The number
45
On day 0, day 1,
TABLE 4-1. Results of a colon transit study
Right colon Left colon Rectosigmoid Total
Day-4 film 15 21 16 52
Day-7 film 0 4 14 18
Transit time (h) 15 25 30 70
The theoretical numbers of ingested markers by time and colonic segment.
This example shows a right colon transit of 15 h, left colon of 25 h, rectosigmoid of 30 h, and a total colonic transit of 70 h.
4. Physiologic Testing 55
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.
47
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 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 significant. Radiation exposure with scintigraphy is
highest for the colon and can be reduced by the administration
of laxatives after the procedure. Radiation to the ovaries is
less than in a plain abdominal X-ray.
References
1. Wexner SD, Jorge JMN. Colorectal physiological tests: use or
abuse of technology? Eur J Surg 1994;160:167–174.
2. Lowry AC, Simmang CL, Boulos P, et al. Report of the tripartite
consensus conference on definitions for anorectal physiology
and rectal cancer, Washington, D.C., May 1, 1999. Dis Colon
Rectum 2001;44(7):915–919.
3. Pedersen IK, Christiansen J. A study of the physiological variation in anal manometry. Br J Surg 1989;76:69–71.
4. Loening-Baucke V, Anuras S. Effects of age and sex on anorectal manometry. Am J Gastroenterol 1991;80:50–53.
5. Hallan RI, Marzouk DEMM, Waldron DJ, et al. Comparison of
digital and manometric assessment of anal sphincter function. Br
J Surg 1989;76:973–975.
6. Felt Bersma RJF, Klinkenberg-Knol, Meuwissen SGM.
Anorectal function investigations in incontinent and continent
patients. Dis Colon Rectum 1990;33:479–486.
7. Duthie HL, Watts JM. Contribution of the external anal sphincter to the pressure zone in the anal canal. Gut 1965;17:64–68.
8. 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;32:726–736.
9. Rattan S, Chakder S. Role of nitric oxide as a mediator of internal anal sphincter relaxation. Am J Physiol 1992;262:G107–112.
10. Perry RE, Blatchford GJ, Christensen MA, et al. Manometric
diagnosis of anal sphincter injuries. Am J Surg 1990;159:
112–117.
11. Tjandra JJ, Sharma BRK, McKirdy HC, et al. Anorectal physiological testing in defecatory disorders: a prospective study. Aust
N Z J Surg 1994;64:322–326.
12. Bouchoucha M, Faye A, Arsac M, Rocaries F. Anal sphincter
response to distension. Int J Colorectal Dis 2001;16:119–125.
13. Tobon F, Reid NCRW, Talbert JL, et al. Nonsurgical test for the
diagnosis of Hirschsprung’s disease. N Engl J Med 1968;278:
188–194.
14. Preston DM, Lennard-Jones JE. Anismus in chronic constipation. Dig Dis Sci 1985;30:413–418.
15. Bremmer S. Peritoneocele: a radiological study with defaecoperitoneography. Acta Radiol Suppl 1998;413:1–33.
16. Maglinte DD, Kelvin FM, Hale DS. Dynamic cystoproctography: a unifying diagnostic approach to pelvic floor and anorectal
dysfunction. AJR Am J Roentgenol 1999;169:759–767.
17. Jorge JMN, Habr-Gama A, Wexner S. Clinical applications and
techniques of cinedefecography. Am J Surg 2001;182:93–101.
18. Wiersma T, Mulder CJJ, Reeders WAJ. Dynamic rectal examination: its significant clinical value. Endoscopy 1997;29:
462–471.
19. Jones HJS, Blake H, Swift RI. A prospective audit of the usefulness of evacuating proctography. Ann R Coll Surg Engl
1998;80:40–45.
20. Halligan S, Bartram C, Hall C, et al. Enterocele revealed by
simultaneous evacuation proctography and peritoneography:
does “defecation block” exist? AJR Am J Roentgenol 1996;167:
461–466.
21. Sentovich SM, Rivela LJ, Thorson AG, et al. Simultaneous
dynamic proctography and peritoneography for pelvic floor disorders. Dis Colon Rectum 1995;38:912–915.
22. Halligan S, Malouf A, Bartram C, et al. Predictive value of
impaired evacuation at proctography in diagnosing anismus.
AJR Am J Roentgenol 2001;177:633–637.
23. Pomerri F, Zuliani M, Mazza C, et al. Defecographic measurements of rectal intussusception and prolapse in patients and in
asymptomatic subjects. AJR Am J Roentgenol 2001;176:641–645.
24. Rao SS, Hatfield R, Soffer E. Manometric tests of anorectal
function in healthy adults. Am J Gastroenterol 1999;94:773–783.
25. Sentovich SM, Blatchford GJ, Rivela LJ, et al. Diagnosing anal
sphincter injury with transanal ultrasound and manometry. Dis
Colon Rectum 1997;40:1430–1434.
26. Bartram CI, Burnett SJD. Atlas of Anal Endosonography.
Oxford: Butterworth-Heinemann; 1991.
27. Bartram C. Radiologic evaluation of anorectal disorders.
Gastroenterol Clin North Am 2001;30:55–75.
28. Sultan AH, Kamm MA, Talbot IC, et al. Anal endosonography
for identifying external sphincter defects confirmed histologically. Br J Surg 1994;81(3):463–465.
29. Barker PG, Lunniss PJ, Armstrong P, et al. Magnetic resonance
imaging of fistula-in-ano: technique, interpretation and accuracy.
Clin Radiol 1994;49:7–13.
30. Fletcher JG, Busse RF, Reiderer SJ, et al. Magnetic resonance
imaging of anatomic and dynamic defects of the pelvic floor in
defecatory disorders. Am J Gastroenterol 2003;98:399–411.
31. Briel JW, Stoker J, Rociu E, et al. External anal sphincter atrophy on endoanal magnetic resonance imaging adversely affects
continence after sphincteroplasty. Br J Surg 1999;86:1322–1327.
32. William AB, Bartram CI, Modhwadia D, et al. Endocoil magnetic resonance imaging quantification of external anal sphincter
atrophy. Br J Surg 2001;88:853–859.
33. Sato T, Konishi F, Kanazawa K. Variations in motor evoked
potential latencies in the anal sphincter system with sacral magnetic stimulation. Dis Colon Rectum 2000;43:966–970.
56 L.E. Smith and G.J. Blatchford
34. deSouza NM, Hall AS, Puni R, et al. High resolution magnetic
resonance imaging of the anal sphincter using a dedicated
endoanal coil. Dis Colon Rectum 1996;39:926–934.
35. Fletcher JG, Busse RF, Riederer SJ, et al. Magnetic resonance
imaging of anatomic and dynamic defects of the pelvic floor in
defecatory disorders. Am J Gastroenterol 2003;98:399–411.
36. Del Rey AP, Entrena BF. Reference values of motor unit potentials (MUPs) of the external anal sphincter muscle. Clin
Neurophysiol 2002;113:1832–1839.
37. Ferrara A, Lujan JH, Cebrian J, et al. Clinical, manometric, and
EMG characteristics of patients with fecal incontinence. Tech
Coloproctol 2001;5:13–18.
38. Osterberg A, Graf W, Eeg-Olofsson KE, et al. Results of neurophysiologic evaluation in fecal incontinence. Dis Colon Rectum
2000;43(9):1256–1261.
39. Jacobs PPM, Scheuer M, Kuijpers JHC, et al. Obstetric fecal
incontinence: role of pelvic floor denervation and results of
delayed sphincter repair. Dis Colon Rectum 1990;33(6):494–497.
40. Yeh CY, Pikarsky A, Wexner SD, et al. Electromyographic findings of paradoxical puborectalis contraction correlate poorly
with cinedefecography. Tech Coloproctol 2003;7:77–81.
41. Lopez A, Nilsson BY, Mellgren A, et al. Electromyography of
the external anal sphincter: comparison between needle and surface electrodes. Dis Colon Rectum 1999;42:482–485.
42. Laurberg S, Swash M, Henry MM. Delayed external sphincter
repair for obstetric tear. Br J Surg 1998;75:786–788.
43. Wexner SD, Marchetti F, Jagelmen DG. The role of sphincteroplasty for fecal incontinence reevaluated: a prospective physiologic and functional review. Dis Colon Rectum 1991;34:22–30.
44. Ashraf W, Park F, Lof J, et al. An examination of the reliability
of reported stool frequency in the diagnosis of idiopathic constipation. Am J Gastroenterol 1996;91:26–32.
45. Metcalf AM, Phillips SF, Zinsmeister AR, et al. Simplified
assessment of segmental colonic transit. Gastroenterology 1987;
92:40–47.
46. Charles F, Camilleri M, Phillips SF, Thomforde GM, Forstrom
LA. Scintigraphy of the whole gut: clinical evaluation of transit
disorders. Mayo Clin Proc 1995;70(2):113–118.
47. Caride VJ, Prokop EK, Troncale FJ, et al. Scintigraphic
determination of small intestinal transit time: comparison with
the hydrogen breath technique. Gastroenterology 1984;86:
714–720.
5
Diagnostic Evaluations—Endoscopy:
Rigid, Flexible Complications
Santhat Nivatvongs and Kenneth A. Forde
The large intestine from cecum to anus can be effectively and
accurately examined as part of a complete physical examination. An ultimate diagnosis of large bowel diseases can only
be made by direct observation of the abnormalities and, if
indicated, a biopsy. Different equipment is designed and used
for different purposes.
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 (Figure 5-1) and the
lighted Welch-Allen scope (Figure 5-2) that uses the same
light source as the rigid proctosigmoidoscope. Another type is
the side-opening Vernon-David scope with Hirschman handle
(Figure 5-3). The Hinkel-James anoscope (Figure 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 fissures,
anal fistulas, anal Crohn’s disease, anal tumors, hemorrhoids,
anal condyloma, bright red rectal bleeding, and pruritus ani.
Anoscopy is frequently used in conjunction with
colonoscopy, flexible sigmoidoscopy, and rigid proctosigmoidoscopy as part of the examination.
Contraindications
Patients who have severe anal pain such as an acute anal fissure 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
The Vernon-David, which is a side-opening endoscope, gives
the best examination. Inspection of the anal area should always
precede any other examination and, for this, good lighting is
essential. The cheeks of the buttock are gently spread to gain
exposure. 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. When the anal verge is pricked with a needle, the
external sphincter visibly contracts because of the anal reflex.
It is useful for testing the sensibility of the anal canal, which
may be absent in areas of previous scar or defect, or in patients
with an underlying neuropathy.
The next step is to do a digital examination. The index finger should be well lubricated with a lubricant jelly, and the
finger pressed on the anal aperture to “warn” the patient.
Then the finger 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
57
58 S. Nivatvongs and K.A. Forde
FIGURE 5-1. Buie anoscope.
operation can be felt. A fibrous cord or induration in the anal
area and the anal canal may indicate a fistulous tract. The
external sphincter, puborectalis, and levator ani muscles can
also be appreciated by digital examination. When the puborectalis is pulled in the posterior quadrant, the anus will
gape but will close immediately when the traction is released.
Persistence of the gaping indicates an abnormal reflex pathway in the thoracolumbar region frequently seen in paraplegic patients. The finger should press gently on these
muscles for signs of tenderness. When the person with good
anal function is asked to contract the muscles, the examiner
not only feels the squeeze of the muscle on the examining
finger but also feels the finger 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
FIGURE 5-3. Vernon-David with Hirschman handle anoscope.
endoscope can be rotated all around without having to
reinsert the obturator. If an inverted (jackknife) position is
used, the examination table need not be tipped down
more than 10–15 degrees. If a left lateral position is used, an
assistant needs to pull up the right cheek of the buttock
for exposure. 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 via an anoscope is not advisable because of its
poor exposure. If indicated, a biopsy via a rigid proctosigmoidoscope or a flexible sigmoidoscope is more appropriate.
Complications
Anal tear, especially at the posterior midline, can occur in
patients with anal stenosis.
FIGURE 5-2. Lighted Welch-Allen anoscope.
FIGURE 5-4. Hinkel-James anoscope.
5. Diagnostic Evaluations—Endoscopy: Rigid, Flexible Complications 59
Rigid Proctosigmoidoscope
Three sizes of rigid proctosigmoidoscope are available (Figure
5-5). A 19 mm × 25 cm scope is the standard size for a general
examination and for polypectomy or electrocoagulation.
A 15 mm × 25 cm endoscope is an ideal size for general
examination. It is much better tolerated by the patient, causing less spasm of the rectum and, thus, minimal air insufflation, yet enables as adequate an examination as the
standard-size endoscope. An 11 mm × 25 cm 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 standard-size rigid proctosigmoidoscope for routine examination.
Indications
Rigid proctosigmoidoscopy has largely been replaced by flexible sigmoidoscopy. However, rigid proctosigmoidoscopy is
still useful in examination of the anorectum. One of its advantages is that any blood clots or stool can easily be washed out.
In fact, in a patient who has massive gastrointestinal bleeding,
a rigid proctosigmoidoscopy is the first line of examination to
rule out the source of bleeding in the anorectum.
A rigid proctosigmoidoscopy is used when an abnormality
of the anal canal and rectum is suspected such as nonspecific
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 fissure, thrombosed
external hemorrhoids, and perianal abscess may not allow an
examination. The examination should be postponed to some other
date. Anal stricture that will not allow the passage of the smallest
size rigid proctosigmoidoscope is a contraindication to its use.
F
IGURE 5-5. Rigid proctosigmoidoscope. Top, 19 mm × 25 cm;
middle, 15 mm × 25 cm; bottom, 11 mm × 25 cm.
Patients with acute abdomen of any cause, rectal and sigmoid anastomosis less than 2 weeks postoperatively should
not have a rigid proctosigmoidoscopy.
Preparation
Two phosphate enemas should be given within 2 hours 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, and
some apprehensive patients.
Technique
Although a standard proctosigmoidoscope is 25 cm in length,
the average distance that the scope can be passed is 20 cm. In
men, the scope can be passed to 21–25 cm half of the time,
and in women, it can be passed that distance one-third of the
1
time.
Rigid proctosigmoidoscopy is suitable only to examine
the rectum and, in some patients, the distal sigmoid colon.
The pain experienced from proctosigmoidoscopy is from
stretching the mesentery of the rectosigmoid colon when the
scope is pushed against the rectal wall, and from the air insufflation. 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 will be helpful.
With the obturator in place and held steady with the right
thumb, the well-lubricated rigid proctosigmoidoscope is gently inserted into the anal canal, aiming toward the umbilicus
for a distance of about 4–5 cm. Then the endoscope is angled
toward the sacrum and advanced another 4–5 cm into the rectum. The obturator is removed and the bowel lumen is negotiated under direct vision. Air insufflation is limited to the
amount necessary to open the lumen. When an angle is
encountered, the endoscope is withdrawn 3–4 cm and then
readvanced. This may be repeated several times to straighten
the angulation. If further advancement is unsuccessful, the
procedure is terminated at this point. Careful examination is
done as the instrument is withdrawn. It is usually necessary to
insufflate a small amount of air for good visualization of the
lumen. The instrument should be rotated on withdrawal to
ensure examination of the entire circumference. The mucosal
folds in the rectum (valves of Houston) can be flattened with
the tip of the endoscope to see the area behind them.
The length of insertion should be measured from the anal
verge without stretching the bowel wall. Some physicians
measure it in relation to the dentate line. The appearance of the
Соседние файлы в папке Библиотека им академика М.И. Перельмана