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60 S. Nivatvongs and K.A. Forde
mucosa and depth of insertion should be accurately described.
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.
Complications
If not careful, the tip of the endoscope can tear the mucosa; a
small or moderate amount of bleeding may occur. Abdominal
pain and distention can occur from excessive air insufflation.
Perforation from diagnostic rigid proctosigmoidoscopy is
extremely rare. Gilbertsen
forations in 103,000 examinations. Nelson et al.
2
reported an incidence of five per-
3
reported two
perforations in more than 16,000 examinations.
Flexible Sigmoidoscopy
The present-day flexible sigmoidoscope is no longer fiberoptic but contains a videochip at the tip of the endoscope. This
videochip transmits the image through the processing unit to
the monitor. The flexible videosigmoidoscope is 60 cm in
functional length (Figure 5-6). The entire sigmoid colon can
be reached by the flexible sigmoidoscope in 45%–85% of
cases and, in a few, the splenic flexure can also be visual-
4,5
ized.
The discrepancies in success depend on patient selection and the experience of the endoscopist. For selective
screening examination, flexible sigmoidoscopy has a 3–6
times greater yield than does rigid proctosigmoidoscopy in
detecting colonic and rectal abnormalities, especially neo-
6,7
plasms.
many physicians have discarded rigid proctosigmoidoscopy.
Because of this higher yield and better exposure,
most cases. However, it is more convenient to use, and in
many cases the entire colon need not be examined.
In acute diarrhea, flexible sigmoidoscopy can be used to
rule out Clostridium difficile colitis, acute bacterial colitis,
amebic colitis, and ischemic colitis particularly after aortic
aneurysm repair. Flexible sigmoidoscopy is also an excellent
tool to examine bright red rectal bleeding to detect its cause
such as nonspecific proctitis, radiation proctitis, anorectal
Crohn’s disease, rectal ulcer, and also anorectal neoplasm.
Flexible sigmoidoscopy is also used for colorectal cancer
screening in conjunction with tests for fecal occult blood and
to complement a barium enema examination. In this situation,
may be used for air insufflation if a barium enema is to
CO
2
follow.
Contraindications
Patients with severe anal pain from anal diseases may not
tolerate the insertion of the scope. This also applies to anorectal stricture and colorectal anastomosis less than 2 weeks postoperatively. Other contraindications include acute sigmoid
diverticulitis, toxic colitis, and patients with an acute abdomen.
Preparation
Bowel preparation with two Fleet enemas given within
2 hours of examination is adequate. The patient may eat normally. Patients with diarrhea do not require the enemas.
Positioning
Left lateral recumbent.
Technique
Indications
The role of flexible sigmoidoscopy is difficult to define
because it can examine only the sigmoid colon and rectum in
FIGURE 5-6. Flexible videosigmoidoscope.
Sedation is unnecessary. The anal canal is lubricated by digital examination. A well-lubricated flexible sigmoidoscope is
then inserted. Advancement of the endoscope is performed
under direct vision. Pushing the endoscope through a bend in
the bowel is a poor technique. Instead, the endoscope should
be withdrawn to straighten the bowel. The key of success is
short withdrawal and advancement of the endoscope or a toand-fro movement, together with rotating the instrument
clockwise and/or counterclockwise as needed. Use of air
insufflation should be kept to a minimum. The procedure
should be completed within 5–10 minutes. If a lesion is
detected and proved by biopsy to be a neoplasm, a complete
colonic investigation is indicated, ideally by total colonoscopy at some other date. A polyp up to 8 mm in size can be
sampled with coagulation (hot) biopsy forceps or biopsied
and electrocoagulated. To prevent possible explosion, because
of hydrogen or methane gas in the lumen, air should be
exchanged in the colon and rectum with repeated insufflation
and suction. A larger polyp should be reserved for
colonoscopy and polypectomy.
5. Diagnostic Evaluations—Endoscopy: Rigid, Flexible Complications 61
Complications
Excessive air insufflation can cause acute abdominal distention and abdominal pain. This is best corrected by reinsertion
of the endoscope and aspiration of air. Too rough and
improper technique can cause perforation and other injuries.
The most common site of perforation in flexible sigmoidoscopy is in the distal sigmoid colon where it is angulated
from the relatively fixed rectum at promontory of the sacrum.
Complications from flexible sigmoidoscopy are uncommon
but can be serious. They can be immediately apparent or
delayed. Gatto et al.
that consisted of a random sample of 5% of Medicare beneficiaries living in the region of the United States covered by
the Surveillance, Epidemiology, and End Results (SEER)
program registries between 1991 and 1998. There were
35,298 flexible sigmoidoscopies performed. The perforation
rate within 7 days of the procedure was 0.9 per 1000.
Anderson et al.
1987 and 1996 at Mayo Clinic, Scottsdale, AZ. There were
49,501 flexible sigmoidoscopies performed. Two perforations
occurred: one of the perforations was in the cecum, likely
from excessive air. Another perforation was in the sigmoid
colon but was not detected until 17 days later as a pelvic
abscess. Both required operation. There was no mortality.
Levin et al.
109,534 flexible sigmoidoscopic screenings as part of
Colorectal Cancer Prevention Program from 1994 to 1996 at
North California Kaiser Permanente Medical Care Program.
There were two perforations, two episodes of diverticulitis
requiring operation, two cases of bleeding requiring blood
transfusion, and one episode of unexplained colitis. In this
study in multivariate models, complications were significantly more common in men than in women (odds ratio, 3.34;
confidence interval, 95%).
10
8
reported a large population-based cohort
9
evaluated the 10-year experience between
analyzed 107,704 individuals who underwent
Ileoscopy
Examination of the small intestine via an ileostomy can be
performed using a rigid proctosigmoidoscope or a flexible
sigmoidoscope.
Indications
Indications for endoscoping the terminal ileum are few. Most
of the time it is to rule out recurrent Crohn’s disease or to find
an abnormality in patients with high ileostomy output.
Positioning
Supine.
Technique
The examination starts with a digital examination to gently
dilate the stoma, which is frequently slightly stenotic. The welllubricated rigid scope is introduced directly into the ileostomy.
The terminal ileum is quite active with frequent spasm. It
requires more air insufflation than scoping the rectum. The distance traversed by the endoscope is usually limited to 12–15
cm. In patients with a large para-ileostomy hernia, the endoscope may usually not be passed beyond 10 cm.
Flexible sigmoidoscopy is much easier to perform. The
angulation of the small bowel can be straightened by push,
pull, and rotation of the scope. A moderate amount of air
insufflation is usually required.
Complications
The small bowel has thin walls and requires gentle maneuvering of the endoscope. Perforation can easily occur. If an
angle cannot be straightened, the procedure should be terminated.
Pouchoscopy
Kock Pouch or Continent Ileostomy
Indications
Although the ileoanal pouch has almost completely
replaced the Kock pouch, there are still many patients with
a Kock pouch constructed more than 30 years ago. One of
the most common problems that require endoscopy is the
extrusion or slippage of the valve causing difficulty or
impossibility of intubation to evacuate the stool. The examination is performed to help decompress the obstructed
pouch and to place a draining tube. Other indications
included Crohn’s disease and complication of the pouch
with fistulas and high output of the pouch. Both rigid and
flexible endoscopes can be used. Church et al.
using a pediatric flexible endoscope.
Contraindications
11
advised
Contraindications
Stricture of the stoma.
Preparation
Bowel preparation is not required, but it is helpful if the patient
has been on a clear liquid diet for 1 day. Sedation is not required.
Stricture of the stoma.
Preparation
Bowel preparation is unnecessary and sedation is not usually
required. If possible, the pouch should be emptied or irrigated
just before the examination. It is also preferable if the patient
has been on a clear liquid diet for 1 day before the procedure.
62 S. Nivatvongs and K.A. Forde
Positioning
Supine.
Technique
The endoscope can usually be passed easily into the pouch
with inspection of the stoma being performed on insertion or
withdrawal. The pouch can be lavaged as necessary.
A general inspection of the pouch is performed noting the
mucosal appearance, the pouch size, distensibility, and the
status of suture lines. If possible, the afferent loop of ileum
should be intubated, especially in patients presenting with
pouch inflammation. The endoscope must be retroflexed
within the pouch to check valve length and symmetry. A careful search for foreign material should be made, particularly
around the base of the valve. If mesh was used to reinforce the
nipple valve, a fistula may form at this area. In patients with
extrusion of the valve, passing the endoscope will be difficult.
For an obstructed pouch from a slipped valve, Church
11
et al.
used a flexible endoscope as an obturator to insert the
rigid proctosigmoidoscope. The rigid endoscope is placed over
the flexible endoscope, which is itself inserted into the pouch.
The rigid endoscope is advanced over the flexible endoscope
into the pouch. Now the flexible endoscope can be withdrawn
and a drainage catheter inserted to temporarily relieve the
obstruction. Surgical repair of the nipple valve is required.
Positioning
Left lateral recumbent.
Technique
The examination starts with a digital examination to evaluate the anal canal and the anal anastomosis. If there is a
stricture, it should first be dilated with a finger or with
Hegar dilators.
The well-lubricated flexible sigmoidoscope or a colonoscope is introduced into the anal canal. The endoscope is
advanced into the pouch. The terminal ileum proximal to the
pouch can usually be intubated. The examiner should evaluate the mucosa of the pouch and anal canal for any edema of
the mucosa, granularity, mucosal bleeding, contact bleeding,
erosion, fibrin exudate, pattern of mucosal ulceration, plaque,
and mass. Abnormal mucosa should be biopsied. Only cold
biopsy should be performed.
Complications
Tear of the anal canal can occur if there is stricture of the anus
or anastomosis. Traumatic injury from the scope may cause
moderate bleeding but it usually stops spontaneously. A perforation can occur from the instrumentation or a biopsy.
Complications
Perforation can occur, particularly when there is an obstruction of the pouch.
Ileoanal Pouch
Examination of the ileoanal pouch is best performed using a flexible sigmoidoscope although a rigid proctoscope can also be used.
Unless there is an anastomotic anal stricture, the examination is
usually easy. The endoscope can be used to examine the entire
pouch and usually the terminal ileum proximal to the pouch.
Indications
Examination of the pouch is indicated for patients with bleeding from the pouch, diarrhea, recent onset of fecal incontinence, obstructive symptoms, pouchitis, for surveillance
follow-up examination to exclude neoplastic changes, and to
rule out Crohn’s disease.
Contraindications
Severe anal or anastomotic stricture.
Preparation
The patient is prepared by taking clear liquids for 1 day or
administered a small enema before the examination. Sedation
is not required.
Colonoscopy
With the many imaging methods available for evaluation and
often therapy of colorectal disorders, colonoscopy has
emerged as the gold standard for diagnosis. It is also, in some
areas, an increasingly frequent option for therapy, be it definitive or palliative.
Indications
Indications for diagnostic colonoscopy include: the evaluation
of virtually all symptoms associated with potential benign or
malignant, acute, or chronic diseases of the colorectum; for
resolution of abnormalities seen on other imaging modalities;
for investigating otherwise unexplained symptoms such as
anemia; the evaluation of chronic and acute bleeding per
annum; for screening and surveillance of patients at high risk
for colon adenomas or carcinoma; and localization of nonpalpable lesions at open or laparoscopic operation. It is also
increasingly possible to combine diagnostic colonoscopy and
other imaging techniques such as ultrasound.
Contraindications
Contraindications to diagnostic colonoscopy may be classified as absolute or relative. Although colonoscopy is appropriately considered a minimally invasive procedure, there are
risks involved that may be avoided, or at least minimized, by
5. Diagnostic Evaluations—Endoscopy: Rigid, Flexible Complications 63
careful patient selection and certainly these risks should be
discussed before the performance of the procedure.
Absolute contraindications are suspected bowel perforation
or recent anastomosis, established peritonitis, and fulminant
colitis.
Relative contraindications include suspected ischemia and
acute colitis, in either of which instance an experienced examiner may safely perform a limited examination. Active bleeding is a relative contraindication unless the examiner has had
significant experience with elective diagnostic colonoscopy
and we believe the procedure should not be attempted if one
is unprepared to provide, or for the patient to accept, treatment of complications of the procedure.
Preparation
Preparation for colonoscopy, of necessity, should include
preparation of the endoscopist, preparation of the patient in
general, and of the colon specifically. Several organizations
have prepared and published guidelines for credentialing the
individual who is permitted to perform colonoscopy in an
institutional setting
Committees have been established that grant privileges.
Although there is some controversy involving required numbers of experiences in training, all recommendations include
the following elements: background knowledge of anatomy,
physiology, and pathology of the colon as well as familiarity
with instruments and accessories used in endoscopy; some
formal training; and quality assurance practices. The concept
of proctoring has also been addressed by some.
for resuscitation should be available and individuals qualified
to perform cardiopulmonary resuscitation should be present
in the area where colonoscopy is performed. We cannot
overstate the necessity for qualified assistance during the
performance of the procedure and for monitoring the patient’s
condition.
Obtaining informed consent is an opportunity for discussing with the patient elements of the past and present medical history, especially medications and operative procedures,
which may expose psychological concerns or the need to
modify preparation, add prophylactic antibiotics, or change
medication, timing, and dosage. In other words, taking an
adequate history and performing pertinent physical examination are important. It is necessary to point out the potential
hazards of colonoscopy, noting aspects of the process that
might cause discomfort but it is also important to give reassurance that although the risk of complication is low the
examiner is prepared for prompt management. The question
of the need for antibiotic prophylaxis stems from concern that
although diagnostic colonoscopy is a low risk procedure for
bacteremia, infection of damaged cardiac valves or implanted
prosthesis is a risk. The American Heart Association and the
American Society of Colon and Rectal Surgeons have issued
joint guidelines recommending antibiotic prophylaxis for
patients with certain conditions associated with carditis.
12
and, in some institutions, Credentials
13
Equipment
These recommendations include implanted prostheses, primarily orthopedic.
Thorough mechanical preparation of the colon is absolutely
essential for efficient, safe, and complete endoscopic examination. In addition, should perforation occur, the empty colon
certainly poses less risk of significant peritoneal contamination. There are various forms of mechanical preparation possible but the most thorough and safest current regimen
involves the use of polyethylene glycol electrolyte lavage
solutions. Other forms of preparation that are sometimes used
involve ingestion of a saline cathartic (usually sodium phosphate or magnesium citrate) as well as enemas. With the latter, there is more concern about electrolyte imbalance
especially in patients taking diuretic medications chronically
or those with renal insufficiency. Some patients after gastrectomy may experience symptoms of dumping after saline
cathartic administration.
Monitoring
Although the use of pulse oximetry and intermittent monitoring of blood pressure as well as electrocardiography (if clinically indicated) have now become standard procedures, it is
important for the assistant as well as the endoscopist to be
aware of any changes in the patient’s level of awareness,
respiration, and abdominal distention.
Bleeding Prophylaxis
Although bleeding is rarely associated with diagnostic
colonoscopy, there are concerns about bleeding at or after
colonoscopy, if biopsy or polypectomy are contemplated, and
this has led to modification of anticoagulation regimens and
cessation of drugs that might alter platelet function. There are
no universally accepted guidelines for management of
antiplatelet therapy in relation to endoscopy, especially
because cessation of these agents may increase the risk of
thromboembolism in some of these patients. If a particular
patient has a known hematologic disorder (for example, factor
V deficiency), precautions should be taken to optimize the
coagulation potential by correcting missing or deficient factors
as necessary before initiation of the endoscopic procedure.
Technique
For successful passage of the colonoscope to the most proximal desired anatomic region (cecum or anastomosis), it is
imperative that a few principles be understood.
iner must appreciate that the colon is of variable length, that
respiratory and peristaltic activity is in progress during the
examination, and that some areas of the colon are more fixed
(by normal anatomy, previous inflammation, or postoperative
change). It is dangerous to proceed with introduction of the
endoscope without knowing at all times the location of
14
the lumen.
15
The exam-
64 S. Nivatvongs and K.A. Forde
Before starting the examination, the equipment should be
checked to verify that it is in good working order. It should be
verified that irrigation, suction, and air insufflation channels
are open and that the directional controls are in the unlocked
position.
With the patient in the left lateral recumbent position,
the examination is initiated by thoroughly inspecting the perianal area for fissures, fistulae, hemorrhoids, condylomata,
and rarer conditions such as melanoma, Bowen’s disease,
extramammary Paget’s disease, squamous and anal gland
carcinomas. Next, the lubricated gloved right index finger is
inserted into the anus and a rectal exanimation carefully performed, giving especial attention to the surface of the prostate
gland in the middle aged and older male patient. With the
right index finger still in the rectum, the endoscopist then
holds the tip of the instrument in the left hand, places it at
right angles to the right index finger, and by effacing the
sphincter with gentle pressure of the right index finger, the
instrument tip can be gently inserted as the right index finger
is withdrawn. The examiner then grasps the head of the
instrument in the palm of the left hand, leaving the thumb and
index finger free to manipulate the knobs for tip deflection
with the former and the air and water insufflation as well as
suction buttons with the other. The right hand is placed on the
instrument shaft. With the instrument in the rectal ampulla, it
is usually necessary to insufflate the lumen with a small
amount of air in order to visualize the direction of the lumen.
The main objective on insertion of the instrument is to
reach the most proximal point desired in as expeditiously a
manner as possible, leaving detailed inspection until the
process of withdrawal of the endoscope. However, detection
of an abnormality on insertion may require a change in strategy. For example, it may be important to detect, localize,
sometimes biopsy, or even remove a small lesion for fear of
not being able to find it easily on withdrawal. In some circumstances, therefore, at least localization and biopsy should
be performed, even on insertion.
One of the earliest challenges to insertion is advancing the
instrument into the descending colon. The unprepared examiner, looking at the stylized cartoons of many an endoscopy
record form and even many anatomic and surgical textbooks
may not recognize how long the sigmoid colon can be and
how easy it may be to insert a considerable length of the
instrument into it. Because the sigmoid is usually not fixed, it
accepts the instrument so readily that when the acute angle at
the junction of the sigmoid and (fixed) descending colon is
reached, the unprepared examiner may think that he/she has
achieved insertion to the splenic flexure. Attempts at further
insertion may be hindered then by the loop created in the sigmoid colon. Most of the time this frustrating situation may be
entirely avoided by attempting to keep the sigmoid collapsed
and shortened as early as possible. We have found that a
clockwise turn with the right hand on the shaft of the instrument and with jiggling of the shaft as well as back and forth
motion will often allow the bowel to fall over the instrument,
so to speak, allowing insertion with a less than one-to-one
motion. It is this pleating or accordioning of the bowel over
the instrument with alternating release that allows for efficient
advancement and more than one-to-one motion. As a matter
of fact, the recognition of this intermittent intussusception and
reduction as part of the normal advancement of the instrument
makes it understandable that, in estimating the extent of intubation or the location of a lesion, the least accurate determination is measuring on the shaft of the instrument.
Having entered the descending colon with the sigmoid
shortened and “straight,” it is usually quite easy to advance to
and around the splenic flexure. Difficulty in intubation
beyond the splenic flexure is, in our experience, more common when the patient has undergone previous operation
within this area with adhesions in the left upper quadrant that
may produce fixation. If the endoscopist recognizes the distal
transverse colon by endoscopic anatomy or transmitted cardiac apical pulsation that one is in, it is to be recalled that,
similar to the sigmoid, the transverse colon is on a long
mesentery and is rarely fixed. The hepatic flexure can be more
easily reached by keeping the transverse colon as collapsed as
possible.
The hepatic is often a more complicated flexure than is the
splenic and one may wander a while before entering the distal ascending colon. However, once the latter has been entered
and there has been no prior right abdominal operation (for
example, cholecystectomy, appendectomy), the cecum is
often rapidly reached by application of suction to collapse the
bowel over the instrument. It is important to be fully cognizant of the vagaries of endoscopic anatomy in order to confirm cecal intubation—by visualization of the appendiceal
orifice and the ileocecal valve. Looking for translumination
from the instrument tip through the abdominal wall in the
right lower quadrant is, unfortunately, a trap for the unsophisticated endoscopist who uses it to verify cecal entry. It merely
points out that the instrument tip is in the right lower quadrant
but the endoscopic tip may be in any mobile part of the colon,
for example, the transverse colon or even the sigmoid. In fact,
the student of anatomy recognizes that the cecum is not
always in the right lower quadrant.
There are aids to overcoming obstacles to cecal intubation.
A common one is the attempt to keep the sigmoid in a straight
position so that on further insertion the tip may progress proximally. Abdominal pressure by an assistant is often used in an
attempt to keep the sigmoid from reforming a loop once it has
already been straightened. We think it important not to expect
or direct the assistant to reduce the loop by compression
because this could theoretically lead to injury of the bowel
wall. Rather, the sigmoid has to be straightened and then pressure may be used to keep the loop from being re-formed. If
one reviews a series of barium enema films or has acquaintance with the position of the omega loop of the sigmoid at
abdominal operation, it helps to understand these maneuvers.
For those who have the capability of fluoroscopy in their
endoscopy units, much can be learned and much assistance
5. Diagnostic Evaluations—Endoscopy: Rigid, Flexible Complications 65
provided in this maneuver, especially in the individual’s early
endoscopic experience. For one, it is humbling to recognize
how inaccurate one can be of the extent of insertion or the
shape of the bowel with the endoscope inserted. There are two
recent developments in endoscopic and related instrumentation that may facilitate overcoming the difficult sigmoid loop,
still the most challenging aspect of diagnostic colonoscopy.
One recent development in the design of some colonoscopies is the ability of the endoscopist to vary the stiffness of
the endoscope to allow a previously shortened and straightened segment of bowel from re-forming a loop. The assumption is that the endoscopist knows with certainty that the loop
has been adequately reduced and that it is safe to insert a now
more rigid instrument. Those who have expertise with fluoroscopy know that this can be a fallible assumption. Another
development is an extracorporeal magnetic device that can
track the course and shape of the endoscope during inser-
16
tion.
If proven accurate, this device could potentially obviate fluoroscopy for localization, reduction of difficult loops,
and even allow for safer stiffening of the endoscope using
either a variable-stiffness endoscope or the external splinting
device introduced by Shinya in the early days of colonoscopy.
Certainly, the external splinting device should never be
used without the benefit of fluoroscopic assistance because,
with an angulated segment of bowel, it is possible to damage
the bowel wall if the mucosa is caught in the space between
the edge of the splinting device and the shaft of the instrument. When using the external splinting device, the fluoroscope is used to first verify that the tip of the instrument is just
beyond the splenic flexure and acutely angled (Figure 5-7).
The deflection knobs are then placed in the locked position
and, as the instrument is withdrawn and the sigmoid loop
straightened under fluoroscopic control, the external splint is
advanced over the endoscope up to, but not beyond, the
14
proximal descending colon.
One does not wish to advance
it to the splenic flexure where the lienocolic ligament may
be vulnerable to avulsion. An assistant has to keep the splinting device fixed at the anus so that the examiner does not
insert it further than desired during the remainder of the
examination.
External manipulation may also be helpful in two other circumstances. Sometimes the transverse colon, having a long
mesentery, may form a loop extending well into the pelvis.
Reduction of this loop by withdrawing the instrument and
using suction will usually achieve rapid progress into the
ascending colon. But one can sometimes keep the loop from
re-forming by having an assistant apply pressure from the
right abdomen directed to the left upper quadrant (because the
transverse colon mesentery is longer on the right and the loop
is therefore more prominent in the right portion of the
abdomen or pelvis). If the cecum is not fixed (as from prior
operation, for example, appendectomy or pelvic surgery), it
may be possible with gentle pressure on the abdominal wall
to collapse it onto the tip of the instrument, remembering,
however, that the cecum is not always in the right lower quadrant. Sometimes placing the patient in the prone position
allows easier intubation of the cecum.
On withdrawal of the instrument, one has to be sure that the
entire mucosa is visualized. As one withdraws the instrument
and the bowel recedes, inspection is accomplished but it
requires close attention because one can easily withdraw too
rapidly as a previously accordioned segment escapes without
the examiner’s control. It may be necessary to go back over an
area not adequately visualized initially. In this connection,
adequate preparation is even more important at this time than
on insertion. If liquid material is present but too thick to be
aspirated by suction through the instrument channel, one may
purposefully change the patient’s position to allow the fluid to
shift to another area. Withdrawal through the sigmoid colon
perforce requires more time and attention because there are
more folds and recesses. Although the experienced examiner
can usually withdraw very slowly through the anal canal and
thus visualize its entire circumference, this is sometimes better if complemented by retroflexing the tip of the instrument
in the anal ampulla to visualize the region of the dentate line
(if the rectal ampulla is readily distensible). As the endoscope
is withdrawn through each segment of the colon, it is useful
to decompress each examined segment with suction so that at
the conclusion of the examination the abdomen is minimally
distended.
FIGURE 5-7. Use of external splint.
Normal Endoscopic Anatomy
Some segments of the colon are more readily recognized than
others and one has to be careful not to be overconfident unless
a classic appearance is present. On insertion it is important to
first recognize the three rectal valves of Houston because the
66 S. Nivatvongs and K.A. Forde
relationship of a lesion to them will have great relevance if
surgical intervention is to be contemplated. Diverticula may
be seen throughout the intraperitoneal colon but rarely below
the peritoneal reflection. The descending colon, being fixed
along the white line of Toldt, will often present a long straight
“tunnel view.” Occasionally the splenic flexure is specifically
recognized if there is an external bulging bluish mass indenting the colon, descending with respiration. More common in
the sigmoid colon, diverticula may be seen throughout the
length of the large intestine. Their orifices may be so wide
that they may be mistaken for the bowel lumen. It is therefore safer to back away somewhat and have a longer view to
be sure of the location of the lumen. In any one field of view,
the diverticulum will of course be at right angles to the lumen
(Figure 5-8).
The transverse colon, on insertion, being suspended by the
three taenia coli presents the appearance of an equilateral triangle (the so-called “cathedral ceiling” appearance). Quite
often, the distal transverse colon can be identified in relation
to the proximal because the point of maximal impulse of the
heart is transmitted through the diaphragm which overlies the
distal transverse colon. Especially in thin patients, the liver
casts a broad, flat, bluish-green cast outside the colon but
because this may be seen for a variable distance from distal
transverse colon to mid-ascending colon, it is not particularly
helpful with localization of a lesion, from a surgeon’s point of
view. At the hepatic flexure, the colon often assumes a spiral
configuration which can cause the taenia to so approximate
each other as to make the novice assume the cecum has been
reached (what one of us has called “the fool’s cecum”).
The interhaustral folds in the ascending colon are low in
profile compared with those in the left colon. The ileocecal
valve is usually recognized as an eccentric bulge with a sometimes visible umbilication. Because there is more adipose tissue in it, the appearance is often a yellowish color compared
with the pink of the rest of the colon. The ileocecal valve is
rarely seen head on but is, of course, more easily recognizable when it is. It is important to intubate proximal to the valve
because the true caput of the colon may be at a variable distance form the ileocecal valve. As the three taenia come
together at the caput (often appearing like the branches of a
tree or a crow’s foot), the appendiceal orifice is usually recognized, even in the patient who has undergone previous
appendectomy.
Abnormal Findings
Exophytic lesions are the easiest to visualize and recognize at
colonoscopy, the most common being adenocarcinoma. All
polypoid lesions of the colon may be visualized at
colonoscopy and virtually all have distinguishing characteristics. Several are submucosal (lymphoid hyperplasia, stromal
tumors, lipomas, carcinoids, endometriomas, hemangiomas,
neurofibromas, lymphoma). A few are metastatic from other
organs (for example, prostate, pancreas, kidney). The diagnosis of most of these lesions can be made by endoscopic visualization or sampling. Some, being of no clinical consequence,
require only recognition (lymphoid, hyperplasia, lipoma).
In addition to lesions that protrude, there are numerous
inflammatory or degenerative conditions that have a recognizable endoscopic appearance and many can be safely sampled if necessary. These include the various colitides
(bacterial, viral, ulcerative, granulomatous), ischemia, radiation proctopathy (formerly called “proctitis”) and melanosis
FIGURE 5-8. Finding lumen in diverticulosis.
5. Diagnostic Evaluations—Endoscopy: Rigid, Flexible Complications 67
include abdominal distension, dehydration, respiratory
depression, vasovagal reaction, thrombophlebitis, incarcerated hernia, splenic capsular tear and subcutaneous and/or
mediastinal emphysema, and equipment failure.
In diagnostic colonoscopy, perforation may be caused by
the instrument itself, traction on a fixed segment of colon, or
over-insufflation of a segment, especially a closed loop as
may occur in patients with multiple strictures (inflammatory
bowel disease) or as a consequence of prior radiation therapy
and with hernia incarceration. Impaction of the instrument in
a diverticulum with overdistention of the latter has also been
a cause of perforation. Adequate training and experience
should decrease adverse events to a minimum. Because
perforation is related to the use of coagulation (“hot”) biopsy
FIGURE 5-9. Cytology through stricture.
forceps and because of the low risk of bleeding from multiple
forceps biopsies, use of the hot biopsy technique has declined.
Perforation during diagnostic colonoscopy tends to be
coli. Melanosis coli, when marked, may help in visualization
of adenomatous tissue because the pigment is not deposited in
only normal mucosa. Areas of angiodysplasia (vascular
ectasias, arteriovenous malformations) can be recognized on
diagnostic colonoscopy but must be distinguished from
bruises created from instrumentation or even preparation. The
endoscopist has to recognize colonic anatomy disturbed by
previous operation and therefore has to be familiar with the
variety of intestinal anastomoses performed.
Areas of stenosis and stricture may be encountered secondary to benign conditions (previous resection and anastomosis,
diverticulitis, colitis, radiation injury) or malignancy. Other
rare findings to be recognized include: colitis cystica profunda, pneumatosis, and Behçet’s syndrome. The manner in
which the nature of a lesion is established at diagnostic
colonoscopy will vary. A tiny sessile lesion (for example, a
diminutive polyp) may be removed in its entirety with the
biopsy forceps for pathologic examination. A pedunculated
lesion suspected of being a benign adenoma may be removed
at the time of diagnostic examination by snare polypectomy.
A sessile lesion suspected of being a carcinoma or villous
adenoma may be biopsied at one or more sites or even partially removed with a snare and cautery to obtain a satisfactory specimen. A stricture may be sampled for possible
malignant cells by advancing a cytology brush into the stricture ahead of the colonoscope (Figure 5-9). Malignant cells
may thus be harvested even though the stricture cannot be traversed with the endoscope. A lesion that appears vascular and
friable may be simply photographed. A submucosal lesion
may be exposed by disrupting the overlying mucosa.
detected earlier when it is from instrumental causes, whereas
perforation from therapeutic procedures is frequently related
to thermal injury and is often delayed. Indeed, the management of perforation after colonoscopy is still controversial.
Whereas there is universal agreement that perforation with
generalized peritonitis demands an operation, some believe
that if the onset of symptoms is delayed, signs are localized,
and the patient is not septic (even with the demonstration of
pneumoperitoneum) that nonoperative management may be
followed. An uncommon presentation of a contained perforation may be the presence of retroperitoneal or mediastinal air
and even subcutaneous emphysema, which usually resolves
without drainage.
Avoidance of perforation during diagnostic colonoscopy,
related as it is to training, skill, and experience may be best
achieved by the following: avoidance of dehydration and
oversedation; discontinuation of the procedure if the preparation is poor; avoiding forceful instrument insertion; recognition of vulnerable bowel (inflammation, ischemia, narrowing,
fixation); careful identification and avoidance of diverticular
ostia; avoidance of bowing of the instrument; awareness of
fixation from pelvic adhesions or tumor extending through
and beyond the colon wall; ensuring that abdominal and
inguinal hernias remain reduced; avoiding over-insufflation;
and looping in the splenic flexure region. There should be
constant identification of the location of the lumen with
avoidance of “slide by” (sidewise passage of the instrument
without direct visualization of the lumen), not attempting
colonoscopy during acute bleeding if one has not had adequate experience with routine diagnostic colonoscopy.
If perforation occurs, early diagnosis will ensure more effi-
Complications
Although colonoscopy is, in general, a safe procedure, it is
invasive and adverse events do occur. The most common serious complication of diagnostic colonoscopy is perforation
with the reported incidence of 0.03%–0.65% and the mortality of 0.01%–0.02%.
17–19
Other reported complications
cient management. Undue and sustained pain (especially
shoulder discomfort), absence of liver dullness on percussion,
demonstration of pneumoperitoneum on upright chest film,
and subcutaneous emphysema all help in making the diagnosis. Signs and symptoms will in general be related to factors
such as adequacy of bowel preparation, size of injury, and
underlying pathologic state of the colon. For example, the
20
68 S. Nivatvongs and K.A. Forde
ischemic colon or one involved with active colitis will be
more vulnerable to instrumental injury. Surgical intervention
is favored by most surgeons for early recognized perforation
at diagnostic colonoscopy. There are, however, some patients
with either a delayed perforation or one that has remained
localized without symptoms or signs of diffuse peritonitis.
Nonoperative management but continuing observation of this
subset of patients may be entirely satisfactory. With early surgical intervention of a mechanical perforation, if technically
feasible, primary closure with or without protective proximal
stoma is, of course, the most desirable and usually is feasible.
However, the surgeon must use good judgment in assessment
of such factors as adequacy of tissue perfusion, degree of
spillage, and colon tissue free of inflammation.
References
1. Nivatvongs S, Fryd DS. How far does the proctosigmoidoscope
reach? A prospective study of 1000 patients. N Engl J Med 1980;
303:380–382.
2. Gilbertsen VA. Proctosigmoidoscopy and polypectomy in reducing
the incidence of rectal cancer. Cancer 1974;34(suppl):936–939.
3. Nelson RL, Abcarian H, Prasad ML. Iatrogenic perforation of
the colon and rectum. Dis Colon Rectum 1982;25:305–308.
4. Lehman GA, Buchner DM, Lappas JC. Anatomic extent of
fiberoptic sigmoidoscopy. Gastroenterology 1983;84:803–808.
5. Ott DJ, Wu WC, Gelfand DW. Extent of colonic visualization with
fiberoptic sigmoidoscope. J Clin Gastroenterol 1982;4:337–341.
6. Marks G, Boggs HW, Castro AF, Gathright JR, Ray JE, Salvati
E. Sigmoidoscopic examinations with rigid and flexible fiberoptic sigmoidoscopes in the surgeon’s office. A comparative
prospective study of effectiveness in 1012 cases. Dis Colon
Rectum 1979;22:162–168.
7. Winnan G, Berci G, Parrish J, Talbot TM, Overholt BF,
McCallum RW. Superiority of the flexible to the rigid sigmoidoscope in routine proctosigmoidoscopy. N Engl J Med 1980;
302:1011–1012.
8. Gatto NM, Frucht H, Sundararajan V, Jacobson JS, Grann VR,
Neugut AI. Risk of perforation after colonoscopy and sigmoidoscopy: a population-based study. J Natl Cancer Inst 2003;95:
230–236.
9. Anderson ML, Pasha TM, Leighton JA. Endoscopic perforation
of the colon: Lessons from a 10-year study. Ann J Gastroenterol
2000;95:3418–3422.
10. Levin TR, Conell C, Shapiro JA, Chazan SG, Nadel MR, Selby
JV. Complications of screening flexible sigmoidoscopy.
Gastroenterology 2002;123:1786–1792.
11. Church JM, Fazio VW, Lavery IC. The role of fiberoptic
endoscopy in the management of the continent ileostomy.
Gastrointest Endosc 1987;33:203–209.
12. Society of American Gastrointestinal Endoscopic Surgery
(SAGES). Granting of privileges for gastrointestinal endoscopy
by surgeons. Los Angeles: SAGES; 1992.
13. Society of American Gastrointestinal Endoscopic Surgeons
(SAGES) framework for postresidency surgical education and
training: a SAGES guideline. Surg Endosc 1994;8:1137–1142.
14. Practice parameters for antibiotic prophylaxis to prevent infective endocarditis or infective prosthesis during colon and rectal
endoscopy. Dis Colon Rectum 2000;43:1193.
15. Forde KA, Technique of diagnostic colonoscopy. In: Greene FI,
Ponsky JL, eds. Endoscopic Surgery. Philadelphia: Saunders;
1994:219–234.
16. Shah SG, Pearson HJ, Moss S, et al. Magnetic endoscopic imaging: a new technique for localizing colonic lesions. Endoscopy
2002;34:900–904.
17. Ackroyd FW. Complications of flexible endoscopy. In: Greene
FL, Ponsky JL, eds. Endoscopic Surgery. Philadelphia:
Saunders; 1994:440–441.
18. Korman LY, Overholt BF, Box T, et al. Perforation during
colonoscopy in endoscopic ambulatory surgical centers. Gastrointest Endosc 2003;58:554–557.
19. Wexner SD, Forde KA, Sellers G, et al. How well can surgeons
perform colonoscopy? Surg Endosc 1998;12:1410–1414.
20. Damore LJ, Rantis PC, Vernava AM, et al. Colonoscopic perforations. Dis Colon Rectum 1996;39:1308–1314.
6
Diagnostic Evaluations—Radiology,
Nuclear Scans, PET, CT Colography
Matthew G. Mutch, Elisa H. Birnbaum, and Christine O. Menias
The goal of this text is not to provide the definitive chapter on
gastrointestinal (GI) radiology, but rather to provide a sturdy
foundation for the techniques, indications, and interpretation
of radiologic imaging studies used in everyday colon and rectal surgery practices. Diagnostic radiology is the application
of data or image acquisition to our knowledge of anatomy and
pathology. Advances in technology have allowed us to diagnose many common diseases at earlier stages as well as identify new pathology previously not detectable with radiologic
studies.
Plain Films
The information or picture provided by plain films is the
result of differential absorption of the X-rays by the various
components of the abdominal wall, bony skeleton, and the
intraabdominal contents. In particular, it is the interfaces
between the different anatomic planes created by the inherent
contrast of the various tissues attributed to the relative fat content of each structure and intraluminal gas of the GI tract that
gives the image seen on the film. It is these interfaces that
allow for the delineation of the liver edge, renal shadow, psoas
shadow and differentiation of the patterns of the stomach,
small bowel, and colon. The typical flat plate X-ray uses
60–75 kV to expose each film. This varies depending on the
equipment used and the size of the patient. A reciprocating
grid and collimation are used to reduce scatter of the radiation
and improve tissue contrast.
Controversy exists over the number of views or films
needed to adequately examine the abdomen. Classical teaching recommends three views consisting of a supine abdomen,
upright or lateral decubitus abdomen, and upright chest. The
rationale for these films is as follows
offers the most detail and contrast of the intraabdominal structures; 2) the upright or decubitus abdominal views allow for a
change in intraluminal gas distribution and identification of
extraluminal free-air; 3) the upright chest contributes diagnostic information in 20% of cases.
1
: 1) the supine abdomen
2
However, Mirvis et al.
argued that the upright abdominal view was unnecessary.
They reviewed 252 examinations and found that the supine
abdominal and upright chest films alone provided the diagnosis 98% of the time. Whether two or three films are obtained
is of secondary importance as long as the entire abdomen is
viewed and the examination is able to address the clinical scenario in question.
Plain films clearly do not offer as much anatomic detail as
the cross-sectional imaging modalities, but they remain
highly sensitive and specific when there is suspicion of a
bowel obstruction or a perforated viscus.
cations for plain films include longitudinal examination of
megacolon, identification of foreign bodies, check positions
of drains or catheters, and evaluation of associated skeletal
diseases.
4
Other useful indi-
Intestinal Obstruction
Small Bowel Obstruction
Investigation of intestinal obstruction, whether it is small versus large bowel or mechanical versus functional, is a common
indication for abdominal plain films. The signs and symptoms
of a small or large bowel obstruction depends on the location
and extent of the obstruction and can include nausea, vomiting, abdominal pain, abdominal distention, and obstipation.
Just as the clinical manifestations of the obstruction depend
on its location so do its radiographic findings. Duration of
symptoms, significant emesis, use of a nasogastric tube, and
degree of obstruction also contribute to the radiographic
appearance of a bowel obstruction. With regard to small
bowel obstruction (SBO), the most common causes in
descending order are adhesions, Crohn’s disease, neoplasia,
and hernia.
diagnostic in 50%–66% of cases with approximately 20%
false-negative rate.
The radiographic diagnosis of an SBO depends on the
intraluminal gas pattern projected upon the plain film. A nor-
3
mal gas pattern is defined as small amounts of gas distributed
5
Abdominal plain films have been shown to be
4
69
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