Douglas J. Sprung, M.D., Ira Shafran, M.D., Matthew N. Apter, M.D., Orlando, FL
Flexible sigmoidoscopy can be mastered only after has an understanding of the technical skills and even more important, the interpretive skills. While technical skills can be mastered in twenty-five examinations, most endoscopists would agree that several years of practice and seeing numerous patients with numerous disease will allow for interpretive skills to develop. Differentiating normal from abnormal, scope artifact from real disease, subtle variations in color, mucosal texture, vascularity, and significant landmarks can take years of time to accrue. Even among skilled, experienced examiners, interpretation variations do occur. Our purpose today is to familiarize you with normal and abnormal findings in flexible sigmoidoscopies as well as discussing the technical aspects of the procedure.
The assistant should prepare the examination room and equipment before bringing the patient to the room. All controls and functions of the scope should be tested before each procedure. Supplies including gloves, gauze, lubrication irrigation solution should be organized within reach of the sigmoidoscopist. It is a good idea to have photography for back-up for documentation and also for teaching purposes. Sedation is not usually necessary for routine flexible sigmoidoscopy, especially when the patient has been well prepared by the proper demonstration and discussion for what is to come.
The ideal patient position is, to some extent, a matter of examiner preference; however, in my experience, and in the experience of the majority of consultants which we use, the left lateral or sims position is optimal for both patient comfort and ease of accomplishing the procedure. The table is raised to an appropriate height and a thorough inspection of the perinal area accomplished before the actual procedure begins. The examiner should look for evidence of hemorrhoids, fissures, rectal prolapse and other pathological processes, common or unusual which may occur. If the specific symptoms such as rectal or anal pain, burning and itching, have occurred as well as any history of bright red rectal bleeding, an anoscopic exam should be performed with a standard metal anoscope or even the clear disposable ones. This separate procedure is not routinely necessary because most pathology will be easily visualized with the sigmoidoscope.
In my office, we routinely double glove the right hand, performing the digital rectal exam and the insertion of the tip of the sigmoidoscope before removing the outer glove, allowing a fresh gloved right hand to complete the procedure. The scope is lubricated without covering the lens and the tip is then carefully pressed at an angle against the anal sphincter and gradually eased into the rectum. The scope is then rotated 90 degrees clockwise, followed by mild sacral tip deflection and then gently inserted under direct visualization to approximately 18 to 20 cm. At this point, the first difficulty of insertion often occurs, and further insertion can be accomplished with a clockwise rotation with mild tip deflection. As long as the scope can continue to be advanced easily, the procedure can be continued. However, at this point or any other where there is doubt of the location of the tip of the scope, it must be withdrawn from 1 to 3 cm to be sure advancement is in the right direction.
The least degree of flexion necessary to visualize the lumen should be used since instrument advancement is more difficult when the tip is sharply angled. Also a tight angle may, in effect, become a leading edge, resulting in little force actually reaching the instrument tip. Serosal tears or even perforation in an extreme case could be the result of this action.
Clockwise rotation is favored over counterclockwise rotation because it will help reduce the angle of the sigmoid curve while counterclockwise rotation will accentuate the angle of the curve. In addition, most sigmoidoscopes are manufactured in such a way that clockwise rotation tends to straighten the scope, while counterclockwise rotation actually kinks the scope shaft.
The least amount of air insufflation required to maintain an open lumen is preferable in performing flexible sigmoidoscopy. Air insufflation is rarely needed on insertion and its use is to be discouraged because of its balloon like effect on the sigmoid curves. Excessive air insufflation causes spasm, colonic distention, and marked patient discomfort, and can actually increase the acuteness of the sigmoid descending junction, making instrument insertion more difficult. The colon is elastic and thus may become elongated and tortuous when overinflated. Another risk of overinflation is perforation of a diverticulum, serosal lacerations or even pneumatic perforation of the cecum. Feel free to use a moderate amount of air on withdrawal. However, it is a good idea to remove as much air as possible just before withdrawing the scope from the rectal vault.
The bowel wall may be pleated onto the scope by dithering. This, in effect, shortens both the sigmoid colon and decreases the major sigmoid angle. When difficulty in insertion is encountered, the patient may also be asked to rotate more onto his abdomen or back, with or without an assistant's hand on the abdomen for counter pressure. The slide-by technique allows the passage of the scope without direct luminal visualization. The wall should be observed easily sliding past the tip of the instrument and never becoming obscured with a "red out". However, this technique should be reserved until the endoscopist has a wider range of experience. The maximum extent of insertion is determined when the maximum insertion depth of the scope itself is reached, when patient discomfort precludes further examination, or when an inadequate prep is encountered. Insertion itself should be accomplished as rapidly as possible with more time being reserved for examination of the bowel wall while the instrument is pulled out. A continuing 360 degree motion of the tip should be accomplished by either using the left-right and up-down controls or by using the up-down control and a left-right torque in a rhythmic pattern. This will be demonstrated during the practical part of the session. Care should be taken to examine the rectal vault carefully and behind all folds or curves. This part of the examination is nearly painless and is well tolerated. The location of lesions by notation of number of centimeters of the instrument inserted is most reliable during withdrawal after sigmoid loops formed during insertion have been reduced.
Remember the cardinal rules for flexible sigmoidoscopy:
1. Keep tip deflection to a minimum.
2. "When in doubt, pull out."
(Withdraw a few centimeters and reorient.)
3. Keep air insufflation to a minimum and,
On normal findings during sigmoidoscopy, one should comment on the appearance of the mucosa. The following are important items which should be described:
1. The color of the mucosa.
2. The texture of the mucosa.
3. The vascularity of the mucosa.
4. The contour or light reflection.
5. The distensibility and peristalsis. 6. The size of the lumen.
When one observes the mucosa, all of these specific descriptors should be kept in mind. Instantaneous documentation is important and should occur in conjunction which each and every procedure, as well as photographic documentation and appropriate labeling.
Each and every procedure should include a statement about
informed consent, as well as the specific finding, your diagnostic
conclusions and recommendations and follow up. It is
important to include all of the elements of informed consent, including
the benefits, diagnostic alternatives, risks, and full disclosure of the
procedure by the physician in the presence of witnesses. You will find
in this syllabus an example of an informed consent document used in a gastroenterologistís
office. Once the procedure is performed, the written report should include
the date of the procedure, the type of procedure, the type of instrument,
and whether or not anesthesia was used and if so, what drug and how much
was administered over what period of time. The findings of the procedure
should then be discussed incorporating into this discussion interpretive
findings. Normal and abnormal should be discussed with reference to the
distance of findings from the anal verge, left, right, posterior, or
anterior wall. This orientation does take some time to develop. In addition
to the specific findings, the sigmoidoscopist should describe the configuration
of the rectosigmoid colon as to itís configuration, whether it is straight,
tortuous, looping, mal-rotated, patulous, or narrowed. The ease or difficulty
encountered in each and every patient with specific reference to the patientís
tolerance is also stated in the procedure note. The depth of insertion,
whether or not extrinsic pressure was required over the left lower quadrant
or other areas of the abdomen, or whether rotating the patient should also
be included in the detailed report. After the procedure is performed and
completed, the examiner should report diagnostic conclusions followed
by specific recommendations and follow up. Proper documentation will serve
as an excellent reference point for future examiners or consultants, who
may need to refer to old records for comparison or follow up. Medicolegally,
one can not stress the importance of proper documentation.
I. ANATOMY OF LARGE INTESTINE
II. INFLAMMATORY BOWEL DISEASE
a. Ulcerative colitis
b. Crohn's colitis
c. Bacterial colitis (Shigella, Campylobacter, Salmonella)
d. Amoebic colitis
e. Intestinal tuberculosis
f. Antibiotic associated colitis
g. Diverticulosis and diverticulitis
h. Radiation colitis
i. Ischemic colitis
III. BENIGN EPITHELIAL TUMORS
b. Villous adenomas
c. Hyperplastic polyps
d. Juvenile polyps
e. Peutz-Jeghers and other inheritable syndrome polyps
IV. COLON MALIGNANCIES
a. Primary malignancies of colon
b. Nonmetastatic invasion from primary malignancies and metastatic lesions to large intestine.
V. MISCELLANEOUS LESIONS
a. Pneumatosis cystoides intestinalis
b. Melanosis coli and cathartic colon
c. Colitis cystica profunda
d. Solitary rectal ulcer syndrome
The normal appearance of the rectal mucosa really depends
on the age of the patient and the type of prep used. In general, rectal
mucosa is pale, pink in color, with a background of blood vessels, which
are finely arborized with side branching of vessels. The rectum is more
patulous and more readily distensible then the sigmoid colon. Generally,
the rectum begins at the distal margin of the dentate line or the squamocolumnar
junction occurs and ends at a depth between 12 cm and 15 cm from the anal
verge at the "rectosigmoid junction". The rectosigmoid junction
is often identifiable by a subtle or acute change in the direction and
the appearance of the rectum, and a change in a mucosa to a more typical
mucosa of the sigmoid colon. The sigmoid colon mucosa is
generally a darker shade of pink with less prominent vascularity and the
salient feature is the presence of muscular valve. The configuration of
the sigmoid colon is highly variable from patient to patient. The appearance
of muscular contractions, spasm, and the requirement for some degree of
air insufflation to keep the lumen open are characteristic of the sigmoid
colon. The average length of the sigmoid is between 25 cm & 35 cm.
The junction of the sigmoid and descending colon usually occurs between
40 cm and 50 cm from the anus. The descending colon is typically
similar to the appearance of the sigmoid with regard to itís mucosal appearance,
however, it is straight and more tubular and often times will allow an
unimpeded view of the entire descending colon all the way to the splenic
flexure. The majority of young healthy colons in relaxed reassured
and well prepared patients can be examined to a full depth of 60 cm with
relative ease and minimal discomfort with new thinner caliber scopes employing
video endoscopy. There are patients who are more difficult to examine completely,
and these include:
1. Patients with extreme diverticular disease.
2. Patients with prior pelvic or general abdominal surgery, hysterectomy, or multiple abdominal operations.
3. Patients with marked redundant looping or laxative dependent colons.
4. Patients with prior radiation therapy.
5. Patients with chronic inflammatory bowel disease.
6. Uncooperative patients.
The examiner should attempt to examine as much of the rectosigmoid and descending colon as possible, remembering that tolerance of the patient will define how far a procedure can be carried out. There is no absolute rule stating that each and every sigmoidoscopic exam has to be carried out to the full depth of insertion. In circumstances where the examiner is too aggressive, complications can occur, particularly in the early part of learning this procedure.
It will not be possible to cover completely all of the disease states, differential diagnosis, and interpretative data in one short session. Therefore you are all advised to read additional references, texts and publications. An overview discussion on abnormal findings would include:
1. Inflammatory diseases
2. Neoplastic diseases
3. Acquired and traumatic conditions
The spectrum of causes for inflammatory colitis is wide.
The most common maladies one should be familiar with would include idiopathic
ulcerative colitis, Crohn's colitis, and infectious colitis due to various
pathogenic bacterial species, most commonly Shigellosis, Salmonellosis,
Campylobacter, amoebic disease, and other less common infections such as
intestinal tuberculosis, cytomegalovirus. The endoscopic appearance of
inflammatory colitis, either due to idiopathic ulcerative colitis or
bacterial etiology is that of:
1. Diffuse inflammation involving the rectum.
2. Symmetrical inflammation.
3. Ulcers surrounded by inflammatory mucosa.
4. No skipped lesions generally or patchy abnormalities separate from the lesion. With active colitis one usually observes hyperemia with velvety reddening or fine granulation of the mucosa and a distortion or loss of vascular pattern.
In this day and age of potent, broad-spectrum antibiotics, we are seeing antibiotic colitis much more commonly. This disorder is due to Clostridium difficile mediated toxin and can occur with any antibiotic including any of the broad-spectrum, systemic or oral antibiotics. The Clostridium difficile toxin elaborates a cytotoxin which causes focal necrosis along with acute inflammatory exudate which is the pseudomembrane. The clinical illness is generally that of abdominal pain, cramping, watery diarrhea which occasionally becomes bloody in 5 - 10% of cases, fever, leukocytosis, and rebound tenderness. The characteristic appearance sigmoidoscopically is that of large confluent pseudomembranes which are often present along with erythema and edema, these pseudomembranes appearing as 1 - 5 mm yellow plaques with their size depending on the timing of colonoscopy in relation to the onset of diarrhea. These are generally smaller in the first 18 hours and generally enlarged after 72 hours into the illness where they may become up to 5 mm size. It is estimated that one third of cases have only mild rectal and sigmoid erythema and in a small percentage of cases, complete rectal sparing has been described. The finding of pseudomembranes in the context of recent antibiotic therapy and C. difficile toxin in rather characteristic and diagnostic of this disease which is important to recognize and treat aggressively since its morbidity and mortality are significant if undiagnosed.
The last type of inflammatory and miscellaneous colitis to be mentioned is that of ischemic colitis which is being recognized increasingly in the elderly patient who presents with lower abdominal pain and rectal bleeding. Generally, the incidence is highest in those patients with concomitant dehydration, cardiogenic shock or the presence of underlying atherosclerosis. The appearance sigmoidoscopically depends on the stage in which it is diagnosed, as in the first 72 hours the acute state of patchy hyperemia mucosa alternating with pale areas are through to result from transient blanching of the mucosal blood vessels. Over a 24 hour period the erythema coalesces and ischemia begins to spread to involve more mucosal area at which point superficial ulcers which are 2 - 4 mm in size occur. In the subacute stage which generally occurs three to seven days after the onset of symptoms, ulcers are found which are elongated and serpiginous (snake-like). These can often times be confused with Crohn's disease. In the chronic stage which generally occurs two weeks to three months after the onset of symptoms, residual granularity can occur and occasionally stricture formation. Rare types of colitis, radiation colitis, Behcet's disease, hemolytic ureic syndrome, malakoplakia, schistosomiasis, colonic tuberculosis, Yersinia enterocolitis cytomegalovirus and drug induced colitis are rare and are not worthy of lengthy discussion at this time.
Diverticular disease (a term which encompasses all stages; prediverticular phase, diverticulosis and diverticulitis), of the colon is a common occurrence in the aged. From 10 - 50% of persons over the age of 40 have diverticulosis coli. The figure rising each year with aging. The sigmoid colon is the most common area of the colon involved, however, any area of the colon can be involved. Diverticula are produced by herniation of the mucous membrane trough the bowel wall in response to high intramural pressure. Diverticular orifices can be recognized endoscopically when they are present associated with muscular hypertrophy, hypertonicity of the colon and spasm. Within the sigmoid they are recognized as 3 - 5 mm circular openings in the central portion of the short haustral segment situated between the enlarged valvulae. Colonic diverticula are often times an incidental finding. The importance to the endoscopist is that these can be easily confused with the lumen making the examiner reluctant to proceed. One often times cannot tell the opening to the diverticulum from the lumen opening which is often times smaller in the examiner have any doubt differentiating lumen versus diverticulum, the prudent measure is to withdraw the scope first and re-establish the general direction of the valvulae rather than to proceed blindly into what may be a larger diverticulum with the likely potential for perforation. In the case of diverticulitis, the area immediately around the diverticula becomes spastic, narrowed, with enlarged valvulae. Purulent material may often times be seen extruding from the mouth of the perforated diverticulum, although this is unusual. In diverticular strictures in late stage disease, one sees varying degrees of narrowing of the lumen which can often times be difficult to differentiate from neoplastic strictures. Often times this differentiation can only be made by appropriate biopsies of the segment, radiographic correlation and in certain percentage of cases, surgical intervention.
Colon polyps are perhaps the most common pathologic
abnormalities found on sigmoidoscopic examination with an incidence approaching
up to 50% of colons examined at the time of autopsy. Up to 30% of all patients
with rectal bleeding will be found to have colonic polyps. In the case
of a patient with one rectal polyp, a synchronous polyp found elsewhere
in the colon may be expected in up to 50% of patients undergoing total
colonoscopy. Colon polyps are classified in numerous ways. The epithelial
types which can be either neoplastic or non-neoplastic.
Neoplastic polyps including adenomas can be tubular, tubulovillous or villous,
and polypoid carcinomas. Our discussion regarding the description of the
most common polyps will include the above. Less common, rare polyp syndromes
will be briefly mentioned, including multiple polyposis, Peutz-Jeghers
disease, and other rare polyposis syndromes.
Adenomas are the most common type of polyp noted at sigmoidoscopy. 65% of these lesions are found between the splenic flexure and rectosigmoid junction. The most common location overall is the sigmoid followed by descending colon, followed by the rectum. The average size is between 5 mm and 2 cm and up to 35% of patients will have more than one. The appearance of a typical adenoma (tubular, tubulovillous or villous) varies depending on the size of the polyp. the tiny adenomas, less than 3 mm, appear as excresences which are somewhat redder than the surrounding mucosa. The small adenomas of 4 - 9 mm are smooth, often perfectly round, sessile, or pedunculated polyps. The moderate sized adenomas from 1 - 2 cms in size are often round but can be lobulated with erythematous mucosa and if stalks are present, thicker stalks than those of smaller adenomas. The larger adenomas of greater than 2 cm size are often times multilobulated with each lobe in excess of 0.5 mm, as if the polyp was made up of multiple small adenomas fused up to make on large polyp. The tubulovillous adenomas are generally 1 - 2 cm or larger and tend to be pedunculated and wider with shorter pedicles than tubular adenomas. The villous adenoma appears as a soft, sessile lesion with a surface consisting of multiple 3 - 6 mm nodules, projecting off the surface for several millimeters. They are generally large with a maximum dimension varying anywhere from 1 cm up to 8 cms, most often sessile and up to 50% incidence of malignancy.
The hyperplastic polyps are the most frequent polyps found in the large intestine. These typically are less than 5 mm size and have a characteristic endoscopic appearance of a small, sessile, smooth, pale lesion which blends in fairly imperceptibly with the surrounding mucosa. These can often be multiple and do not generally have neoplastic potential.
Juvenile polyps, as the name indicates, are most common amongst children and adolescents with the average age of 4 or 5 years but they are occasionally found in adults. The rectum and sigmoid are most common sites for occurrence and these polyps typically are less than 2 cm in size and are stalked and endoscopically often times appear beefy red, smooth and hemorrhagic appearing. Peutz-Jeghers is a rare polyposis syndrome consisting of GI polyps and pigmentation of the skin and/or mucous membrane transmitted as a mendelian dominant gene. These polyps often resemble adenomas which can vary in size.
Familial polyposis coli is another rare syndrome of hundreds and thousands of adenomas found in the rectosigmoid and remaining colon. This disorder is inherited as a mendelian dominant gene which is not sex-linked and is easily recognizable by a literal carpeting of the colon with small sized polyps varying in sizes and shapes. The high incidence of malignancy at an early age is well-known in this condition. Rare syndromes of Gardner's syndrome, Canada-Cronkhite syndrome and Turcot's syndrome will not be discussed in any detail at this time. Generally, the practitioner should document the presence of a polypoid lesion and make the appropriate referral to one who performs total colonoscopy to ultimately excise the polypoid lesion and look for additional ones.
Colorectal carcinomas are the most common gastrointestinal malignancies in industrialized countries with the exception of Japan where gastric carcinoma is the most common. These have much the same distribution as adenomas, most frequently situated in the distal colon and rectum (up to 75% of all lesions). Colorectal cancers have characteristic appearances so that endoscopic diagnosis is generally easy. If the scope is able to reach the lesion the diagnosis is made by biopsy and occasionally cytology increasing the diagnostic potential of the examination. The following are limitations of endoscopy:
1. It is often difficult to obtain an entire picture of the lesion, particularly in cases where there is high grade stenosis.
2. Bleeding may prevent observation.
3. Remaining stool may obscure the whole or part of the tumor.
4. Occasionally sigmoidoscopy can be hazardous in a situation where intestinal adhesions produced by the cancer are extensive.
5. Colon carcinomas can have a polypoid configuration where they are grossly cauliflower-shaped and a sessile, polypoid configuration, friability and bleeding with an endoscopic appearance of a raw hamburger steak which "chunks off" with biopsies is very characteristic.
Other neoplastic diseases involving the colon can be confused with primary colon cancer. Primary colon carcinoid which can occur in the rectum as a central, submucosal, umbilicated lesion, lymphosarcoma, and other secondary malignancies metastasizing to the colon such as that from the ovary, uterus, prostate, pancreas, gallbladder, appendix or other distant organs often can be confused with primary lesions. Those non-neoplastic lesions such as inflammatory disease involving neighboring organs of female genitalia, pancreas, kidney, can be confused with malignant disease and benign inflammatory bowel disease with associated stenosis, stricture or pseudopolyps are often indistinguishable endoscopically and can only be differentiated in the context of the clinical history and with appropriate histopathologic information. In general, a raised, ulcerated, cauliflower, or exophytic lesion should be biopsied, taking a small bite of tissue from the friable lesion itself, not near the area where it is attached to the bowel wall and not within an ulcer crater. Generally, cancer tissue is very hard and fragments off and does not require sharp biopsy, whereas normal tissue is elastic and easily movable. For distal rectal lesions, retroflexion of the sigmoidoscope is often times valuable for seeing very distal lesions which are not as clearly visible by direct vision. This maneuver is often times technically difficult and occasionally painful for patients, particularly with large bore endoscopes. Certainly, one must never forget the importance of a careful digital examination which, in most cases, detects up to 35% of malignancies and polyps.
Colonic appearances secondary to cathartics, melanosis coli and laxative colon, are seen in conditions where patients have been using laxatives in the class of anthraquinones which include Cascara, Senna, rhubarb, and other emodins where the active agent is hydroxylmethylanthraquinone. Other laxatives such as Phenolphthalein (Ex-Lax), Bisacodyl (Dulcolax), have also been implicated as a cause for cathartic colon but not melanosis coli. The appearance of melanosis coli is that of brown patches of streaks throughout the colon which appear to be interconnected in a reticulated pattern. In the cathartic colon, the principal involvement is in the right colon where the patulous ileocecal valve is noted and loss of haustration. Colonic ulcer syndromes, a solitary rectal ulcer syndrome (stercoral ulcer), this uncommon condition of solitary rectal ulcer can occur due to excessive straining, fecal stasis, bedridden states, where ischemic necrosis of the surface epithelium will occur and in the ulcer state, ulcers varying from 2 - 8 mms in size 5 - 10 cms from the anal verge are noted as discrete, punched out, well demarcated ulcers with raised, erythematous mucosa surrounding the edges.
Colitis cystic profunda - this non-neoplastic condition is possibly related to the solitary rectal ulcer syndrome and is rare and it appears that of single or multiple nodules which on biopsy have a rubbery consistency with slight erythematous overlying mucosa.
Pneumatosis coli - This is an unusual condition of the colon characterized by gas-filled cysts in the wall of the colon, often associated with other underlying diseases, i.e. chronic obstructive pulmonary disease, gastric cancer, peptic ulcer disease with obstruction. The appearance of these lesions are those of submucosal polypoid masses ranging from 2 - 3 mm in size which are soft and easily compressible, which on biopsy often pop or hiss as if air is being expelled and the cyst is seen to deflate.
Colonic anastamoses - The sigmoidoscopist needs to be aware of the range of appearances for an uncomplicated anastamosis and that of a recurrent neoplasm or inflammatory condition involving the anastomosis. A wide variation in the degree of nodularity and appearance of the folds may occur depending on the technique used by the surgeon, whether it be hand sutured or stapled. One may find suture granuloma, anastomotic stricture, or significant deformity secondary to unusual healing processes.
1. Watch the patient and assess his condition with every movement of the scope.
2. Once the procedure has begun do not move your eye from the eyepiece, viewing the interior of the colon constantly.
3. Always be alert to find out the center of the lumen & adjust the tip to it.
4. Do not bend the scope acutely while inserting it.
5. When advancing the scope recall the pathway it followed upon entering the colon and think of the shape of this pathway when further introducing the scope.
6. Remember always that advancement of the scope does not rely solely on pushing the scope but rather on a combination of pushing forward and pulling back.
8. Remember that pain is a warning sign do not persist in any maneuvers that cause the patient pain.
9. Do the procedure as rapidly as possible to avoid irritation of the colon and patient.
10. Be aware of your own abilities and know when to stop the examination and withdraw the scope.
"FLEXIBLE SIGMOIDOSCOPY WORKSHOP"
FLORIDA SOCIETY OF INTERNAL MEDICINE
Workshop designed and presented by
IRA SHAFRAN, M.D.