Flexible Sigmoidoscopy

Jeffrey A. German, MD and Clint N. Wilson, MD

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Subject: Flexible Sigmoidoscopy

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Flexible sigmoidoscopy is a commonly performed technique for examination of the rectum and distal colon. Sigmoidoscopy has been advocated every 3 to 5 years for individuals older than 50 years of age as a screening strategy to detect adenomas and colon cancer. The technique is safe, easily performed in an office setting, and produces a 30% to 40% reduction in colon cancer mortality. Training in endoscopic maneuvering and in anatomy and pathology recognition is required for the performance of sigmoidoscopy. Experienced practitioners often perform the procedure in less than 10 minutes. Most physicians report comfort with performing the procedure unsupervised after completing 10 to 25 preceptor-guided sessions. 
About 60% of all colorectal cancers are within reach of the sigmoidoscope. Rectal bleeding in individuals older than 50 years should be evaluated by full colonoscopy because of the risk for isolated proximal neoplasms beyond the view of the sigmoidoscope. Multiple options exist when evaluating a younger individual with rectal bleeding. For persons between the ages of 30 and 39 years, the incidence of colon cancer is only three cases per 1,000 people, but differentiating the few with serious pathology from those with anal disease can be difficult. Because proximal lesions also peak in individuals before the age of 40 years, full colonoscopy and flexible sigmoidoscopy with barium enema are appropriate strategies for individuals between the ages of 30 and 49 years. Most bleeding in individuals younger than 30 years is caused by benign anal disease. Flexible sigmoidoscopy is a reasonable option in that age group if anoscopic findings are normal. 
About 7% to 10% of flexible sigmoidoscopies reveal the presence of adenomas. Historically, the presence of an adenoma necessitated referral for colonoscopy to look for proximal neoplasia. Some physicians have recommended colonoscopy only for larger (>1 cm) adenomas, because larger lesions were more likely to have higher-risk villous features. However, the major benefit of universal biopsy of polyps discovered at sigmoidoscopy may be to distinguish tubular adenomas from villous adenomas. Persons with tubular adenomas of any size appear to have the same rate of proximal neoplasia as individuals with no adenomas at sigmoidoscopy (about 5.5%). A distal tubulovillous or villous adenoma has a higher rate of proximal neoplasia (about 12%), and this finding should incur referral for colonoscopy. 
Diminutive (<5 mm) polyps found at sigmoidoscopy often are hyperplastic. Although hyperplastic polyps generally are not thought to be associated with proximal adenomas, this opinion is not universally accepted in the literature. Many practices offer barium enema, and others recommend no further screening when hyperplastic polyps are found on sigmoidoscopic biopsy. 
Many physicians recommend full colonoscopy for colon cancer screening every 10 years for all individuals older than 50 years. Individuals at higher risk (i.e., those with a family history of colon cancer) may benefit from this strategy. Significant feasibility issues continue to prevent this approach from being recommended for population screening. A more feasible strategy is to perform screening sigmoidoscopy at age 50 for average-risk individuals. Only a small proportion of screened individuals with an occult proximal neoplasm will have the lesion progress to symptomatic colon cancer, and those that do progress take many years. Periodic sigmoidoscopy followed by a single screening colonoscopy at age 65 may be a more appropriate, cost-effective population strategy. 
The average procedure time for sigmoidoscopy without biopsy is about 17 minutes. Performance of a biopsy adds about 10 minutes to the procedure. Although it is desirable to insert the entire scope length (60 to 70 cm), the average depth of insertion is about 52 cm. Both procedure time and the depth of insertion appear to be operator dependent. Women have a more acute angle at the rectosigmoid junction, making endoscope passage more difficult. Studies in women also demonstrate that a history of prior pelvic or abdominal surgery increases the discomfort and decreases the depth of endoscope insertion. Sigmoidoscopy in women averages insertion depths of only 40 cm. 
In a large series in England, about 80% of individuals rated the discomfort of sig- moidoscopy as “no or mild pain.” The remainder rated their discomfort as moderate to severe, with women reporting significantly more discomfort. About 16% stated that their discomfort was greater than what they expected. Most procedures can be performed without sedation or analgesia, but if patients insist, premedication options include oral diazepam (10 mg) or triazolam (0.5 mg) taken 1 hour before the procedure, intranasal butorphanol (two squirts) immediately before the procedure, or intramuscular ketorolac (60 mg) administered 30 minutes before the procedure. 
Adequate preparation of the left colon is essential for flexible sigmoidoscopy. Eating after midnight is highly associated with stool in the sigmoid, and patients must be instructed to consume only clear liquids the morning of the procedure. Most practices recommend the administration of one or two enemas before the procedure. Home administration of the enemas may reduce patient embarrassment and time demands on office nursing staffs. However, many patients refuse to administer home enemas, feeling unable to perform the task or fearing a mess. Proper education of enema administration and offering an alternate, orally administered bowel preparation may reduce noncompliance with home bowel cleansing. 
Individuals often choose not to undergo sigmoidoscopy. Offering fecal occult blood testing simultaneously with sigmoidoscopy can cause some patients to avoid the invasive procedure. Increased acceptance of sigmoidoscopy can be achieved by sending a letter describing the significance of colon cancer and inviting individuals to participate in colon screening. Other factors that may favorably increase the uptake of the procedure include enthusiasm of the primary care physician and staff for the procedure, telephone reminders before the procedure, higher levels of general education in the target population, and skill of the practitioner performing endoscopy (especially for repeated screening). 
About one half of primary care physicians who are trained to perform flexible sigmoidoscopy do not continue the procedure in practice. One study documented that the main deterrents to continuing to offer the service included the time required to perform the procedure, the availability of the procedure from other physicians in their locale, and the availability of adequately trained staff. Low reimbursement for the time involved in the procedure, especially from the Medicare program, is often cited as a reason for discontinuing sigmoidoscopy screening. 


  • Sigmoidoscope and video monitoring equipment


  • Colorectal cancer screening

  • Evaluation of bright red rectal bleeding, especially in younger patients

  • Evaluation of an abnormal finding on rectal examination (e.g., palpable mass, polyp)

  • Evaluation of a woman with prior gynecologic malignancy

  • Evaluation of an abnormality identified radiographically

  • Investigation of abdominal pain

  • Suspected foreign body

  • Evaluation of symptoms that could be attributable to the colon (e.g., weight loss, iron-deficiency anemia, persistent diarrhea, change in bowel habits, painful defecation)

  • Surveillance of colon pathology (e.g., inflammatory bowel disease, prior polypectomy)

  • Follow-up after colectomy

Contraindications (Relative)

  • Acute peritonitis

  • Uncooperative patient

  • Coagulopathy or bleeding diathesis

  • Acute diverticulitis (do not insert the scope past a newly discovered inflamed diverticulum)

  • Acute fulminant colitis

  • Suspected ischemic bowel necrosis

  • Inadequate bowel preparation

  • Extensive pelvic adhesions

  • Severe cardiac or pulmonary disease

  • Pelvic adhesions (especially women with a prior hysterectomy), which can increase the procedure’s discomfort

  • Toxic megacolon

  • Anticoagulant or aspirin use at time of the procedure (discontinue aspirin at least 10 days before and coumadin at least 2 days before the procedure)

  • Paralytic ileus

  • Large (>5 cm) abdominal aneurysm

  • Suspected perforation of the bowel

The Procedure

Step 1

The patient is positioned in the Sims or left lateral decubitus position, with the left side of the body down on the table. The right hip and knee are both flexed, and the left leg remains fairly straight. A rectal examination is performed with the lubricated, gloved index finger. The nondominant hand lifts the right buttock. The anal canal and distal rectum are examined for pathology and to exclude any obstruction, foreign body, or stool that may prevent endoscope insertion. Use of 5% lidocaine ointment may decrease discomfort from the subsequent endoscopic procedure. 
  • PITFALL: Overly aggressive performance of a digital examination will make the patient uncomfortable and possibly reduce patient tolerance of the ensuing endoscopy. Perform the examination gently, and talk to the patient (i.e., verbal anesthesia) from the very beginning.

  • Pearl: Because the endoscope does not visualize the anal canal well, many authorities recommend performance of anoscopy before sigmoidoscopy (see Anoscopy with or without Biopsy).

Step 2

The endoscope is held in the left hand. The umbilical cord to the light source sits over the thumb web space and travels across the wrist. The endoscope head sits in the palm of the hand. The left thumb operates the inner (up and down) and outer (right and left) control knobs. The index finger and middle finger depress the air or water and suction valves. The left fourth and fifth fingers grasp and support the endoscope. 
  • PITFALL: Many individuals with small hands complain about the difficulty of holding the endoscope. It may be difficult for the thumb to reach the outer knob if the operator’s hand is small. Most operators can learn to manipulate the wheels with the left hand only; however, in rare cases, individuals with small hands must learn to operate the wheels using the right hand.

Step 3

The right hand is used to grasp the scope and to twist the scope (A). This helps with the insertion techniques described later. As the left thumb moves the scope tip up and down (B), the right hand can torque the curled scope tip to move it right or left (C). Alternately, some practitioners prefer to have a nurse assistant perform the scope insertion and withdrawal and to use the right hand to work the outer (right or left) knob. Insertion by a second person limits the ability to feel tension on the colon wall and to perform torquing maneuvers. 

Step 4

The scope is lubricated with water-soluble jelly, and insertion is performed by direct insertion of the scope tip into the anus or by pushing the scope tip inside with the index finger behind the scope. Some practitioners press tangentially on the anal verge to facilitate insertion. 
  • PITFALL: Do not apply lubricating jelly on the tip of the scope, as it will smear the lens and distort the image.

  • PITFALL: Care must be taken when inserting the scope in women to avoid an embarrassing and potentially injurious intravaginal insertion.

Step 5

The scope is inserted into the rectum (7 to 17 cm), and air is insufflated to reveal the lumen. Some practitioners suction fluid from the rectum. The lumen is used as a guide for insertion, thereby reducing patient discomfort and risk of perforation. Air can be continuously or intermittently inserted to open the inside of the colon for passage and viewing. 
  • PITFALL: Avoid suctioning any solid stool (shown), because this can rapidly dry and clog the suction channel, necessitating costly repairs to the endoscope. Even fluid in the rectum may have stool, and suctioning should be performed only when needed.

Step 6

Insert the scope as rapidly as possible to limit patient discomfort and spasm, which can make insertion more difficult. Three transverse folds of mucosa are seen in the rectum, and these are passed to enter the rectosigmoid. 

Step 7

When maneuvering around folds or bends, torquing the endoscope with the right hand allows passage through turns. Dithering is the rapid back-and-forth motion that sometimes facilitates finding the lumen and passing the scope. 

Step 8

The hooking and straightening technique may be used for passage through a tortuous sigmoid. As the endoscope is inserted in the sigmoid, the sigmoid may bow upward, producing significant patient discomfort (A). The endoscope tip is maximally deflected, and the sigmoid is “hooked” (B) as the scope is withdrawn (C). The scope tip can paradoxically appear to move forward through the lumen as the endoscope is withdrawn. The sigmoid is straightened, and the endoscope passes through the sigmoid (D). 

Step 9

The endoscope is then maximally inserted. Viewing takes place as the endoscope is withdrawn. Use the markings on the endoscope to document depth of insertion of the scope for all pathology encountered. 
  • PITFALL: Do not mistake a large diverticular orifice for the lumen. The posterior walls of diverticular sacs can be quite thin, and perforation is easily accomplished by inadvertent entry into a diverticular sac.

Step 10

Biopsy is performed by threading the metal biopsy instrument through the biopsy channel. The open biopsy forceps can serve as a guide to the size of lesions, measuring approximately 5 mm when opened. A syringelike plunger on the end of the biopsy forceps is used to open and close the forceps. 
Step 10
Step 10

Step 11

After the endoscope is withdrawn to the rectum (i.e., 10 to 15 cm inserted), the scope tip is retroverted to examine the distal rectal vault. This area is not well visualized by the forward-directed scope as it passes the area. Retroversion is achieved by maximally deflecting both the inner and outer knobs with the left thumb while simultaneously inserting the scope with the right hand. 
Step 11
Step 11

Step 12

Finally, the scope is straightened and the lumen viewed. Air is withdrawn from the rectum before the scope is withdrawn. The scope tip is immediately placed in soapy water, and the water is suctioned to prevent clogging of the suction channel. The anus is wiped clean with gauze, and the patient is offered the opportunity to go to the bathroom. The patient is permitted to get dressed after the procedure and before the findings are discussed. 
  • PITFALL: Vasovagal responses are possible during or after the procedure. Patients should be allowed to sit for a minute with the legs dangling off the table before being allowed to get off the examination table.

Step 12
Step 12


  • Perforation

  • Bleeding following polypectomy

Pediatric Considerations

Pediatric scopes are available that are of a smaller diameter than adult scopes. Alternatively, a gastroscope can be used. 

Postprocedure Instructions

After the procedure, patients may resume their regular diet and activity. They should be warned to contact their doctor immediately if they experience severe abdominal pain (not just gas cramps); a firm, distended abdomen; vomiting; fever; or bleeding greater than a few tablespoons. 

Coding Information and Supply Sources

For coding purposes, sigmoidoscopy involves examination of the entire rectum and sigmoid colon and may include a portion of the descending colon. 

Common ICD-9 Codes

Instrument and Materials Ordering

  • The Ives slotted anoscope is available from Redfield Corporation, 336 West Passaic Street, Rochelle Park, NJ (phone: 800-678-4472; http://www.redfieldcorp.com)

  • Recommendations for endoscope cleaning appear in Procedural (Conscious) Sedation.

  • Complete endoscopy equipment such as endoscopes, light sources, video endoscopy monitors, cleaning and disinfection aids, and mouthpieces are available from the following manufacturers:

  • A viscous 2% lidocaine topical solution is available from Alpharma USPD, Bridgewater, NJ (http://www.alpharma.com)

  • Butorphanol tartrate (Stadol) nasal spray is available from Bristol-Myers Squibb (http://www.bms.com)

  • Intravenous materials (e.g., intracaths, normal saline solution, intravenous tubing) can be obtained from local hospitals or surgical supply houses.


American Academy of Family Physicians. Flexible Sigmoidoscopy Preceptorial Training Program: A Syllabus for the Physician Starting to Perform Flexible Sigmoidoscopy in the Office. Kansas City, MO: Author;  1985.
Atkin WS, Hart A, Edwards R, et al. Uptake, yield of neoplasia, and adverse effects of flexible sigmoidoscopy screening. Gut.  1998;42:560–565. [View Abstract]
Cohen LB. A new illustrated “how to” guide to flexible sigmoidoscopy. Prim Care Cancer.  1989;9:13–20.
Davis PW, Stanfield CB. Flexible sigmoidoscopy: illuminating the pearls for passage. Postgrad Med.  1999;105:51–62. [View Abstract]
Esber EJ, Yang P. Retroflexion of the sigmoidoscope for the detection of rectal cancer. Am Fam Physician.  1995;51:1709–1711. [View Abstract]
Herman M, Shaw M, Loewen B. Comparison of three forms of bowel preparations for screening flexible sigmoidoscopy. Gastroenterol Nurs.  2001;24:178–181. [View Abstract]
Holman JR, Marshall RC, Jordan B, et al. Technical competence in flexible sigmoidoscopy. J Am Board Fam Pract.  2001;14:424–429. [View Abstract]
Levin TR, Palitz A, Grossman S, et al. Predicting advanced proximal colonic neoplasia with screening sigmoidoscopy. JAMA.  1999;281:1611–1617. [View Abstract]
Lewis JD, Asch DA. Barriers to office-based screening sigmoidoscopy: does reimbursement cover costs?Ann Intern Med.  1999;130:525–530. [View Abstract]
Lewis JD, Asch DA, Ginsberg GG, et al. Primary care physicians’ decisions to perform flexible sigmoidoscopy. J Gen Intern Med.  1999;14:297–302. [View Abstract]
Lund JN, Buckley D, Bennett D, et al. A randomized trial of hospital versus home administered enemas for flexible sigmoidoscopy. Br Med J.  1998;317:1201. [View Abstract]
Mayberry MK, Mayberry JF. Towards better informed consent in endoscopy: a study of information and consent processes in gastroscopy and flexible sigmoidoscopy. Eur J Gastroenterol Hepatol.  2001;13:1467–1476. [View Abstract]
McCallion K, Mitchell RM, Wilson RH, et al. Flexible sigmoidoscopy and the changing distribution of colorectal cancer: implications for screening. Gut.  2001;48:522–525. [View Abstract]
Ransohoff DF, Lang CA. Sigmoidoscopic screening in the 1990s. JAMA.  1993;269:1278–1281. [View Abstract]
Rees MK. We should all be performing flexible sigmoidoscopy. Mod Med.  1987;55:3, 12.
Sanowski RA. Flexible Fiberoptic Sigmoidoscopy. Research Triangle Park, NC: Glaxo,  1992.
Verne JE, Aubrey R, Love SB, et al. Population based randomized study of uptake and yield of screening by flexible sigmoidoscopy compared with screening by faecal occult blood testing. Br Med J.  1998;317:182–185. [View Abstract]
Wallace MB, Kemp JA, Trnka YM, et al. Is colonoscopy indicated for small adenomas found by screening flexible sigmoidoscopy?Ann Intern Med.  1998;129:273–278. [View Abstract]
Williams JJ. Why family physicians should perform sigmoidoscopy [Editorial]. Am Fam Physician.  1990;4:1722, 1724.
Winawer SJ. Office screening for colorectal cancer. Prim Care Cancer.  1993;13:37–46.
Zuber TJ. Flexible sigmoidoscopy. Am Fam Physician.  2001;63:1375–1380, 1383–1388.
Zuber TJ. Office Procedures. The Academy Collection Quick Reference Guides for Family Physicians. Baltimore: Williams & Wilkins;  1999:35–42.
2008 MAG Mutual Healthcare Solutions, Inc.’sPhysicians’ Fee and Coding Guide. Duluth, Georgia. MAG Mutual Healthcare Solutions, Inc.2007.