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This procedure uses a proctoscope, sigmoidoscope, or colonoscope and digital examination to evaluate the lining of the distal sigmoid colon, rectum, and anal canal. It's indicated in patients with recent changes in bowel habits, lower abdominal and perineal pain, prolapse on defecation, pruritus, and passage of mucus, blood, or pus in the stool. Specimens may be obtained from suspicious areas of the mucosa by biopsy, lavage or cytology brush, or culture swab.

Possible complications of this procedure include rectal bleeding and, rarely, bowel perforation.


  • To aid diagnosis of inflammatory, infectious, and ulcerative bowel disease.
  • To diagnose malignant and benign neoplasms
  • To detect hemorrhoids, hypertrophic anal papilla, polyps, fissures, fistulas, and abscesses in the rectum and anal canal

Patient preparation

  • Explain to the patient that this procedure allows visual examination of the lining of the distal sigmoid colon, rectum, and anal canal.
  • Tell him that the test requires passage of two special instruments through the anus, who will perform the procedure and where, and that it takes 15 to 30 minutes.
  • Check the patient's history for allergies, medications, and information pertinent to the current complaint. Find out if he has had a barium test within the past week because barium in the colon hinders accurate examination.
  • Because dietary and bowel preparations for this procedure vary according to the doctor's preference, follow the orders carefully. If a special bowel preparation is ordered, explain to the patient that this clears the intestine to ensure a better view.
  • Instruct the patient to maintain a clear liquid diet the evening before the test and to fast the morning of the procedure, according to the doctor's preference.
  • Describe the position the patient will be asked to assume, and assure him that he'll be adequately draped.
  • Tell him that he may be secured to a tilting table that rotates into horizontal and vertical positions.
  • Tell the patient that the examiner's finger and the instrument are well lubricated to ease insertion, that the instrument initially feels cool, and that he may experience the urge to defecate when the instrument is inserted and advanced. Instruct the patient to breathe deeply and slowly through his mouth to relax the abdominal muscles; this reduces the urge to defecate and eases discomfort.
  • Inform him that the instrument may stretch the intestinal wall and cause transient muscle spasms or colicky lower abdominal pain.
  • Explain to the patient that air may be introduced through the endoscope into the intestine to distend its walls. Tell him that this causes flatus to escape around the endoscope, and he should not attempt to control it.
  • Inform him that a suction machine may remove blood, mucus, or liquid stool that obscures vision but that it won't cause discomfort.
  • Inform the patient that an I.V.line will be started if an I.V. sedative is to be used. If the procedure is being done on an outpatient basis and the patient is receiving conscious sedation, advise him to arrange for someone to drive him home. Conscious sedation may affect his reflexes and reaction time, even though he may feel fine.
  • Make sure the patient or a responsible family member has signed a consent form.
  • If the patient has rectal inflammation, provide a local anesthetic about 15 to 20 minutes before the procedure to minimize discomfort.

Procedure and posttest care

  • Obtain baseline vital signs, and leave the blood pressure cuff in place if the patient is to receive I. V. conscious sedation. Monitor the patient throughout the procedure and observe his skin color, temperature, and dryness; abdominal distention; level of consciousness;
    and pain tolerance.
  • Place the patient in a knee-chest or left lateral position with knees flexed, and drape him.
  • If a left lateral position is used, a sandbag may be placed under the patient's left hip so that the buttocks project over the edge of the table. The right buttock is gently raised, and the
    anus and perianal region are examined.
  • Instruct the patient to breathe deeply and slowly through his mouth as the examiner palpates the anal canal, rectum, and rectal mucosa for induration and tenderness; the examiner then withdraws his finger and checks for the presence of blood, mucus, or stool.
  • The sigmoidoscope is lubricated, and the patient is told that the instrument is about to be inserted. The right buttock is raised, and the sigmoidoscope is inserted into the anus. As the scope is passed with steady pressure through the anal sphincters, instruct the patient
    to bear down as though defecating to aid its passage. The sigmoidoscope is advanced through the anal canal into the rectum.
  • At the rectosigmoid junction, a small amount of air may be insufflated to open the bowel lumen. The scope is then gently advanced to its full length into the distal sigmoid colon.
  • As the sigmoidoscope is slowly withdrawn, air is carefully insufflated, and the intestinal mucosa is thoroughly examined.
  • If stool obscures vision, the eyepiece on the scope is removed, a cotton swab is inserted through the scope, and the bowel lumen is swabbed.
  • To obtain specimens from suspicious areas of the intestinal mucosa, a biopsy forceps, cytology brush, or culture swab is passed through the sigmoidoscope.
  • A laser, Bicap, or Argon Plasma Coagulator may be used to treat areas of bleeding or polyps.
  • Polyps may be removed for histologic examination by inserting an electrocautery snare through the sigmoidoscope.
  • Specimens are immediately placed in a specimen bottle containing 10% formaldehyde; cytology slides are placed in a Coplin jar containing 95% ethyl alcohol; culture swabs are placed in a culture tube.
  • Depending on the facility and the doctor's preference, after the sigmoidoscope is withdrawn, the proctoscope is lubricated and the patient is told that it's about to be inserted. Assure him that he'll experience less discomfort during passage of the proctoscope.
  • The right buttock is raised, and the proctoscope is inserted through the anus and gently advanced to its full length.
  • The obturator is removed, and the light source is inserted through the proctoscope handle.
  • As the instrument is slowly withdrawn, the rectal and anal mucosa are carefully examined. Specimens may be obtained from suspicious areas of the intestinal mucosa.
  • If a biopsy of the anal canal is required, a local anesthetic may be administered first.
  • After the examination is completed, the proctoscope is withdrawn.
  • If the patient has been examined in a knee-chest position, instruct him to rest in a supine position for several minutes before standing to prevent postural hypotension.
  • Observe the patient closely for signs of bowel perforation and for vasovagal attack due to emotional stress. Report such signs immediately.
  • If air was introduced into the intestine, tell the patient that he may pass large amounts of flatus. Provide privacy while he rests after the test.
  • If a biopsy or polypectomy was performed, inform the patient that blood may appear in his stool.

If a tissue specimen or culture swab has been obtained, label it and send it to the appropriate laboratory immediately.

Normal findings

The mucosa of the sigmoid colon appears light pink-orange and is marked by semilunar folds and deep tubular pits. The rectal mucosa is redder due to its rich vascular network, deepens to a purple hue at the pectinate line (the anatomic division between the rectum and anus), and has three distinct valves. The lower two-thirds of the anus (anoderm) is lined with smooth gray-tan skin and joins with the hair­fringed perianal skin.

Abnormal findings

Visual examination and palpation demonstrate abnormalities of the anal canal and rectum, including internal and external hemorrhoids, hypertrophic anal papilla, anal fissures, anal fistulas, and anorectal abscesses. The examination may also reveal inflammatory bowel diseases, polyps, cancer, and other tumors. Biopsy, culture, and other laboratory tests are often necessary to detect various disorders.

Interfering factors
  • Barium in the intestine from previous diagnostic studies (hinders visualization)
  • Large amounts of stool in the intestine (hinders visual examination and advancement of the endoscope)
  • Failure to place histologic or cytologic specimens in the appropriate preservative or to send the specimens to the laboratory immediately.

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