Fig. 31.1
Large rectal polyp
Fig. 31.2
Colon cancer
Fig. 31.3
Colonic diverticula
Fig. 31.4
Angiodysplasia
Fig. 31.5
Hemorrhoids
Therapeutic procedures performed
Biopsy sites
Complications
Recommendations/plan
31.2.2 Colonoscopy
The designation of a “diagnostic” or “therapeutic” procedure can only be assigned after the procedure. It is generally unacceptable to perform diagnostic procedures without the skill to also perform the therapeutic maneuvers that are likely to be indicated. All colonoscopists must be trained in polypectomy and must perform colonoscopy with the intent to clear the colon of polyps at the initial examination [1–3].
31.2.2.1 Indications
In clinical practice, opinions differ regarding indications for colonoscopy. Standard indications are:
Evaluation of an abnormality seen on barium enema or virtual colonoscopy
Evaluation of unexplained GI bleeding
Melena after an upper GI source has been excluded by gastroscopy
Presence of fecal occult blood (positive fecal occult blood test)
Unexplained iron-deficiency anemia
Follow-up/surveillance after polypectomy for adenomas
Follow-up/surveillance after colorectal cancer resection
Clearing the colon of synchronous neoplasia (polyps or cancer) in patients with colorectal cancer
After identification of adenomas on sigmoidoscopy
Follow-up/surveillance of ulcerative colitis
Follow-up/surveillance of Crohn’s colitis
Colorectal cancer screening
Chronic inflammatory bowel disease of the colon (to make a more precise diagnosis or determine the extent and activity of disease)
Significant diarrhea of unexplained origin
Intraoperatively to identify a lesion that is not apparent during surgery
31.2.2.2 Generally Accepted Nonindications/Relative Indications
Irritable bowel syndrome
Acute self-limited diarrhea
Stable inflammatory bowel disease (except in cancer surveillance)
Melena with clear suspicion of an upper GI source
Hematochezia with an anorectal source clearly seen on sigmoidoscopy
Surveillance after curative resection for colon cancer, to rule out a cancer recurrence on the suture line
Routine evaluation before elective noncolonic abdominal surgery with no symptoms related to the colon or rectum
31.2.2.3 Contraindications
There are similar to those for sigmoidoscopy but also include situations where the patient is unable to cooperate and/or cannot be adequately sedated.
31.2.2.4 High-Risk Situations (Relative Contraindications)
Uncontrolled lower GI bleeding (hemodynamic instability)
Recent colorectal surgery/immediate postoperative stage
Multiple pelvic surgeries in the past
Severe chronic obstructive pulmonary disease or severe arteriosclerotic heart disease
Acute or recent myocardial infarction/pulmonary embolism
Very large and/or symptomatic abdominal aortic aneurysm
Pregnancy in the second or third trimester
31.2.2.5 Patient Preparation
Informed Consent on the Basis of Information Given to the Patient
Patient preparation is similar to that for sigmoidoscopy and includes providing the patient with a description of the technique and information about the possibility of biopsy, polypectomy, and other applicable procedures.
Bowel Preparation
Thorough bowel cleaning is mandatory. A wide variety of methods use dietary restrictions with various purgatives and laxatives. Diet and cathartics, gut lavage, and phosphates are three commonly used options.
Diet and Cathartics
The patient should ingest clear liquids for 72 h or a low residual diet for 1–3 days. Cathartics such as magnesium citrate and bisacodyl should be used. A tap-water enema should be administered the evening or morning before the procedure.
Gut Lavage
Peroral gut lavage with osmotically balanced electrolyte solutions such as polyethylene glycol electrolyte lavage solution (volume, 2–4 L; lavage rate, 1.5 L/h) should be performed. Several adverse experiences have been reported, including disagreeable taste, hypothermia, feeling of fullness, nausea, bloating, aspiration, reactivation of bleeding, esophageal tear, perforation, pill malabsorption, and allergic reaction (angioedema, urticaria, anaphylaxis).
Phosphates
Phosphates are available as solutions or tablets – an attractive alternative because of the lower volume that must be ingested. Oral sodium phosphates (45 mL) diluted with water (to 90 mL) should be administered the evening before and repeated 4 h before colonoscopy. The solution is very hypertonic. Adverse experiences have been reported and include electrolyte disturbances, hyperphosphatemia, hypocalcemia, vomiting, dehydration, colonic aphthous ulcerations, and seizures.
Contraindications for colonoscopy bowel preparation
Preparation should not be performed if there is a contraindication for colonoscopy or if a gastric or bowel obstruction is suspected. Gut lavage should be avoided in gastroparesis.
An increased risk to bowel preparation exists in patients with congestive heart failure, ascites, renal insufficiency, dehydration, debility, GI obstruction, gastric retention, colitis, megacolon, and ileus; those who are unable to take oral fluid; and those taking diuretics or medications that affect electrolytes.
Premedication and Sedation
Based on tradition, culture, and economics, acceptance of colonoscopy can differ from country to country. Sedation and analgesia are commonly provided for colonoscopy. The goal is to increase the patient’s tolerance for the procedure and to increase the satisfaction of both the patient and endoscopist. Standard sedation (a combination of a narcotic and benzodiazepine) is safe and effective when administered by the endoscopist. Propofol provides excellent patient and endoscopist satisfaction. It can cause profound apnea, however, and needs to be administered by an anesthesiologist or others with special/similar training. Colonoscopy can be done without sedation in selected patients.
31.2.2.6 Special Considerations
The risk for bacteremia during colonoscopy is low. There is not complete consensus on antibiotic prophylaxis for bacterial endocarditis in patients undergoing colonoscopy. It is common to administer antibiotics to patients with prosthetic valves or a history of endocarditis. Several accepted regimens can be used, depending on local guidelines.
31.2.2.7 Complications
Major Complications
Perforation (estimated at 0.14–0.8 %)
Hemorrhage (negligible; 0–0.5 %)
Respiratory depression (oversedation, especially in patients with chronic lung disease)
Bacteremia (incidence varies from 0% to 0.5 %)
Other Complications
Vasovagal reactions
Splenic laceration
Transient electrocardiography changes
Dehydration resulting from bowel cleansing
Volvulus
Explosion of combustible gases in the colon (hydrogen, methane) when in contact with an electric spark
31.2.2.8 Report Chart
The report chart for colonoscopy is similar to that for sigmoidoscopy (refer to the “Report Chart” section related to sigmoidoscopy earlier in this chapter).
31.2.2.9 Alternatives to Diagnostic Colonoscopy
Virtual Colonoscopy
Computed tomography (CT) is the preferred method for image acquisition. Some centers use magnetic resonance imaging. Bowel preparation with complete cleansing of the colon together with colonic insufflation of gas is required for “virtual” colonoscopy using CT.
Virtual colonoscopy has several indications/clinical roles:
Evaluation of the colon after incomplete conventional colonoscopy
Evaluation of the colon secondary to an obstructing neoplasm
Evaluation in patients who are not fit for conventional colonoscopy (chronic obstructive lung disease, bleeding diathesis, allergic reactions to sedation)
Contribute to colorectal screening
Patients who refuse colonoscopy
Double-Contrast Barium Enema
A double-contrast barium enema has a higher risk of missing colorectal cancer than colonoscopy. It has a sensitivity of about 50 % for adenomas. This procedure does not allow for biopsy or treatment.
A double-contrast barium enema is most appropriate for low-prevalence populations and indications if imaging of the colon is necessary (patients younger than 50 without a family history of colorectal cancer and nonbleeding symptoms for instance).
31.3 Therapeutics
31.3.1 Polypectomy
The ability to find and remove colon polyps is one of the major reasons for colonoscopy. Removal of polyps has affected the incidence, morbidity, and mortality of colorectal cancer [1–3]. A safe polypectomy is one that:
Removes the polyp through transection with a snare loop
Achieves hemostasis using heat/coagulation
Maintains the integrity of the colon wall
31.3.1.1 Snare Loops
Snare loops are available in a wide variety of shapes and sizes. Colonoscopists should be familiar with a few types.
Polypectomy Technique
Anyone undertaking colonoscopy with polypectomy is recommended to read dedicated textbooks describing therapeutic endoscopy in detail. One should be aware of a few important steps:
Mark the handle at the point where the snare is just closed at the tip. This makes it possible to estimate the tissue volume in the closed snare.
Check for a smooth “feel” when moving the handle to open and close the snare. Provide maximum feedback to the assistant controlling the snare.
Be aware of the thickness of the snare wire; this greatly affects the speed of electrocoagulation and transection of the polyp.
Be aware of the squeeze pressure. If it is inadequate, transection will rely on high-power cutting, increasing the risk of bleeding due to insufficient coagulation of stalk vessels.
31.3.1.2 Additional Devices
Hot Biopsy Polypectomy Forceps
These forceps are used to destroy small polyps (≤5 mm in diameter), enabling simultaneous cautery of a polyp base while obtaining a biopsy specimen.
Polyp Retrieval
Polyps can be retrieved using various tools:
Nylon net
Multiprong grasping forceps
Polyp suction trap
Injection Needles
Needles can be used to inject various fluids:
Saline
Adrenaline-saline
India ink (to tattoo a polypectomy site)
Clipping Devices
Clipping devices are used for a few indications:
Hemostasis after polypectomy
Prevent bleeding
Nylon-Loop Devices
Nylon-loop devices can be used in various circumstances:
Strangulation of a polyp stalk (to prevent bleeding)
Treatment of bleeding after polypectomy
31.3.1.3 Complications of Polypectomy
Bleeding
Immediate Bleeding
Immediate bleeding is usually a slow ooze but it can be an arterial spurt. This is usually treated by injection of adrenalin-saline solution. Stalk bleeding can also be treated by resnaring the remnant stalk. Hemostatic clips can be applied to the polyp transection area.
Secondary (Delayed) Hemorrhage
Delayed bleeding can occur up to 2 weeks after polypectomy, particularly after the removal of larger polyps. It usually is self-limiting but may require re-endoscopy and hemostatic treatment.
“Post-Polypectomy Syndrome”
This syndrome is characterized by fever, pain, and localized signs of peritonitis/peritonism. It represents a “closed perforation,” with full-thickness heat damage to the bowel wall. Conservative treatment with bed rest and antibiotics is indicated, and the syndrome rarely requires surgical intervention.
Frank Perforation
Frank perforation is rare. Management is often conservative, depending on the area and localization of the polyp base. A surgeon should always be consulted.
31.3.2 Placement of Self-Expanding Metal Stents
Self-expanding metal stents (SEMSs) are used for the nonsurgical relief of a malignant colorectal obstruction [4]. Obstruction occurs in 8–25 % of patients with colorectal cancer. An emergency operation is associated with a high morbidity rate (up to 60 %) and a mortality rate up to 22 %, and often results in a temporary or permanent colostomy, which affects quality of life.
The need for alternative procedures is obvious. The placement of SEMSs is a procedure that has quickly become more widespread because it avoids a high-risk emergency operation and reduces the need for a colostomy.
31.3.2.1 SEMS: Two Main Techniques for Placement
Radiological Placement
The obstruction is located fluoroscopically using a water-soluble contrast medium. The stricture is then passed with a guide wire, over which the stent is inserted into the obstruction and released under fluoroscopic guidance. Depending on the outer diameter of the application system and the degree of the obstruction, some surgeons dilate the stricture with a balloon.
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