Complications of Colonoscopy


Colonoscopy remains the gold standard for colonic investigation. It is a sensitive diagnostic tool and provides a nonsurgical approach for the removal of colonic and rectal polyps. However, colonoscopy is invasive. It can be a challenging procedure to perform and is associated with infrequent but potentially serious complications. Most of these complications occur after therapeutic procedures have been performed. Potential complications are listed in Box 86-1 .

BOX 86-1

  • Bowel preparation complications

  • Sedation complications

  • Hemorrhage

  • Perforation

  • Diastatic serosal tears

  • Bacteremia

  • Vasovagal reflex

  • Postcolonoscopy distension

  • Splenic trauma

  • Cardiac events

  • Missed disease

  • Death

Potential Complications

Adverse events can occur before, during, or after a procedure. Postprocedure complications can occur immediately, within days, or sometimes years after the procedure (e.g., a stricture related to previous endoscopic mucosal resection). Knowledge of the potential complications together with early recognition and appropriate management of the situation will help improve patient outcomes.

Risk Management

Perhaps the most important aspect of colonoscopy is minimizing risk for the patient, which starts with a targeted history that includes cardiac and respiratory risk factors, history of renal impairment, the presence of diabetes or bleeding disorders, drug history (particularly antiplatelet and anticoagulant agents), and a history of allergies. The patient’s comorbidities are balanced against the possible benefits of colonoscopy to determine whether the procedure should be performed at all. Comorbidities also influence choice of bowel preparation (renal function status) and the depth and duration of conscious sedation (respiratory function).

Although the skill and experience of each colonoscopist varies, every colonoscopy should be performed or supervised by an endoscopist with adequate training as defined by the various supervising societies. The complication rate is highest for inexperienced colonoscopists who have performed a low volume of procedures. The risk of complications can be up to three times higher after a polypectomy performed by a “low-volume” colonoscopist (i.e., an endoscopist who has experience with 1 to 141 colonoscopies) when compared with a “high-volume” colonoscopist (i.e., an endoscopist who has experience with 379 to 1225 colonoscopies). Inherent in the better outcome of experienced endoscopists is experience and knowledge of the equipment, including the electrocautery generator and the various adjuncts. A poorly functioning scope and lack of familiarity with equipment will place the patient at an unnecessary risk. It is also important that colonoscopists be aware of their own limitations because overambition may lead to adverse events. As the complexity of polypectomy increases, the risk of complications also increases. Using lower risk procedures when appropriate, or referring patients to “high-volume” endoscopists, can reduce the risk of perforation and gastrointestinal bleeding.

In this chapter we will concentrate on the management of two potentially life-threatening and surgically important complications of colonoscopy: perforation and hemorrhage.


Hemorrhage is a rare complication of diagnostic colonoscopy because clinically significant bleeding from mucosal biopsy sites is uncommon. However, hemorrhage is the most common complication associated with endoscopic polypectomy. Hemorrhage can be defined as acute blood loss after a polypectomy that is severe enough to mandate admission to the hospital.

Steps Prior to Colonoscopy

It is important to ascertain whether the patient has a history of a bleeding disorder or is undergoing anticoagulant or antiplatelet therapy. Use of anticoagulant and antiplatelet agents should be stopped for a sufficient period before a polypectomy is performed. A comprehensive guide to the management of anticoagulant and antiplatelet therapy in patients undergoing endoscopic procedures is available in a document published by the working party for the British Society of Gastroenterology (see Suggested Reading ).

The patient and his or her family need to be warned about the possibility of postpolypectomy bleeding. Patients should not travel to areas remote from medical care for the next 2 weeks.

Risk Factors for Bleeding

Postpolypectomy bleeding rates between 0.16% and 6.1% have been reported. Factors associated with an increased risk of bleeding include patient age (elderly persons have a higher risk), size of the polyp, location of the polyp (right colonic polyps have a higher risk of bleeding), number and structure of the polyps (sessile and thick-stalked polyps are more likely to bleed) and the use of anticoagulant drugs. Some series report bleeding rates after polypectomy of up to 10% for large (>2 cm) right-sided colonic polyps. In addition to these factors, the type of diathermy setting can affect the risk of postpolypectomy bleeding. The use of pure-cut diathermy is associated with a higher rate of immediate bleeding, whereas blend and coagulation diathermy settings are associated with lower rates of hemorrhage.

Prevention of Bleeding

The European Society of Gastrointestinal Endoscopy has concluded that the placement of detachable loop ligating devices for large pedunculated polyps and the submucosal injection of diluted (1:10,000) epinephrine for sessile polyps are effective strategies to reduce postpolypectomy bleeding. The efficacy of other measures, including endoclip placement and argon plasma coagulation, has not been proven. A helpful strategy in a high-risk patient with multiple polyps is to remove the largest polyp and leave the others, so that if bleeding occurs, the site is already known.

Treatment of Bleeding

Hemorrhage sometimes occurs despite adequate risk assessment and good technique. In this situation, it is important to have an appropriate management strategy. A suggested approach is summarized in Figure 86-1 . Bleeding can occur immediately or can be delayed up to 30 days after the procedure. In most cases of immediate hemorrhage, it is possible to treat the bleeding endoscopically. A working knowledge of endoscopic hemostatic techniques is important, and use of a combination of these techniques can be helpful.


Algorithm for postcolonoscopy bleeding. CT, Computed tomography.

Injection of epinephrine (a 1:10,000 solution) via a flexible injector needle causes vasoconstriction and controls most bleeding. The aim is to form a bleb of the solution at the site of bleeding by injection into the submucosal plane. Injection of several milliliters around the bleeding site may be necessary to achieve the desired effect.

Should bleeding occur after removal of a pedunculated polyp, hemostasis is achieved by snaring the stalk and holding it for at least 5 minutes. Some snares are detachable and can be left in situ. Repeat transection of the base of the polyp is not recommended because this maneuver can make regrasping of the base impossible should the bleeding continue. Hemoclips are safe to use to treat immediate bleeding. However, accurate placement is sometimes difficult, and multiple clips are often required.

Methods of direct-contact thermal treatment including the use of a heater probe, electrocautery, and argon plasma coagulation can be useful in the treatment of hemorrhage. Although these techniques carry a risk of perforation, short bursts of light contact without excessive pressure will reduce the likelihood of perforation.

When endoscopic techniques prove unsuccessful in achieving hemostasis, decisions must be made about further management. The volume and flow of bleeding should be estimated and the likelihood of spontaneous cessation should be assessed at colonoscopy. Should the flow of blood be brisk and continuous, then appropriate resuscitation with blood products is often necessary. Angiographic transarterial embolization can be successful in achieving hemostasis. However, patients must be stable enough to be transferred to the radiology department and must be aware of the significant risk (approximately 11%) of colonic ischemia requiring colectomy.

Surgery is a last resort. A laparoscopic approach is appropriate and preferable to open surgery. In cases of immediate postpolypectomy bleeding, the site of hemorrhage is usually known. This knowledge can allow a segmental colonic resection and primary anastomosis because the colon should be clean after the bowel preparation used for the patient’s colonoscopy. In unusual cases, depending on the availability of angiography, a subtotal colectomy may be required when delayed hemorrhage occurs or if uncertainty exists about the site of bleeding. On-table colonoscopy can be helpful in facilitating potential endoscopic control of hemorrhage or can identify the site of bleeding and allow segmental colonic resection.

Delayed bleeding often can be managed expectantly if the volumes of blood are relatively small and the patient is hemodynamically stable. However, should the bleeding be more profuse, then colonoscopy has a role. In this situation, it may be safer to perform colonoscopy in an operating room with an anesthetist and blood products available in the event that the patient requires an emergency laparotomy. Usually a bowel preparation can be administered at the same time that resuscitation is occurring, although repeat scoping of an unprepared colon can be performed. The site of bleeding is often marked by an adherent clot, which must be removed by irrigation before hemostasis can be obtained. Adrenalin injection, clips, or coagulation can be used.

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Jul 15, 2019 | Posted by in GENERAL | Comments Off on Complications of Colonoscopy

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