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As with any procedure, colonoscopy has risks. These range from oversedation, hypoxia, and other airway or hemodynamic problems to complications more directly related to the scope itself, such as bleeding or perforation. Sedation complications and endoscopic hemostasis will be discussed elsewhere in this book. This section will address the management of colonic perforation.

One of the most feared complications is perforation of the viscera. The risk for this is low with perforation rates of roughly 1 in 1,000 for colonoscopy [18]. Perforation can occur in a number of ways. One cause is from the scope tip exerting too much pressure on the wall of the colon when incorrect technique is used by attempting to advance the scope while in “red‐out.” This occurs when novices attempt to blindly push the scope around tight turns in the colon or when the endoscopist inadvertently intubates a diverticulum. For this reason, all trainees are warned from day one of training, not to advance the scope if the lumen is not visualized. This is the most avoidable method of perforation. When a trainee cannot find the lumen, it is always advisable to slowly pull the scope back specifically to avoid perforation. The second, and probably one of the more common causes of perforation with more experienced endoscopists, is injury to the sigmoid due to excessive looping in this region even though the scope tip may be well beyond this portion of the colon (Figure 6.20). An excessive loop can exert too much lateral pressure on the colon wall, causing a tear. This can be avoided by using repetitive loop reduction techniques and avoidance of excessive pushing force against significant resistance. Severe patient discomfort can also be a warning of excessive loop force against the colon wall. Excess air insufflating the colon can also lead to perforation. This leads to ballooning of the colon and subsequent perforation of the cecum (thinnest wall of the colon). Finally, retroflexion in the rectum also can lead to perforation due to incorrect technique or simply due to attempting the maneuver in a rectum that is too small to accommodate the maneuver. This maneuver should be avoided in patients with significant active inflammatory bowel disease involving the rectum. In the hands of more experienced endoscopists, perforations still occur but typically with therapeutic maneuvers, such as complex polypectomy.

Figure 6.20 Looping causing perforation. In this sigmoid loop, the scope is pushing against the wall of the sigmoid colon in the direction of the arrow. One cause of perforation is due to excessive lateral pressure against the colon wall from a loop in the colon and scope.

(Copyrighted and used with permission of Mayo Foundation for Medical Education and Research.)

The key to managing colonic perforation is early recognition. Often if the perforation is caused by the scope's tip, the peritoneal cavity, organs, or serosa will be readily visible to the camera lens. When perforation occurs as a result of looping, the defect and fresh blood will commonly be identified during withdrawal. Commonly with perforations, the patient will develop increased distention of the abdomen due to free air or worsening abdominal pain either during the procedure or in recovery. If perforation is at all suspected, immediate evaluation with imaging such as an abdominal CT scan is indicated to evaluate for free peritoneal air. A CT scan can detect much smaller collections of free air than upright abdominal X‐rays and as such is preferred; however, if not available, upright abdominal X‐rays can help identify free abdominal air. If identified, immediate evaluation and likely intervention by a surgeon is required. Delay in intervention can lead to sepsis and even death. If perforation is identified during the endoscopic examination, immediate endoscopic closure is ideal followed by a single dose of broad‐spectrum antibiotic and overnight observation in the hospital for signs of peritonitis. Attempts at endoscopic closure of perforations using hemoclips or other closure devises will be discussed in Chapter 24. Endoscopic closure of defects should only be attempted by skilled endoscopists. Less commonly, perforations may be retroperitoneal (as can occur in the distal rectum) and walled off. In these cases, free air will not be identified on abdominal X‐ray. In these cases, CT scanning would be needed to identify and locate the problem. These can often be managed more conservatively with fasting and IV antibiotics with close inpatient monitoring. Occasionally, incidental radiographic findings of free air in the peritoneal cavity occur following endoscopy, yet in the absence of any clinical symptoms of perforation. The clinical significance, if any, of these findings is unclear, yet conservative management and close observation also is recommended.

Training fellows to manage perforations is difficult, as these do not occur often. The main teaching point is to never underappreciate or deny to oneself the possibility of a perforation. If there is any suspicion that a perforation has occurred, this needs to be aggressively pursued with diagnostic and therapeutic intervention as needed. In the event of a perforation, it is also paramount that the endoscopist personally stays in direct communication with the patient and family and not to simply ship the patient off to the emergency room and distance oneself from the case.