Perforation

Perforation is defined as a traumatic breach of intestinal integrity. Perforations may roughly be divided into those in which the injury is relatively small and those in which the injury is relatively large. In conjunction with the quality of the pre-colonoscopic bowel preparation, the patient's medical status, and the time between perforation and diagnosis, this distinction has important therapeutic and prognostic significance. Small perforations most intuitively result from direct mechanical trauma, such as the result of forceful passage of the tip of the endoscope through a diverticulum (misidentified as lumen), inadvertent penetration of the side of a tight flexure or bend, or tearing during traversal of a narrowed stricture. Theoretically, perforation may also occur from pneumatic forces, when attempts to increase visualization lead to over-distension. Although this mechanism is uncommon, Burt stated in 1931 that 4.07 psi were necessary to rupture normal human intestine (Burt 1931). More recent cadaver studies demonstrated that luminal pressure increases of 169 mmHg were necessary to rupture the sigmoid colon (Kozarek 1980). Finally, a small perforation may occur during the mechanical trauma of biopsy or the electrical and thermal injuries inherent in snare polypectomy or therapeutic cauterization.

Large intestinal disruptions may unfortunately be as common as these small perforations. Substantial intestinal ruptures are caused by the lateral pressure of a bowed loop of colonoscope against a stretched loop of colon. Such pressure may split a loop of sigmoid or transverse colon longitudinally while the endoscopist attempts to advance the tip of the colonoscope more proximally. These tears are particularly dangerous both because of their large size and because they occur without direct visualization of the perforated area at the time of injury. The suspicion of such an injury militates very strongly against attempts at non-operative management, as such an injury should be managed by resection of the injured segment.

Perforation has been estimated to occur in approximately 0.2% of diagnostic colonoscopies and 0.6% of colonoscopies where biopsy is also performed (Gebedou 1996), but may in fact occur less frequently (Basson 1998). In 50–60% of cases, perforation occurs at the rectosigmoid region of the large bowel, with an additional 10–20% perforation rate at the cecum (Farley 1997). Because of its rarity and the likelihood of variations with regional colonoscopic practice patterns, useful data distinguishing the relative rates of “small” and “large” intestinal ruptures is not consistently available.

Hemorrhage

The presence of blood in the stool after colonoscopy (particularly after colonoscopic biopsies) is not necessarily a complication. The hemorrhagic complications of colonoscopy may be defined as bleeding that requires further medical attention. This bleeding may be immediate, and evident on initial colonoscopy, or delayed by several hours or even days. Certainly, the distinction must be made between diagnostic and therapeutic colonoscopy, as the incidence of hemorrhage during polypectomy is intuitively higher than during colonoscopy alone. Various authors (Smith 1976, Silvis 1978, Frühmorgen 1979, Nivatvongs 1988) have reported the incidence of clinically significant hemorrhage after diagnostic colonoscopy to be less than 0.1%, and 1–2% after polypectomy.

Diagnosis

Evaluation of complications after colonoscopy requires a detailed history and careful physical diagnosis. In particular, the patient (and the endoscopist, if available), should be asked specifically about the anomalous findings and a full description of the symptoms which occurred after the procedure. The duration of the procedure, the quality of the bowel preparation, pain associated with the study, the amount of analgesia required, whether prolonged abdominal pressure was required (to control an intraabdominal colonic loop), whether biopsies or polypectomies were performed (and if so how many, location, size, with what technique, and with what hemostasis) all may help identify the exact injury.

Together with careful evaluation of the patient's medical condition and comorbidity, answers to these questions provide the surgeon with the information necessary to surmise what intervention, if any, the patient is likely to require.

Management

As for any trauma, understanding the precise mechanism of injury is central to successful management. It is essential to acquire all possible information from the endoscopist concerning the exact details of the injury, as this will help to choose among the various management options.

Perforation

Perforation after colonoscopy represents not a discrete entity, but a spectrum of illness dependent on many variables. The mechanism of perforation, severity of symptoms, duration of time between procedure and diagnosis, adequacy of the pre-colonoscopic mechanical bowel preparation, patient reliability, immunologic status, and hemodynamic stability all contribute to the decision whether to take the patient to the operating room. Older surgical literature stresses the importance of early laparotomy in the management of bowel perforation (Woodhall 1951). However, similar to some spontaneous diverticular perforations, perforation after colonoscopy may be limited and contained, and may not result in clinically significant contamination of the peritoneal cavity.

Adair and Hishon presented a case series of eight patients with recognized perforation during colonoscopy (Adair 1981). Although limited by power and methodology, the successful non-operative management of half of the patients in this early series highlighted the difference between traumatic or ischemic rupture of the fecally-loaded colon, and the smaller, cleaner defect produced by some colonoscopic perforations in mechanically cleansed bowel. Thus, Christie described the “mini-perforation”, where transmural injury to the bowel occurs, but is followed by spontaneous closure (Christie 1991). In such cases, conservative management with antibiotics, intravenous fluids and observation would spare the patient the potential morbidity and mortality of a laparotomy. In the absence of evidence-based criteria, the difficulty and the art of clinical judgement lies in predicting which patients are likely to have the minimal clean perforations which can be managed conservatively and which will require surgical intervention.

Hall performed a retrospective survey of perforation during 134,383 colonoscopies, and reported that the combined mortality rate was three times greater when surgical therapy was employed (10.1% mortality) then when patients were managed conservatively (3% mortality) (Hall 1991). Such a retrospective analysis is highly likely to exhibit a selection bias in that sicker patients were probably selected for operative intervention. However, this data is certainly consistent with the feasibility of a non-operative approach to diagnosed colonoscopic perforations in selected patients. Thomson suggests five conditions for non-operative management: a small defect, retroperitoneal perforation, adequate pre-colonoscopic mechanical bowel preparation, good overall health, and the absence of generalized peritonitis (Thomson 1994). Certainly, the history of the procedure should also play a significant role in the decision whether to operate. Knowledge that the case was particularly difficult or involved substantial looping may sway the surgeon to explore the patient, whereas the report of a quick, straightforward, clean procedure including a snare polypectomy of a small polyp in wellcleansed colon may suggest conservative management (see table I).

Table I

Factors suggesting operative intervention.

Although it seems unlikely that a randomized controlled trial of conservative management of colonoscopic perforation will ever be conducted, the published literature is consistent with the practice of a conservative approach for selected patients with minor injury and good overall health status in order to minimized surgical morbidity and mortality. Non-operative management may be considered in the most stable subset of patients. “Conservative management” includes strict fasting, intravenous hydration, broad-spectrum antibiotics, nasogastric decompression (in many surgeons' practice), and frequent reassessment for clinical deterioration which may require surgical intervention. The following algorithm is suggested for the evaluation of possible perforation secondary to colonoscopy (Fig. 1).

Figure 1

Diagnostic algorithm for evaluation of a perforation secondary to colonoscopy.

Hemorrhage

In cases of suspected hemorrhage, initial evaluation should include determination of a baseline hematocrit and confirmation that the rectal contents contain occult blood through anoscopy or digital rectal examination. In the hemodynamically stable patient with normal hematocrit, close observation and monitoring is warranted, with periodic re-examination. In Johnson's retrospective review of forty-four cases of hemorrhage after colonoscopy, 68% of patients were successfully managed by intravenous fluids and/or transfusions without more invasive intervention (Johnson 1993).

If the hematocrit should fall or the patient should exhibit temporary instability which responds to resuscitation, colonoscopy should be used to identify and ablate the source of bleeding. Angiography may also be employed to eradicate bleeding vessels through vasopressin injection or embolization, although it is limited by local availability (particularly in the emergency setting), dye allergy, the local complications of arterial puncture, and the ischemic risks of embolization itself. Johnson's review cited a 83% success rate in controlling hemorrhage by this technique (Johnson 1993), although other authors have reported a success rate closer to 50% (Vernava 1997). In cases where the hematocrit falls precipitously or the patient is unstable, immediate laparotomy with resection of the bleeding segment is indicated. Gibbs proposed an algorithm of stabilization, radiographic studies, and repeat colonoscopy [adapted below] based on a retrospective review of one center's four-year experience (Gibbs 1996). In this series, none of the thirteen bleeding complications after 12,058 colonoscopies encountered required surgical intervention. (Underlined steps represent possible endpoints of pathway) (Fig. 2).

Figure 2

Algorithm of stabilization, radiographic studies and repeat colonoscopy [adaptec from Gibbs].

Conclusion

No prospective, randomized controlled trials have been performed to define the optimal approach to the management of colonoscopic complications. In the absence of such data, surgeons pursuing evidence-based practice must rely on case studies, surveys, and reviews.

Although definitive studies are lacking and patients with clinical peritonitis or historical details suggestive of a longitudinal sigmoid tear following rupture of a large sigmoid loop, criteria may be proposed for non-surgical management of colonoscopic perforation in selected patients utilizing fasting, parenteral antibiotics, and careful monitoring with a low threshold for operative intervention. In cases of hemorrhage, conservative management is likely to suffice for hemodynamically stable patients, while even patients with substantial bleeding may frequently be successfully managed by endoscopic or angiographic techniques for hemostasis.

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