For example, the odds of developing colorectal cancer between the ages of 20 and 40 in the absence of specific risk factors are about 1 in 1,250 (0.08%).The rate of complications varies with the practitioner and institution performing the procedure, and other variables. Perforation
The most serious complication generally is gastrointestinal perforation, which is life-threatening and in most cases requires immediate major surgery for repair. Fewer than 20% of cases may be successfully managed with a conservative (non-surgical) approach.A 2003 analysis of the relative risks of sigmoidoscopy and colonoscopy brought into attention that the risk of perforation after colonoscopy is approximately double that after sigmoidoscopy (consistent with the fact that colonoscopy examines a longer section of the colon), a difference that appeared to be decreasing. Bleeding
Bleeding complications may be treated immediately during the procedure by cauterization using the instrument. Delayed bleeding may also occur at the site of polyp removal up to a week after the procedure, and a repeat procedure can then be performed to treat the bleeding site. Even more rarely, splenic rupture can occur after colonoscopy because of adhesions between the colon and the spleen. Anaesthesia
As with any procedure involving anaesthesia, other complications would include cardiopulmonary complications such as a temporary drop in blood pressure and oxygen saturation usually the result of overmedication, and are easily reversed. Anesthesia can also increase the risk of developing blood clots and lead to pulmonary embolism or deep venous thrombosis.
After total ischemia occurs, the myocardium switches immediately from aerobic glycolysis to anaerobic glycolysis resulting in the reduced ability to produce high energy phosphates such as ATP and Creatinine Phosphate. At this point, the lack of the energy and lactate accumulation results in cessation of contraction within 60 seconds of ischemia (i.e. Vessel Occlusion). Subsequent to this is a period of "myocardial stunning," in which reversible ischemic damage is taking place. At approximately 30 minutes after the onset of total ischemia the damage becomes irreversible, thereby ending the phase of myocardial stunning. The generation of oxygen-derived [free radicals] during the initial period of reperfusion after ischemia is believed to contribute to the pathogenesis of myocardial stunning.Some evidence suggests that brief, repetitive episodes of myocardial ischemia may result in chronic myocardial stunning and ventricular contractile impairment. Diagnosis
Imaging techniques such as echocardiography, ventriculography, and nuclear imaging can be used to detect a contractile dysfunction following reperfusion after an episode of ischemia. The area of dysfunction should also maintain normal perfusion, detected via Positron Emission Tomography, echocardiography with contrast, and/or thallium scintigraphy in order for a diagnosis of myocardial stunning to be considered. However, there are many practical challenges to diagnosing myocardial stunning using these methods. Accurate detection of regional myocardial blood flow and contraction function abnormalities must be detected at levels of high sensitivity. The diagnosis of myocardial stunning must also be differentiated from other conditions such as hibernating myocardium and persistent (silent) subendocardial ischemia, which can also co-exist with superimposed stunning.