Recent years have witnessed a particularly noticeable development in minimally invasive surgery, including colonoscopy. This development is accompanied by advances in anaesthetic techniques. Full collaboration between surgical and anaesthetic teams, with mutual understanding of needs and expectations, is a necessary condition for the further development of endoscopic surgery. The use of diagnostic and therapeutic colonoscopy has increased since the introduction of flexible fibre endoscopes. Much significance is currently attached to one-day procedures. This faces anaesthetic teams with a range of challenges related to general anaesthesia and analgosedation, both of which are intended to protect the patient against pain and other unpleasant experiences during colonoscopy, and may also contribute to reduced frequency of hospitalisations. The more common use of colonoscopy is also associated with increased rates of complications after therapeutic colonoscopy, e.g. polypectomy. Since these complications are relatively rare and may be the reason for lawsuits for damages, no prospective randomised studies to assess their incidence have been conducted. The paper discusses the mechanism, diagnosis and management of the two most common colonoscopic complications, i.e. colonoscopic perforation and bleeding.

Lower GI perforation is defined as a traumatic loss of intestinal wall integrity. The extent of perforation can vary from microinjuries to extensive damage to the intestinal wall. Due to the varying level of intestinal preparation, overall patient’s health status and the time elapsed between perforation and diagnosis, the extent of injury has a significant impact on the treatment used and prognosis. Minor perforations are caused by direct mechanical trauma to the large intestine, such as forcing the endoscope tip through the intestinal diverticulum mistaken for the colonic lumen, lateral perforation of the colonic flexure or transverse tear at the site of a large tight bowel stenosis. Colonic perforation due to pressure forces during an attempt to improve visualisation by means of increased colonic distension under gas pressure is also theoretically possible. However, such mechanism is rare. It was shown in one of publications that gas pressure of 4.07 psi (about 52 mmHg) is necessary to rupture normal human intestine (1). A more recent study showed that sigmoid pressure of 169 mmHg is necessary for its rupture (2, 3). Mechanical intestinal trauma during biopsy and electrical or thermal injury associated with polypectomy and post-polypectomy electrocoagulation is another mechanism underlying colonic perforation. Extensive colon damage is less common and may be caused by lateral colonoscope compression on the distended colonic wall. This compression may lead to a longitudinal dissection of the sigmoid or transverse colon wall during attempts at proximal colonoscopic manoeuvres. This type of colonic tears is particularly dangerous due to large size and the fact that they often develop beyond the field of vision. If such a mechanism of colonic trauma is suspected, urgent surgical intervention is needed. The incidence of colonoscopic perforation is estimated at 0.2% for diagnostic and 0.6% for colonoscopy with colon wall biopsy (4), but it may be actually less common (5). About 50-60% of colonic perforations occur in the sigmoid colon and the rectum, while caecal perforations account for 10-20% of cases (6). Risk factors for colonoscopic perforation include age > 75 years and comorbidities, as well as diverticulosis and constipations in the case of screening (7). Indications for surgical treatment include peritoneal symptoms, unsuccessful conservative treatment and size of perforation (> 1 cm) (8). Conservative treatment is mainly used in stable patients, without peritoneal symptoms, with early diagnosis of perforation in the retroperitoneal part of the large intestine (9, 10).