Complications of clinical colonoscopic consultation, although relatively rare, are unavoidable and can be fatal in severe cases and should not be ignored by either the endoscopist or the patient. According to the literature, a group of over 25,000 diagnostic colonoscopy studies reported an overall complication rate (mainly bleeding and perforation) of 0.35%, with an elevated complication rate of 2.3% for colonoscopic polypectomy. Of course, as the endoscopist’s experience increases, the complication rate decreases.
I. Perforation
The proportion of colonoscopy complicating intestinal perforation is low, and the incidence of diagnostic intestinal perforation is gradually decreasing. With the widespread development of colonoscopic treatment, the proportion of therapeutic intestinal perforation increases, and the occurrence of perforation can cause pneumoperitoneum, infection, sepsis, prolonged hospitalization days and even death. Most of the perforation sites are located in the sigmoid colon and its metastasis because of the relative narrowing of the intestinal cavity, long colonic mesentery, large intestinal tube tortuous free, easy to stretch the free intestinal tube during microscopy or easy to loop the mirror body, which can easily cause sigmoid colon perforation.
Second, the reasons for perforation
1, into the mirror does not follow the principle of lumen into the mirror, in the absence of intestinal cavity or resistance, blindly into the mirror top break the intestinal wall, the mirror body in the intestinal cavity loop, excessive elongation of the colon appears tear perforation;
2, excessive pressure in the intestinal cavity caused by excessive gas injection during the examination, coupled with the original disease is likely to cause injury and perforation;
3.Take biopsy with too deep bite, especially ulcerated colorectal cancer is prone to perforation, should be taken at the edge of the ulcerated lesion, not at the bottom of the ulcer with forceful clamping, pay attention to the site and depth of the bite;
4.Incomplete preparation of the intestinal tract leads to blurred vision, and inexperience and rough movements can easily cause perforation;
5.When treating polyps under colonoscopy, especially the non-tipped or subtipped polyps, if the position of the trap is too close to the intestinal wall and the power, time and location of electrocoagulation are not well mastered, the whole intestinal wall is easily damaged;
6, in the painless colonoscopy, because the examined person has no stress response to abdominal distension and abdominal pain, the muscle tone is relaxed, the intestinal cavity is over-inflated and other factors are prone to intestinal mucosal tear perforation.
When intestinal perforation is suspected, the intestinal gas is immediately removed and the scope is withdrawn, the patient is laid down, oxygen is administered, and a standing abdominal plain film is performed, and the diagnosis of intestinal perforation is confirmed if a pneumoperitoneum is found. The treatment of intestinal perforation depends on the patient’s ability to tolerate surgery and the presence of intestinal organic diseases. For larger perforations, especially when combined with infection or unclean intestine with more contents flowing into the abdominal cavity, surgical treatment should be performed as soon as possible to remove or repair the perforation site; for patients with clean intestine and no combined intestinal tumors and other diseases, simple perforation repair can be used. For patients with combined tumors, if they can tolerate major surgery, they undergo radical tumor resection followed by one-stage suturing; for elderly patients with poor health, repair plus fistula is feasible, and second-stage surgery is performed after the general condition improves. Enteroscopic perforation can also be closed or sealed immediately by endoscopic closure methods (such as titanium clips and endoscopic-assisted suturing instruments), thus avoiding surgery and promoting patient recovery.
II. Pneumothorax, mediastinal emphysema, scrotal emphysema and venous thrombosis
The gas in the intestine escapes into the abdominal cavity after perforation of the large intestine, and the consequences are different due to different perforation sites: if the gas in the abdominal cavity enters the thoracic cavity through the diaphragmatic fissure, a pneumothorax occurs; if the gas enters the retroperitoneal cavity and then the mediastinum, a mediastinal emphysema occurs; if the mediastinal pleura ruptures, both thoracic and mediastinal emphysema may occur, and in a few patients, a bilateral pneumothorax may occur, causing cardiopulmonary failure.
Third, bleeding
Colonoscopy, especially after therapeutic procedures, intestinal bleeding is one of the most likely complications. Biopsy, polypectomy, electrocautery and other colonoscopic treatments are much more likely to result in bleeding than diagnostic colonoscopy. Bleeding may occur soon after polyp removal or only a few days after the procedure. The site of bleeding can be determined by endoscopy or erythrocyte nuclear scan. The reported incidence of post-polypectomy bleeding ranges from 0.3% to 6.1%, and the incidence of diagnostic colonoscopy bleeding is 0.09%. Bleeding that occurs 1 h after colorectal polyp removal is called delayed bleeding. Patients with heavy bleeding require endoscopic hemostatic therapy, while most patients with small bleeding are self-limited and do not require endoscopic hemostatic therapy. In case of persistent abdominal pain or decreased blood pressure after colonoscopy, we should be alert to intra-abdominal bleeding and should promptly perform abdominal ultrasound and CT examinations.
The hemostatic methods taken for complicated bleeding after colon polypectomy are mainly electrocoagulation hemostasis, argon gas spray coagulation, hemostatic clip to close the wound, spray hemostatic drugs, and colonoscopic injection of hemostatic drugs.
IV. Complications related to intestinal preparation
Cleaning the bowel before colonoscopy is to better observe the colonic mucosa and, in addition, to reduce the concentration of potentially explosive gases in the intestinal lumen. Very few complications of gas explosions in the intestine have been reported. One group of studies found flammable hydrogen and methane gases in the intestinal cavity in 10% of patients despite pre-sigmoidoscopy preparation with only standard phosphoric acid soda enemas, while patients with intestinal preparation with polyethylene glycol (PEG) had no flammable gases. Other studies have found a potential risk of intestinal gas explosion with mannitol for bowel preparation (an explosion can still occur with colonoscopy?). . Balanced salt solutions containing polyethylene glycol and non-polyethylene glycol solutions such as magnesium citrate and phosphate (oral phosphate soda), both preparation methods can cause fatal water-electrolyte disturbances in the elderly, in patients with renal insufficiency or bruised heart failure. Other rare complications of oral bowel preparation are vomiting-induced pancreatic mucosal tear syndrome, esophageal perforation, and aspiration pneumonia.
V. Chemical colitis
Chemical colitis is acute damage to the colonic mucosa caused by the use of exogenous chemical agents. Clinical symptoms are dominated by abdominal pain, abdominal distension and urgency, mucus and blood stools, which are generally not accompanied by systemic symptoms such as fever, chills, nausea, vomiting or weight loss. The common drugs that can cause chemical colitis are: water-soluble contrast agent panadol, disinfectant glutaraldehyde and peroxyacetic acid, soap and water used in common enemas, and even reports of chemical colitis caused by enemas such as Chinese herbs, corkage, and edible vinegar.
Glutaraldehyde is currently the most commonly used disinfectant for thorough disinfection of medical equipment and is widely used for disinfection of various endoscopes. For patients undergoing colonoscopy, the possibility of disinfectant-related acute chemical colitis should be considered when acute abdominal pain, diarrhea, chills and fever, blood volume deficiency, and elevated blood leukocytes occur within 2 to 48 h after the procedure, and patients should be kept in the hospital for observation and strict monitoring of changes in vital signs if necessary. Patients with severe symptoms should take active therapeutic measures, especially blood volume supplementation, shock prevention, antispasmodic, anti-inflammatory and other symptomatic treatments, and if necessary, hormone therapy.
VI. Post-polypectomy electrocoagulation syndrome
Post-polypectomy electrocoagulation syndrome (PPCS) refers to the inflammatory reaction of the plasma membrane layer caused by the transmural damage caused by high-frequency electrocoagulation during the endoscopic treatment. The latest foreign literature reports its incidence to be 0.7%, and earlier reports have reported its incidence to be 0.5%-1.2% and 0.5%, respectively. The post-polypectomy complications may be related to the size, type, number, location, electrocoagulation time and intensity of the polyps. It is often manifested by postoperative manifestations such as fever, abdominal pain, and elevated leukocytes, and limited pressure pain and rebound pain are common on examination, mostly occurring within 24 h after surgery. The prognosis of this complication is good, and most of them can be relieved after conservative medical treatment such as anti-infection, fasting, fluid replacement and nutritional support. It is not easily distinguished from intestinal perforation and peritonitis, which should be considered for clinical evidence of intestinal perforation, but should be re-evaluated to avoid missing the perforation if it does not resolve after treatment.