Colonoscopy is a medical procedure that utilizes endoscopic technology to observe the mucosa of the colon and rectum. It is primarily used for diagnosing and treating gastrointestinal diseases. The technique involves inserting a flexible optical instrument through the anus, equipped with a camera and lighting system, allowing physicians to directly visualize the interior of the intestines. When necessary, tissue biopsies or treatments can be performed. This examination not only accurately detects polyps, ulcers, or tumors but also allows for endoscopic resection and other treatments, making it an essential method for colorectal cancer screening and disease monitoring.
Colonoscopy is divided into two main types: "diagnostic" and "therapeutic." Diagnostic colonoscopy is used to observe structural abnormalities in the intestines, with high-resolution cameras used to examine the mucosa and record the location and morphology of abnormal lesions. Therapeutic colonoscopy builds on the diagnostic process by adding immediate surgical functions, such as using electrocautery to remove adenomatous polyps or applying hemostatic clips to control bleeding. The mechanism relies on the combination of high-resolution imaging and miniature instruments, enabling minimally invasive procedures within living tissues.
This procedure is suitable for symptoms suggestive of colorectal cancer, chronic diarrhea, rectal bleeding, intestinal obstruction, or familial adenomatous polyposis. When fecal occult blood tests remain positive, colitis recurs, or patients aged 50 and above meet screening criteria, physicians often recommend the examination. Additionally, for post-treatment follow-up patients showing signs of recurrence, this procedure can evaluate intestinal recovery.
Pre-examination bowel preparation involves thorough cleansing. Patients are required to drink a hyperosmotic laxative solution starting 12 hours before the procedure and to fast from solid foods. During the procedure, patients typically lie on their side, with sedation or general anesthesia administered as needed by the anesthesiologist. The endoscope is slowly advanced through the anus to the cecum, with the entire process taking approximately 30-60 minutes; therapeutic procedures may extend to 90 minutes. There is no fixed dosage, but the operation time and scope are adjusted according to individual needs.
The non-invasive nature enables rapid recovery, and a single examination can complete both diagnosis and treatment, reducing medical resource consumption. High-resolution imaging can detect tiny lesions smaller than 5mm, improving early cancer detection rates.
Main risks include bowel perforation (occurring in about 0.1-0.3%), bleeding (especially after polypectomy), and anesthesia-related complications. Some patients may experience incomplete examination due to inadequate bowel cleansing or increased difficulty due to intestinal strictures. Elderly patients or those with coagulation disorders may have a 2-3 times higher risk of post-procedure bleeding.
Anticoagulants (such as warfarin) should be discontinued at least 5 days before the procedure, and a low-fiber diet should be followed 3 days prior. Contraindications include severe heart or lung failure, acute peritonitis, uncontrolled bleeding disorders, and complete intestinal obstruction. Patients with severe peritonitis or ascites should not undergo the procedure to avoid triggering intra-abdominal infection.
Interactions with anticoagulant medications require coordination with a hematologist to adjust dosages. Patients undergoing radiation therapy should inform their physicians to prevent exacerbation of mucosal damage. Compared to abdominal CT scans, colonoscopy provides tissue-level observation but requires bowel preparation, whereas imaging can evaluate surrounding tissues without tissue sampling.
Research by the American Cancer Society shows that regular colonoscopy screening can reduce colorectal cancer mortality by 30-60%. Large randomized controlled trials confirm that removing adenomatous polyps reduces the risk of malignant transformation by 90% over five years. Multi-center studies in Taiwan also indicate that this examination has a sensitivity of 95% for detecting early malignancies and a specificity exceeding 85%.
Fecal occult blood testing can serve as an initial screening, but its accuracy is only about 70%. Virtual colonoscopy (CT colonography) can detect tumors but cannot obtain tissue samples and involves higher radiation exposure. Sigmoid colonoscopy is limited to the rectum and sigmoid colon and cannot evaluate the entire bowel. Genetic testing can assess hereditary gastrointestinal risks but cannot replace direct visualization.
What are the effects if bowel cleansing is incomplete before the examination?
If bowel cleansing is inadequate, it may obscure the view during colonoscopy, leading to missed lesions and increasing the risk of missing precancerous or early tumors. Strict adherence to the prescribed laxatives and continued intake of clear fluids before the procedure are recommended.
When can I resume normal diet and exercise after treatments like polyp removal?
Generally, after local excision, a low-fiber diet is recommended for 2-3 days, and strenuous exercise should be avoided for one week. If extensive mucosal resection or hemostasis was performed, the doctor might suggest a longer recovery period. The specific timeline depends on individual health and the scope of treatment.
Is it safe to immediately remove polyps found during the procedure? Is anesthesia required?
Benign polyps smaller than 2 cm can usually be removed immediately during colonoscopy using techniques like LEEP or snare resection, with local anesthesia or mild sedation. The risk of bleeding or perforation is less than 1%. Patients with compromised cardiopulmonary function should be evaluated by an anesthesiologist beforehand.
How should I judge if ongoing abdominal pain or bleeding after colonoscopy is a complication?
Mild bloating or small amounts of blood in stool may be normal post-procedure. However, persistent severe abdominal pain, heavy bleeding, fever, or black stools require immediate medical attention. These symptoms may indicate perforation, infection, or vascular injury, which are serious complications needing urgent treatment.
Does previous abdominal surgery reduce the success rate of colonoscopy?
Patients with prior abdominal surgery may have increased adhesions, making the procedure more challenging. However, experienced gastroenterologists can often adjust the angle with flexible endoscopes, achieving success rates above 85%. In cases of severe anatomical abnormalities, 3D laparoscopic-assisted colonoscopy (CE) may be necessary.
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