A colonoscopy is an investigative technique used to examine the entire length of the large bowel. It involves the insertion of a long, flexible tube with a camera, which includes lighting, irrigiation and insufflation systems, into the anus through to the rectum and colon.

A colonoscopy is useful in diagnosing ulcers, polyps and cancers. Using different accessory instruments, it can be used to both diagnose and treat a range of conditions through procedures such as biopsy (taking a tissue sample for further examination), polypectomy (removal of polyps), endoscopic dissection (removal of larger lesions), haemostasis and stenting (to relieve obstruction).

Indications that a colonoscopy may be required include:

Diagnostic colonoscopy – if you have abnormal symptoms

• Receive a positive result from a faecal occult blood test
• Experience any of the below:
  • Blood or mucus discharge from the rectum or in stool
  • Recent change in bowel habits
  • Feeling like you still need to go to the bathroom after a bowel movement
  • Anaemia
  • A palpable mass in the abdomen
  • Chronic diarrhoea or constipation

Screening/surveillance colonoscopy – if you have a high risk of developing colorectal cancer

• Are over 50 years of age
• Have a family history of colorectal cancer
• Have a personal history of:
  • Colorectal cancer
  • Inflammatory bowel disease

如您有任何藥物敏感、常用藥物（例如：口服降血糖藥、抗凝血藥物（薄血藥）及抗血小板藥）或已有病症（例如：糖尿病、高血壓、缺血性心臟病、瓣膜性心臟病及有植入心臟起搏器），請務必於檢查前通知您的醫生。如果您目前正在服用薄血藥，請按照醫生的建議在檢查前停止服用有關藥物。

您需要在檢查前飲用瀉藥排清大便，並於檢查前最少6小時開始禁食禁水，以清空腸胃，為您的結腸鏡檢查做好準備。

• 飲食－在大腸鏡檢查的前3天應開始實行低渣飲食，避免進食高纖維食物，例如：蔬菜、水果、豆類和穀物。在手術前至少 3 至 4 天停止服用鐵質補充劑。在腸鏡檢查的前1天應開始進行流質飲食（例如：米水、清湯和流質食物，避免乳製品）。
• 瀉藥－按照醫生指示，在腸鏡檢查前1天的晚上或當天的早上服用所提供的瀉藥
• 液體－為避免脫水，建議您在禁食禁水時限前喝清水
• 藥物－除非您的醫生另有建議，否則請繼續服用任何處方藥物