Oesophago-gastro-duodenoscopy (OGD) is an examination of the inside of the upper digestive tract by using a flexible video-endoscope which is passed through the mouth into the oesophagus, stomach and duodenum. It allows your doctor to have direct vision of the upper digestive tract and to detect pathological change, for example, tumour, ulceration or polyps etc. Your doctor will take biopsy for pathological examination and may perform polypectomy and therapeutic haemostasis when necessary.
Colonoscopy is a procedure that enables the examiner to view the inside of the large bowel. This is accomplished by passing a flexible video-endoscope through the anus into the rectum, then advancing slowly through sigmoid colon, descending colon, transverse colon, ascending colon and lastly to the caecum.
The examiner can have direct vision of the colon and pathological changes inside the colon, such as tumour, ulceration or polyps. Doctor may take biopsy for pathological examination, perform polypectomy and therapeutic haemostasis when necessary.
Among all the cancers along the digestive tract, colorectal cancer is the most common one, accounting for the second commonest cancer in Hong Kong. In many of the gastrointestinal cancers, particularly colorectal cancer, they start as polyps or mild abnormalities in the lining of the gastrointestinal tract, which if removed early, can prevent their progression into cancer stage.
By passing an endoscope to the digestive system, the camera at the tip of the endoscope allows early detection and biopsy of areas suspicious of cancer or pre-cancer changes, facilitating earlier diagnosis and treatment. Through the same procedure, treatments may also be performed to remove abnormal lesion at early stage (e.g. removal of polyp, laser ablation and endoscopic resection of mucosal lesion in the oesophagus or stomach) allowing early control of the disease.
Gastrointestinal endoscopies are safe procedures. Although complications may occur, they are rare. Thorough assessment by experienced specialists are needed prior to the examination. Please inform your doctor should you have any of the followings:
Different endoscopic examinations require different diet and bowel preparation beforehand. Some of your medications may need to be withheld before the procedure. Specific instructions will be provided by your doctors prior to the examinations.
Before the endoscopy begins, an anaesthetic procedure will be performed to minimise your discomfort.
During the endoscopy, a flexible tube with a video scope at the tip (i.e. endoscope) will be inserted to examine the lining of the digestive tract (through the mouth to examine the stomach in OGD; through the anus to examine the large bowel in Colonoscopy and Sigmoidoscopy).
If indicated, detectable polyps can be removed for examination. Abnormal areas can also be biopsied to investigate for their underlying pathology.