Colonoscopy vs Gastroscopy:
What's the Difference?

How Is a Colonoscopy Performed?

• Preparation: Before the procedure, the colonoscopy clinic will provide instructions to ensure a clear view of the colon during the examination. This preparation involves following a special diet and taking laxatives to clear out any stool.
• Anaesthesia: Before the procedure starts, patients are given anaesthesia to either help them relax and minimise discomfort during the procedure, or put them to sleep entirely.
• Positioning: Patients are positioned on their sides on an examination table with their knees drawn towards their chest to facilitate access to the rectum.
• Insertion of the Colonoscope: The doctor gently inserts a colonoscope—a long, flexible tube with a camera—into the rectum. This instrument is advanced through the entire colon length while air or carbon dioxide is introduced to inflate the colon, allowing for better visibility.
• Examination and Procedures: As the colonoscope moves through the colon, the doctor examines the lining for abnormalities such as polyps or signs of disease. Tools can be passed through the colonoscope to take biopsies or remove polyps during this step if necessary.
• Completion and Recovery: The procedure typically lasts 30 to 60 minutes. Afterwards, patients are taken to a recovery area and monitored as the sedative wears off. Due to the effects of sedation, patients should arrange for someone to drive them home.

When Is a Colonoscopy Necessary?

• Screening for Cancer: Colonoscopy is a vital tool in the early detection and prevention of colorectal cancer. It enables doctors to identify and remove precancerous polyps before they develop into malignancies. Regular screening is recommended for adults at age 50, as early detection significantly improves treatment outcomes.
• Diagnosis of Gastrointestinal Conditions: Beyond cancer screening, colonoscopy is also used to diagnose other gastrointestinal disorders. It helps identify causes of symptoms such as chronic diarrhoea, unexplained abdominal pain, rectal bleeding, and changes in bowel habits. Conditions like inflammatory bowel disease, diverticulosis, and colonic strictures can be diagnosed through this procedure.
• Treatment and Intervention: Colonoscopy is not only diagnostic but also therapeutic. During the procedure, doctors can perform interventions such as polyp removal (polypectomy), control of bleeding sites, dilation of narrowed segments (strictures), and removal of foreign bodies.

How Is a Gastroscopy Performed?

• Preparation: Before the procedure, patients are instructed to fast for at least six hours to ensure their stomachs are empty. This is crucial for clear visibility during the examination.
• Sedation: Patients are typically given a sedative to help them relax and minimise discomfort during the procedure. A local anaesthetic may also be sprayed into the back of the throat to numb it and reduce the gag reflex.
• Positioning: Patients are then asked to lie on their left side on an examination table. A plastic mouth guard is placed between their teeth to protect them during the procedure.
• Insertion of the Gastroscope: The doctor gently inserts the gastroscope—a thin, flexible tube with a camera—guiding it down the oesophagus into the stomach and duodenum.
• Examination: As the gastroscope is advanced, air is introduced into the stomach to inflate it, which helps improve the visibility of the lining. The doctor examines images on a monitor for abnormalities like inflammation, ulcers, or tumours.
• Completion and Recovery: The gastroscope is withdrawn after the examination, which usually lasts about 10 minutes. Patients are then monitored in a recovery area until the effects of sedation wear off, typically for one to two hours.

When Is a Gastroscopy Necessary?

• Diagnosis and Evaluation: Gastroscopy is instrumental in diagnosing and assessing symptoms such as persistent indigestion, heartburn, abdominal pain, nausea, vomiting, difficulty swallowing (dysphagia), and unexplained weight loss.
• Identification of Abnormalities: During the procedure, the endoscope allows for the detection of abnormalities like inflammation, ulcers, tumours, polyps, and structural issues such as strictures or hiatal hernias.
• Biopsies and Tissue Sampling: Gastroscopy enables the collection of tissue samples (biopsies) from suspicious areas within the upper digestive tract. These samples are analysed to detect infections and to diagnose conditions like coeliac disease or oesophagus and stomach cancers. Biopsies provide essential information that guides treatment decisions.
• Therapeutic Interventions: Beyond diagnosis, gastroscopy can be used therapeutically. It allows for removing foreign objects, treating bleeding sites through cauterisation or clipping, and removing polyps. It also facilitates the placement of feeding tube for patients unable to eat normally.

Key Differences Between Colonoscopy and Gastroscopy