A lower endoscopy is a medical procedure used to examine the lining of the lower part of the gastrointestinal (GI) tract, which includes the large intestine and rectum. This examination uses a tool called an endoscope, which is a long, thin, and flexible tube equipped with a camera and a light source at its tip. The endoscope is gently guided through the rectum, allowing a healthcare provider to visualize the internal surfaces of the colon on a high-definition monitor.
What Lower Endoscopy Examines
The term “lower endoscopy” primarily refers to two distinct procedures: a colonoscopy and a flexible sigmoidoscopy. Both procedures utilize an endoscope, which is a sophisticated instrument that includes working channels for inserting tiny tools to perform tasks like taking tissue samples or removing polyps. They differ significantly in the extent of the colon they examine.
A colonoscopy is the more comprehensive procedure, involving the examination of the entire large intestine, from the rectum all the way to the junction with the small intestine. This provides a complete view of the approximately five-foot-long colon. A flexible sigmoidoscopy is a more limited examination that only inspects the rectum and the lower portion of the large intestine, known as the sigmoid colon. This shorter procedure is less invasive and requires a less extensive preparation process.
Essential Preparation Before the Procedure
A successful lower endoscopy requires thorough bowel preparation, as the colon must be completely clear of stool for the physician to see the lining clearly. This preparation process typically begins a few days before the procedure with dietary modifications. Patients are instructed to switch to a low-fiber diet about three days prior to the test, avoiding foods like whole grains, nuts, and seeds.
The day before the procedure, a clear liquid diet is strictly required, meaning the consumption of only transparent liquids like water, clear broth, apple juice, and plain gelatin. This step is followed by the use of potent laxative solutions to flush the digestive tract. The laxative is usually taken in a split-dose regimen, with the first portion consumed the evening before and the second portion taken several hours before the procedure itself. Inadequate preparation can obscure the view, potentially causing the physician to miss abnormalities and necessitating repeating the entire process.
Primary Indications for the Test
Lower endoscopy serves as both a screening method and a diagnostic tool. As a screening test, colonoscopy is the primary method for the early detection and prevention of colorectal cancer. It is recommended for individuals at average risk, typically beginning at age 45, to find and remove precancerous growths called polyps before they develop into cancer.
For diagnostic purposes, the procedure investigates specific symptoms suggesting a problem within the lower GI tract. These symptoms include chronic, unexplained diarrhea, persistent abdominal pain, and rectal bleeding or blood in the stool. Lower endoscopy is also used to monitor chronic conditions like Inflammatory Bowel Disease (IBD), such as Crohn’s disease and ulcerative colitis, allowing for the direct visualization of inflammation, ulcers, or other irregularities.
What Happens During and After the Endoscopy
During the procedure, the patient is typically given sedation to ensure comfort and minimize awareness. Once the patient is relaxed, the lubricated endoscope is gently inserted through the rectum and advanced through the colon. The physician introduces air or carbon dioxide into the colon, which temporarily inflates the organ to create a clear working space and a better view of the lining.
If the physician identifies a polyp, it can often be removed immediately using a technique called polypectomy, where a wire loop or snare cuts the polyp away. Tissue samples, known as biopsies, can also be collected from any suspicious-looking areas for later laboratory analysis.
After the endoscope is withdrawn, the patient is moved to a recovery area to wake up from the sedation, which usually takes a few hours. Common, temporary side effects include bloating and cramping, resulting from the air used to inflate the colon. Due to the lingering effects of the sedation, a responsible adult must escort the patient home, and patients must avoid driving or operating machinery for up to 24 hours.