Lower Endoscopy: Understanding Colonoscopy and Flexible Sigmoidoscopy

Lower endoscopy procedures are valuable diagnostic tools used to examine the lower part of your digestive tract, primarily the large intestine (colon) and rectum. These procedures help doctors identify and treat various conditions affecting the lower gastrointestinal system, from inflammatory bowel disease to colorectal cancer.

In the UK, the two most common types of lower endoscopy procedures are colonoscopy and flexible sigmoidoscopy. Understanding what these procedures involve, how they differ, and what to expect can help ease concerns and ensure you're properly prepared if you need to undergo one of these examinations.

Lower endoscopy is a general term for procedures that examine the lower part of your digestive tract using a flexible tube with a light and camera (endoscope). Lower gastrointestinal endoscopy includes colonoscopy procedures which look at the whole length of the large bowel and flexible sigmoidoscopy procedures which look at just the lower part of the large bowel. Nhs

These procedures allow doctors to:

• Visually examine the lining of your bowel
• Take tissue samples (biopsies) for further testing
• Remove abnormal growths such as polyps
• Diagnose conditions affecting the lower digestive tract
• Screen for colorectal cancer

Colonoscopy

A colonoscopy is a comprehensive examination of the entire large intestine (colon) and rectum. During this procedure:

• A thin, flexible tube with a camera (colonoscope) is inserted through the rectum
• The colonoscope is advanced through the entire large intestine to the junction with the small intestine
• Air or carbon dioxide is introduced to inflate the colon for better visibility
• The doctor examines the lining of the entire colon and rectum for abnormalities

A colonoscopy usually takes around 30 to 45 minutes, though you'll likely be in the hospital for around two hours in total, including preparation and recovery time.

Flexible Sigmoidoscopy

A flexible sigmoidoscopy is a more limited examination that focuses only on the lower part of the large intestine:

• It examines the rectum and sigmoid colon (the final section of the large intestine)
• The procedure uses a shorter flexible tube (sigmoidoscope)
• It's quicker and often less uncomfortable than a colonoscopy
• Usually requires less extensive bowel preparation

In most cases, sedatives or anaesthesia are not necessary for a flexible sigmoidoscopy, meaning you can drive yourself home after the procedure. The procedure typically takes between 5 to 15 minutes.

A colonoscopy looks around the entire rectum and colon, while a sigmoidoscopy is when doctors look at just the rectum and lower part of colon.

Healthcare providers may recommend a lower endoscopy for various reasons:

Diagnostic Purposes

• Investigating symptoms such as unexplained abdominal pain, rectal bleeding, or changes in bowel habits
• Evaluating abnormal results from other tests
• Investigating unexplained weight loss or anaemia
• Assessing inflammatory bowel conditions like Crohn's disease or ulcerative colitis

Screening and Surveillance

• Bowel cancer screening, particularly for those aged 56-74 in the UK
• Monitoring patients with a history of polyps or colorectal cancer
• Surveillance for those with inflammatory bowel disease
• Follow-up after abnormal findings in other tests

In the UK, bowel cancer screening is initially via a FIT (Faecal Immunochemical Test) kit which looks for hidden blood in stools. If this test reveals anything unusual, further investigation via colonoscopy may be recommended.

Proper preparation is essential for a successful lower endoscopy, as the bowel needs to be clear for the doctor to see the lining properly.

For Colonoscopy

Preparation typically involves:

• Following a special low-fibre diet for 1-3 days before the procedure
• Taking strong laxatives (bowel preparation) to clear your bowel
• Fasting from solid foods for at least 24 hours before the procedure
• Drinking clear fluids only on the day of the procedure
• Temporarily adjusting or stopping certain medications as advised by your doctor

For Flexible Sigmoidoscopy

Preparation is usually less intensive:

• An enema may be administered shortly before the procedure
• You may be asked to follow a special diet for 24 hours before the test
• Some patients may receive a small-volume laxative to take at home

If you're having a flexible sigmoidoscopy, you may be given an arrival time in advance so that endoscopy nursing staff can give you an enema in a private room about 30 minutes before the procedure.

What to Expect During a Colonoscopy

• You'll usually lie on your left side
• You may be offered sedation to help you relax
• The colonoscope is gently inserted through the rectum and advanced through the colon
• Air or carbon dioxide is used to inflate the bowel for better visibility
• You might experience mild cramping or the urge to pass gas
• The doctor will examine the lining of your entire colon for abnormalities
• If polyps are found, they can often be removed during the procedure

A sedative is given and then a thin, flexible tube with a tiny camera attached (a colonoscope) is passed into the back passage and guided around the bowel. If polyps are found, most can be removed painlessly, using a wire loop passed down the colonoscope tube. NW Anglia Website

What to Expect During a Flexible Sigmoidoscopy

• Similar to a colonoscopy, but examining only the lower part of the colon
• Often performed without sedation
• Generally causes less discomfort than a colonoscopy
• Takes less time than a colonoscopy
• You can usually return to normal activities immediately afterward

After a lower endoscopy, you'll be monitored in a recovery area until the effects of any sedation wear off. You might experience:

• Mild abdominal cramping
• Bloating or gas
• A small amount of bleeding if biopsies were taken or polyps removed

For colonoscopy with sedation, you'll need someone to take you home and should not drive for 24 hours. With flexible sigmoidoscopy without sedation, you can usually drive and return to normal activities immediately.

Lower endoscopy procedures are generally safe, but like all medical procedures, they carry some risks:

• Bleeding from biopsy sites or after polyp removal
• Perforation (a tear in the bowel wall) - very rare but serious
• Adverse reaction to sedation
• Missed abnormalities
• Infection (extremely rare)

The risk of perforation in a sigmoidoscopy is approximately 1 in 5,000, increasing to 1 in 2,500 if polyps are removed.

Lower endoscopy procedures are valuable tools for diagnosing and treating conditions affecting the lower digestive tract. In the UK, both colonoscopy and flexible sigmoidoscopy are widely available through the NHS and private healthcare providers.

If you're referred for one of these procedures, understanding what to expect and following the preparation instructions carefully will help ensure accurate results. Most people find these procedures much less uncomfortable than anticipated, and the potential benefits in terms of early diagnosis and treatment far outweigh the temporary discomfort.

Remember that lower endoscopy plays a crucial role in bowel cancer screening and early detection, which can significantly improve treatment outcomes for this common cancer.