Sigmoidoscopy-Introduction, Principle, Handling Procedure, Application, and Keynotes


Sigmoidoscopy is a medical procedure used to examine the lower part of the large intestine, specifically the sigmoid colon and rectum. It is a type of endoscopy and is performed by a healthcare provider known as a gastroenterologist or colorectal surgeon. Sigmoidoscopy is a valuable diagnostic and screening tool for various gastrointestinal conditions, including colorectal cancer, polyps, and inflammatory bowel disease.

Here’s an introduction to sigmoidoscopy:

Procedure Overview:

  • Sigmoidoscopy involves the insertion of a flexible, narrow tube called a sigmoidoscope into the rectum and lower part of the colon.
  • The sigmoidoscope has a light and a camera on the end, allowing the healthcare provider to view the interior of the colon and rectum on a monitor in real-time.
  • The procedure is typically performed without the need for sedation, although local anesthesia may be used to numb the rectal area and reduce discomfort.

Purposes and Applications:

  1. Diagnostic Tool: Sigmoidoscopy is used to diagnose and evaluate various gastrointestinal conditions, including colorectal cancer, polyps, diverticulosis, and inflammatory bowel disease (such as Crohn’s disease and ulcerative colitis).
  2. Screening for Colorectal Cancer: It is a valuable screening method for detecting colorectal cancer and precancerous polyps in individuals over the age of 50 or those with a family history of colorectal cancer.
  3. Evaluation of Symptoms: Healthcare providers may recommend sigmoidoscopy to investigate symptoms such as rectal bleeding, changes in bowel habits, abdominal pain, or unexplained weight loss.
  4. Follow-Up: Sigmoidoscopy can be used as a follow-up procedure for individuals with abnormal results from other colorectal screening tests like fecal occult blood tests (FOBT).

Types of Sigmoidoscopy:

  1. Flexible Sigmoidoscopy: This is the most common type of sigmoidoscopy. The flexible sigmoidoscope allows the healthcare provider to examine the rectum and sigmoid colon. The procedure is relatively quick, typically taking 10 to 20 minutes.
  2. Rigid Sigmoidoscopy: This older technique uses a rigid sigmoidoscope and provides a limited view of the rectum and sigmoid colon. It is less commonly used today due to its limitations.


  • Preparing for sigmoidoscopy may involve fasting, using laxatives, or undergoing an enema to clear the colon and ensure a clear view during the procedure. Your healthcare provider will provide specific instructions.

During the Procedure:

  • During the sigmoidoscopy, the healthcare provider carefully advances the sigmoidoscope through the rectum and sigmoid colon, examining the lining of the intestine.
  • If polyps are detected, they may be removed or biopsied for further examination.

After the Procedure:

  • After the sigmoidoscopy, patients can usually resume their normal activities. Some individuals may experience mild discomfort or temporary gas and bloating.

Benefits and Risks:

  • Sigmoidoscopy is a valuable tool for early detection of colorectal cancer and other gastrointestinal conditions, potentially saving lives through early intervention.
  • While generally safe, sigmoidoscopy does carry some risks, including perforation of the colon, bleeding, or discomfort during or after the procedure.


The principle of sigmoidoscopy revolves around using a specialized medical instrument called a sigmoidoscope to visually examine the interior of the lower part of the large intestine, specifically the sigmoid colon and rectum. This procedure is performed to diagnose and evaluate various gastrointestinal conditions, including colorectal cancer, polyps, inflammatory bowel disease, and other abnormalities. Here’s how sigmoidoscopy works:

  1. Instrumentation: The core of sigmoidoscopy is the sigmoidoscope, which is a flexible or rigid, narrow, and elongated tube-like instrument. The sigmoidoscope contains a light source and a camera or fiber-optic system at its tip, along with channels for air or water insufflation and instruments for taking biopsies or removing polyps if necessary.
  2. Patient Preparation: Before the procedure, the patient is typically asked to follow specific preparation instructions, which may include fasting, taking laxatives, or using an enema. These steps are essential to ensure that the colon is clean and free of stool, allowing for a clear view during the examination.
  3. Insertion: The healthcare provider, often a gastroenterologist or colorectal surgeon, carefully inserts the sigmoidoscope into the patient’s rectum and advances it through the sigmoid colon. The insertion is performed gently and gradually to minimize patient discomfort.
  4. Visualization: As the sigmoidoscope is advanced, its light source illuminates the colon’s interior, and the camera or fiber-optic system captures real-time images. These images are transmitted to a monitor, allowing the healthcare provider to visualize the mucosal lining, identify abnormalities, and assess the health of the colon.
  5. Examination and Biopsies: During the procedure, the healthcare provider examines the colon’s lining, looking for signs of pathology, such as polyps, tumors, inflammation, or ulcerations. If abnormal tissue is detected, the healthcare provider can take biopsies or remove polyps for further evaluation and diagnosis.
  6. Air or Water Insufflation: To create a clear field of view and gently distend the colon for examination, air or water may be introduced through the sigmoidoscope’s channels. This helps provide better visibility and maneuverability within the colon.
  7. Completion and Withdrawal: Once the examination is complete, the sigmoidoscope is carefully withdrawn, and the healthcare provider continues to observe the colon’s lining during this process to detect any issues or bleeding caused by the procedure.
  8. Patient Recovery: After the procedure, patients are usually allowed to recover in the medical facility briefly. Depending on the patient’s condition and the use of sedation, they may need some time to regain alertness. In most cases, patients can return to their normal activities shortly after the procedure.

The principle behind sigmoidoscopy is to enable direct visual inspection of the lower part of the large intestine for diagnostic purposes. It provides valuable information about the condition of the colon and rectum, aiding in the early detection and management of gastrointestinal disorders and diseases. The procedure is relatively safe and minimally invasive compared to other colon examination methods.

Handling Procedure

Sigmoidoscopy is a medical procedure that requires careful handling and execution to ensure patient safety, comfort, and accurate results. It’s essential to follow established protocols and guidelines. Here’s a general handling procedure for sigmoidoscopy:

Before the Procedure:

  1. Patient Preparation:
    • Instruct the patient to follow pre-procedure guidelines, which may include fasting or a clear liquid diet the day before the procedure.
    • Provide instructions for bowel preparation, which may involve taking laxatives, using an enema, or taking prescribed medications to cleanse the colon.
  2. Informed Consent: Obtain informed consent from the patient, explaining the purpose, benefits, and potential risks of the sigmoidoscopy. Ensure the patient has an opportunity to ask questions.
  3. Patient Assessment:
    • Conduct a thorough medical history review to identify any contraindications, allergies, or relevant medical conditions.
    • Evaluate the patient’s vital signs, including blood pressure, heart rate, and oxygen saturation.
    • Assess the patient’s overall health status and readiness for the procedure.
  4. Sedation Options:
    • Discuss sedation options with the patient, if applicable. Some sigmoidoscopies are performed with local anesthesia or mild sedation, while others may require conscious sedation. Obtain the patient’s consent for sedation if necessary.

During the Procedure:

  1. Patient Positioning:
    • Position the patient on the examination table in a left lateral decubitus position, with the knees bent toward the chest. This position facilitates access to the rectum and sigmoid colon.
  2. Privacy and Dignity:
    • Ensure that the patient is covered with a drape or gown to maintain privacy and dignity during the procedure.
  3. Anesthesia:
    • If local anesthesia is used, apply an anesthetic gel to the rectal area to numb the region and reduce discomfort.
  4. Insertion of Sigmoidoscope:
    • Gently insert the sigmoidoscope into the patient’s rectum and advance it through the sigmoid colon while closely monitoring the patient’s comfort and vital signs.
    • Insufflate air or use water to distend the colon for better visualization.
  5. Visualization and Examination:
    • Examine the mucosal lining of the sigmoid colon and rectum using the sigmoidoscope’s camera and light source.
    • Carefully inspect the walls of the colon for abnormalities, such as polyps, inflammation, or tumors.
    • If necessary, take biopsies or remove polyps for further analysis.

After the Procedure:

  1. Sigmoidoscope Removal:
    • Slowly and gently withdraw the sigmoidoscope while monitoring the patient’s condition and vital signs.
  2. Recovery:
    • Allow the patient to recover in a designated recovery area, where they can regain alertness if sedation was used.
    • Monitor the patient for any immediate complications, such as bleeding or discomfort.
  3. Post-Procedure Care:
    • Provide the patient with post-procedure instructions, which may include dietary restrictions or recommendations.
    • Offer any necessary medications or treatments to address discomfort or potential side effects.
  4. Follow-Up:
    • Discuss the findings of the sigmoidoscopy with the patient and provide guidance on any necessary follow-up tests or treatments.
  5. Documentation:
    • Document the procedure, including patient consent, vital signs, findings, any interventions (biopsies or polyp removal), and post-procedure instructions.
  6. Patient Discharge:
    • Ensure the patient is stable and alert before discharging them. Arrange for transportation if necessary.


Sigmoidoscopy is a valuable medical procedure with various applications in the diagnosis, evaluation, and management of gastrointestinal conditions, particularly those affecting the lower part of the large intestine (colon and rectum). Here are some common applications of sigmoidoscopy:

  1. Colorectal Cancer Screening: Sigmoidoscopy is used as a screening tool to detect colorectal cancer and precancerous polyps in individuals at average risk. It provides a visual examination of the sigmoid colon and rectum, allowing for the early detection of abnormal growths.
  2. Diagnostic Evaluation: Sigmoidoscopy is employed to diagnose and evaluate a range of gastrointestinal conditions, including:
    • Colorectal cancer: To confirm the presence and extent of tumors.
    • Polyps: To identify and assess the size, number, and characteristics of polyps.
    • Inflammatory bowel disease (IBD): To evaluate the severity and extent of inflammation in conditions like ulcerative colitis.
    • Diverticulosis: To examine diverticula (small pouches in the colon wall) and assess their condition.
    • Hemorrhoids: To visualize and evaluate hemorrhoidal tissue for treatment planning.
  3. Follow-Up Examinations: Sigmoidoscopy may be performed as a follow-up procedure when abnormalities or symptoms are detected in previous colorectal screenings, such as fecal occult blood tests (FOBT).
  4. Assessment of Symptoms: When patients experience symptoms such as rectal bleeding, changes in bowel habits (e.g., diarrhea or constipation), abdominal pain, or unexplained weight loss, sigmoidoscopy can help identify the underlying cause.
  5. Biopsy and Tissue Sampling: During sigmoidoscopy, biopsies of abnormal tissue or suspected lesions can be taken for further analysis and diagnosis. This is especially important in the evaluation of conditions like IBD and colorectal cancer.
  6. Treatment and Polyp Removal: In some cases, sigmoidoscopy allows for therapeutic interventions, such as the removal of small polyps or the treatment of bleeding hemorrhoids using specialized instruments.
  7. Monitoring of Chronic Conditions: Patients with chronic gastrointestinal conditions like ulcerative colitis may undergo regular sigmoidoscopies to monitor disease activity, assess treatment effectiveness, and identify any complications.
  8. Evaluation of Bleeding: Sigmoidoscopy can help identify the source of rectal bleeding and guide appropriate treatment.
  9. Surveillance After Colorectal Surgery: Patients who have undergone colorectal surgery may have follow-up sigmoidoscopies to monitor the surgical site and assess for recurrence of conditions like colorectal cancer.
  10. Research and Clinical Trials: Sigmoidoscopy is used in clinical research to study various aspects of gastrointestinal health, assess the effectiveness of new treatments, and gather data on disease prevalence.


here are keynotes on sigmoidoscopy:

  • Definition: Sigmoidoscopy is a medical procedure used to visually examine the lower part of the large intestine, specifically the sigmoid colon and rectum, using a specialized instrument called a sigmoidoscope.
  • Purpose: It serves various purposes, including colorectal cancer screening, diagnosis of gastrointestinal conditions, assessment of symptoms like rectal bleeding, and monitoring of chronic gastrointestinal diseases.
  • Instrument: Sigmoidoscopy is performed using a sigmoidoscope, which has a light source, a camera or fiber-optic system, and channels for air or water insufflation and biopsy or polyp removal instruments.
  • Patient Preparation: Patients typically undergo bowel preparation, which may involve fasting, laxatives, or enemas to clear the colon and ensure a clear view during the procedure.
  • Procedure: The sigmoidoscope is gently inserted into the patient’s rectum and advanced through the sigmoid colon while the patient is in a left lateral decubitus position.
  • Visualization: Real-time images of the colon’s interior are transmitted to a monitor, allowing the healthcare provider to examine the mucosal lining, identify abnormalities, and assess the health of the colon.
  • Applications: Sigmoidoscopy is used for colorectal cancer screening, diagnostic evaluation of conditions like colorectal cancer, polyps, inflammatory bowel disease, and diverticulosis, as well as for assessing symptoms and conducting biopsies or therapeutic interventions.
  • Biopsy and Polyp Removal: During the procedure, biopsies of abnormal tissue or removal of small polyps can be performed for further analysis or treatment.
  • Follow-Up and Surveillance: It may be used as a follow-up procedure after abnormal screening results or surgery and for the surveillance of chronic gastrointestinal conditions.
  • Patient Privacy and Consent: Patients should be informed about the procedure, its purpose, benefits, and potential risks, and their informed consent should be obtained.
  • Post-Procedure Care: After the procedure, patients may receive post-procedure instructions and, if necessary, be monitored for immediate complications.
  • Documentation: A comprehensive record of the procedure, including findings, interventions, and post-procedure care, should be documented.
  • Safety and Patient Comfort: Ensuring patient safety and comfort is essential throughout the entire sigmoidoscopy process.

Further Readings

  1. Medical Textbooks: Look for textbooks on gastroenterology, endoscopy, or colorectal surgery, as they often include comprehensive sections on sigmoidoscopy. Examples include “Gastrointestinal Endoscopy” by Jacques Van Dam and “Colorectal Surgery” by Michael W. Beetz.
  2. Clinical Guidelines: Explore clinical practice guidelines published by organizations such as the American College of Gastroenterology (ACG), the American Society for Gastrointestinal Endoscopy (ASGE), and the World Gastroenterology Organisation (WGO). These guidelines provide recommendations on the appropriate use of sigmoidoscopy in clinical practice.
  3. Research Articles: Use medical databases like PubMed to search for research articles on sigmoidoscopy. You can find studies on its applications, diagnostic accuracy, patient outcomes, and advancements in the field. Look for articles published in peer-reviewed medical journals.
  4. Patient Information: Check healthcare organization websites, such as the American Cancer Society, the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), or the American Society of Colon and Rectal Surgeons (ASCRS), for patient-friendly resources and information on sigmoidoscopy.
  5. Endoscopy Journals: Journals like “Gastrointestinal Endoscopy” and “Endoscopy International Open” often feature articles related to endoscopic procedures, including sigmoidoscopy. These journals may provide insights into the latest developments and research in the field.
  6. Colorectal Cancer Screening Programs: Explore websites and publications related to national and regional colorectal cancer screening programs. These resources often include information on the role of sigmoidoscopy in screening and early detection.
  7. Colorectal Health and Cancer Awareness Organizations: Organizations like the Colon Cancer Alliance, Fight Colorectal Cancer, and the Colorectal Cancer Coalition may offer educational materials and resources related to colorectal health and screening methods, including sigmoidoscopy.
  8. Colorectal Surgery and Gastroenterology Associations: Visit the websites of professional associations such as the American College of Surgeons (ACS), the American Gastroenterological Association (AGA), and the American Society of Gastrointestinal Endoscopy (ASGE) for publications, guidelines, and educational materials related to sigmoidoscopy.
  9. Academic Institutions: Universities and medical schools often publish research papers and educational materials on medical procedures, including sigmoidoscopy. Explore the websites of reputable institutions for relevant resources.
  10. Clinical Trials: Investigate ongoing or completed clinical trials related to sigmoidoscopy and its applications. Clinical trial databases like can provide valuable information on the latest research in the field.

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