Flexible sigmoidoscopy is a minimally invasive procedure that allows physicians to directly visualize the lining of the rectum, sigmoid colon, and the distal portion of the descending colon using a thin, flexible tube (sigmoidoscope) equipped with a light and camera. It typically examines up to 60 cm from the anal verge, focusing on the lower third of the large intestine.

Indications

Flexible sigmoidoscopy is performed to:

  • Investigate rectal bleeding, identifying sources such as hemorrhoids, polyps, or malignancy.

  • Assess changes in bowel habits (diarrhea, constipation) or abdominal pain localized to the left lower quadrant.

  • Screen for colorectal polyps and early-stage colorectal cancer, particularly in average‐risk adults starting at age 45.

  • Evaluate known or suspected inflammatory bowel disease (ulcerative colitis, Crohn’s disease) by obtaining biopsies of abnormal mucosa.

  • Monitor response to treatment or surveillance after polyp removal or colorectal cancer therapy.

Preparation

Preparation is less intensive than for full colonoscopy but essential for clear visualization:

  1. Dietary restrictions

    • Clear liquid diet (water, broth, clear juices, tea/coffee without milk) beginning 8 hours before the procedure; avoid solid foods and any red or purple liquids.

  2. Bowel cleansing

    • Two enemas (e.g., Fleet®) administered 1–2 hours before arrival, or a single mild laxative regimen per institutional protocol.

  3. Medication management

    • Continue most routine medications; adjust or withhold anticoagulants, antiplatelets, and certain diabetic or weight‐loss agents per provider guidance at least 3–7 days prior.

  4. Day-of instructions

    • Arrive 30–60 minutes before the exam; bring a responsible adult if sedation or anxiolytics are planned.

Procedure

  • The patient lies on the left side with knees bent.

  • A lubricant and, if needed, local anesthetic gel are applied to the anal canal.

  • The sigmoidoscope is gently inserted and advanced to the sigmoid and descending colon while air or water is insufflated to optimize visualization.

  • Biopsies or polypectomies are performed through the scope as indicated.

  • Total procedure time is typically 15–30 minutes.

Risks and Complications

Flexible sigmoidoscopy is generally safe, with a lower complication rate than full colonoscopy:

  • Perforation (< 0.1%)

  • Bleeding at biopsy or polypectomy sites (< 0.5%)

  • Post‐procedure discomfort (cramping, bloating) that resolves within hours.

  • Rarely, adverse reactions to sedation or cleansing agents.

Aftercare

  • Resume clear liquids immediately; advance diet as tolerated.

  • Expect mild bloating or cramping, which typically subsides within a few hours.

  • Review biopsy or polyp pathology within 1–2 weeks; follow surveillance intervals as recommended.

Advantages

  • Less intensive preparation than colonoscopy improves patient compliance.

  • Shorter procedure time (often without sedation) allows for rapid recovery and same-day discharge.

  • Effective for targeted screening of distal colorectal pathology, with the ability to biopsy or remove polyps during the same visit.

Flexible sigmoidoscopy offers a safe, efficient, and cost-effective means of evaluating and screening the lower gastrointestinal tract. Proper preparation and adherence to follow-up recommendations ensure optimal outcomes and early detection of colorectal disease.

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