Endoscopy: Transanal (Lower) Endoscopy

Transanal (Lower) Endoscopy

Definitions

  • Colonoscopy: Endoscopic Evaluation of the Entire Colon
  • Sigmoidoscopy: Endoscopic Evaluation of the Sigmoid Colon
    • Does Not Evaluate the Entire Colon
  • Proctoscopy: Endoscopic Evaluation of the Rectum & Anus
    • Rectoscopy: Endoscopic Evaluation of the Rectum
    • Anoscopy: Endoscopic Evaluation of the Anus

Scopes

  • Colonoscope – Flexible Endoscope, 130-168 cm
  • Sigmoidoscope – Flexible (Most Common) or Rigid, 35-60 cm
    • Equivalent for Most Indications
    • Rigid is Better for Measurement of Distance from Anal Verge to a Low Rectal Tumor (Rectosigmoid Tumors are Equivalent)
  • Rectoscope – Rigid Tube, 25 cm
  • Proctoscope – Rigid Tube, 13 cm
  • Anoscope – Rigid Tube, 10 cm

Quality Guidelines

  • Intubate Cecum ≥ 90-95% of the Time
    • Intubate Terminal Ileum if Concern for Lower GI Bleed
  • Adenoma Detection Rates ≥ 25% of All Patients Over 50 Years Old
    • 30% in Men & 20% In Women
  • Mean Withdrawal Time ≥ 6-8 Minutes
  • Resect All Mucosal Polyps < 2 cm
  • Perforation Rate < 1:500 (1:1,000 in Screening)
  • Post-Polypectomy Bleeding < 1% Incidence
  • Post-Polypectomy Bleeding Nonoperative ≥ 90% of Cases

Anatomical Landmarks

  • Rectum: Wide Lumen, Prominent Vasculature & Semi-Lunar Transverse Folds (Houston’s Valves)
  • Sigmoid: Tortuous
  • Descending: Straight Lumen & Minimal Haustration
  • Transverse: Long Segment & Triangular Folds
  • Hepatic Flexure: Bluish Hue
  • Cecum: Tenia Coli Converge (“Crow’s Feet”/“Mercedes Sign”/Tri-Radiate Fold), Appendiceal Orifice & Ileocecal Valve
    • Most Reliable Cecal Landmark: Ileocecal Valve

“Looped” Colon

  • Definition: Bowing in the Colon with Mobile Mesentery
    • Prevents Colonoscope Advancement
  • Indicated by “Paradoxical Movements” – Advancing Scope Causes it to Retract
  • Techniques to Relieve:
    • Partially Withdraw the Scope with Applied Torque – Should Be the First Step Until the Loop is Reduced
    • Assistant Applies External Abdominal Pressure
    • Position Adjustment – Supine, Right Lateral Decubitus or Prone

Therapeutic Interventions

  • Polypectomy
  • Endoscopic Hemostasis
    • Dilute Epinephrine Injection
    • Electrocautery
    • Endoscopic Clips
  • Balloon Dilation
  • Stent Placement
  • Foreign Body Removal
  • Placement of a Colonic Decompression Tube

Repeat Colonoscopy Recommendations