What is the recommended endoscopic management for laterally spreading polyps detected during colonoscopy?

Endoscopic Management of Laterally Spreading Polyps

Endoscopic mucosal resection (EMR) is the recommended first-line treatment for laterally spreading tumors (LSTs) ≥20 mm, with the goal of complete resection in a single session using the safest minimum number of pieces. 1

Classification and Risk Stratification

LSTs are non-polypoid lesions ≥10 mm that extend laterally along the colonic wall with a low vertical axis. Critical morphologic distinction guides your resection approach 1:

• Granular-type LSTs (LST-G): Nodular surface

  • Homogeneous subtype (LST-G-H): Lowest submucosal invasion risk (0.5%)
  • Mixed nodular subtype (LST-G-NM): Intermediate risk

• Non-granular type LSTs (LST-NG): Smooth surface

  • Flat elevated subtype (LST-NG-FE): Moderate risk
  • Pseudodepressed subtype (LST-NG-PD): Highest submucosal invasion risk (31.6%) 1

Use enhanced imaging (NBI, chromoendoscopy) to assess for deep submucosal invasion before attempting resection—this is mandatory proficiency. 1

Resection Technique for LSTs ≥20 mm

Pre-Resection Steps

1. Document: Location, size in millimeters, Paris classification, and granular vs. non-granular morphology 1
2. Photo documentation of the lesion before resection 1
3. Assess for submucosal invasion using pit pattern/vascular pattern analysis—depressed areas (0-IIc) carry 27-35.9% invasion risk 1

EMR Execution

• Inject viscous submucosal solution (hydroxyethyl starch, Eleview, ORISE Gel) to enable fewer pieces and shorter procedure time 1
• Add contrast agent (indigo carmine or methylene blue) to the injection to distinguish mucosal layers 1
• Never use tattoo (carbon particles) in the injection—causes submucosal fibrosis that prevents future resection attempts 1
• Resect all grossly visible tissue in a single session using the minimum number of pieces—prior failed attempts dramatically increase recurrence risk 2, 1
• Never use ablative techniques (APC, snare tip coagulation) on visible residual tissue—this increases recurrence 1

Post-Resection Management

• Apply adjuvant thermal ablation to the EMR margin where no visible adenoma remains after meticulous inspection 1
• Inspect the defect for perforation risk and close with clips accordingly 1
• Prophylactically close defects ≥20 mm in the right colon when feasible—this reduces delayed bleeding and perforation 1

Surveillance Protocol

Intensive follow-up is mandatory after piecemeal EMR of lesions ≥20 mm 1:

1. First surveillance at 6 months
2. Second surveillance at 1 year (12 months from resection)
3. Third surveillance at 3 years (if clear at 1 year)

At each surveillance 1:

• Use enhanced imaging (chromoendoscopy or electronic methods) to examine the scar
• Obtain targeted biopsies of the scar site—normal macroscopic AND microscopic findings have highest predictive value for eradication
• If recurrence detected: repeat EMR/snare avulsion, consider ablation of perimeter, then return to 6-12 month intervals until clear

The 12-month recurrence rate is the key performance indicator (not 3-month), with acceptable rates of 2-16.3% reported in high-quality series 2. Late recurrence can occur even when 3-month surveillance was clear 2.

When to Refer

Refer to an endoscopist experienced in advanced polypectomy rather than to surgery when you encounter a suspected benign LST you're not confident removing 1. Surgery should be reserved for:

• Lesions with endoscopic features of deep submucosal invasion unsuitable for endoscopic resection
• Malignant polyps with unfavorable histologic features after resection

The British data shows 16.1-16.3% ultimately require surgery even in expert hands, but endoscopic management should always be attempted first given surgery's 0.7% 30-day mortality and 14% major complication rate versus 0.08% mortality for endoscopic resection 2, 1.

Critical Pitfalls to Avoid

• Never attempt piecemeal resection without proper training—incomplete resection leads to recurrence
• Never inject tattoo into the submucosa—creates fibrosis preventing future attempts
• Never ablate visible residual tissue—always resect it with snare
• Never skip the 6-month surveillance—this is when most recurrences are detected and can be treated before progression