How should a sessile colorectal polyp be removed and followed up, considering its size, histology, and patient comorbidities?

Management of Sessile Colorectal Polyps

Removal Technique Based on Size

For sessile polyps 10–19 mm, use lifting agents (submucosal injection) or underwater endoscopic mucosal resection (EMR) to achieve complete removal. 1 This size category represents the most commonly encountered sessile polyps requiring technique beyond simple snare polypectomy.

Small Sessile Polyps (<10 mm)

• Use cold snare polypectomy for all sessile polyps <10 mm in size. 1 Cold techniques eliminate thermal injury risk and provide adequate resection margins for benign lesions.
• Never use hot forceps polypectomy for any polyp. 1

Intermediate Sessile Polyps (10–19 mm)

• Submucosal injection with saline or other lifting agents followed by hot snare resection (inject-and-cut EMR) is the preferred technique. 1 This creates a safety cushion between the polyp and muscularis propria, reducing perforation risk.
• Underwater EMR is an acceptable alternative that uses water immersion to separate mucosa from the muscular layer without injection. 1
• Piecemeal resection is acceptable for this size range when en bloc removal is not technically feasible. 1

Large Sessile Polyps (≥20 mm)

• Refer all sessile polyps ≥20 mm to endoscopic referral centers with expertise in advanced resection techniques. 1 These lesions require EMR, endoscopic submucosal dissection (ESD), or hybrid techniques that should only be performed by therapeutic endoscopists.
• Tattoo the lesion near its base and on the opposite colonic wall to facilitate future localization. 1 Do not tattoo cecal polyps, as the cecum is easily identified anatomically.
• Piecemeal resection is expected for most lesions >20 mm. 1

Pre-Resection Assessment

Perform structured visual assessment using high-definition white light and/or electronic chromoendoscopy with photodocumentation for every sessile polyp. 1 Specifically inspect for:

• Depressed areas, ulceration, irregular surface nodularity, or firm consistency—these features suggest submucosal invasive cancer requiring surgical evaluation rather than endoscopic resection. 1
• Sessile polyps with pseudodepressed or ulcerated morphology carry 42% risk of deep submucosal invasion compared to 6% for flat elevated lesions. 1

Specimen Handling for Pathology

For sessile polyps resected en bloc with suspected malignancy, retrieve the specimen intact, pin it to a flat surface (cork board or foam pad) before formalin fixation, and submit with documentation of size, location, and morphology. 1 This orientation allows pathologists to section perpendicular to the resection plane for accurate margin assessment.

• Include in the pathology requisition: polyp location, size in millimeters, morphology (sessile vs pedunculated), and whether resection was en bloc or piecemeal. 1
• For piecemeal resections, submit all fragments together but note that margin assessment will be impossible. 1

Management of Malignant Sessile Polyps

Sessile polyps with submucosal invasive cancer have significantly higher risk of adverse outcomes than pedunculated malignant polyps, but can still be managed endoscopically if they meet strict favorable criteria. 1 The controversy exists because sessile configuration alone increases risk, but when combined with favorable histology, endoscopic removal is curative.

Favorable Histologic Features (Endoscopic Management Sufficient)

• Grade 1 or 2 differentiation (well or moderately differentiated)
• No lymphovascular invasion
• Negative resection margin (≥1 mm from cut edge)
• En bloc resection allowing margin assessment 1, 2

If all four favorable criteria are met, no surgery is required; proceed to surveillance colonoscopy. 1, 2

Unfavorable Histologic Features (Surgery Required)

• Grade 3 or 4 differentiation (poorly differentiated)
• Lymphovascular invasion present
• Positive resection margin (<1 mm from cut edge)
• Piecemeal resection preventing margin assessment
• Submucosal invasion depth >1 mm 1, 2

If any unfavorable feature is present, refer for segmental colectomy with en bloc lymph node dissection (minimum 12 nodes examined). 1, 2 Sessile malignant polyps carry approximately 10% lymph node metastasis risk even with favorable pathology, higher than pedunculated lesions. 2

Follow-Up After Complete Resection

For Benign Sessile Polyps

After complete removal of a 6–8 mm sessile polyp with low-grade dysplasia, perform surveillance colonoscopy in 7–10 years. 3 This assumes:

• Complete excision confirmed endoscopically and pathologically
• No high-grade dysplasia, villous features, or serrated histology
• Adequate quality examination (complete to cecum, adequate prep, ≥6-minute withdrawal time) 3

If the sessile polyp shows high-grade dysplasia, tubulovillous/villous histology, or measures 10–19 mm, perform surveillance in 3 years. 3

For Piecemeal Resection of Large Sessile Polyps

When sessile polyps >15 mm are removed piecemeal, perform verification colonoscopy in 3–6 months to confirm complete removal. 1 If the site is clear, extend subsequent surveillance to 1 year, then longer intervals if no recurrence. 1

• Recurrence rates after piecemeal EMR of large sessile polyps range from 9–17%, but recurrences are typically small and amenable to repeat endoscopic treatment. 4, 5
• For sessile serrated polyps ≥10 mm removed by EMR, recurrence occurs in <5% of cases at mean 18 months follow-up. 6

For Completely Resected Malignant Sessile Polyps

After complete endoscopic removal of a malignant sessile polyp with favorable histology, perform surveillance colonoscopy in 3 years (not the standard 7–10 years for benign adenomas). 2 This reflects the highest-risk category for metachronous lesions.

• If the 3-year exam shows normal findings or only 1–2 small tubular adenomas, extend the next interval to 5 years. 2
• If ≥3 adenomas or any advanced features are found, maintain 3-year surveillance. 2

Common Pitfalls to Avoid

• Do not attempt endoscopic resection of sessile polyps with endoscopic features of deep invasion (ulceration, firmness, irregular nodularity)—refer directly for surgical evaluation. 1 These features predict submucosal cancer in >40% of cases.

• Do not apply 7–10 year surveillance intervals to malignant polyps even when completely resected with favorable histology—the correct interval is 3 years. 2

• Do not assume sessile polyps have the same low metastatic risk as pedunculated polyps—consider surgical consultation even with favorable pathology due to 10% nodal metastasis risk. 2

• Do not cut large sessile polyps to facilitate removal through the suction channel—this destroys margin assessment capability. 1

• Do not proceed with extended surveillance intervals after piecemeal resection without first performing a 3–6 month verification colonoscopy to document complete removal. 1, 2