Sessile and Pedunculated Polyps: Definitions
Sessile polyps are flat lesions that arise directly from the mucosal layer without a stalk, while pedunculated polyps extend from the mucosa through a fibrovascular stalk (pedicle). 1
Morphological Characteristics
Sessile Polyps
- Flat or broad-based attachment directly to the colonic wall
- No intervening stalk between the polyp head and the mucosal surface
- More commonly found throughout the colon, particularly in the right colon (hepatic flexure to cecum) 2
- Represent the majority of colonic polyps 2
Pedunculated Polyps
- Possess a distinct stalk (pedicle) composed of pulled-out mucosa and submucosa
- The stalk forms due to constant peristaltic action as the colon attempts to evacuate the polyp 2
- More commonly located in the sigmoid colon 2
- The stalk allows the polyp head to move freely within the lumen
Clinical Relevance for Your 14mm and 10mm Polyps
For polyps in the 10-19mm range, the morphology (sessile vs. pedunculated) significantly impacts the removal technique and risk profile. 3
Management Implications
Non-pedunculated (sessile) lesions 10-19mm:
- Cold or hot snare polypectomy with or without submucosal injection is recommended 3
- EMR (endoscopic mucosal resection) should be considered for non-polypoid and serrated lesions in this size range, as conventional polypectomy has shown 31% incomplete resection rates for these morphologies 3
Pedunculated lesions:
- Hot snare remains the gold standard for removal 4
- Generally easier to remove completely compared to sessile polyps of similar size 5
Risk Stratification
Sessile polyps are considered more technically difficult to remove than pedunculated polyps, with larger diameters falling into the "very difficult" category requiring advanced polypectomy techniques 2. The British Society of Gastroenterology defines large non-pedunculated colorectal polyps (LNPCPs) as sessile or flat polyps of at least 20mm, highlighting the clinical significance of this morphology 6.
Common Pitfalls
- Do not assume all flat lesions are benign: Sessile morphology, particularly non-granular laterally spreading tumors, carries increased malignancy risk 6
- Avoid biopsy before planned resection: Targeted biopsies should only be performed if there is suspicion of malignancy, as biopsy may complicate subsequent complete resection 6
- Recognize that sessile polyps have higher recurrence rates: Studies show 5.5% residual and 11% recurrent disease rates for sessile adenomas after piecemeal resection 7