What are the criteria for excision of gallbladder (GB) polyps?

Criteria for Excision of Gallbladder Polyps

Cholecystectomy is indicated for gallbladder polyps ≥15 mm, polyps 10-14 mm with high-risk morphology (sessile or focal wall thickening), or any polyp demonstrating rapid growth of ≥4 mm within 12 months. 1, 2

Size-Based Surgical Criteria

Immediate Surgical Consultation Required

• Polyps ≥15 mm warrant immediate surgical referral regardless of morphology or other features 1, 2, 3
• This threshold is based on significantly increased malignancy risk, with neoplastic polyps averaging 18-21 mm compared to 4-7.5 mm for nonneoplastic polyps 1
• Studies show polyps ≥10 mm have a malignancy rate of 128 per 100,000 patients, compared to 1.3 per 100,000 for polyps <6 mm 1, 3

Borderline Size (10-14 mm) - Risk-Stratified Approach

For polyps 10-14 mm, surgical decision depends on morphology 1, 2:

• Sessile polyps or those with focal wall thickening: Consider cholecystectomy, as these carry higher malignancy risk 1, 2
• Pedunculated polyps with thin stalk: May undergo surveillance with ultrasound at 6,12, and 24 months 1, 2
• Neoplastic lesions are more likely to manifest as focal wall thickening (29.1%) than lumen-protruding polyps (15.6%) 1

Growth-Based Criteria

Rapid growth of ≥4 mm within any 12-month period mandates surgical consultation regardless of absolute polyp size 1, 2, 3

Important caveats:

• Minor fluctuations of 2-3 mm are part of the natural history of benign polyps and should not trigger intervention 2, 4
• Benign polyp growth rates typically range from 0.16-2.76 mm/year 2, 4
• In one study, 507 polyps initially <10 mm grew to ≥10 mm over follow-up, yet none developed malignancy in 1,549 person-years 4

Morphology-Based Risk Stratification

The Society of Radiologists in Ultrasound categorizes polyps into three risk groups 1:

Extremely Low Risk (No Surgery)

• Pedunculated with "ball-on-the-wall" configuration or thin stalk 1, 2
• If ≤9 mm: no follow-up needed 2
• If 10-14 mm: surveillance ultrasound at 6,12, and 24 months 1, 2

Low Risk (Surgery for Larger Polyps)

• Pedunculated with thick/wide stalk or sessile configuration 1, 2
• If ≤6 mm: no follow-up needed 2
• If >6 mm: follow-up recommended 2

Indeterminate Risk (Consider Surgery)

• Focal wall thickening adjacent to polyp 1
• These lesions have higher association with neoplasia (37.9% of cancers manifest this way) 1

Special Patient Populations

Primary Sclerosing Cholangitis (PSC)

The SRU guidelines do not apply to PSC patients 1

• PSC patients have 18-50% association of gallbladder lesions with cancer and 25-35% with premalignant lesions 1
• Consider cholecystectomy for polyps ≥8 mm in PSC patients 2, 4
• Refer to gastroenterology specialty guidelines for PSC-specific management 1

Age and Other Risk Factors

• Age >60 years, Asian ethnicity, and focal wall thickening are additional risk factors 2
• However, the SRU consensus determined that age alone should not influence risk stratification due to lack of evidence 1
• Coexisting gallstones should not influence risk stratification, despite their ubiquity 1

Polyps NOT Requiring Surgery

Size <10 mm Without High-Risk Features

• Polyps ≤5 mm have 0% malignancy rate in multiple studies and require no follow-up 1, 2
• Polyps ≤6 mm with pedunculated "ball-on-the-wall" configuration require no follow-up 1, 2
• No documented cases of malignancy in polyps <10 mm at initial detection in large series 1, 3

Multiple Small Polyps

• Multiple small polyps are more likely to be nonneoplastic than single polyps 4
• Malignant or neoplastic polyps are more likely to be single rather than multiple 4

Surgical Risk Considerations

When weighing surgery versus observation, consider 2, 3:

• Cholecystectomy morbidity: 2-8% (including bile duct injury in 3-6 per 1,000 patients) 2, 3
• Mortality: 0.2-0.7% (2-7 per 1,000 patients), related to operative complexity and comorbidities 2, 3
• These risks increase with patient age and frailty 1

Common Pitfalls to Avoid

• Do not confuse tumefactive sludge with true polyps: Use power Doppler, B-Flow, or microvascular Doppler to differentiate; consider contrast-enhanced ultrasound or MRI if uncertain 1, 2
• Do not overinterpret small size changes: 61-69% of polyps seen on ultrasound are not identified at subsequent cholecystectomy; for polyps ≤5 mm, up to 83% are not found at surgery 1, 2
• Do not rely on vascularity: Both neoplastic and nonneoplastic polyps can demonstrate internal vascularity on Doppler 4
• Do not assume all growth indicates malignancy: Many polyps that grow to 10 mm remain benign 4

Surveillance Protocol for Non-Surgical Polyps

For polyps not meeting surgical criteria 1, 2, 3:

• 6-9 mm (low risk morphology): Ultrasound at 12 months
• 10-14 mm (extremely low risk morphology): Ultrasound at 6,12, and 24 months
• 10-14 mm (low risk morphology): Ultrasound at 6,12,24, and 36 months
• Extended follow-up beyond 3-4 years is not productive 3