Management of 0.7 cm (7 mm) Nonmobile Gallbladder Polyp with Internal Vascularity
This 7 mm sessile polyp with internal vascularity requires ultrasound surveillance at 6 months, 1 year, and 2 years, with surgical consultation if the polyp grows to 10 mm or demonstrates rapid growth (≥4 mm within 12 months). 1, 2
Risk Stratification
This polyp falls into an intermediate-risk category based on multiple features:
Size (7 mm): The polyp is in the 6-9 mm range, which carries a malignancy rate of 8.7 per 100,000 patients—significantly higher than polyps <6 mm (1.3 per 100,000) but lower than polyps ≥10 mm (128 per 100,000). 1
Sessile morphology: The description of "nonmobile" with "internal vascularity" suggests a sessile (broad-based) configuration rather than a pedunculated "ball-on-the-wall" appearance. Sessile polyps have consistently higher rates of malignancy compared to pedunculated polyps across multiple studies. 1, 2
Internal vascularity: The presence of internal vascularity on Doppler imaging confirms this is a true polyp rather than tumefactive sludge, which would be avascular. 1
Surveillance Protocol
Follow-up ultrasound is recommended at 6 months, 1 year, and 2 years. 2 This surveillance schedule is based on evidence showing that 68% of gallbladder cancers associated with polyps are detected within the first year, and extended follow-up beyond 3-4 years is not productive. 1, 3
Surveillance should be discontinued after 2 years if:
- The polyp remains stable in size 2
- No growth of ≥2 mm occurs during the surveillance period 2
- The polyp disappears (occurs in up to 34% of cases) 1, 2
Triggers for Surgical Consultation
Immediate surgical referral is warranted if:
Growth to ≥10 mm: This represents the established threshold for cholecystectomy regardless of other features. 1, 2
Rapid growth of ≥4 mm within 12 months: This constitutes concerning rapid growth, even if the absolute size remains <10 mm. 1, 4, 3 The SRU consensus defines growth of ≥4 mm within 1 year as rapid growth, with documented cases of polyps growing from 7 to 16 mm over 6 months developing into malignancy. 1
Growth of ≥2 mm during the 2-year follow-up period: This requires reassessment of current polyp size along with patient risk factors to determine whether continued monitoring or cholecystectomy is necessary. 2
Additional Risk Factors to Consider
The following patient-specific factors would lower the threshold for cholecystectomy:
Age >60 years: This is an established risk factor for malignancy in 6-9 mm polyps. 2
Primary sclerosing cholangitis (PSC): PSC patients have dramatically elevated malignancy risk (18-50%) and should undergo cholecystectomy for polyps ≥8 mm rather than the standard 10 mm threshold. 4, 3, 2
Asian ethnicity: This represents an independent risk factor for gallbladder carcinoma. 2
Symptomatic polyp: If the patient has biliary-type pain without alternative explanation, cholecystectomy should be considered even for smaller polyps. 2
Critical Pitfalls to Avoid
Do not confuse natural polyp fluctuation with concerning growth: Minor size changes of 2-3 mm are part of the natural history of benign polyps, with almost half of polyps increasing or decreasing in size over time. 1, 3 Only sustained growth of ≥4 mm within 12 months constitutes rapid growth requiring intervention. 1
Ensure proper imaging technique: The patient should be fasting for accurate ultrasound assessment, as 61-69% of polyps seen on ultrasound are not identified at subsequent cholecystectomy, highlighting the importance of proper technique and differentiation from pseudopolyps. 4, 5
Recognize that this polyp has malignant potential despite small size: While rare, there are documented cases of polyps as small as 5 mm undergoing malignant transformation over 2 years, emphasizing the importance of adherence to surveillance protocols. 6