SRU management guidelines for gallbladder polyps

The Society of Radiologists in Ultrasound (SRU) consensus recommendation for the management of incidentally detected gallbladder polyps was published in 2021 ¹.

Usage

The SRU consensus recommendation is one of many guidelines for the management of incidentally detected gallbladder polyps. The SRU consensus recommendation has been found to have substantial agreement amongst abdominal radiologists ³.

Classification

The SRU ¹ examined existing research and discovered no substantial relationship between gallbladder cancer and gallbladder polyps. They identified three types of polyps: non-neoplastic, benign neoplastic, and malignant.

This classification system can be used after the following exclusions have been applied ¹:

• technically inadequate scan or poorly visualized suspected gallbladder polyp: follow-up ultrasound in 1-2 months

• suspected gallbladder polyp unable to be distinguished from >10 mm tumefactive sludge or adenomyomatosis: contrast-enhanced ultrasound or MRI

• high suspicious for invasive/malignant tumor: specialist referral

• history of primary sclerosing cholangitis: refer to ACG Clinical Guideline: Primary Sclerosing Cholangitis ²

Gallbladder polyps are classified into three groups based on their morphological characteristics: extremely low risk, low risk, and indeterminate risk.

Extremely low risk

• pedunculated ball-on-the-wall or pedunculated with thin stalk

  • ≤9 mm: no follow-up

  • 10-14 mm: follow-up ultrasound at 6, 12, 24 months

  • ≥15 mm: surgical consultation

NB thin stalks can be very difficult to visualize on gray-scale ultrasound and are non-measurable; the presence of a vessel at the poylp base or "wiggling" in place implies a think stalk is present ¹. Thick stalks are visible/measurable ³.

Low risk

• pedunculated with thick/wide stalk or sessile

  • ≤6 mm: no follow up

  • 7-9 mm: follow up ultrasound at 12 months

  • 10-14 mm:  follow up ultrasound at 6, 12, 24, and 36 months vs surgical consultation

  • ≥15 mm: surgical consultation

NB pedunculated polyps have a clear border to the gallbladder wall with the stalk creating an acute angle ³.

Indeterminate risk

• focal wall-thickening ≥4 mm adjacent to polyp

  • ≤6 mm: follow up ultrasound at 6, 12, 24, 36 months vs surgical consultation

  • ≥7 mm: surgical consultation

Practical points

• polyp size should be rounded to the closest millimeter ¹

• the number of polyps does not change risk stratification - follow SRU recommendations for the largest polyp ^1,3

• vascularity (presence or absence) does not change risk stratification ³

• on follow-up ¹

  • if increase ≥4 mm in ≤12 months or reaches the threshold size within the category, surgical consultation is recommended

  • if decrease ≥4 mm, discontinue follow-up

• surgical consultation may be an appropriate option for polyps 10-14 mm in the extremely low risk group ¹

• if specific ethnicities are recognized, polyps may be considered low risk rather than extremely low risk ¹

• if the category is unclear, go with the lowest risk ¹

The follow-up time has been decreased to three years. The annual growth rate has been boosted to more than 4 mm. It is usual for benign polyps to develop slowly, up to 2 mm each year, while many small polyps vanish. Most malignant polyps are larger than 20 mm.