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Ultraschall Med
DOI: 10.1055/a-2655-8601
Review

Gallbladder polyps: ultrasound diagnosis, updated guidelines, and clinical management

Gallenblasen-Polypen: Ultraschalldiagnostik, aktualisierte Leitlinien und klinisches Management

Authors

  • Andrea Boccatonda 

    1   Diagnostic and Therapeutic Interventional Ultrasound Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna Policlinico di Sant'Orsola, Bologna, Italy (Ringgold ID: RIN18508)

  • Cosima Schiavone

    2   Department of Medicine and Science of Aging, Università degli Studi Gabriele d'Annunzio Chieti Pescara Scuola di Medicina e Scienze della Salute, Chieti, Italy (Ringgold ID: RIN60219)

  • Carla Serra

    1   Diagnostic and Therapeutic Interventional Ultrasound Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna Policlinico di Sant'Orsola, Bologna, Italy (Ringgold ID: RIN18508)

  • Fabio Piscaglia 

    3   Division of Internal Medicine, Hepatobiliary and Immunoallergic Diseases, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy
    4   Dept of Medical and Surgical Sciences, University of Bologna, Bologna, Italy
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Abstract

Ultrasound is a relevant tool in the diagnosis and characterization of gallbladder polyps. B-mode imaging can be used for the identification of echogenic formations attached to the gallbladder wall, while advanced techniques such as color Doppler, power Doppler, and micro-flow allow a thorough assessment of polyp vascularization. The integration of CEUS further improves diagnostic accuracy by confirming the integrity of the wall and the absence of pathological washout, which is characteristic of malignant lesions. In recent years, several guidelines have been published on the integrated clinical and ultrasound management of polypoid formations of the gallbladder. This review aims to summarize the main evidence regarding the ultrasound study of gallbladder polyps and to provide the sonographer with a clear and practical approach to the clinical management and follow-up of these patients.


 

Zusammenfassung

Ultraschall ist ein wichtiges Instrument zur Diagnose und Charakterisierung von Gallenblasen-Polypen. Die B-Bildgebung kann zur Identifizierung echogener Strukturen an der Gallenblasenwand eingesetzt werden, während modernere Techniken wie Farbdoppler, Power-Doppler und Microflow eine eingehende Beurteilung der Vaskularisation der Polypen ermöglichen. Die Kombination mit dem CEUS (kontrastmittelverstärkter Ultraschall) verbessert die diagnostische Genauigkeit zusätzlich, indem sie die Integrität der Wand und das Fehlen eines pathologischen Wash-outs bestätigt, der für maligne Läsionen charakteristisch ist. In den letzten Jahren wurden mehrere Leitlinien zur integrierten klinischen und ultraschallgestützten Behandlung polypoider Formationen der Gallenblase veröffentlicht. Diese Übersichtsarbeit fasst die wichtigsten evidenzbasierten Erkenntnisse zur Ultraschall-Untersuchung von Gallenblasen-Polypen zusammen und bietet dem Ultraschall-Diagnostiker einen klaren und praxisorientierten Ansatz für die klinische Behandlung und Nachsorge dieser Patienten.


 

Keywords

gallbladder - polyp - ultrasound - CEUS - neoplasm

Introduction

Gallbladder polyps are projections arising from the gallbladder wall into its lumen. They are typically discovered incidentally during abdominal ultrasound or post-cholecystectomy, with an estimated prevalence of up to 9.5% [1]. While the majority of these lesions are benign and asymptomatic – such as cholesterol polyps and inflammatory pseudo-polyps – a small subset may represent true neoplastic formations with malignant potential [2] [3]. Differentiating between benign and malignant polyps remains a critical clinical challenge, as management strategies range from simple surveillance to surgical intervention [2] [3] [4] [5].

Several risk factors have been associated with their development and potential malignancy [6]. The most consistent and well-established risk factor is polyp size, with lesions ≥10mm carrying a higher risk of neoplastic transformation. Age – particularly over 50 years – and male sex have also been linked to an increased risk [6] [7]. Other imaging features such as sessile morphology, rapid growth, and adjacent gallbladder wall thickening raise suspicion for malignancy [8]. Beyond imaging, metabolic factors such as obesity, dyslipidemia, insulin resistance, and the presence of MASLD may contribute to gallbladder polyp development [8] [9]. A recent study observed that metabolic dysfunction-associated steatotic liver disease (MASLD) itself was not directly associated with polyp development, but a significant risk emerged in patients with ≥4 MASLD components [10]. Men with ≥4 components had a 3.4-fold increased risk of developing polyps ≥6mm, and women had a 5.3-fold increased risk of developing polyps ≥5mm [10]. Additionally, a higher NAFLD fibrosis score was linked to increased polyp risk in women [10]. These findings highlight the need for targeted surveillance of patients with multiple MASLD components, particularly men with larger polyps and women with advanced liver fibrosis. Additional factors such as primary sclerosing cholangitis (PSC) and elevated tumor markers (e.g., CA 19–9) further elevate the suspicion of malignancy [11].

Ultrasound is the primary imaging modality for the detection and initial assessment of gallbladder polyps – due to its widespread availability, non-invasive nature, and high sensitivity [12] [13] [14]. Conventional B-mode imaging enables the characterization of polyp morphology, number, and size, while Doppler techniques provide insight into vascular patterns that may indicate malignancy [12] [13] [15]. More recently, contrast-enhanced ultrasound (CEUS) and high-resolution techniques have emerged as valuable tools to further refine diagnosis, allowing for the assessment of enhancement patterns and wall integrity [4] [16] [17] [18].

A recent study evaluated the cost-effectiveness of ultrasound surveillance (USS) for gallbladder polyps (GBPs) <10mm using a health economic model in a hypothetical UK cohort of 1000 patients [19]. Over a 2-year period, USS incurred substantial additional costs (£213,441–£750,045 for GBPs <6mm and £420,275–£531,297 for GBPs 6–9mm), associated with numerous cholecystectomies and the prevention of only a small number of gallbladder cancer (GBC) cases (1.3 and 8.7 cases, respectively) [19]. The model suggests that the cost of routine USS outweighs potential savings from avoided GBC treatment and leads to a high rate of potentially unnecessary surgeries [19].

This review aims to provide an updated overview of the current diagnostic and management strategies for gallbladder polyps based on the latest guidelines and evidence. This study strives to support clinicians in making informed decisions regarding patient care, whether through imaging surveillance, additional diagnostic steps such as contrast-enhanced ultrasound (CEUS), or surgical intervention when warranted.


 

Key Ultrasound Features

Gallbladder polyps are protrusions of the gallbladder wall extending into the lumen [1]. Polyps do not move into the gallbladder lumen, and they do not cause posterior acoustic shadowing. They can manifest as either sessile or pedunculated growths. Pseudo-polyps, which are benign, encompass conditions like cholesterolosis, cholesterinic polyps and inflammatory polyps ([Fig. 1]). True gallbladder polyps may be benign or malignant, with adenomas being the 2nd most common benign type and adenocarcinomas and metastases representing malignant forms [20] ([Fig. 2], [Fig. 3]).

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Fig. 1 The images show a polyp (white arrow; echogenic structure without shadow) in close proximity to a gallstone (structure with posterior shadow). The images show the absence of color Doppler signals within the polyp as in a pseudo-polyp (cholesterol polyp).
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Fig. 2 The images show a polyp of the fundus of the gallbladder. In detail, the color study highlights a vascular peduncle (white arrow), which suggests the diagnosis of “true polyp”.
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Fig. 3 Polypoid “cluster” structure (details with linear high frequency probe) protruding into the lumen of the gallbladder. Irregular margins, growth into the lumen of the gallbladder, alteration of the wall profile, and size > 15mm suggest a diagnosis of malignancy.

Pseudo-polyps (e.g., cholesterol or inflammatory) are typically small, often under 5mm, tend to be multiple with a smooth outline, and typically lack internal vascular flow on Doppler examination [21]; they usually present as highly echogenic on ultrasound and may show a characteristic “comet tail” or ring-down artifact [1]. Benign polyps (e.g., adenomas) are often solitary and can be slightly larger than pseudo-polyps; they generally have a smoother, more uniform contour and may exhibit minimal or no detectable flow with Doppler. Moreover, they usually have a stable size and appearance on serial imaging [1]. Malignant polyps are often larger than 10mm and may have an irregular or lobulated contour and heterogeneous internal echoes or mixed echogenicity ([Fig. 3]) [21]; they frequently demonstrate internal vascular flow on Doppler, and they are often associated with focal or diffuse gallbladder wall thickening and signs of local invasion ([Fig. 4]) [1].

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Fig. 4 Polypoid wall structure at the fundus level with sessile growth and alteration of the wall profile. A “disorganized” polyp vascularization is evident without a clear and single vascular pedicle.

Pseudo-polyps typically do not enhance on CEUS [22]. On CEUS, benign true polyps (adenomas) are often characterized by homogeneous enhancement without rapid washout [22]. Otherwise, malignant polyps display rapid washout on CEUS ([Table 1]) [22].

Table 1 Comparative table summarizing the typical B-mode ultrasound (US), Doppler, and contrast-enhanced ultrasound (CEUS) findings for pseudo-polyps versus true gallbladder polyps (benign and malignant).

Type of Polyp

B-Mode Ultrasound features

Doppler features

CEUS features

Pseudopolyps (e.g., cholesterol, inflammatory)

  • Small, often < 5mm

  • Often multiple

  • Smooth outline

  • Brightly echogenic; cholesterol polyps frequently show a “comet-tail” artifact

  • Lack of posterior acoustic shadow

  • Stable size

  • No internal vascular flow on color Doppler

  • Inflammatory polyps can show minimal flow if inflamed, but usually negligible

  • Do not enhance or show minimal enhancement

  • No washout phenomenon

  • No gallbladder wall infiltration

Benign True Polyps (e.g., adenomas)

  • Often solitary

  • May be slightly larger than pseudo-polyps (5–10mm)

  • Smooth or slightly lobulated contour

  • Uniform internal echogenicity

  • May remain stable on follow-up

  • Minimal or absent flow on Doppler

  • Possible small “feeding vessel” in some cases

  • Homogeneous hyper-enhancement in arterial phase

  • Iso-enhancement in venous phase

  • No rapid washout

  • Intact gallbladder wall

Malignant Polyps (e.g., adenocarcinoma, metastasis)

  • Usually > 10mm

  • Irregular or lobulated contour

  • Heterogeneous echogenicity

  • Possible adjacent gallbladder wall thickening (focal or diffuse)

  • Features suggestive of local invasion or infiltration (e.g., liver)

  • Increased blood flow on color/power Doppler

  • Prominent feeding vessel suggests malignancy

  • Heterogeneous hyper-enhancement in arterial phase

  • Rapid washout in venous phase

  • Possible early involvement of gallbladder wall

  • May show infiltration into surrounding tissues

Additionally, other rare benign and malignant true gallbladder polyps exist, such as mesenchymal tumors and lymphoma metastasis. Ultrasound has a sensitivity and specificity of 83.1% and 96.3%, respectively, with a positive predictive value of 14.9% (7.0% for malignant polyps) and a negative predictive value of 99.7% for the diagnosis of true polyps of the gallbladder [23].


 

Update on Gallbladder Polyps

Recent guidelines on gallbladder polyps have been published by the Society of Radiologists in Ultrasound (SRU) in 2022 [24]. Those guidelines divide polyps into intermediate, low, or extremely low risk of malignancy depending on their morphology, wall thickening, and size [24]. The authors suggested that when an ultrasound examination is inconclusive for polyps, a short-term follow-up (1–2 months) is recommended. Moreover, CEUS/magnetic resonance imaging (MRI) or short-term follow-up are recommended when it is not possible to differentiate between wall polyp or sludge or adenomyomatosis [24]. A specialist consultation should be requested when there is a high suspicion of cancer or a positive history of primary sclerosing cholangitis (PSC), in particular, aspects suggestive of the invasion of the wall, presence of concomitant neoplastic liver lesions, biliary obstruction, presence of pathological lymph nodes [24]. There are different dimensional cut-offs for the surgical indication. Furthermore, if ultrasound follow-up shows an increase in polyp size > 4mm in less than 1 year or the polyp reaches the threshold size, surgical consultation is indicated [24]. On the contrary, if there is a decrease in the size of the polyp > 4mm, interruption of follow-up is indicated [24].

Based on those recommendations, recent studies showed a substantial agreement for polyp risk categorizations and surgical consultations based on the SRU 2022 guidelines among abdominal radiologists [25] [26] [27]. Jeans et al. analyzed 251 patients with 407 gallbladder polyps, most of which were small (<10mm) and classified as either extremely low risk (51.6%) or low risk (48.2%), with only one intermediate-risk case, according to the SRU classification [28]. Follow-up was deemed unnecessary for 88.4% of polyps, and among those monitored, nearly 90% remained stable, decreased, or resolved [28]. Of 28 patients who had surgery, only 2 had neoplastic polyps, including one invasive carcinoma [28].

In 2022, further multi-society guidelines were published, which more clearly divides true polyps according to whether they are larger or smaller than 1cm; pseudo-polyps are immediately excluded from the diagnostic process [29]. Cholecystectomy is suggested in the absence of contraindications in the case of true polyps > 1cm in size [29]. If the polyp is less than 1cm, the symptoms and a series of risk factors such as advanced age (> 60 years), primary sclerosing cholangitis, Asian ethnicity, and morphology of the polyp are considered [29]. If the polypoid lesion grows and exceeds 10mm during follow-up, cholecystectomy becomes recommended [29]. If the polypoid lesion grows 2mm or more within a 2-year follow-up period, the current size of the polypoid lesion should be considered along with the patient's risk factors [29]. Multidisciplinary discussion can be used to decide whether to continue monitoring or whether cholecystectomy is indicated [29].

There is a further World Federation of Ultrasound in Medicine and Biology (WFUMB) position paper, also published in 2022, that recommends cholecystectomy when the polyp size exceeds 1cm. High-resolution endoscopic ultrasound (EUS) and CEUS may be performed before cholecystectomy to evaluate malignancy risk and potential infiltration [30].

In the case of polyps measuring 7–9mm, in patients without individual risk factors for malignancy or suspicious B-mode US features apart from size, follow-up after 6, 12, and 24 months is recommended [30]. Evaluation using high-resolution and/or CEUS or EUS may be performed in patients with individual risk factors (Indian ethnicity, history of primary sclerosing cholangitis [PSC], age >50 years] or B-mode US features associated with increased/high risk of malignancy or growth ≥ 2mm [30]. Otherwise, surgical treatment should be offered to patients with Indian ethnicity, PSC, and/or ultrasound features (B-mode ultrasound, high-resolution EUS, CEUS) associated with a high risk of malignancy [30].

In the case of a polyp < 7mm, in patients without individual risk factors or suspicious B-mode ultrasound features, no evaluation, no follow-up, and no treatment are recommended [30]. Follow-up after 6, 12, and 24 months should be considered in patients with Indian ethnicity or a history of PSC and/or patients with B-mode ultrasound features associated with increased/high risk of malignancy [30]. Follow-up can be stopped when gallbladder polyps disappear, there is no growth (≥2mm to ≥10mm), no ultrasound high-risk features are observed within 24 months, and no individual risk factors are present [30].

Moreover, the authors suggested technical details such as measurement in the long axis of the gallbladder polyp, which can be supplemented by measurement perpendicular to the long axis (short axis) to give the height/width ratio as a parameter to describe polyp shape [30]. In the case of multiple polyps, their number should be indicated (at least up to 5 or 10); indeed, the measurement of the largest gallbladder polyp is sufficient [30].

The Italian Society of Ultrasound in Medicine and Biology (SIUMB) guidelines argued in 2023 that criteria used in the therapeutic clinical management of polypoid lesions of the gallbladder should take into account the size of the polyp and the presence of some risk factors of malignancy (age > 50 years; presence of PSC; Indian ethnicity, sessile polyp with thickening of the gallbladder wall > 4mm) [31]. Polyps ≥ 10mm in size have an increased risk of malignancy and specialist evaluation should be recommended [31]. However, if the patient has no risk factors, annual ultrasound follow-up is suggested when the polyp is < 6mm or every 6 months when the polyp is between 6 and 9mm [31].

The 2025 guidelines from the Korean Society of Abdominal Radiology (KSAR) provide comprehensive recommendations for the interpretation, reporting, and management of incidentally detected GBPs and gallbladder wall thickening, emphasizing the role of ultrasound as the primary diagnostic tool [32]. For size measurement, the guidelines recommend using the longest diameter from outer margin to outer margin, including the stalk in pedunculated polyps but excluding any associated wall thickening [32]. Risk stratification plays a key role in guiding follow-up and treatment. GBPs less than 6mm in size without concerning imaging features – defined as adjacent wall thickening, a sessile morphology, or significant growth – are considered likely benign and typically do not require follow-up [32]. For polyps measuring between 6 and 9mm, management decisions should be based on the patient’s age and the presence of these suspicious features [32]. If warranted, surveillance includes biannual ultrasound during the first year, followed by annual scans for up to 4 additional years [32]. Polyps 10mm or larger raise suspicion for neoplastic transformation, particularly when suspicious features are present [32]. Routine use of CT or MRI is not recommended for incidentally detected GBPs. However, these modalities may be considered when ultrasound is inconclusive, when malignancy is suspected, or during preoperative planning for cholecystectomy [32]. CEUS is also not recommended routinely but may be useful in evaluating GBPs ≥10mm if surgery is deferred, or when CT and MRI are contraindicated [32]. Doppler ultrasound, while limited with respect to differentiating between benign and malignant lesions, can still be used to assess vascularity, especially when interpreted alongside B-mode imaging [32]. Surgical management by means of cholecystectomy is advised for patients who are candidates for surgery and have GBPs measuring ≥15mm, or those with GBPs between 10 and 14mm if suspicious imaging features are present [32]. Cholecystectomy may also be considered in patients aged 50 or older with polyps measuring 6–9mm that show suspicious features [32]. Conversely, GBPs between 10 and 14mm without such features may be managed conservatively with regular follow-up [32]. Demographic risk factors such as older age, Asian ethnicity, and PSC are recognized as relevant, but the guidelines advise against incorporating these non-imaging factors into radiology reports, except in the presence of elevated tumor markers like CA 19–9 [32]. Additionally, the presence of gallstones alone should not be viewed as indicative of malignancy. Instead, a thorough ultrasound evaluation should be performed to ensure an accurate risk assessment [32].

A summary of findings about ultrasound features of polyps and recommendations of different societies are listed in [Table 2], [Table 3], [Table 4].

Table 2 Main features on B-mode ultrasound about gallbladder polyps and corresponding risk of malignancy. Gallbladder: GB; gallbladder polyps: GBP. Adapted from Jenssen C et al. Ultrasound Med Biol. 2022.

US feature of GBP

Predictive of

Risk of malignancy

Solitary

Neoplastic polyps and focal adenomyomatosis

Increased

Multiple

Cholesterol polyps

Low

Sessile with disruption and/or focal thickening of GB wall ≥4mm

Neoplastic polyp

High

Sessile, without wall disruption and without thickening of GB wall ≥4mm

Benign polyps and focal adenomyomatosis

Increased

Pedunculated

Cholesterol polyps and other benign GBPs

Low

Surface irregular/lobulated

Neoplastic and benign fibro-myoglandular polyps

Increased

Surface smooth

Cholesterol polyps

Low

Small cysts

Focal adenomyomatosis

Low

Reverberation artifacts

Focal adenomyomatosis, cholesterol polyps

Low

Hyperechoic foci

Cholesterol polyps, focal adenomyomatosis

Low

Focal GB wall disruption

Malignant GBP, focal adenomyomatosis

Increased

Table 3 Comparison of management recommendations for gallbladder polyps based on their size and follow-up between different guidelines. Society of Radiologists in Ultrasound: SRU; European Society of Gastrointestinal and Abdominal Radiology: ESGAR; European Association for Endoscopic Surgery and other Interventional Techniques: EAES; International Society of Digestive Surgery-European Federation: EFISDS; European Society of Gastrointestinal Endoscopy: ESGE; World Federation of Ultrasound in Medicine and Biology: WFUMB; Italian Society of Ultrasound in Medicine and Biology: SIUMB; Korean Society of Abdominal Radiology: KSAR; gallbladder: GB; GB polyp: GBP; GB wall thickening: GBWT; ultrasound: US; primary sclerosing cholangitis: PSC. *GB-related symptoms: pain in the upper right abdomen, nausea, or vomiting.

SRU guidelines

ESGAR, EAES, EFISDS, ESGE guidelines

WFUMB position paper

SIUMB guidelines

KSAR guidelines

< 6.0 mm

  • Extremely low risk: no follow-up

  • Low risk: no follow-up

  • Indeterminate risk: US follow-up at 6, 12, 24, 36 months vs. surgical consult

  • In the case of GB-related symptoms*: surgical consult;

  • If there are no GB-related symptoms, no risk factors for malignancy: follow-up not required;

  • If there are no GB-related symptoms, with risk factors for malignancy: US follow-up at 6 months, 1 year, and 2 years

  • In the case of patients without risk factors or suspicious B-mode US features: no evaluation, no follow-up and no treatment are recommended.

  • In the case of patients with Indian ethnicity or history of PSC and/or suspicious US features: US follow-up at 6, 12, 24 months

Annual US follow-up

  • No follow-up for GBPs without suspicious features

  • Follow-up in the case of adjacent GBWT, sessile morphology

6.1–9.0mm

  • Extremely low risk: no follow-up

  • Low risk: US follow-up at 12 months

  • Indeterminate risk: surgical consult

  • In the case of GB-related symptoms: surgical consult;

  • If there are no GB-related symptoms, no risk factors for malignancy: US follow-up at 6 months, 1 year, and 2 years

  • If there are no GB-related symptoms, with risk factors for malignancy: surgical consult

  • In the case of patients without risk factors for malignancy or suspicious B-mode US features: follow-up after 6, 12, and 24 months.

  • In the case of patients with Indian ethnicity, PSC and/or US features associated with high risk of malignancy: surgical consult

US follow-up every 6 months

  • US follow-up based on age and suspicious features. If needed: US every 6 months in first year, then annually for 4 years

  • Optional surgery if suspicious features present and patient age ≥50

9.1–15.0mm

  • Extremely low risk: US follow-up at 6, 12, 24 months

  • Low risk: US follow-up at 6, 12, 24, 36 months vs. surgical consult

  • Indeterminate risk: surgical consult

Surgical consult

Surgical consult

Surgical consult

  • Surgery for GBPs 10–14mm with suspicious features

  • Conservative management and follow-up for others. Follow-up protocol same as for 6–9mm if surgery deferred.

>15.0mm

  • Extremely low risk: surgical consult

  • Low risk: surgical consult

  • Indeterminate risk: surgical consult

Surgical consult

Surgical consult

Surgical consult

Surgery recommended in suitable patients

Table 4 Comparison of follow-up strategies for gallbladder polyps based on their size and follow-up between different guidelines. Society of Radiologists in Ultrasound: SRU; European Society of Gastrointestinal and Abdominal Radiology: ESGAR; European Association for Endoscopic Surgery and other Interventional Techniques: EAES; International Society of Digestive Surgery-European Federation: EFISDS; European Society of Gastrointestinal Endoscopy: ESGE; World Federation of Ultrasound in Medicine and Biology: WFUMB; Italian Society of Ultrasound in Medicine and Biology: SIUMB; Korean Society of Abdominal Radiology: KSAR; gallbladder: GB; ultrasound: US; primary sclerosing cholangitis.

SRU guidelines

ESGAR, EAES, EFISDS, ESGE guidelines

WFUMB position paper

SIUMB guidelines

KSAR 2025 guidelines

Follow-up

If GB polyp increases > 4mm in less than 1 year or reaches threshold size: surgical consult;

If GB polyp decreases > 4mm: stop follow-up

US follow-up should be discontinued after 2 years in the absence of growth

Follow-up can be stopped when GB polyps disappear, there is no growth (≥2mm to ≥10mm), no US high-risk features are observed within 24 months and no individual risk factors are present

Not specified

Biannual US in year 1, then annually for 4 years.

Consider significant growth to be a change in size that results in a polyp moving from one size category to another.

Discontinue after 5 years if stable.

No follow-up needed for resolved polyps.

 

Critical Revision of Guidelines and Recent Evidence

From the comparison of those recent guidelines, strong points of agreement emerge, together with unclear aspects among the different recommendations.

The first point is that pseudo-polyps, when diagnosed using the color Doppler ultrasound method and with the possible aid of CEUS, are not included in the follow-up criteria or possible surgical procedures, as they are considered certainly benign lesions.

Secondly, the finding of a true polyp in a patient with symptoms attributable to biliary and gallbladder problems is preferentially a candidate for surgery, in the absence of contraindications [29] [33]. Third, when it comes to dimensional assessment, there is unanimous agreement that a polyp > 15mm in size should be treated surgically. Even concerning polyps between 10 and 14.9mm, there would be general agreement regarding the recommendation for surgery, apart from the SRU guidelines, which introduces a qualitative and morphological evaluation of the polyp and the underlying gallbladder wall [24]. If the polyp is placed in the extremely low-risk category, ultrasound follow-up is indicated. However, uncertainty remains between the 2 strategies when the polyp is considered low-risk [24].

The category of polyps measuring between 7 and 9mm is characterized by greater heterogeneity in recommendations: while the SIUMB guidelines recommend an ultrasound follow-up every 6 months [31], the other 3 guidelines attempt to categorize these polyps into different risk classes based on ultrasound/morphological factors, symptoms, age, ethnicity, and any associated biliary tract pathology (PSC) [24] [29] [30]. Therefore, they range from truly low-risk polyps in SRU, in which follow-up is not even indicated, to recommendations for surgery when symptoms or risk factors are present.

The recommendations regarding the category of polyps with dimensions < 6mm are also quite heterogeneous. The SIUMB guidelines offer a clear recommendation, proposing annual ultrasound follow-up [31]. Other guidelines recommend not performing an ultrasound follow-up in the absence of risk factors and/or ultrasound features suspicious for malignancy. Otherwise, an ultrasound check is recommended every 6 months [24] [29] [30].

Even with respect to the decision-making criteria for follow-up, there is clear heterogeneity regarding both timing and size criteria. Two of the guidelines also provide a time criterion (2 years) for suspending follow-up [29] [30].

Therefore, a simplified step-by-step diagnostic-clinical approach could be extrapolated as follows ([Fig. 5]):

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Fig. 5 Flowchart showing the step-by-step diagnostic-clinical approach to a gallbladder polypoid lesion.

  1. Establish a differential diagnosis between a true polyp vs. a pseudo-polyp (to continue when true polyps are found or in the case of uncertainty)

  2. Evaluation of symptoms reported by the patient (related to gallbladder and biliary tract diseases)  if present, surgical indication

  3. Dimensional evaluation: if polyp > 15mm  surgical indication

  4. If the polyp is between 10–14mm  surgical indication, unless the polyp is classified as extremely low risk or low risk based on morphological criteria. In this instance, ultrasound follow-up is indicated.

  5. If a polyp is between 7–9mm  evaluate ultrasound morphology and clinical risk factors  surgical indication if present, follow-up if absent.

  6. If a polyp < 6mm  evaluate ultrasound and clinical risk factors  ultrasound follow-up if present.

Recent evidence has pointed out the relevant role of gallbladder wall thickening (GWT), often related to polyps. The Gallbladder Reporting and Data System (GB-RADS) is a recently developed system aimed at assessing and determining risk levels in non-acute scenarios [34]. The diagnosis of benign GWT (GB-RADS 2) relies on identifying a layered appearance or detecting intramural cysts and echogenic foci [34] ([Table 5]). The layered appearance, which involves seeing both the inner and outer layers of the gallbladder, is most commonly associated with diffuse GWT. However, in cases of malignant GWT, this characteristic layered structure is lost, due to the disruption of the mucosa and the infiltration of tumor cells into the deeper layers of the GB wall [35]. Intramural findings, including intramural cyst and echogenic foci, suggest benign GWT and may present in either a focal or diffuse pattern [34]. Intramural cysts, seen as anechoic areas within the thickened gallbladder wall, correspond to enlarged Rokitansky-Aschoff sinuses (RAS) and are considered characteristic of adenomyomatosis (ADM). Conversely, intramural hyperechoic foci are caused by the accumulation of cholesterol crystals within the RAS [36]. An indistinct gallbladder-liver interface may suggest infiltration by gallbladder cancer, with this feature showing high specificity and a positive predictive value for diagnosing malignant GWT, corresponding to GB-RADS 4. A clear diagnosis of extramural extension is made when the gallbladder lesion affects surrounding bile ducts or blood vessels, or when an extramural mass is observed infiltrating the liver. These ultrasound findings make the likelihood of GBC very high, classifying the case as GB-RADS 5 [34]. A recent study indicates that while there is generally good inter-reader agreement regarding GB-RADS categories, agreement on individual findings within the system is less reliable [37]. The study also highlighted that the GB-RADS 2 category carries a very low risk of malignancy, whereas the GB-RADS 5 category presents the greatest malignancy risk [37] ([Fig. 6], [Fig. 7], [Fig. 8]).

Table 5 The Gallbladder Reporting and Data System (GB-RADS). Adapted from Gupta P. et al. Gallbladder reporting and data system (GB-RADS) for risk stratification of gallbladder wall thickening on ultrasonography: an international expert consensus. Abdom Radiol (NY). 2022. CT: computed tomography, MRI: magnetic resonance imaging, US: ultrasonography.

GB-RADS score

Risk category

Findings

Management

0

Inadequate evaluation due to technical or patient factors or gallbladder-related factors

Morbid obesity

Repeat ultrasound in selected cases

Consider multiphasic contrast-enhanced CT/MRI after multidisciplinary discussion

Wall-echo-shadow complex

Porcelain gallbladder

Gas in the gallbladder lumen

1

Normal

Adequate gallbladder distension

No additional imaging or follow-up is needed

Wall thickness ≤ 3mm

2

Benign (risk of malignancy <2%)

Symmetric circumferential thickening with or without intramural changes or focal thickening with intramural changes

No additional imaging or follow-up needed

Layered appearance

Preserved interface with liver

3

Equivocal (risk of malignancy 2–50%)

Circumferential thickening without layered appearance

Consider multiphasic contrast-enhanced CT/MRI after multidisciplinary discussion

Focal thickening without intramural features (cysts or echogenic foci) or layered appearance

Distinct interface with liver

4

Malignancy is likely (risk of malignancy 50–90%)

Circumferential or focal thickening without layered appearance and with loss of interface with liver

Multiphasic contrast-enhanced CT/MRI

5

Malignancy is highly likely (risk of malignancy > 90%)

Same as GB-RADS 4 with definite extramural invasion as suggested by one of the following:

Multiphasic contrast-enhanced CT/MRI

Biliary or vascular involvement by direct extension of mural thickening

Liver mass in contiguity with the mural thickening
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Fig. 6 Large eccentric hypoechoic thickening of the gallbladder wall with infiltrative aspects on the liver parenchyma (GB-RADS 5).
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Fig. 7 CEUS (0:40 minutes) at the gallbladder wall thickening typified as GB-RADS 5: the lesion presents hyper-enhancement in the arterial phase, with subsequent washout in the portal and late phases. CEUS allows better delineation of the infiltrative portion of the mass towards the liver parenchyma.
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Fig. 8 CEUS (4:00 minutes) at the gallbladder wall thickening typified as GB-RADS 5: the lesion presents hyper-enhancement in the arterial phase, with subsequent washout in the portal and late phases. CEUS allows better delineation of the infiltrative portion of the mass towards the liver parenchyma.

In a recent study by Wang and colleagues, the incidence of malignant tumors increased markedly across higher GB-RADS categories, ranging from 9% in GB-RADS 2 up to 100% in GB-RADS 5 [38]. GB-RADS achieved an AUC of 0.855, with solid but not optimal sensitivity, specificity, and accuracy values [38]. Notably, the addition of color Doppler flow imaging (CDFI) to GB-RADS considerably boosted these diagnostic metrics. The combined approach yielded an AUC of 0.965, reflecting a high level of reliability in differentiating malignant from benign lesions [38]. Finally, the high Kappa value (0.870) indicated excellent inter-observer agreement, suggesting that both experienced radiologists and less-seasoned practitioners could consistently apply the combined method [38].


 

New Insights on the Role of CEUS

Notably, in the main diagnostic algorithms proposed, there is no reference to a specific role of CEUS. According to the 2018 EFSUMB guidelines, adenomas are characterized by a wide vascular stalk that is best seen on CEUS [22]. Moreover, polyps > 10mm which show an iso- and inhomogeneous enhancement pattern may be a criterion to differentiate adenomas from cholesterol polyps [22]. A study by Zheng et al. showed sensitivity, specificity, and accuracy rates of 94.1%, 95.5%, and 95.2%, respectively, for CEUS with regard to distinguishing between benign and malignant gallbladder lesions [39]. Sludge masses remained unenhanced, while polyps and adenomas predominantly exhibited homogeneous hyper-enhancement in the arterial phase and iso-enhancement in the venous phase [39]. Conversely, tumors typically appeared heterogeneously hyper-enhanced in the arterial phase and exhibited rapid washout in the venous phase [40]. Notably, CEUS was particularly beneficial with regard to improving diagnostic accuracy for polyps larger than 10mm in size [39].

According to the SIUMB 2023 guidelines, adenomatous polyp vascularization is characterized by regular vessels with a tree-like distribution [31]. CEUS appearance is generally characterized by hyper-enhancement in the arterial phase, followed by iso-enhancement in the venous phase or, more rarely, by hypo-enhancement [31]. The gallbladder wall appears intact, and the surrounding tissue appears normal, without any signs of invasion [41]. Moreover, washout of the lesion ≤ 28s is more frequent in malignant lesions [31]. Gallbladder metastases exhibit moderate to intense contrast enhancement in the arterial phase, followed by a more or less fast washout in the venous phase [42]. Furthermore, CEUS can better highlight any wall thickening associated with polyps, a finding indicative of an increased risk of malignancy [40] ([Table 6]). It is specified that the studies refer to the contrast medium sulfur hexafluoride.

Table 6 Main features of gallbladder polyps (GBP) on contrast-enhanced ultrasound (CEUS) and relative risk of malignancy. Adapted from Jenssen C et al. Ultrasound Med Biol. 2022.

CEUS feature of GBP

Risk of malignancy

Arterial hyper-enhancement

Increased

Heterogeneous enhancement

High

Irregular vessel pattern

High

Late-phase hypo-enhancement

High

Homogeneous enhancement

Low

Continuous mucosal layer enhancement

Low

Washout < 28s

High

 

Conclusion

Ultrasound is a fundamental tool in the diagnosis and characterization of gallbladder polyps. B-mode imaging allows for the identification of echogenic formations attached to the gallbladder wall, while advanced techniques such as color Doppler, power Doppler, and micro-flow enable a thorough assessment of polyp vascularization, distinguishing between benign pseudo-polyps, such as cholesterol polyps, and potentially neoplastic formations. The integration of CEUS further improves diagnostic accuracy, confirming the integrity of the wall and the absence of pathological washout, which is characteristic of malignant lesions. Overall, ultrasound and its advanced modalities provide a non-invasive, effective, and accurate approach for the differential diagnosis of gallbladder polyps, aiding clinicians in the management and follow-up of patients.


 

 

Conflict of Interest

Prof. Piscaglia reports serving on advisory boards for AstraZeneca, Eisai, Exact Sciences, MSD, Roche, and Siemens Healthineers; receiving lecture fees from AstraZeneca, Bayer, Bracco, Esaote, Eisai, GE HealthCare, Ipsen, MSD, Roche, and Samsung; and receiving consulting fees from Bracco and Nerviano Medical Sciences. Dr. Serra reports receiving lecture fees from Bracco, Esaote, GE HealthCare, Samsung, and Philips. No other potential conflict of interest relevant to this letter was reported.


Correspondence

Dr. Andrea Boccatonda
Diagnostic and Therapeutic Interventional Ultrasound Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna Policlinico di Sant'Orsola
Bologna
Italy   

Publication History

Received: 26 October 2024

Accepted after revision: 14 July 2025

Article published online:
17 September 2025

© 2025. Thieme. All rights reserved.

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Zoom
Fig. 1 The images show a polyp (white arrow; echogenic structure without shadow) in close proximity to a gallstone (structure with posterior shadow). The images show the absence of color Doppler signals within the polyp as in a pseudo-polyp (cholesterol polyp).
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Fig. 2 The images show a polyp of the fundus of the gallbladder. In detail, the color study highlights a vascular peduncle (white arrow), which suggests the diagnosis of “true polyp”.
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Fig. 3 Polypoid “cluster” structure (details with linear high frequency probe) protruding into the lumen of the gallbladder. Irregular margins, growth into the lumen of the gallbladder, alteration of the wall profile, and size > 15mm suggest a diagnosis of malignancy.
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Fig. 4 Polypoid wall structure at the fundus level with sessile growth and alteration of the wall profile. A “disorganized” polyp vascularization is evident without a clear and single vascular pedicle.
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Fig. 5 Flowchart showing the step-by-step diagnostic-clinical approach to a gallbladder polypoid lesion.
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Fig. 6 Large eccentric hypoechoic thickening of the gallbladder wall with infiltrative aspects on the liver parenchyma (GB-RADS 5).
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Fig. 7 CEUS (0:40 minutes) at the gallbladder wall thickening typified as GB-RADS 5: the lesion presents hyper-enhancement in the arterial phase, with subsequent washout in the portal and late phases. CEUS allows better delineation of the infiltrative portion of the mass towards the liver parenchyma.
Zoom
Fig. 8 CEUS (4:00 minutes) at the gallbladder wall thickening typified as GB-RADS 5: the lesion presents hyper-enhancement in the arterial phase, with subsequent washout in the portal and late phases. CEUS allows better delineation of the infiltrative portion of the mass towards the liver parenchyma.