The diagnostic accuracy of transabdominal ultrasonography needs to be considered when managing gallbladder polyps. Surg Endosc. 2013;27:4021-4025. [PMID: 23749271 DOI: 10.1007/s00464-013-3033-1]

Gallbladder polypoid lesions: Current practices and future prospects

ABSTRACT

Gallbladder polypoid lesions (GPLs) refer to any elevated lesion of the mucosal surface of the gallbladder wall, and the prevalence is estimated to be between 0.9% and 12.1%. GPLs include benign polyps and malignant polyps. Benign polyps are further classified as non-neoplastic polyps and neoplastic polyps. Cholesterol polyps are the most common benign polyps and adenocarcinoma is the main type of malignant polyp. Hepatitis B virus infection, liver function abnormalities, dyslipidemia, and obesity are the main risk factors for GPLs. Studies of biological mechanisms have focused on malignant gallbladder polyps, the development of which is regulated by hormone levels in vivo , gut microbiota, inflammation, oxidative stress, Salmonella typhimurium , and related molecules. Diagnostic modalities include chemical examination and imaging examination, with imaging examination currently being the mainstay. Treatment of patients with GPLs is based on the presence or absence of symptoms, age, size of the polyps, tendency of the polyp to increase, and risk factors for symptomatic malignancy to determine whether surgery should be performed.

Practical approach to linear endoscopic ultrasound examination of the gallbladder

The gallbladder (GB) is a susceptible organ, prone to various pathologies that can be identified using different imaging techniques. Transabdominal ultrasound (TUS) is typically the initial diagnostic method due to its numerous well-established advantages. However, in cases of uncertainty or when a definitive diagnosis cannot be established, computed tomography (CT) or magnetic resonance imaging may be employed to provide more detailed information. Nevertheless, CT scans may sometimes offer inadequate spatial resolution, which can limit the differentiation of GB lesions, particularly when smaller yet clinically relevant abnormalities are involved. Conversely, endoscopic ultrasound (EUS) provides higher frequency compared to TUS, superior spatial resolution, and the option for contrast-enhanced harmonic imaging, enabling a more comprehensive examination. Thus, EUS can serve as a supplementary tool when conventional imaging methods are insufficient. This review will describe the standard EUS examination of the GB, focusing on its endosonographic characteristics in various GB pathologies.

Risk stratification of gallbladder masses by machine learning-based ultrasound radiomics models: a prospective and multi-institutional study

OBJECTIVE

This study aimed to evaluate the diagnostic performance of machine learning (ML)-based ultrasound (US) radiomics models for risk stratification of gallbladder (GB) masses.

METHODS

We prospectively examined 640 pathologically confirmed GB masses obtained from 640 patients between August 2019 and October 2022 at four institutions. Radiomics features were extracted from grayscale US images and germane features were selected. Subsequently, 11 ML algorithms were separately used with the selected features to construct optimum US radiomics models for risk stratification of the GB masses. Furthermore, we compared the diagnostic performance of these models with the conventional US and contrast-enhanced US (CEUS) models.

RESULTS

The optimal XGBoost-based US radiomics model for discriminating neoplastic from non-neoplastic GB lesions showed higher diagnostic performance in terms of areas under the curves (AUCs) than the conventional US model (0.822-0.853 vs. 0.642-0.706, p < 0.05) and potentially decreased unnecessary cholecystectomy rate in a speculative comparison with performing cholecystectomy for lesions sized over 10 mm (2.7-13.8% vs. 53.6-64.9%, p < 0.05) in the validation and test sets. The AUCs of the XGBoost-based US radiomics model for discriminating carcinomas from benign GB lesions were higher than the conventional US model (0.904-0.979 vs. 0.706-0.766, p < 0.05). The XGBoost-US radiomics model performed better than the CEUS model in discriminating GB carcinomas (AUC: 0.995 vs. 0.902, p = 0.011).

CONCLUSIONS

The proposed ML-based US radiomics models possess the potential capacity for risk stratification of GB masses and may reduce the unnecessary cholecystectomy rate and use of CEUS.

CLINICAL RELEVANCE STATEMENT

The machine learning-based ultrasound radiomics models have potential for risk stratification of gallbladder masses and may potentially reduce unnecessary cholecystectomies.

KEY POINTS

• The XGBoost-based US radiomics models are useful for the risk stratification of GB masses. • The XGBoost-based US radiomics model is superior to the conventional US model for discriminating neoplastic from non-neoplastic GB lesions and may potentially decrease unnecessary cholecystectomy rate for lesions sized over 10 mm in comparison with the current consensus guideline. • The XGBoost-based US radiomics model could overmatch CEUS model in discriminating GB carcinomas from benign GB lesions.

Is ultrasonography accurate for the diagnosis of gallbladder polyps? A review of cholecystectomy specimens from patients diagnosed with gallbladder polyps over a 14-years period

INTRODUCTION

Incidence of gallbladder polyps is 0,3-12%. It is important to differentiate pseudopolyps (cholesterol polyps, adenomyomatosis, inflammatory polyps), which do not have the capacity to become malignant, from true polyps (adenomas and adenocarcinomas). The main risk factors for malignancy are >6-10 mm, growth, sessile morphology, Indian ethnicity and primary sclerosing cholangitis. Ultrasound is the gold standard for diagnosis. Most polyps diagnosed by ultrasound are pseudopolyps. The main objective of this study is to analyse whether ultrasound is accurate for diagnosing true polyps in patients undergoing surgery for this reason.

METHODS

Retrospective observational study with prospective data entry of patients undergoing elective cholecystectomy for gallbladder polyps from 2007 to 2021. Surgery was indicated in symptomatic patients and in those with risk factors. The study has been approved by the Clinical Research Ethics Committee of our hospital.

RESULTS

We included 124 patients in our study. An elective laparoscopic cholecystectomy was performed in all of them. The mean age was 55,4 years and 61% were women. Of all patients, 65% were symptomatic at diagnosis. Only 3 patients had true polyps (2,4%). All of them were tubular adenomas. The rest of patients were false positives (97,6%). The adenoma size was 11, 6 and 5 mm, respectively. The surgical indication was due to polyp size or due to associated biliary symptoms.

CONCLUSION

Ultrasonography is not accurate for the diagnosis of gallbladder polyps. Validation of other complementary tests for the diagnosis of gallbladder polyps in asymptomatic patients could be relevant to avoid unnecessary surgeries.

A New Risk Scoring System to Predict Malignancy in Gallbladder Polyps: a Single-Center Study

OBJECTIVE

Ultrasonography (US) is the most commonly used radiological method in the diagnosis of gallbladder polyps (GBPs). Patients diagnosed with GBPs on US are operated on with risk factors that do not have a high level of evidence. Our aim in this study is to determine the sensitivity of US in diagnosis GBPs, to define risk factors for neoplastic (NP) polyps, and to develop the risk scoring system.

MATERIALS AND METHODS

Between July 2011 and July 2021, 173 patients who were found to have GBPs in the pathology specimens after cholecystectomy were included in the study. Patients were divided into two groups: nonneoplastic and NP groups.

RESULTS

GBPs in patients who underwent abdominal US for any reason was 4.5%. The sensitivity of US in the diagnosis of GBPs was 56.6%. Comparison between groups, age ≥50, presence of symptoms, polyp size >12.5mm, single polyp, concomitant gallstones, and gallbladder wall thickness ≥4mm were statistically in the NP group. A risk scoring system was developed using these values. If the risk score was <4, 0.6% of GBPs was NP polyps. If the risk score was ≥4, 63.2% of GBPs were NP polyps.

CONCLUSION

Our risk scoring system can prevent unnecessary choelcystectomy. Because the incidence of NP polyps in low-risk patients (risk score <4) is extremely rare.

Risk of developing gallbladder cancer in patients with gallbladder polyps detected on transabdominal ultrasound: a systematic review and meta-analysis

OBJECTIVE

To estimate the risk of malignancy in gallbladder polyps of incremental sizes detected during transabdominal ultrasound (TAUS).

METHODS

We searched databases including MEDLINE, Embase, and Cochrane Library for eligible studies recording the polyp size from which gallbladder malignancy developed, confirmed following cholecystectomy, or by subsequent follow-up. Primary outcome was the risk of gallbladder cancer in patients with polyps. Secondary outcome was the effect of polyp size as a prognostic factor for cancer. Risk of bias was assessed using the Quality in Prognostic Factor Studies (QUIPS) tool. Bayesian meta-analysis estimated the median cancer risk according to polyp size. This study is registered with PROSPERO (CRD42020223629).

RESULTS

82 studies published since 1990 reported primary data for 67,837 patients. 67,774 gallbladder polyps and 889 cancers were reported. The cumulative median cancer risk of a polyp measuring 10 mm or less was 0.60% (99% credible range 0.30-1.16%). Substantial heterogeneity existed between studies (I2 = 99.95%, 95% credible interval 99.86-99.98%). Risk of bias was generally high and overall confidence in evidence was low. 13 studies (15.6%) were graded with very low certainty, 56 studies (68.3%) with low certainty, and 13 studies (15.6%) with moderate certainty. In studies considered moderate quality, TAUS monitoring detected 4.6 cancers per 10,000 patients with polyps less than 10 mm.

CONCLUSION

Malignant risk in gallbladder polyps is low, particularly in polyps less than 10 mm, however the data are heterogenous and generally low quality. International guidelines, which have not previously modelled size data, should be informed by these findings.

ADVANCES IN KNOWLEDGE

This large systematic review and meta-analysis has shown that the mean cumulative risk of small gallbladder polyps is low, but heterogeneity and missing data in larger polyp sizes (>10 mm) means the risk is uncertain and may be higher than estimated.Studies considered to have better methodological quality suggest that previous estimates of risk are likely to be inflated.

Surveillance of Gallbladder Polyps: A Literature Review

Little has been documented in existing literature regarding incidentally found gallbladder (GB) polyps. These clinically asymptomatic lesions are mostly benign, with only 5% progressing to malignancy. GB cancer, although rare, presents as an end-stage incurable disease. According to the current guidelines, cholecystectomy is recommended for polyps >10 mm in size for a better outcome. Thus, it is essential to know the clinical picture, surveillance, and treatment of these polyps earlier in the course of the disease to avoid the advancement of polyps to malignancy. This paper discusses the signs and symptoms, surveillance, treatment, and prognosis of GB polyps.

Accuracy of Ultrasound in Diagnosing Gallbladder Polyps at a Community Hospital

Background and Objectives:

Polyps are reported on 1–10% of routine transabdominal ultrasound studies of the gallbladder. Prior studies have reported poor sensitivity and specificity for this diagnostic modality at determining malignant potential of polyps. The aim of this study is to determine the incidence of gallbladder polyps documented on ultrasound at a community hospital, evaluate the congruency of ultrasound with final histopathology, and explore factors which may improve ultrasound accuracy at diagnosing true adenomatous polyps.

Methods:

We conducted a 5-year retrospective cohort study of patients undergoing cholecystectomy at Danbury Hospital between 2014 and 2019, identifying those with a pre-operative ultrasound mention of a “polyp” or “mass.” We assessed the congruency of ultrasound findings with pathology reports.

Results:

Of the 2,549 cholecystectomies performed, 1,944 (76%) had pre-operative ultrasounds. Of those, 98 (5.0%) reported a polyp, measuring an average of 8.1 mm (SD 7.1 mm). Three (3.1%) specimens were identified as adenomas on final histopathology; the majority were benign pathologies including cholesterol polyp (18), cholesterolosis (20), adenomyoma (4), adenomyomatosis (7), and chronic or acute cholecystitis (44). Interestingly, only 1 of the 3 adenomas measured > 10 mm on ultrasound, the accepted indication for surgical resection.

Conclusions:

The accuracy of transabdominal ultrasound in diagnosing true polyps is poor, with only 3% of polyps identified as adenomas based on pathology. Surgeons should use caution when making clinical decisions based on polyps identified on ultrasound, and more stringent diagnostic criteria are needed in order to decrease the false positive rate for diagnosis and screening.

Contrast-enhanced ultrasound to assess gallbladder polyps

PURPOSE

To assess the value of contrast-enhanced ultrasound (CEUS) in distinguishing adenomatous gallbladder polyps from cholesterol gallbladder polyps.

METHODS

A total of 164 patients with gallbladder polyps were retrospectively analyzed. All patients underwent B-mode ultrasound (US) and CEUS before cholecystectomy. Gallbladder polyps were divided into cholesterol polyp group and adenomatous polyp group according to pathology. Differences in patient's age, gender, maximum polyp size, number, presence of gallstones, vascularity and stalk width measured by US and vascular stalk width measured by CEUS were tested between the two groups. The diagnostic performance of specific US features was evaluated. The independent factors related with adenomatous polyps were analyzed by multiple logistic regression analyses.

RESULTS

There were 114 cholesterol polyps and 50 adenomatous polyps in 164 patients analyzed in the study. Differences in maximum size, vascularity, and stalk width of the gallbladder polyp were significant between the two groups (p < 0.05), whereas differences in patient's age, gender, number of gallbladder polyp, and presence of gallstones between the two groups were not (p > 0.05). Stalk width was wider than vascular stalk width between the two groups (p < 0.05). Vascular stalk width was also statistically different between the two groups (p < 0.05). The diagnostic performance of vascular stalk width was more significant than stalk width. Only vascular stalk width and vascularity were independent factors related with adenomatous polyps.

CONCLUSION

Vascular stalk width measured by CEUS is more accurate than stalk width measured by grayscale US in distinguishing adenomatous polyps from cholesterol polyps.

Imaging based flowchart for gallbladder polyp evaluation

BACKGROUND

Preoperative differentiation between neoplastic and nonneoplastic gallbladder polyps, and the subsequent indication for cholecystectomy remains a clinical dilemma. The current 1 cm size threshold for neoplasia is unspecific. The aim of this study was to improve diagnostic work-up for gallbladder polyps using sonographic and MRI characteristics of neoplastic and nonneoplastic polyps.

METHODS

A prospective, exploratory study including patients undergoing cholecystectomy for gallbladder polyp(s) was conducted. Patients underwent targeted transabdominal ultrasound (TAUS) and MRI. Outcomes were sensitivity and specificity for polyp diagnosis, and the radiological characteristics of neoplastic and nonneoplastic polyp types. Histopathology after cholecystectomy was used as reference standard.

RESULTS

Histopathology demonstrated gallbladder polyps in 20/27 patients (74%): 14 cholesterol polyps, three adenomyomatosis, two adenomas and one gastric heterotopia. Sensitivity of polyp identification were 72% (routine TAUS) and 86% (targeted TAUS and MRI). Both adenomas were identified as neoplastic on targeted TAUS and MRI. Sonographic presentation as multiple, pedunculated polyps, either heterogeneous or with hyperechoic foci, or as single polyps containing cysts were limited to nonneoplastic polyps. On MRI hyperintense polyps on T1-weighted image were cholesterol polyps. An adenoma with high-grade dysplasia showed foci of decreased ADC values. We propose a checklist for polyp evaluation by targeted TAUS and a flowchart for radiological work-up of gallbladder polyps.

CONCLUSIONS

The presented checklist and flowchart could aid diagnostic work-up for gallbladder polyps compared to current routine ultrasound, by elimination of nonneoplastic polyps and ultimately improve treatment decision for patients with gallbladder polyps.

Overtreatment of Nonneoplastic Gallbladder Polyps due to Inadequate Routine Ultrasound Assessment

BACKGROUND

The primary aim was to assess the diagnostic accuracy of routine ultrasound assessment for gallbladder polyps. The secondary aim was to identify the characteristics that differentiate neoplastic polyps from nonneoplastic polyps.

METHODS

A total of 156 patients with histopathologically proven gallbladder polyps in 4 Dutch hospitals between 2003 and 2013 were included. Sensitivity and specificity of ultrasound for polyp size, number of polyps, and polyp type were assessed using histopathological findings as a reference standard. In addition, diagnostic accuracy of sonographic size ≥1 cm for neoplasia was assessed. Subgroup analysis for patients with polyps as primary indication for cholecystectomy was performed. The sonographic polyp characteristics on preoperative routine ultrasound were described.

RESULTS

Fifty-six percent of gallbladder polyps were preoperatively identified on ultrasound, of which 31% were neoplastic. Sensitivity and specificity of ultrasound to estimate polyp size were 93 and 43% (subgroup; 92 and 33%). Sensitivity and specificity of sonographic polyp size ≥1 cm for neoplasia were 86 and 32% (subgroup; 94 and 26%). No specific sonographic characteristics for neoplastic polyps could be established due to lack of reporting.

CONCLUSION

Routine ultrasound assessment of polyps is associated with overestimation of polyp size and low specificity of sonographic size ≥1 cm for neoplasia, which contributes to surgical overtreatment of nonneoplastic polyps.

Management of gallbladder polyps

A gallbladder polyp (GP) is defined as an elevation of the gallbladder mucosa that protrudes into the gallbladder lumen. Gallbladder polyps (GPs) have an estimated prevalence in adults of 0.3–12.3%. However, only 5% of polyps are considered “true” GPs that have malignant potential or are even already cancerous. The most important imaging method for diagnosis and follow-up of GPs is transabdominal ultrasound, but it fails to discriminate between true and pseudo polyps at a clinically relevant level. Although gallbladder cancer (GBC) arising from polyps is a rare event, malignancy is significantly more common among polyps from a size of 10 mm. In light of this, the consensus, which is reflected in current guidelines, is that surgery should be considered for polyps of 10 mm or greater. However, 10 mm is an arbitrary cutoff, and high-quality evidence to support this is lacking. Lowering the threshold for cholecystectomy when patients have additional risk factors for gallbladder malignancy may improve the cancer detection rate in polyps smaller than 10 mm. Nevertheless, the evidence behind this is also weak. This review shows the shortcomings in the available evidence and underlines the decision-making process regarding the surgical indication, surveillance, or both.

The accuracy of ultrasonography for diagnosis of gallbladder polyps

INTRODUCTION

Gallbladder polyps (GBPs) are gallbladder lesions which can progress to gallbladder malignancy. The incidence has been estimated as high as 12.1% of all cholecystectomy patients. Gallbladder malignancy typically presents late, and therefore carries a poor prognosis. By identifying potential GBPs early, it would be possible to treat polyps before they undergo malignant change. The current gold standard for GBP identification is with histological examination which is performed after cholecystectomy. This study sought to assess whether radiological imaging could reliably identify GBPs and therefore guide management.

METHODS

1000 consecutive patients already undergoing cholecystectomy were sampled from two UK hospitals. Patients who underwent ultrasonography and had histological analysis of their gallbladders were selected. Overall 905 patients were included in the study.

RESULTS

There were 12 histologically confirmed GBPs in the cohort (1.33%). US correctly detected 1 GBP, with a sensitivity of 8.3% (95% CI 0.2-38.5%) and specificity of 96.0% (95% CI 94.5-97.2%). The overall accuracy was 94.8 (95% CI 93.2-96.2%).

CONCLUSION

These data show that US is an ineffective tool for GBP identification. The lack of prior operator exposure, imprecise nature of US and possible obstruction of images from underlying gallstone disease delivered a high rate of false positives.

IMPLICATIONS FOR PRACTICE

Surgical or oncological decisions regarding GBPs should not be based upon US findings alone as this would lead to unnecessary interventions. MRI should be investigated as an alternative imaging modality for GBP identification, as its differentiation of soft tissues could guide surgical management.

Differential diagnosis of gallbladder polypoid lesions using contrast-enhanced ultrasound

PURPOSE

The purpose of the study is to evaluate the utility of contrast-enhanced ultrasound (CEUS) for the differential diagnosis of gallbladder polypoid lesions (GPLs).

METHODS

Thirty-six patients with GPLs (17 with gallbladder cancer, 19 with benign polyps) who underwent CEUS were enrolled in the study. The mean age of patients was 65.7 ± 12.6 years. Perflubutane-based contrast agent and high-mechanical index mode, which can eliminate the background B-mode and provide precise visualization of tumor vessels, were used for CEUS, and two blinded readers evaluated the images, retrospectively.

RESULTS

Patient age and size of malignant GPLs (72.4 ± 9.4 years and 23.4 ± 7.5 mm) were significantly greater than those for benign lesions (59.6 ± 12.3 years and 12.4 ± 2.9 mm) (P < 0.01, respectively), and the receiver operating characteristic analysis showed the cut-off value as over 65 years and 16 mm. Univariate analysis showed that heterogeneity in B-mode (80% [12/15]), sessile shape (76% [13/17]), dilated vessel (71% [12/17]), irregular vessel (82% [14/17]), and heterogeneous enhancement (59% [10/17]) on CEUS were significantly correlated with malignant GPLs (P < 0.01, respectively). On CEUS, the diagnostic criterion for malignant GPLs was defined as having one or more of the above four features because of the highest accuracy. Sensitivity, specificity, and accuracy for malignant GBLs were 88%, 68%, and 78% for patient age; 76%, 89%, and 83% for size of GPLs; 80%, 68%, and 74% for B-mode; and 94%, 89%, and 92% for CEUS, respectively.

CONCLUSIONS

CEUS is useful for the differential diagnosis of malignant and benign GPLs.

Gallbladder Polyps: Real or Imagined?

The finding of gallbladder polyps on imaging studies prompts further workup. Imaging results are often discordant with final pathology. The goal of this study is to compare polypoid lesions of the gallbladder found on preoperative ultrasound (US) with final pathologic diagnosis after cholecystectomy to help guide clinical decision-making. A retrospective study was conducted identifying adult patients who were diagnosed with polyps via US and who underwent cholecystectomy from 2008 through 2015. Imaging data, final pathology, and demographics were manually reviewed. A total of 2290 cholecystectomy patients had US-based polyps. Of these, 1661 patients (73%) did not have polyps on final pathology; primarily, stones or sludge were identified. Adenomyosis was diagnosed in 61 patients (2.7%). A total of 556 patients (24.2%) had pathologic polypoid lesions with the following breakdown: 463 (20.2%) cholesterol polyps, 43 other benign polyps (1.8%), 40 adenomas (1.7%), and 10 adenocarcinomas (0.4%). All patients with adenocarcinoma were older than 40 years and 91 per cent had US findings of polyps >10 mm. Ultrasound alone is an unreliable method of detecting real gallbladder polyps. This large database study found a very low risk of cancer. Size on US and patient age should be considered in the selection of appropriate surgical candidates with sonographic “polyps.”

Transabdominal ultrasound and endoscopic ultrasound for diagnosis of gallbladder polyps

BACKGROUND

Approximately 0.6% to 4% of cholecystectomies are performed because of gallbladder polyps. The decision to perform cholecystectomy is based on presence of gallbladder polyp(s) on transabdominal ultrasound (TAUS) or endoscopic ultrasound (EUS), or both. These polyps are currently considered for surgery if they grow more than 1 cm. However, non-neoplastic polyps (pseudo polyps) do not need surgery, even when they are larger than 1 cm. True polyps are neoplastic, either benign (adenomas) or (pre)malignant (dysplastic polyps/carcinomas). True polyps need surgery, especially if they are premalignant or malignant. There has been no systematic review and meta-analysis on the accuracy of TAUS and EUS in the diagnosis of gallbladder polyps, true gallbladder polyps, and (pre)malignant polyps.

OBJECTIVES

To summarise and compare the accuracy of transabdominal ultrasound (TAUS) and endoscopic ultrasound (EUS) for the detection of gallbladder polyps, for differentiating between true and pseudo gallbladder polyps, and for differentiating between dysplastic polyps/carcinomas and adenomas/pseudo polyps of the gallbladder in adults.

SEARCH METHODS

We searched the Cochrane Library, MEDLINE, Embase, Science Citation Index Expanded, and trial registrations (last date of search 09 July 2018). We had no restrictions regarding language, publication status, or prospective or retrospective nature of the studies.

SELECTION CRITERIA

Studies reporting on the diagnostic accuracy data (true positive, false positive, false negative and true negative) of the index test (TAUS or EUS or both) for detection of gallbladder polyps, differentiation between true and pseudo polyps, or differentiation between dysplastic polyps/carcinomas and adenomas/pseudo polyps. We only accepted histopathology after cholecystectomy as the reference standard, except for studies on diagnosis of gallbladder polyp. For the latter studies, we also accepted repeated imaging up to six months by TAUS or EUS as the reference standard.

DATA COLLECTION AND ANALYSIS

Two authors independently screened abstracts, selected studies for inclusion, and collected data from each study. The quality of the studies was evaluated using the QUADAS-2 tool. The bivariate random-effects model was used to obtain summary estimates of sensitivity and specificity, to compare diagnostic performance of the index tests, and to assess heterogeneity.

MAIN RESULTS

A total of 16 studies were included. All studies reported on TAUS and EUS as separate tests and not as a combination of tests. All studies were at high or unclear risk of bias, ten studies had high applicability concerns in participant selection (because of inappropriate participant exclusions) or reference standards (because of lack of follow-up for non-operated polyps), and three studies had unclear applicability concerns in participant selection (because of high prevalence of gallbladder polyps) or index tests (because of lack of details on ultrasound equipment and performance). A meta-analysis directly comparing results of TAUS and EUS in the same population could not be performed because only limited studies executed both tests in the same participants. Therefore, the results below were obtained only from indirect test comparisons. There was significant heterogeneity amongst all comparisons (target conditions) on TAUS and amongst studies on EUS for differentiating true and pseudo polyps.Detection of gallbladder polyps: Six studies (16,260 participants) used TAUS. We found no studies on EUS. The summary sensitivity and specificity of TAUS for the detection of gallbladder polyps was 0.84 (95% CI 0.59 to 0.95) and 0.96 (95% CI 0.92 to 0.98), respectively. In a cohort of 1000 people, with a 6.4% prevalence of gallbladder polyps, this would result in 37 overdiagnosed and seven missed gallbladder polyps.Differentiation between true polyp and pseudo gallbladder polyp: Six studies (1078 participants) used TAUS; the summary sensitivity was 0.68 (95% CI 0.44 to 0.85) and the summary specificity was 0.79 (95% CI 0.57 to 0.91). Three studies (209 participants) used EUS; the summary sensitivity was 0.85 (95% CI 0.46 to 0.97) and the summary specificity was 0.90 (95% CI 0.78 to 0.96). In a cohort of 1000 participants with gallbladder polyps, with 10% having true polyps, this would result in 189 overdiagnosed and 32 missed true polyps by TAUS, and 90 overdiagnosed and 15 missed true polyps by EUS. There was no evidence of a difference between the diagnostic accuracy of TAUS and EUS (relative sensitivity 1.06, P = 0.70, relative specificity 1.15, P = 0.12).Differentiation between dysplastic polyps/carcinomas and adenomas/pseudo polyps of the gallbladder: Four studies (1,009 participants) used TAUS; the summary sensitivity was 0.79 (95% CI 0.62 to 0.90) and the summary specificity was 0.89 (95% CI 0.68 to 0.97). Three studies (351 participants) used EUS; the summary sensitivity was 0.86 (95% CI 0.76 to 0.92) and the summary specificity was 0.92 (95% CI 0.85 to 0.95). In a cohort of 1000 participants with gallbladder polyps, with 5% having a dysplastic polyp/carcinoma, this would result in 105 overdiagnosed and 11 missed dysplastic polyps/carcinomas by TAUS and 76 overdiagnosed and seven missed dysplastic polyps/carcinomas by EUS. There was no evidence of a difference between the diagnostic accuracy of TAUS and EUS (log likelihood test P = 0.74).

AUTHORS' CONCLUSIONS

Although TAUS seems quite good at discriminating between gallbladder polyps and no polyps, it is less accurate in detecting whether the polyp is a true or pseudo polyp and dysplastic polyp/carcinoma or adenoma/pseudo polyp. In practice, this would lead to both unnecessary surgeries for pseudo polyps and missed cases of true polyps, dysplastic polyps, and carcinomas. There was insufficient evidence that EUS is better compared to TAUS in differentiating between true and pseudo polyps and between dysplastic polyps/carcinomas and adenomas/pseudo polyps. The conclusions are based on heterogeneous studies with unclear criteria for diagnosis of the target conditions and studies at high or unclear risk of bias. Therefore, results should be interpreted with caution. Further studies of high methodological quality, with clearly stated criteria for diagnosis of gallbladder polyps, true polyps, and dysplastic polyps/carcinomas are needed to accurately determine diagnostic accuracy of EUS and TAUS.

Current practices and future prospects for the management of gallbladder polyps: A topical review

A gallbladder polyp is an elevation of the gallbladder mucosa that protrudes into the gallbladder lumen. Gallbladder polyps have an estimated prevalence in adults of between 0.3%-12.3%. However, only 5% of polyps are considered to be "true" gallbladder polyps, meaning that they are malignant or have malignant potential. The main radiological modality used for diagnosing and surveilling gallbladder polyps is transabdominal ultrasonography. However, evidence shows that other modalities such as endoscopic ultrasound may improve diagnostic accuracy. These are discussed in turn during the course of this review. Current guidelines recommend cholecystectomy for gallbladder polyps sized 10 mm and greater, although this threshold is lowered when other risk factors are identified. The evidence behind this practice is relatively low quality. This review identifies current gaps in the available evidence and highlights the necessity for further research to enable better decision making regarding which patients should undergo cholecystectomy, and/or radiological follow-up.

Ultrasound-based scoring system for differential diagnosis of polypoid lesions of the gallbladder

BACKGROUND AND AIM

Polypoid lesions of the gallbladder may be neoplastic or non-neoplastic. Correct diagnosis would help reduce unnecessary cholecystectomies. This study aimed to determine the predictive value of individual ultrasound characteristics for diagnosis of neoplastic polyps and to build a scoring system based on these characteristics.

METHODS

A total of 109 patients with gallbladder polyps ≥ 6 mm underwent conventional ultrasound examination and received finally diagnosis by pathological examination. All images were analyzed to determine characteristics of the lesions. Univariate and multivariate analyses were used to identify the predictors of neoplastic polyps, and a scoring system was built based on multivariate analysis.

RESULTS

Maximum diameter, height/width ratio, base width, presence of hyper-echoic spots, and intralesional blood flow were statistically significant (P = 0.011, P = 0.016, P = 0.003, P = 0.031, and P = 0.022, respectively) predictors of neoplastic lesions. The total score = (Maximum diameter, ≥ 13.9 mm = 1, < 13.9 = 0) + (Base width, ≥ 3.5 mm = 1, < 3.4 = 0) + (Height/width ratio, ≤ 1.05 = 1, > 1.05 = 0) + (Hyper-echoic spots, presence = 0, absence = 1) + (Blood flow, presence = 1, absence = 0). Receiver operating characteristic curve showed that the sensitivity, specificity, and accuracy for the risk of neoplastic polyps with scores of 3 or higher were 81.6%, 86.7%, and 84.4%, respectively.

CONCLUSION

This ultrasound-based scoring system could be a useful means for differentiating between neoplastic and non-neoplastic gallbladder polyps in the clinic.

Diagnostic accuracy of transabdominal ultrasonography for gallbladder polyps: systematic review

BACKGROUND

Previous research has shown variable but generally poor accuracy of transabdominal ultrasonography in the diagnosis of gallbladder polyps. We performed a systematic review of the literature with the aim of helping surgeons interpret and apply these findings in the preoperative assessment and counselling of their patients.

METHODS

We searched PubMed, MEDLINE and the Cochrane database using the keywords "gallbladder," "polyp," "ultrasound," "pathology" and "diagnosis" for English-language articles published after 1990 with the full-text article available through our institutional subscriptions. Polyps were defined as immobile features that on transabdominal ultrasonography appear to arise from the mucosa and that lack an acoustic shadow, and pseudopolyps were defined as features such as inflammation, hyperplasia, cholesterolosis and adenomyomatosis that convey no risk of malignant transformation.

RESULTS

The search returned 1816 articles, which were narrowed down to 14 primary sources involving 15 497 (range 23-13 703) patients who had preoperative transabdominal ultrasonography, underwent cholecystectomy and had postoperative pathology results available. Among the 1259 patients in whom a gallbladder polyp was diagnosed on ultrasonography, 188 polyps were confirmed as true polyps on pathologic examination, and 81 of these were found to be malignant. Of the 14 238 patients for whom a polyp was not seen on ultrasonography, 38 had a true polyp on pathologic examination, none of which were malignant. For true gallbladder polyps, transabdominal ultrasonography had a sensitivity of 83.1%, specificity of 96.3%, positive predictive value of 14.9% (7.0% for malignant polyps) and negative predictive value of 99.7%.

CONCLUSION

Transabdominal ultrasonography has a high false-positive rate (85.1%) for the diagnosis of gallbladder polyps. Further study of alternative imaging modalities and reevaluation of existing management guidelines are warranted.

Management and follow-up of gallbladder polyps : Joint guidelines between the 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) and European Society of Gastrointestinal Endoscopy (ESGE)

Objectives

The management of incidentally detected gallbladder polyps on radiological examinations is contentious. The incidental radiological finding of a gallbladder polyp can therefore be problematic for the radiologist and the clinician who referred the patient for the radiological examination. To address this a joint guideline was created by the 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) and European Society of Gastrointestinal Endoscopy (ESGE).

Methods

A targeted literature search was performed and consensus guidelines were created using a series of Delphi questionnaires and a seven-point Likert scale.

Results

A total of three Delphi rounds were performed. Consensus regarding which patients should have cholecystectomy, which patients should have ultrasound follow-up and the nature and duration of that follow-up was established. The full recommendations as well as a summary algorithm are provided.

Conclusions

These expert consensus recommendations can be used as guidance when a gallbladder polyp is encountered in clinical practice.

Key Points

• Management of gallbladder polyps is contentious

• Cholecystectomy is recommended for gallbladder polyps >10 mm

• Management of polyps <10 mm depends on patient and polyp characteristics

• Further research is required to determine optimal management of gallbladder polyps

Determinants for gallstone formation - a new data cohort study and a systematic review with meta-analysis

OBJECTIVE

Only few determinants of gallstone formation have been identified in cohort studies. The aim was to identify further determinants for gallstones in a Danish cohort and to perform a meta-analysis of results from existing cohorts.

MATERIAL AND METHODS

Data from a cohort study was used. Gallstone incidence was assessed through repeated ultrasound examinations. Body mass index (BMI), blood pressure, self-rated health, lifestyle variables, blood lipids, and use of female sex hormones were measured at the baseline examination. Statistical analyses included logistic regression. Based on a prospective protocol, a systematic review of the literature was performed identifying all articles dealing with determinants of incident gallstones. Meta-analyses of comparable determinants were performed through fixed effect models.

RESULTS

Participants with no gallstones at baseline and with at least one re-examination were followed-up completely (mean 11.6 years, N = 2848). The overall cumulative incidence of gallstones was 0.60% per year. Independent positive determinants for incident gallstones were age, female sex, non-high density lipoprotein (non-HDL) cholesterol, and gallbladder polyps. In addition, BMI was positively associated in men. The systematic review additionally identified associations for comorbidities, parity, and dietary factors. Meta-analysis confirmed the significant associations for incident gallstones and age, female sex, BMI, and non-HDL cholesterol. No significant associations were found for blood pressure, smoking, alcohol consumption, HDL cholesterol, or triglycerides in meta-analyses.

CONCLUSIONS

Age, female sex, BMI, non-HDL cholesterol, and polyps are independent determinants for gallstone formation. Incident gallstones and the metabolic syndrome share common risk factors. More studies are needed for further exploration.

Evidence based management of polyps of the gall bladder: A systematic review of the risk factors of malignancy

BACKGROUND

There are no evidence-based guidelines to dictate when Gallbladder Polyps (GBPs) of varying sizes should be resected.

AIM

To identify factors that accurately predict malignant disease in GBP; to provide an evidence-based algorithm for management.

METHODS

A systematic review following PRISMA guidelines was performed using terms "gallbladder polyps" AND "polypoid lesion of gallbladder", from January 1993 and September 2013. Inclusion criteria required histopathological report or follow-up of 2 years. RTI-IB tool was used for quality analysis. Correlation with GBP size and malignant potential was analysed using Euclidean distance; a logistics mixed effects model was used for assessing independent risk factors for malignancy.

RESULTS

Fifty-three articles were included in review. Data from 21 studies was pooled for analysis. Optimum size cut-off for resection of GBPs was 10 mm. Probability of malignancy is approximately zero at size <4.15 mm. Patient age >50 years, sessile and single polyps were independent risk factors for malignancy. For polyps sized 4 mm-10 mm, a risk assessment model was formulated.

CONCLUSIONS

This review and analysis has provided an evidence-based algorithm for the management of GBPs. Longitudinal studies are needed to better understand the behaviour of polyps <10 mm, that are not at a high risk of malignancy, but may change over time.

Management and diagnosis of gallbladder polyps: a systematic review

PURPOSE

Recommendation for management of gallbladder polyps (GBPs) >1 cm is cholecystectomy. No consensus exists on management of GBPs <1 cm. This systematic review examines current evidence on management of GBPs.

METHODS

MEDLINE, EMBASE and Cochrane library databases were searched from January 1991 to June 2013 using specified terms. A predefined protocol for data extraction was used to retrieve specified end points.

RESULTS

Literature search yielded 43 manuscripts with a dataset of 11,685 patients with GBPs. M:F ratio was 1.3:1. Average age (range) was 49 years (32-83). Patients with malignant GBPs had an average (range) age of 58 (50-66) years with M:F ratio of 0.78:1. Cholesterol polyps constituted 60.5% of GBPs followed by adenomas (15.2%) and cancer (11.6%). Malignant GBPs ≥1 cm, <1 cm and <5 mm constituted 8.5, 1.2 and 0% of GBPs, respectively. Majority of patients requiring surgical intervention had laparoscopic cholecystectomy.

CONCLUSIONS

Presently employed policy of cholecystectomy for GBPs >1 cm is appropriate. For GBPs <1 cm, the authors propose (accepting existence of differing proposals) the following: 1. Surveillance may not be needed for GBPs <5 mm. 2. For GBPs between 5 and 10 mm, two scans at six monthly intervals is suggested and after that, tailor surveillance to age, growth and ethnicity. In the non-Asian population, if GBP remains the same size or number, discontinuation of surveillance may be considered. In the Asian population, if GBPs remain the same, yearly surveillance is continued for a suggested period of 3 years. 3. Discontinue surveillance if GBPs is/are smaller/ disappeared. Cholecystectomy is advised where size increases to >10 mm.

Growth rate and malignant potential of small gallbladder polyps--systematic review of evidence

THE BACKGROUND AND PURPOSE

The overall aim of this systematic review was to determine whether ultrasound (US) follow up for gallbladder polyps (GBPs) measuring less than 10 mms is necessary.

METHODS

A search was performed in MEDLINE and EMBASE between January 1976 and January 2012 using keywords: gallbladder, polyps, neoplasm, cancer, tumour, carcinoma, malignant, adenoma. Included were studies involving adult patients, examined with transabdominal US at least twice. The outcomes of included studies were gallbladder polyp growth as demonstrated on US over time, followed where available by histological examination of cholecystectomy specimens.

MAIN FINDINGS

Ten studies met the inclusion criteria for the review. Altogether 1958 subjects with mean age between 41.5 and 59 years were followed up with US. The percentage of GBPs which showed growth over the follow up period ranged from 1% to 23%. 43 neoplastic polyps were found in total irrespective of size, 20 of which were malignant and at least 7 of those were >10 mms. At least 7 malignancies were present in polyps <10 mms but it was unknown if they had undergone growth on follow up.

CONCLUSIONS

Level II-2 and below evidence on rate of growth of small GBPs <10 mms exists in the literature. It indicates that growth does occur in a significant minority of small GBPs, but it is slow. Due to deficient reporting and small numbers of cases, the correlation between growth of GBP and development of malignancy cannot be established using currently available evidence. Malignancy can be present in polyps <10 mms although it is significantly more frequent in polyps >10 mms. Cholecystectomy for symptomatic GBPs irrespective of their size, alongside the current practice for removal of gall bladders containing asymptomatic polyps >10 mms, is proposed. No evidence based US follow up schedule can be recommended at present for asymptomatic polyps <10 mms, and in its absence an intuitive follow up with US is likely to continue.