Global birdsong embeddings enable superior transfer learning for bioacoustic classification.

Automated bioacoustic analysis aids understanding and protection of both marine and terrestrial animals and their habitats across extensive spatiotemporal scales, and typically involves analyzing vast collections of acoustic data. With the advent of deep learning models, classification of important signals from these datasets has markedly improved. These models power critical data analyses for research and decision-making in biodiversity monitoring, animal behaviour studies, and natural resource management. However, deep learning models are often data-hungry and require a significant amount of labeled training data to perform well. While sufficient training data is available for certain taxonomic groups (e.g., common bird species), many classes (such as rare and endangered species, many non-bird taxa, and call-type) lack enough data to train a robust model from scratch. This study investigates the utility of feature embeddings extracted from audio classification models to identify bioacoustic classes other than the ones these models were originally trained on. We evaluate models on diverse datasets, including different bird calls and dialect types, bat calls, marine mammals calls, and amphibians calls. The embeddings extracted from the models trained on bird vocalization data consistently allowed higher quality classification than the embeddings trained on general audio datasets. The results of this study indicate that high-quality feature embeddings from large-scale acoustic bird classifiers can be harnessed for few-shot transfer learning, enabling the learning of new classes from a limited quantity of training data. Our findings reveal the potential for efficient analyses of novel bioacoustic tasks, even in scenarios where available training data is limited to a few samples.

Pairing a user-friendly machine-learning animal sound detector with passive acoustic surveys for occupancy modeling of an endangered primate.

Population declines and range contractions due to habitat loss are pervasive among nonhuman primates, with 60% of species threatened with extinction. However, the extensive vocal activity displayed by many primates makes them excellent candidates for passive acoustic surveys. Passive acoustic survey data is increasingly being used to support occupancy models, which have proven to be an efficient means of estimating both population trends and distributions. Passive acoustic surveys can be conducted relatively quickly and at broad scales, but efficient audio data processing has long proven elusive. The machine learning algorithm BirdNET was originally developed for birds but was recently expanded to include nonavian taxa. We demonstrate that BirdNET can accurately and efficiently identify an endangered primate, the Yucatán black howler monkey (Alouatta pigra), by sound in passive acoustic survey data (collected in southeastern Chiapas, Mexico), enabling us to use a single-season occupancy model to inform further survey efforts. Importantly, we also generated data on up to 286 co-occurring bird species, demonstrating the value of integrated animal sound classification tools for biodiversity surveys. BirdNET is freely available, requires no computer science expertise to use, and can readily be expanded to include more species (e.g., its species list recently tripled to >3000), suggesting that passive acoustic surveys, and thus occupancy modeling, for primate conservation could rapidly become much more accessible. Importantly, the long history of bioacoustics in primate research has yielded a wealth of information about their vocal behavior, which can facilitate appropriate survey design and data interpretation.

The Pierced Colon: When Biliary Stents Go the Wrong Way.

Bowel perforation of biliary stents is a rare complication of biliary stenting. We report the successful endoscopic treatment of a 78-year-old man with a straight biliary plastic stent perforating the ascending colon without underlying structural abnormality in the affected segment. Perforation was detected incidentally during computed tomography; the patient had been under continued antibiotic therapy for liver abscess. Stent extraction was performed by using an endoscopic snare; the site of perforation was closed with through-the-scope clips. The patient remained asymptomatic. In addition, we reviewed published cases of perforated biliary stents and outlined that most perforations are caused by straight plastic stents.

The machine learning-powered BirdNET App reduces barriers to global bird research by enabling citizen science participation.

The BirdNET App, a free bird sound identification app for Android and iOS that includes over 3,000 bird species, reduces barriers to citizen science while generating tens of millions of bird observations globally that can be used to replicate known patterns in avian ecology.

Source attribution of community-acquired cases of Legionnaires' disease-results from the German LeTriWa study; Berlin, 2016-2019.

INTRODUCTION: Sources of infection of most cases of community-acquired Legionnaires' disease (CALD) are unknown. OBJECTIVE: Identification of sources of infection of CALD. SETTING: Berlin; December 2016-May 2019. PARTICIPANTS: Adult cases of CALD reported to district health authorities and consenting to the study; age and hospital matched controls. MAIN OUTCOME MEASURE: Percentage of cases of CALD with attributed source of infection. METHODS: Analysis of secondary patient samples for monoclonal antibody (MAb) type (and sequence type); questionnaire-based interviews, analysis of standard household water samples for Legionella concentration followed by MAb (and sequence) typing of Legionella pneumophila serogroup 1 (Lp1) isolates; among cases taking of additional water samples to identify the infectious source as appropriate; recruitment of control persons for comparison of exposure history and Legionella in standard household water samples. For each case an appraisal matrix was filled in to attribute any of three source types (external (non-residence) source, residential non-drinking water (RnDW) source (not directly from drinking water outlet), residential drinking water (RDW) as source) using three evidence types (microbiological results, cluster evidence, analytical-comparative evidence (using added information from controls)). RESULTS: Inclusion of 111 study cases and 202 controls. Median age of cases was 67 years (range 25-93 years), 74 (67%) were male. Among 65 patients with urine typable for MAb type we found a MAb 3/1-positive strain in all of them. Compared to controls being a case was not associated with a higher Legionella concentration in standard household water samples, however, the presence of a MAb 3/1-positive strain was significantly associated (odds ratio (OR) = 4.9, 95% confidence interval (CI) 1.7 to 11). Thus, a source was attributed by microbiological evidence if it contained a MAb 3/1-positive strain. A source was attributed by cluster evidence if at least two cases were exposed to the same source. Statistically significant general source types were attributed by calculating the population attributable risk (analytical-comparative evidence). We identified an external source in 16 (14%) cases, and RDW as source in 28 (25%). Wearing inadequately disinfected dentures was the only RnDW source significantly associated with cases (OR = 3.2, 95% CI 1.3 to 7.8) and led to an additional 8% of cases with source attribution, for a total of 48% of cases attributed. CONCLUSION: Using the appraisal matrix we attributed almost half of all cases of CALD to an infectious source, predominantly RDW. Risk for LD seems to be conferred primarily by the type of Legionella rather than the amount. Dentures as a new infectious source needs further, in particular, integrated microbiological, molecular and epidemiological confirmation.

Management of Incidental Pancreatic Cystic Lesions.

BACKGROUND: Pancreatic cystic lesions (PCL) are common. They are increasingly detected as an incidental finding of transabdominal ultrasound or cross-sectional imaging. In contrast to other parenchymal organs, dysontogenetic pancreatic cysts are extremely rare. In symptomatic patients the most frequent PCL are acute and chronic pseudocysts. The majority of incidental cystic lesions, however, are neoplasias which have different risks of malignancy. METHODS: PubMed was searched for studies, reviews, meta-analyses, and guidelines using the following key words: ('pancreatic cystic lesions' OR 'cystic pancreatic lesions' OR 'intraductal papillary mucinous neoplasia' OR 'mucinous cystic neoplasia' OR 'pancreatic cyst' OR 'pancreatic pseudocyst') AND (management OR treatment OR outcome OR prognosis OR diagnosis OR imaging OR 'endoscopic ultrasound' EUS-FNA OR EUS OR 'endoscopic ultrasonography' OR CT OR MRI). Retrieved papers were reviewed with regard to the diagnostic and therapeutic management of incidental PCL. RESULTS: In addition to clinical criteria, transabdominal ultrasonography including contrast-enhanced ultrasonography, cross-sectional radiological imaging, and endoscopic ultrasound (EUS) are used for diagnostic characterization and risk assessment. EUS plays an outstanding role in differential diagnosis and prognostic characterization of incidental PCL. In a single examination it is possible to perform high-resolution morphological description, perfusion imaging, as well as fine-needle aspiration of cyst content, cyst wall, and solid components. An international consensus guideline has defined worrisome and high-risk criteria for the risk assessment of mucinous pancreatic cysts, which are mainly based on the results of EUS and cross-sectional imaging. Nevertheless, despite diagnostic progress and guideline recommendations, differential diagnosis and management decisions remain difficult. This review will discuss problems in and approaches to the diagnosis of incidental PCL. CONCLUSION: An evidence-based algorithm for the diagnosis of incidental PCL is proposed.

25-O-acetyl-23,24-dihydro-cucurbitacin F induces cell cycle G2/M arrest and apoptosis in human soft tissue sarcoma cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Quisqualis indica is used in traditional Chinese medicine to treat cancer and related syndromes and also known for its anthelminthic effects. AIM OF THE STUDY: Soft tissue sarcomas represent a rare group of malignant tumors that frequently exhibit chemotherapeutic resistance and increased metastatic potential. In this study, we evaluated the cytotoxic, apoptosis inducing and cell cycle arresting effects of 25-O-acetyl-23,24-dihydro-cucurbitacin F which has been isolated from leaves and twigs of Q. indica. MATERIAL AND METHODS: The present study investigates the effects of 25-O-acetyl-23,24-dihydro-cucurbitacin F (1) on cell viability, cell cycle distribution, and apoptotic induction of three human sarcoma cell lines of various origins by using the CellTiter 96(®) AQueous One Solution Cell Proliferation Assay, flow cytometrical experiments, real-time RT-PCR, Western blotting, and the Caspase-Glo(®) 3/7 Assay RESULTS: We could show that 1 reduced cell viability in a dose-dependent manner and arrested the cells at the G2/M interface. The accumulation of cells at the G2/M phase resulted in a significant decrease of the cell cycle checkpoint regulators cyclin B1, cyclin A, CDK1, and CDK2. Interestingly, 1 inhibited survivin expression significantly, which functions as a key regulator of mitosis and programmed cell death, and is overexpressed in many tumor types including sarcomas. Moreover, 1 induced apoptosis in liposarcoma and rhabdomyosarcoma cells caspase-3 dependently. CONCLUSION: Our data strongly support 1 as a very interesting target for further investigation and development of novel therapeutics in sarcoma research.

The effect of oral pancreatic enzyme supplementation on the course and outcome of acute pancreatitis: a randomized, double-blind parallel-group study.

CONTEXT: Pancreatic exocrine insufficiency is a significant problem after acute pancreatitis. OBJECTIVE: To evaluate whether oral pancreatic enzyme supplementation improves the recovery of pancreatic exocrine function and to explore the efficacy, safety and tolerability of pancreatic enzyme supplementation in patients during the refeeding period after acute pancreatitis. DESIGN: Prospective double-blind, placebo controlled, randomized study. PATIENTS: The sudy included 56 patients with acute pancreatitis. MAIN OUTCOME MEASURES: Primary efficacy variable was recovery from pancreatic exocrine insufficiency. Secondary objectives were body weight, abdominal pain, course of APACHE II score, patient's symptoms and quality of life. RESULTS: Twenty of the 56 patients showed low fecal elastase values indicating pancreatic exocrine insufficiency after acute pancreatitis. Median time to recovery from exocrine pancreatic insufficiency was 14 days in the enzyme supplementation group and 23 days in the placebo group but overall differences for primary and all but one secondary endpoint did not reach statistical significance. However, a positive tendency in favour of enzyme supplementation was found for quality of life parameters (FACT-Pa) in all subscores. There were no relevant differences between placebo and oral pancreatic enzyme supplementation detected with respect to safety and tolerability. CONCLUSION: Enzyme supplementation positively effects the course of acute pancreatitis if administered during the early refeeding phase after acute pancreatitis. There is evidence that oral pancreatic enzyme supplementation has a positive impact on the course of the disease and the global health status (less weight loss, less flatulence, improved quality of life). Oral pancreatic enzyme supplementation was safely administered and can be added to the treatment regimen of patients in a refeeding status after severe acute pancreatitis.

Clinical characteristics and time trends in etiology of hepatocellular cancer in Germany.

INTRODUCTION: The incidence of hepatocellular cancer (HCC) continues to rise in Europe with a shift of the primary cause towards alcoholic and non-alcoholic fatty liver disease. Metabolic factors like diabetes mellitus and overweight have been identified as significant risk factors for HCC development. PATIENTS AND METHODS: A retrospective analysis in a large single-center cohort of 650 patients diagnosed with HCC was performed. Demographic characteristics, risk factors, tumor stage at diagnosis and survival were evaluated. RESULTS: Among 650 patients (aged 17-87 years, with a male: female ratio of 4:1), 80.8% had underlying liver cirrhosis. Alcohol abuse was identified as the only risk factor for liver cirrhosis in 52.2% of patients. Viral infection with hepatitis C and hepatitis B was present in 13.7 and 3.6% of patients, respectively. 66.1% of patients with HCC were overweight with a body mass index exceeding 25, 25.5% even exceeding 30; 52% of patients had diabetes mellitus. CONCLUSION: Strategies aiming at prevention and surveillance of patients at risk to develop HCC in the future need to widen the focus from patients with chronic viral hepatitis and a history of alcohol abuse to patients with metabolic risk factors.

Long-term outcome of self expandable metal stents for biliary obstruction in chronic pancreatitis.

CONTEXT: Insertion of a self-expandable metal stent is still controversial for treatment of benign common bile duct stenosis but can be a valuable alternative to surgical treatment. OBJECTIVE: Aim of our study was to analyze the efficacy of covered and uncovered self-expandable metal stent in patients with chronic pancreatitis and common bile duct stenosis. MATERIAL AND METHODS: Twenty patients with common bile duct stenosis due to alcoholic chronic pancreatitis were retrospective analyzed. All patients had advanced chronic pancreatitis, presenting with calcifications in pancreatic head. Uncovered self-expandable metal stent (uSEMS) were used in 11 patients (3 females, 8 males) while in 9 patients (3 females, 6 males) partially covered self-expandable metal stent (cSEMS) were inserted. All patients treated with self-expandable metal stent had contraindications for surgery. RESULTS: Overall mean follow up time was 155 weeks: 206 (52-412) weeks in uSEMS, and 93 (25-233) weeks in cSEMS, respectively. Stent patency was in mean 118 weeks: 159 (44-412) weeks in uSEMS and 67 (25-150) weeks in cSEMS (P=0.019). In the uSEMS group, reintervention was necessary in 5 patients (45%) due to stent obstruction, whereas in the cSEMS group 4 patients (44%) needed reintervention (2 obstructions, 2 migration). Stent migration is an early complication, compared to obstruction (P<0.05), and in cSEMS obstruction occurred significantly earlier compared to uSEMS (P<0.05). CONCLUSION: Patency of uSEMS was significantly longer compared to partially cSEMS. Available self-expandable metal stent, unfortunately, do not meet the demands on successful treatment of benign common bile duct stenosis.

Delayed Diagnosis of HCC with Chronic Alcoholic Liver Disease.

BACKGROUND: Adherence to surveillance recommendations for patients at risk of developing hepatocellular carcinoma (HCC) is influenced by several factors, including the etiology of chronic liver disease. AIM: The aim of this study was to analyze whether tumor stage at diagnosis and prognosis differ in patients with alcohol-related HCC compared to those with chronic viral hepatitis-related HCC. PATIENTS AND METHODS: Medical records of 650 patients diagnosed with HCC between 1994 and 2011 were analyzed retrospectively. Groups were formed from patients having either alcohol abuse or viral hepatitis (chronic hepatitis B or C virus infection) as the only known HCC risk factors. Demographic data (age and gender), tumor stage at diagnosis, survival, liver function [Child-Pugh-Turcotte (CPT) score] in patients with liver cirrhosis, complications of liver cirrhosis, and serologic parameters were compared between the two groups. RESULTS: A total of 393 HCC cases (male 84%, median age 65 years) were identified, with alcohol abuse as the causative factor in 76.8% and chronic viral hepatitis in 23.2%. In patients with alcohol abuse, 278 (92.1%) were diagnosed with liver cirrhosis (CPT A 49.3%, CPT B 31.1%, CPT C 9.6%), while in patients with viral hepatitis, 84 (92.3%) suffered from liver cirrhosis (CPT A 59.3%, CPT B 23.1%, CPT C 8.8%). Tumor stage in patients with alcohol abuse was Barcelona Clinic Liver Cancer (BCLC) C in 43.7%, BCLC B in 30.5%, and BCLC A in 14.6%. Patients with viral hepatitis showed a trend toward diagnosis at an earlier tumor stage (BCLC B 35.2%, BCLC C 34.1%, BCLC A 22.2%). Etiology of liver cirrhosis did not significantly influence survival in intermediate and advanced tumor stages, but BCLC-A patients with alcohol-related disease demonstrated prolonged survival compared to patients with viral hepatitis. CONCLUSION: Tumor stage at diagnosis of HCC is influenced by the etiology of underlying chronic liver disease and is more progressed in patients having a disease with alcoholic etiology. Majority of HCC patients are not diagnosed at a curable stage, which underlines the need for specialized care for all patients with chronic liver disease, independent of etiology and consequent adherence to current surveillance guidelines.

Inhibition of P-glycoprotein at the blood-brain barrier by phytochemicals derived from traditional Chinese medicine.

The blood-brain barrier (BBB) is a key determinant for drug transport through brain vessels. It restricts the pharmacological efficacy in numerous neurological diseases, including brain tumors. A major functional constituent of BBB is P-glycoprotein, which is also a major obstacle for effective chemotherapy of brain tumors. An appealing strategy is to selectively modulate BBB function using P-glycoprotein inhibitors. We assessed 57 chemically defined compounds derived from medicinal plants used in traditional Chinese medicine for their potential to inhibit P-glycoprotein. Nine phytochemicals inhibited P-glycoprotein in porcine brain capillary endothelial cells (PBCECs) and multidrug-resistant CEM/ADR5000 cells as shown by a calcein fluorescence assay. The cytotoxicity of the 57 phytochemicals was measured by a growth inhibition assay. Seven compounds inhibiting P-glycoprotein at lower doses were cytotoxic to drug-sensitive parental CCRF-CEM cells at higher doses. Of them, five were not cross-resistant to CEM/ADR5000 cells (baicalein, bufalin, glybomine B, deoxyserofendic acid, and shogaol). Bufalin was chosen as a lead compound. Of a further six bufalin-related compounds, scillarenin showed improved features in comparison to bufalin. It was cytotoxic to cancer cells at a nanomolar range. COMPARE and hierarchical cluster analyses of microarray-based mRNA expression were used to investigate determinants of sensitivity or resistance of the bufalin-related compounds downstream of P-glycoprotein. CEM/ADR5000 cells were not cross-resistant, but were collaterally sensitive towards scillarenin. Finally, scillarenin inhibited P-glycoprotein in PBCECs. Taken together, these data show that scillarenin is a potential novel candidate for P-glycoprotein inhibition at BBB, and, thereby, may improve the efficacy of therapy regimens in treating brain diseases.

Sister Mary Joseph's nodule as the first sign of pregnancy-associated gastric cancer: a case report.

Sister Mary Joseph's nodule is an inconspicuous and uncommon clinical sign of advanced malignant disease, especially gastric cancer. Pregnancy-associated gastric cancer is an extremely rare condition and can be difficult to diagnose, due to the absence or misinterpretation of symptoms as pregnancy-related. Diagnostic aids, such as a basic chemistry panel and imaging techniques, may not show any abnormalities. We present a case of a 37-year-old pregnant patient whose umbilical nodule was the first presenting physical sign of gastric cancer, which had metastasized throughout the abdominal and pelvic regions.

Phytochemistry and pharmacogenomics of natural products derived from traditional Chinese medicine and Chinese materia medica with activity against tumor cells.

The cure from cancer is still not a reality for all patients, which is mainly due to the limitations of chemotherapy (e.g., drug resistance and toxicity). Apart from the high-throughput screening of synthetic chemical libraries, natural products represent attractive alternatives for drug development. We have done a systematic bioactivity-based screening of natural products derived from medicinal plants used in traditional Chinese medicine. Plant extracts with growth-inhibitory activity against tumor cells have been fractionated by chromatographic techniques. We have isolated the bioactive compounds and elucidated the chemical structures by nuclear magnetic resonance and mass spectrometry. By this strategy, we identified 25-O-acetyl-23,24-dihydro-cucurbitacin F as a cytotoxic constituent of Quisqualis indica. Another promising compound identified by this approach was miltirone from Salvia miltiorrhiza. The IC50 values for miltirone of 60 National Cancer Institute cell lines were associated with the microarray-based expression of 9,706 genes. By COMPARE and hierarchical cluster analyses, candidate genes were identified, which significantly predicted sensitivity or resistance of cell lines to miltirone.

Molecular biology of cantharidin in cancer cells.

Herbal medicine is one of the forms of traditional medical practice. Traditional Chinese medicine (TCM) and traditional Vietnamese medicine (TVM) are well-known for their long-standing tradition of herbal medicine. Secreted by many species of blister beetle, most notably by the 'Spanish fly' (Lytta vesicatoria), cantharidin inhibits protein phosphatases 1 and 2A (PP1, PP2A). Blister beetle has been used in Asian traditional medicine to treat Molluscum contagiosum virus (MCV) infections and associated warts, and is now also used for cancer treatment. A combination of both genomic and postgenomic techniques was used in our studies to identify candidate genes affecting sensitivity or resistance to cantharidin. Cantharidin was not found to be related to multidrug resistance phenotype, suggesting its potential usefulness for the treatment of refractory tumors. Oxidative stress response genes diminish the activity of cantharidin by inducing DNA strand breaks which may be subject to base excision repair and induce apoptosis in a p53- and Bcl2-dependent manner. Cantharidin is one of many natural products used in traditional Chinese medicine and traditional Vietnamese medicine for cancer treatment. Combined methods of pharmaceutical biology and molecular biology can help elucidate modes of action of these natural products.

A giant pancreatic serous microcystic adenoma with 20 years follow-up.

BACKGROUND AND AIMS: There is only little information about the spontaneous course of large pancreatic serous tumours. We followed up a white woman with a giant serous microcystic adenoma over more than 20 years. CASE REPORT: At first clinical presentation, in 1986, the tumour measured 4.5 cm in diameter. Two years later, it measured 6 cm and was considered as non-resectable at laparotomy. A biopsy was obtained, and the tumour was diagnosed as lymphangioma, based on hematoxylin and eosin-staining. During the follow-up, the tumour progressively increased in size, measuring 12 cm in diameter in 1993 and 17 cm in 2000. Thus, an average growth rate of 0.83 cm per year was calculated. Unspecific abdominal discomfort and pain were the leading clinical symptoms. A colonic resection was necessary because of compression by the tumour in 1993. Portal hypertension was detected at laparotomy. Finally, the initial biopsy specimen was re-evaluated, using immunohistochemistry, and the final diagnosis of a serous microcystic adenoma was made. CONCLUSION: This unique case demonstrates that the spontaneous course of serous microcystic adenoma of the pancreas may be favourable even with huge tumour size and that immunohistochemistry may prove a valuable tool for differential diagnosis of cystic pancreatic lesions. Due to their size and progressive, space-occupying growth, these biologically benign tumours may cause injury to adjacent organs and thus clinical symptoms. For this reason, curative surgical resection is the treatment of choice for this tumour entity except for small, asymptomatic lesions, which do not require intervention. When radical resection is impossible, palliative surgery may improve the quality of life for several years. The risk of malignant transformation seems to be low even in the long-term course.

Prevalence of H pylori associated "high risk gastritis" for development of gastric cancer in patients with normal endoscopic findings.

AIM: To investigate the prevalence of H pylori associated corpus-predominant gastritis (CPG) or pangastritis, severe atrophy, and intestinal metaplasia (IM) in patients without any significant abnormal findings during upper-GI endoscopy. METHODS: Gastric biopsies from 3548 patients were obtained during upper GI-endoscopy in a 4-year period. Two biopsies from antrum and corpus were histologically assessed according to the updated Sydney-System. Eight hundred and forty-five patients (mean age 54.8 +/- 2.8 years) with H pylori infection and no peptic ulcer or abnormal gross findings in the stomach were identified and analyzed according to gastritis phenotypes using different scoring systems. RESULTS: The prevalence of severe H pylori associated changes like pangastritis, CPG, IM, and severe atrophy increased with age, reaching a level of 20% in patients of the age group over 45 years. No differences in frequencies between genders were observed. The prevalence of IM had the highest increase, being 4-fold higher at the age of 65 years versus in individuals less than 45 years. CONCLUSION: The prevalence of gastritis featuring at risk for cancer development increases with age. These findings reinforce the necessity for the histological assessment, even in subjects with normal endoscopic appearance. The age-dependent increase in prevalence of severe histopathological changes in gastric mucosa, however, does not allow estimating the individual risk for gastric cancer development--only a proper follow-up can provide this information.

Impact of the operator's experience on value of high-resolution transabdominal ultrasound in the diagnosis of choledocholithiasis: a prospective comparison using endoscopic retrograde cholangiography as the gold standard.

OBJECTIVE: Transabdominal ultrasound (US) is the most frequently used imaging method for the diagnosis of choledocholithiasis. The aim of this prospective study was to evaluate the diagnostic accuracy of high-resolution US in the diagnosis of common bile duct stones depending on the operator's experience and in comparison with endoscopic retrograde cholangiography (ERC) as the gold standard. MATERIAL AND METHODS: From April 2003 through November 2004, 126 patients referred because of clinically and biochemically suspected common bile duct stones were included in the study. Two patients were excluded because they refused to undergo ERC. Consequently, the study comprised 124 patients (86 F, 38 M, mean age 63.2 years, range 21-91 years). High-resolution US was performed (2-5 MHz sector scanner; Siemens Elegra, Erlangen, Germany) by operators who were unaware of the results of other imaging procedures. The definitive diagnosis was established by means of ERC. RESULTS: Thirty-five out of 124 patients were investigated by experienced examiners. Twenty-seven of 35 patients (77%) were found to have stones at ERC. Bile duct stones were correctly found by US in 22 out of 27 patients (sensitivity 82%, 95% CI: 63-92). Of the 8 patients without stones at ERC, one false-positive diagnosis was made with US (specificity 88%, 95% CI: 53-98). Correct diagnoses were made in 29 out of 35 (accuracy 83%, 95% CI: 67-92) patients investigated by experienced examiners. Eighty-nine out of 124 patients were investigated by less-experienced examiners. Fifty-four of 89 patients (61%) were found to have stones at ERC. Choledocholithiasis was found correctly in only 25 out of 54 patients (sensitivity 46%, 95% CI: 34-59). Of the 35 patients without stones at ERC, three false-positive diagnoses were made with US (specificity 91%, 95% CI: 78-97). In conclusion, correct diagnoses were observed in 57 of 89 patients (accuracy 64%, 95% CI: 54-73) investigated by less-experienced examiners (p<0.05 in comparison with the results of experienced examiners). CONCLUSIONS: High-resolution US carried out by experienced examiners has a high diagnostic accuracy in the diagnosis of choledocholithiasis. Therefore, good training and continued experience are prerequisites for successful sonographic detection of bile duct stones using US. Under these conditions, further expensive and invasive methods such as ERC, magnetic resonance cholangiopancreatography and endoscopic ultrasonography may not be necessary in cases with a clear sonographic diagnosis.