Association between skin suture devices and incidence of incisional surgical site infection after gastrointestinal surgery: A systematic review and network meta-analysis.

AIM: We aimed to compare which suture devices could reduce the incidence of incisional surgical site infections (SSIs) after gastrointestinal surgery using a systematic review and network meta-analysis. METHODS: The CENTRAL, PubMed, and ICHUSHI-Web databases were searched from January 1st, 2000, to December 31st, 2022, for randomised clinical trials (RCTs) comparing the incidence of incisional SSI after gastrointestinal surgery among patients treated with different surgical suture devices, including non-absorbable sutures, absorbable sutures, skin staplers, and tissue adhesives (last searched in August 23th 2023). The risk of bias was assessed using the criteria of the Cochrane Handbook for Systematic Reviews of Interventions. To estimate the pooled odds ratios (ORs) for each comparison, we employed a fixed-effect inverse-variance model based on the Mantel-Haenszel approach. This study was registered in PROSPERO and supported in part by the Japan Surgical Infection Society. RESULTS: A total of 18 RCTs with 5,496 patients were included in this study. The overall SSIs in absorbable sutures were significantly lower than the ones in skin staplers (OR: 0.77; 95% confidence intervals (CI): 0.63-0.95) and non-absorbable sutures (OR: 0.62; 95% CI: 0.39-0.99). On the other hand, SSIs in absorbable sutures were not statistically different from the SSIs in tissue adhesive. The highest P-score was 0.91 for absorbable sutures. A funnel plot for estimating the heterogeneity of the studies revealed that a publication bias would be minimal (Egger test, P = 0.271). CONCLUSION: This study showed that absorbable sutures reduced incisional SSIs in gastrointestinal surgical operations compared to any other suture devices.

Current Development of Lanthanide Complexes for Biomedical Applications.

Luminescent molecule-based bioimaging system is widely used for precise localization and distinction of cancer/tumor cells. Luminescent lanthanide (Ln(III)) complexes offer long-lived (sub-millisecond time scale) and sharp (FWHM <10 nm) emission, arising from the forbidden 4f-4f electronic transitions. Luminescent Ln(III) complex-based bioimaging has emerged as a promising option for both in vitro and in vivo visualizations. In this mini-review, the historical development and recent significant progress of luminescent Ln(III) probes for bioapplications are introduced. The recent studies are mainly focused on three points: (i) the structural modifications of Ln(III) complexes in both macrocyclic and small ligands, (ii) the acquirement of high resolution luminescence images of cancer/tumor cells and (iii) the constructions of ratiometric biosensors. Furthermore, our recent study is explained as a new Cancer GPS (cancer grade probing for determining tumor grade through photophysical property analyses of intracellular Eu(III) complex.

Structure-changeable luminescent Eu(III) complex as a human cancer grade probing system for brain tumor diagnosis.

Accurate determination of human tumor malignancy is important for choosing efficient and safe therapies. Bioimaging technologies based on luminescent molecules are widely used to localize and distinguish active tumor cells. Here, we report a human cancer grade probing system (GPS) using a water-soluble and structure-changeable Eu(III) complex for the continuous detection of early human brain tumors of different malignancy grades. Time-dependent emission spectra of the Eu(III) complexes in various types of tumor cells were recorded. The radiative rate constants (kr), which depend on the geometry of the Eu(III) complex, were calculated from the emission spectra. The tendency of the kr values to vary depended on the tumor cells at different malignancy grades. Between T = 0 and T = 3 h of invasion, the kr values exhibited an increase of 4% in NHA/TS (benign grade II gliomas), 7% in NHA/TSR (malignant grade III gliomas), and 27% in NHA/TSRA (malignant grade IV gliomas). Tumor cells with high-grade malignancy exhibited a rapid upward trend in kr values. The cancer GPS employs Eu(III) emissions to provide a new diagnostic method for determining human brain tumor malignancy.

Surgical antimicrobial prophylaxis in Japanese hospitals: Real status and challenges.

BACKGROUND: Information regarding the status of surgical antimicrobial prophylaxis (SAP) in Japanese hospitals is lacking. This study aimed to explore the status of SAP prescriptions for surgeries and adherence to Japanese SAP guidelines. METHODS: From February to July 2020, a 1-day multicentre point prevalent survey was conducted at 27 hospitals in Aichi Prefecture, Japan. Patients prescribed SAP were included in this study. The appropriateness of the SAP was evaluated based on the guidelines for selection of antimicrobials and their duration. Surgery was defined as appropriate when all the items were appropriate. RESULTS: A total of 728 patients (7.1 %; 728/10,199) received antimicrobials for SAP. Among them, 557 patients (76.5 %, 557/728) underwent the surgeries described in the guidelines. The overall appropriateness of all surgeries was 33.9 % (189/557). The appropriate selection of antimicrobial before/during and after surgery and their durations were 67.5 % (376/557), 67.5 % (376/557), and 43.3 % (241/557), respectively. The overall appropriateness ranged from 0 % (0/37, oral and maxillofacial surgery) to 58.7 % (88/150, orthopaedic surgery) and 27.7 % (36/130, community hospitals with 400-599 beds) to 47.2 % (17/36, specific hospitals). Cefazolin was the most prevalent antimicrobial prescribed before/during (55.5 %, 299/539), and after (45.1 %, 249/552) surgery. In total, 101 oral antimicrobials were prescribed postoperatively. CONCLUSIONS: SAP adherence by specific surgical fields and hospitals was shown in this study. Intensive intervention and repeated surveillance are necessary to improve SAP prescriptions in Japanese hospitals.

Recent evidence for subcutaneous drains to prevent surgical site infections after abdominal surgery: A systematic review and meta-analysis.

BACKGROUND: Surgical site infections (SSIs) increase mortality, hospital stays, additional medical treatment, and medical costs. Subcutaneous drains prevent SSIs in gynecological and breast surgeries; however, their clinical impact in abdominal surgery remains unclear. AIM: To investigate whether subcutaneous drains were beneficial in abdominal surgery using a systematic review and meta-analysis. METHODS: The database search used PubMed, MEDLINE, and the Cochrane Library. The following inclusion criteria were set for the systematic review: (1) Randomized controlled trial studies comparing SSIs after abdominal surgery with or without subcutaneous drains; and (2) Studies that described clinical outcomes, such as SSIs, seroma formation, the length of hospital stays, and mortality. RESULTS: Eight studies were included in this meta-analysis. The rate of total SSIs was significantly lower in the drained group (54/771, 7.0%) than in the control group (89/759, 11.7%), particularly in gastrointestinal surgery. Furthermore, the rate of superficial SSIs was slightly lower in the drained group (31/517, 6.0%) than in the control group (49/521, 9.4%). No significant differences were observed in seroma formation between the groups. Hospital stays were shorter in the drained group than in the control group. CONCLUSION: Subcutaneous drains after abdominal surgery prevented SSIs and reduced hospital stays but did not significantly affect seroma formation. The timing of drain removal needs to be reconsidered in future studies.

Over 1000 nm Near-Infrared Multispectral Imaging System for Laparoscopic In Vivo Imaging.

In this study, a laparoscopic imaging device and a light source able to select wavelengths by bandpass filters were developed to perform multispectral imaging (MSI) using over 1000 nm near-infrared (OTN-NIR) on regions under a laparoscope. Subsequently, MSI (wavelengths: 1000-1400 nm) was performed using the built device on nine live mice before and after tumor implantation. The normal and tumor pixels captured within the mice were used as teaching data sets, and the tumor-implanted mice data were classified using a neural network applied following a leave-one-out cross-validation procedure. The system provided a specificity of 89.5%, a sensitivity of 53.5%, and an accuracy of 87.8% for subcutaneous tumor discrimination. Aggregated true-positive (TP) pixels were confirmed in all tumor-implanted mice, which indicated that the laparoscopic OTN-NIR MSI could potentially be applied in vivo for classifying target lesions such as cancer in deep tissues.

Visualization of quantitative lipid distribution in mouse liver through near-infrared hyperspectral imaging.

Lipid distribution in the liver provides crucial information for diagnosing the severity of fatty liver and fatty liver-associated liver cancer. Therefore, a noninvasive, label-free, and quantitative modality is eagerly anticipated. We report near-infrared hyperspectral imaging for the quantitative visualization of lipid content in mouse liver based on partial least square regression (PLSR) and support vector regression (SVR). Analysis results indicate that SVR with standard normal variate pretreatment outperforms PLSR by achieving better root mean square error (15.3 mg/g) and higher determination coefficient (0.97). The quantitative mapping of lipid content in the mouse liver is realized using SVR.

The Japan Society for Surgical Infection: guidelines for the prevention, detection, and management of gastroenterological surgical site infection, 2018.

BACKGROUND: The guidelines for the prevention, detection, and management of gastroenterological surgical site infections (SSIs) were published in Japanese by the Japan Society for Surgical Infection in 2018. This is a summary of these guidelines for medical professionals worldwide. METHODS: We conducted a systematic review and comprehensive evaluation of the evidence for diagnosis and treatment of gastroenterological SSIs, based on the concepts of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. The strength of recommendations was graded and voted using the Delphi method and the nominal group technique. Modifications were made to the guidelines in response to feedback from the general public and relevant medical societies. RESULTS: There were 44 questions prepared in seven subject areas, for which 51 recommendations were made. The seven subject areas were: definition and etiology, diagnosis, preoperative management, prophylactic antibiotics, intraoperative management, perioperative management, and wound management. According to the GRADE system, we evaluated the body of evidence for each clinical question. Based on the results of the meta-analysis, recommendations were graded using the Delphi method to generate useful information. The final version of the recommendations was published in 2018, in Japanese. CONCLUSIONS: The Japanese Guidelines for the prevention, detection, and management of gastroenterological SSI were published in 2018 to provide useful information for clinicians and improve the clinical outcome of patients.

Association between preoperative tumor necrosis factor alpha inhibitor and surgical site infection after surgery for inflammatory bowel disease: a systematic review and meta-analysis.

Tumor necrosis factor-alpha inhibitor (TNFi) treatment is effective for ulcerative colitis (UC) and Crohn's disease (CD). Although several meta-analyses have been performed to evaluate the association between TNFi treatment and surgical morbidity, the results are controversial. We conducted a systematic review and meta-analysis of the prevention of surgical site infection (SSI) after surgery for UC and CD in patients on TNFis, based on literature published between January 2000 and May 2019 (registered on PROSPERO, No. CRD42019134156). Overall, 2175 UC patients in 13 observational studies (OBSs) and 7084 CD patients in 16 OBSs were included. The incidences of incisional (INC) SSI and organ/space (O/S) SSI after surgery for UC were 179/1985 (9.0%) and 176/2175 (8.1%), respectively. TNFi use was not associated with the incidences of INC SSI (odds ratio (OR) 1.04, 95% confidence interval (CI) (0.47-2.32) or O/S SSI (OR 1.85, 95% CI (0.82-4.20)) after surgery for UC. The INC SSI and O/S SSI incidences after surgery for CD were 289/3089 (9.4%) and 526/7,084 (7.4%), respectively. Preoperative TNFi use was not associated with INC SSI (OR 0.98, 95% CI (0.52-1.83)) or O/S SSI incidence (OR 1.09, 95% CI (0.78-1.52)) after surgery for CD. We did not find a significant association between preoperative TNFi use and SSI in surgery for UC or CD.

Distinction of surgically resected gastrointestinal stromal tumor by near-infrared hyperspectral imaging.

The diagnosis of gastrointestinal stromal tumor (GIST) using conventional endoscopy is difficult because submucosal tumor (SMT) lesions like GIST are covered by a mucosal layer. Near-infrared hyperspectral imaging (NIR-HSI) can obtain optical information from deep inside tissues. However, far less progress has been made in the development of techniques for distinguishing deep lesions like GIST. This study aimed to investigate whether NIR-HSI is suitable for distinguishing deep SMT lesions. In this study, 12 gastric GIST lesions were surgically resected and imaged with an NIR hyperspectral camera from the aspect of the mucosal surface. Thus, the images were obtained ex-vivo. The site of the GIST was defined by a pathologist using the NIR image to prepare training data for normal and GIST regions. A machine learning algorithm, support vector machine, was then used to predict normal and GIST regions. Results were displayed using color-coded regions. Although 7 specimens had a mucosal layer (thickness 0.4-2.5 mm) covering the GIST lesion, NIR-HSI analysis by machine learning showed normal and GIST regions as color-coded areas. The specificity, sensitivity, and accuracy of the results were 73.0%, 91.3%, and 86.1%, respectively. The study suggests that NIR-HSI analysis may potentially help distinguish deep lesions.

Effect of the Hydrophilic-Hydrophobic Balance of Antigen-Loaded Peptide Nanofibers on Their Cellular Uptake, Cellular Toxicity, and Immune Stimulatory Properties.

Recently, nanofibers (NFs) formed from antigenic peptides conjugated to ß-sheet-forming peptides have attracted much attention as a new generation of vaccines. However, studies describing how the hydrophilic-hydrophobic balance of NF components affects cellular interactions of NFs are limited. In this report, three different NFs were prepared by self-assembly of ß-sheet-forming peptides conjugated with model antigenic peptides (SIINFEKL) from ovalbumin and hydrophilic oligo-ethylene glycol (EG) of differing chain lengths (6-, 12- and 24-mer) to investigate the effect of EG length of antigen-loaded NFs on their cellular uptake, cytotoxicity, and dendritic cell (DC)-stimulation ability. We used an immortal DC line, termed JAWS II, derived from bone marrow-derived DCs of a C57BL/6 p53-knockout mouse. The uptake of NFs, consisting of the EG 12-mer by DCs, was the most effective and activated DC without exhibiting significant cytotoxicity. Increasing the EG chain length significantly reduced cellular entry and DC activation by NFs. Conversely, shortening the EG chain enhanced DC activation but increased toxicity and impaired water-dispersibility, resulting in low cellular uptake. These results show that the interaction of antigen-loaded NFs with cells can be tuned by the EG length, which provides useful design guidelines for the development of effective NF-based vaccines.

The Efficacy of Antimicrobial-Coated Sutures for Preventing Incisional Surgical Site Infections in Digestive Surgery: a Systematic Review and Meta-analysis.

BACKGROUND: Antimicrobial-coated sutures have recently become well known for preventing surgical site infections (SSIs). However, the evidence and recommendations from some organizations remain controversial. Therefore, we conducted a systematic review and meta-analysis to analyze the efficacy of antimicrobial-coated sutures for preventing SSIs in digestive surgery. METHODS: We performed a systematic review of literature published from 2000 to 2017 (registered on PROSPERO, No. CRD42017076780). We included studies defined as randomized controlled trials (RCTs) and observational studies (OBSs) for the prevention of SSIs and the reduction in hospital stay length associated with digestive surgery. RESULTS: In the 10 RCTs, the incidence rates of incisional SSIs were 160/1798 (8.9%) with coated sutures and 205/1690 (12.1%) with non-coated sutures. Overall, antimicrobial-coated sutures were superior for reducing the incidence of incisional SSI (risk ratio (RR) 0.67, 95% confidence intervals (CI) 0.48-0.94, p = 0.02) in RCTs for digestive surgery with the mixed wound class and surgeries limited to a clean-contaminated wound (RR 0.66, 95% CI 0.44-0.98, p = 0.04). A superior effect of antimicrobial-coated sutures was found in 9 RCTs that involved only colorectal surgeries (RR 0.69, 95% CI 0.49-0.98, p = 0.04). The mean hospital stay length was similar with coated or uncoated sutures in 5 RCTs involving colorectal surgery (mean difference (MD) - 5.00, 95% CI 16.68-6.69, p = 0.4). CONCLUSION: Antimicrobial-coated sutures are significantly more efficacious for preventing SSIs during digestive and colorectal surgery, even when restricted to clean-contaminated wounds. However, the hospital stay length was not affected.

Haloperidol prophylaxis for preventing aggravation of postoperative delirium in elderly patients: a randomized, open-label prospective trial.

PURPOSES: The aim of this study was to evaluate the safety and efficacy of the early administration haloperidol in preventing the aggravation of postoperative delirium in elderly patients. METHODS: A total of 201 patients (age ≥75 years) who underwent elective surgery were enrolled. The patients were divided into two groups: the intervention group (n = 101) received prophylactic haloperidol (5 mg); the control group (n = 100) did not. Haloperidol was administered daily during postoperative days 0-5 to the patients who presented with NEECHAM scores of 20-24 when measured at 18:00. The primary endpoint was the incidence of severe postoperative delirium. RESULTS: The incidence of severe postoperative delirium in all patients was 25.1%. The incidence of severe postoperative delirium in the intervention group (18.2%) was significantly lower than that in the control group (32.0%) (p = 0.02). The difference between the two groups was larger when the analysis was limited to the 70 patients who had NEECHAM scores of 20-24 for at least one day during postoperative days 0-5. No adverse effects of the haloperidol were observed. CONCLUSION: The prophylactic administration of haloperidol at the early stage of delirium significantly reduced the incidence of severe postoperative delirium in elderly patients. Clinical Trial Registration UMIN000007204.

Effects of background anionic compounds on the activity of the hammerhead ribozyme in Mg(2+)-unsaturated solutions.

Cellular ribozymes exhibit catalytic activity in media containing large numbers of anionic compounds and macromolecules. In this study, the RNA cleavage activity of the hammerhead ribozyme induced by Mg(2+) was investigated using the solutions containing background nucleic acids, small phosphate and carboxylic acid compounds, and neutral polymers. Analysis of the substrate cleavage kinetics showed that the anionic compounds do not affect the ribozyme activity in Mg(2+)-saturated solutions and there is almost no effect of the anion-Mg(2+) complexes formed. On the other hand, the rate of substrate cleavage in Mg(2+)-unsaturated solutions was reduced under conditions of a high background of anionic compounds found in cells. The extent of the reduction was more with a greater net negative charge, caused by decreased amounts of Mg(2+) that could be used for the ribozyme reaction. It was remarkable that background DNA and RNA molecules having phosphodiester bonds reduced the cleavage rate as much as adenosine monophosphates having a charge of -2 when the effects of the same amount of phosphate groups were compared. Greater reductions in rates than those expected from the molecular charge were also observed in the background of fatty acids that form micelles. An addition of poly(ethylene glycol) to the solutions partially restored the ribozyme activity, suggesting a possible role of macromolecular crowding in counteracting the inhibitory effects of background anions on the ribozyme reaction. The results have biological and practical implications with respect to the effects of molecular environment on the efficiency of ion binding to RNA.

Assessment of the risk of postoperative delirium in elderly patients using E-PASS and the NEECHAM Confusion Scale.

BACKGROUND: The incidences of surgery-field disorders such as femur neck fracture and colorectal cancer in elderly persons have increased with the rapid aging of society. In such patients, postoperative delirium is also frequent. Patients should be generally assessed from the aspect of both physical and mental conditions in order to predict a high-delirium risk group. If so, delirium may be prevented more efficiently. In this study, we investigated whether the early detection of postoperative delirium in elderly patients is possible using a simple, useful behavior-assessing scale, the NEECHAM Confusion Scale, and a method for comprehensively evaluating elderly persons' stress related to surgery, E-PASS. METHODS: The subjects were 160 patients aged more than 75 years who underwent surgery. Among them, three patients had vascular surgery-field disorders, 67 had orthopedic-field disorders, and 90 had digestive surgery-field disorders. To comprehensively evaluate surgery-related stress, E-PASS was employed. In addition, we assessed recognition, activities of daily living (ADL), and the quality of life (QOL). For delirium diagnosis and severity assessment, we used the NEECHAM Confusion Scale. The cut-off value of the NEECHAM score was established as 20 points, and patients showing values less than this after surgery were regarded as having postoperative delirium. Evaluation was performed until 10 days after surgery. RESULTS: Postoperative delirium was noted in 54.7% of the subjects. There was a decrease in the NEECHAM score between the first and fourth postoperative days, but it gradually increased thereafter. Both uni- and multivariate analyses showed that postoperative delirium was associated with an advanced age (more than 80 years), low preoperative NEECHAM and MMSE scores, the preoperative QOL, and E-PASS. In groups showing an MMSE score of less than 25 or a preoperative NEECHAM score of less than 27, the incidence of postoperative delirium was 76%. CONCLUSION: The results suggest that E-PASS and the NEECHAM score facilitate assessment of the risk of postoperative delirium in elderly patients, contributing to early prevention/treatment.

Occupant kinematics and estimated effectiveness of side airbags in pole side impacts using a human FE model with internal organs.

When a car collides against a pole-like obstacle, the deformation pattern of the vehicle body-side tends to extend to its upper region. A possible consequence is an increase of loading to the occupant thorax. Many studies have been conducted to understand human thoracic responses to lateral loading, and injury criteria have been developed based on the results. However, injury mechanisms, especially those of internal organs, are not well understood. A human body FE model was used in this study to simulate occupant kinematics in a pole side impact. Internal organ parts were introduced into the torso model, including their geometric features, material properties and connections with other tissues. The mechanical responses of the model were validated against PMHS data in the literature. Although injury criterion for each organ has not been established, pressure level and its changes can be estimated from the organ models. Finite element simulations were conducted assuming a case where a passenger vehicle collides against a pole at 29km/h. Occupant kinematics, force-deformation responses and pressure levels were compared between cases with and without side airbag deployment. The results indicated that strain to the ribs and pressure to the organs was smaller with side airbag deployment. The side airbag widened the contact area at the torso, helping to distribute the force to the shoulder, arm and chest. Such distributed force helped generate relatively smaller deformation in the ribs. Furthermore, the side airbag deployment helped restrict the spine displacement. The smaller displacement contributed to lowering the magnitude of contact force between the torso and the door. The study also examined the correlations between the pressure levels in the internal organs, rib deflection, and V*C of chest. The study found that the V*C(t) peak appeared to be synchronized with the organ pressure peak, suggesting that the pressure level of the internal organs could be one possible indicator to estimate their injury risk.

Activities of daily living and quality of life of elderly patients after elective surgery for gastric and colorectal cancers.

OBJECTIVE: To establish reliable standards for surgical application to elderly patients 75 years old or older with gastric or colorectal cancer with special reference to the postoperative recovery of activities of daily living (ADL) and quality of life (QOL). SUMMARY BACKGROUND DATA: ADL and QOL are important outcomes of surgery for the elderly. However, there has been only limited evidence on the natural course of recovery of functional independence. METHODS: Two hundred twenty-three patients 75 years old or older with gastric or colorectal cancer were prospectively examined. Physical conditions, ADL, and QOL were evaluated preoperatively and at the first, third, and sixth postoperative month. RESULTS: The mortality and morbidity rates were 0.4% and 28%, respectively. Twenty-four percent of patients showed a decrease in ADL at 1 month postoperatively, but most patients recovered from this transient reduction, with only 3% showing a decline at the sixth postoperative month (6POM). ADL of these patients was likely to decrease after discharge from the hospital. QOL of the patients showed a recovery to an extent equal to or better than their average preoperative scores. CONCLUSIONS: Of the patients 75 years old or older who underwent elective surgery for gastric or colorectal cancer, only a few showed a protracted decline in ADL and most exhibited better QOL after surgery. This indicates that surgical treatment should be considered, whenever needed, for elderly patients 75 years old or older with gastric or colorectal cancer. Estimation of Physical Ability and Surgical Stress is useful for predicting postoperative declines in ADL and protracted disability; this could aid in establishing a directed rehabilitation program for preventing protracted disability in elderly patients.

Cooperative roles of Par-3 and afadin in the formation of adherens and tight junctions.

Par-3 is a cell-polarity protein that regulates the formation of tight junctions (TJs) in epithelial cells, where claudin is a major cell-cell adhesion molecule (CAM). TJs are formed at the apical side of adherens junctions (AJs), where E-cadherin and nectin are major CAMs. We have revealed that nectin first forms cell-cell adhesions, and then recruits cadherin to nectin-based cell-cell adhesion sites to form AJs and subsequently recruits claudin to the apical side of AJs to form TJs. The cytoplasmic tail of nectin binds afadin and Par-3. Afadin regulates the formation of AJs and TJs cooperatively with nectin. Here, we studied the role of Par-3 in the formation of these junctions by using Par-3-knockdown MDCK cells. Par-3 was necessary for the formation of AJs and TJs but was not necessary for nectin-based cell-cell adhesion. Par-3 promoted the association of afadin with nectin, whereas afadin was not necessary for the association of Par-3 with nectin. However, the association of afadin with nectin alone was not sufficient for the formation of AJs or TJs, and Par-3 and afadin cooperatively regulated it. We describe here these novel roles of Par-3 in the formation of junctional complexes.

Intrahepatic segmental bile duct patterns in hepatolithiasis: a comparative cholangiographic study between Taiwan and Japan.

BACKGROUND/PURPOSE: We analyzed confluence patterns of intrahepatic segmental bile ducts, seeking to relate hepato-lithiasis to anatomic variation. The comparative study was completed patients with hepatolithiasis in Taiwan and Japan. METHODS: Direct cholangiography was performed in 103 hepatolithiasis patients in Taiwan and 77 in Japan. Segmental ducts patterns were classified as type I, normal configuration; type II, "triad" confluence; type III, posterior segmental duct joining left hepatic duct; or type IV, distal confluence of the right posterior segmental duct. RESULTS: Taiwanese patients had only calcium bilirubinate or black stones, and were mostly female. As overall analysis, types I, II, III, and IV were found in 61, 26, 13, and 3 patients, respectively. In Japanese, types I, II, III, and IV were found in 52, 10, 13, and 2, respectively. There was no difference between the two institutes. Since no patients in Taiwan had cholesterol calculi, Japanese patients were reanalyzed including only 58 patients with calcium bilirubinate or black stones. Differences in those populations remained insignificant. CONCLUSION: Anatomic variations in segmental ducts apparently do not contribute to pathogenesis of hepatolithiasis.