Lygia Stewart

San Francisco VA Medical Center, San Francisco, California, United States

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Publications (31)109.8 Total impact

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    ABSTRACT: BACKGROUND: Obesity has been associated with worse infectious disease outcomes. It is a risk factor for cholesterol gallstones, but little is known about associations between body mass index (BMI) and biliary infections. We studied this using factors associated with biliary infections. METHODS: A total of 427 patients with gallstones were studied. Gallstones, bile, and blood (as applicable) were cultured. Illness severity was classified as follows: none (no infection or inflammation), systemic inflammatory response syndrome (fever, leukocytosis), severe (abscess, cholangitis, empyema), or multi-organ dysfunction syndrome (bacteremia, hypotension, organ failure). Associations between BMI and biliary bacteria, bacteremia, gallstone type, and illness severity were examined using bivariate and multivariate analysis. RESULTS: BMI inversely correlated with pigment stones, biliary bacteria, bacteremia, and increased illness severity on bivariate and multivariate analysis. CONCLUSIONS: Obesity correlated with less severe biliary infections. BMI inversely correlated with pigment stones and biliary bacteria; multivariate analysis showed an independent correlation between lower BMI and illness severity. Most patients with severe biliary infections had a normal BMI, suggesting that obesity may be protective in biliary infections. This study examined the correlation between BMI and biliary infection severity.
    American journal of surgery 08/2012; · 2.36 Impact Factor
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    ABSTRACT: Pigment stones are thought to form as a result of deconjugation of bilirubin by bacterial beta-glucuronidase, which results in precipitation of calcium bilirubinate. Calcium bilirubinate is then aggregated into stones by an anionic glycoprotein. Slime (glycocalyx), an anionic glycoprotein produced by bacteria causing foreign body infections, has been implicated in the formation of the precipitate that blocks biliary stents. We previously showed that bacteria are present within the pigment portions of gallstones and postulated a bacterial role in pigment stone formation through beta-glucuronidase or slime production. Ninety-one biliary bacterial isolates from 61 patients and 12 control stool organisms were tested for their production of beta-glucuronidase and slime. The average slime production was 42 for biliary bacteria and 2.5 for stool bacteria (P <0.001). Overall, 73% of biliary bacteria and 8% of stool bacteria produced slime (optical density >3). In contrast, only 38% of biliary bacteria produced beta-glucuronidase. Eighty-two percent of all patients, 90% of patients with common bile duct (CBD) stones, 100% of patients with primary CBD stones, and 93% of patients with biliary tubes had one or more bacterial species in their stones that produced slime. By comparison, only 47% of all patients, 60% of patients with CBD stones, 62% of patients with primary CBD stones, and 50% of patients with biliary tubes had one or more bacteria that produced beta-glucuronidase. Most biliary bacteria produced slime, and slime production correlated better than beta-glucuronidase production did with stone formation and the presence of biliary tubes or stents. Patients with primary CBD stones and biliary tubes had the highest incidence of slime production. These findings suggest that bacterial slime is important in gallstone formation and the blockage of biliary tubes.
    Journal of Gastrointestinal Surgery 04/2012; 4(5):547-53. · 2.36 Impact Factor
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    ABSTRACT: Many hepatobiliary centres are increasingly utilizing thermocoagulative devices such as bipolar-radiofrequency ablation (B-RFA). Compared with monopolar-radiofrequency ablation (M-RFA), B-RFA does not require grounding pads, thereby avoiding dermal burn injuries, and does not position probes directly into the tumour but rather on the perimeter. Additionally, B-RFA can precoagulate parenchyma to assist in hepatic resection. Herein, we report our early experience using B-RFA. A retrospective review identified 68 patients who underwent M-RFA or B-RFA between June 2004 and September 2010 in an academic centre. Peri-operative metrics were analysed. M-RFA was used to treat 30 patients, whereas B-RFA was used for 17 patients. There were no differences in peri-operative metrics, survival or disease recurrence between M-RFA and B-RFA. Seventeen additional patients underwent B-RFA precoagulation during laparoscopic resection (segmentectomy in eleven patients and multi-segmental resection in six patients). Four patients with multifocal disease underwent procedures that combined B-RFA with resection. The early experience utilizing B-RFA demonstrates equivalency to M-RFA with respect to peri-operative metrics and survival. Moreover, B-RFA can be utilized to precoagulate tissue during a planned resection, making it not only a useful tool for tumour therapy but also a useful adjunct during surgical resections.
    HPB 09/2011; 13(9):656-64. · 1.94 Impact Factor
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    ABSTRACT: The development of a hepatic surgery center within a US Department of Veterans Affairs hospital is dependent on proper training and institutional support, which can translate into low operative morbidity and mortality rates. Patients who underwent hepatic procedures between 2003 and 2009 were retrospectively reviewed. A subset analysis of laparoscopic liver resections for patients with hepatocellular cancer (HCC) was performed. One hundred twenty-six patients underwent 130 hepatic procedures, 65% of which were hepatic resections. Ninety-seven percent of cases were for malignant disease, including HCC (70%). The morbidity and mortality rates were 15.5% and 2.4%, respectively. For patients with HCC there was no difference in operative outcomes or overall survival when procedures were performed laparoscopically. A Veterans Affairs (VA) hospital specializing in hepatic surgery can achieve low complication rates comparable with those of high-volume centers. The numbers of patient referrals and hepatic resections and the proportion of laparoscopic operations increased after the creation of a dedicated hepatic surgery center within a single VA hospital.
    American journal of surgery 11/2010; 200(5):591-5. · 2.36 Impact Factor
  • Francis A Wolf, Lawrence W Way, Lygia Stewart
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    ABSTRACT: Medical team training (MTT) has been touted as a way to improve teamwork and patient safety in the operating room (OR). OR personal completed a 1-day intensive MTT training. A standardized briefing/debriefing/perioperative routine was developed, including documentation of OR miscues, delays, and a case score (1-5) assigned by the OR team. A multidisciplinary MTT committee reviewed and rectified any systems problems identified. Debriefing items were analyzed comparing baseline data with 12 and 24-month follow-up. A safety attitudes questionnaire was administered at baseline and 1 year. A total of 4863 MTT debriefings were analyzed. One year following MTT, case delays decreased (23% to 10%, P < 0.0001), mean case score increased (4.07-4.87, P < 0.0005), and both changes were sustained at 24 months. One-year and 24-month follow-up data demonstrated decreased frequency of preoperative delays (16%-7%, P = 0.004), hand-off issues (5.4%-0.3%, P < 0.0001), equipment issues/delays (24%-7%, P < 0.0001), cases with low (<3) case scores (23%-3%, P < 0.0005), and adherence to timing guidelines for prophylactic antibiotic administration improved (85%-97%, P < 0.0001). Surveys documented perception of improved teamwork and patient safety. A major systems issue regarding perioperative medication orders was identified and corrected. MTT produced sustained improvement in OR team function, including decreased delays and improved case scores. When combined with a high-level debriefing/problem-solving process, MTT can be a foundation for improving OR performance. This is the largest case analysis of MTT and one of the few to document an impact of MTT on objective measures of operating room function and patient safety.
    Annals of surgery 09/2010; 252(3):477-83; discussion 483-5. · 7.90 Impact Factor
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    ABSTRACT: Little is known about how closely operative reports reflect what was actually performed during an operation, nor has the construction of operative reports been adequately studied with the aims of clarifying the objectives of those reports and improving their efficacy. We hypothesized that if more attention is paid to the objectives of operative reports, their content will more predictably contain the most relevant information, which might channel thinking in beneficial directions during performance of the operation. Multivariate analysis of 250 laparoscopic cholecystectomy operative reports (125 uncomplicated and 125 with bile duct injury). Academic research. University (105 cases) and community (145 cases) hospitals. Variations in content and design of operative reports. Cognitive task analysis of laparoscopic cholecystectomy was conducted, and a model operative report was generated and compared with the actual operative reports. Descriptions of key elements in adequate dissection of the Calot triangle were present in 24.8% and 0.0% of operative reports from uncomplicated and bile duct injury cases, respectively. Thorough dissection of the Calot triangle, identification of the cystic duct-infundibulum junction, and lateral retraction of the infundibulum correlated with uncomplicated cases, while irregular cues (eg, perceived anatomic or other deviations) correlated with bile duct injury cases. Current practice generates operative reports that vary widely in content and too often omit important elements. This research suggests that the construction of operative reports should be constrained such that the reports routinely include the fundamental goals of the operation and what was performed to meet them. Cognitive task analysis is based on the ways the mind controls the performance of tasks; it is an excellent method for determining the extra content needed in operative reports. The resulting designs should also serve as mental guidelines to facilitate learning and to enhance the safety of the operation.
    Archives of surgery (Chicago, Ill.: 1960) 09/2010; 145(9):865-71. · 4.32 Impact Factor
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    ABSTRACT: To describe the biological behavior and surgical management of ampullary neuroendocrine tumors in 7 patients. Case series and literature review. University hospital. Seven patients with ampullary neuroendocrine tumors. Clinical presentation, pathologic findings, and survival. The patients presented with jaundice (3 patients), anemia (1 patient), gastric outlet obstruction (1 patient), or incidental discovery (2 patients). No patients had neurofibromatosis. Preoperative biopsy was diagnostic in 5 of 6 patients. All of the tumors expressed chromogranin and synaptophysin. Even when the tumor expressed gastrin, vasoactive intestinal peptide, or somatostatin, no patient had a hypersecretion syndrome. Five patients were treated by pancreaticoduodenectomy, 4 for low-grade neuroendocrine tumors and 1 for high-grade neuroendocrine carcinoma. The lesions measured 1.0 to 3.5 cm in diameter. Computed tomographic scans failed to detect nodal metastases that were present in 4 patients. One patient with a high-grade malignant neoplasm died after 15 months. The rest were disease-free after 19 to 48 months. Two patients had transduodenal local resections, one for a 1.1-cm paraganglioma (disease-free, 11 years) and the other for a 0.6-cm carcinoid tumor (disease-free, 7 months). This is one of the largest series of neuroendocrine tumors of the ampulla. Preoperative biopsy was accurate, but computed tomographic scans were insensitive in detecting nodal metastases. Unlike duodenal carcinoid tumors, hypersecretion syndromes were absent and small tumor size did not preclude locoregional metastases. Tumor grade predicted survival. We recommend pancreaticoduodenectomy for this disease, with local resection reserved for mobile, superficial lesions.
    Archives of surgery (Chicago, Ill.: 1960) 07/2009; 144(6):527-31. · 4.32 Impact Factor
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    ABSTRACT: Motivation - Understanding surgeons' intraoperative sensemaking and whether linguistic and descriptive choices reflect unconscious thought. Research approach - Analysis of surgeons' sensemaking, using laparoscopic cholecystectomy operative reports of cases with and without bile duct injuries, examining for linguistic modifiers of uncertainty and description of irregular cues. Findings/Design - qualifiers of uncertainty and an increased number of irregular cues were more common in bile duct injury cases. Research Implications - These data suggest the unconscious mind detects aberrations whose significance cannot break through to conscious recognition. Originality/Value - Both complicated and uncomplicated cases were studied. The importance of linguistic qualifiers has not been previously studied in this domain. Take away message - descriptive and linguistic choices reflect unconscious thought.
    Proceedings of the 9th Bi-annual international conference on Naturalistic Decision Making; 06/2009
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    Lygia Stewart, Lawrence W Way
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    ABSTRACT: Many factors contribute to the success of biliary reconstructions following laparoscopic bile duct injury. We previously reported that control of intra-abdominal infection, complete preoperative cholangiography, surgical technique and surgical experience affected the results. There is no consensus, however, on whether the timing of the operation is important. We examined factors influencing the success of the first repair of 307 major bile duct injuries following laparoscopic cholecystectomy. Factors were assessed for cases initially repaired either by the primary surgeon or a biliary specialist. Bivariate and multivariate analyses were used to determine the significance of comparisons. A total of 137 injuries were initially repaired by a biliary surgeon and 163 injuries were initially repaired by the primary surgeon; seven were managed non-surgically. Repairs by primary surgeons were performed earlier than those by biliary surgeons (11 vs. 59 days; P < 0.0001). Bivariate analysis of the entire cohort suggested that later repairs might have been more successful than earlier ones (17 vs. 50 days; P = 0.003). Multivariate analysis, however, showed that the timing of the repair was unimportant (P = 0.572). Instead, success correlated with: eradication of intra-abdominal infection (P = 0.0001); complete preoperative cholangiography (P = 0.002); use of correct surgical technique (P = 0.0001), and repair by a biliary surgeon (P = 0.0001). Separate multivariate analyses of outcomes for primary and biliary surgeons revealed that timing was unrelated to success in either case. The success of biliary reconstruction for iatrogenic bile duct injuries depended on complete eradication of abdominal infection, complete cholangiography, use of correct surgical technique, and repair by an experienced biliary surgeon. If these objectives were achieved, the repair could be performed at any point with the expectation of an excellent outcome. We see no reason to delay the repair for some arbitrary period.
    HPB 01/2009; 11(6):516-22. · 1.94 Impact Factor
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    ABSTRACT: The histology and clinical behavior of ampullary tumors vary substantially. We speculated that this might reflect the presence of two kinds of ampullary adenocarcinoma: pancreaticobiliary and intestinal. We analyzed patient demographics, presentation, survival (mean followup 44 months), and tumor histology for 157 consecutive ampullary tumors resected from 1989 to 2006. Histologic features were reviewed by a pathologist blinded to clinical outcomes. Survival was compared using Kaplan-Meier/Cox proportional hazards analysis. There were 33 benign (32 adenomas and 1 paraganglioma) and 124 malignant (118 adenocarcinomas and 6 neuroendocrine) tumors. One hundred fifteen (73%) patients underwent a Whipple procedure, 32 (20%) a local resection, and 10 (7%) a palliative operation. For adenocarcinomas, survival in univariate models was affected by jaundice, histologic grade, lymphovascular, or perineural invasion, T stage, nodal metastasis, and pancreaticobiliary subtype (p < 0.05). Size of tumor did not predict survival, nor did cribriform/papillary features, dirty necrosis, apical mucin, or nuclear atypia. In multivariate models, lymphovascular invasion, perineural invasion, stage, and pancreaticobiliary subtype predicted survival (p < 0.05). Patients with pancreaticobiliary ampullary adenocarcinomas presented with jaundice more often than those with the intestinal kind (p = 0.01) and had worse survival. In addition to other factors, tumor type (intestinal versus pancreaticobiliary) had a major effect on survival in patients with ampullary adenocarcinoma. The current concept of ampullary adenocarcinoma as a unique entity, distinct from duodenal and pancreatic adenocarcinoma, might be wrong. Intestinal ampullary adenocarcinomas behaved like their duodenal counterparts, but pancreaticobiliary ones were more aggressive and behaved like pancreatic adenocarcinomas.
    Journal of the American College of Surgeons 08/2008; 207(2):210-8. · 4.50 Impact Factor
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    ABSTRACT: Biliary bacteria are more common in elderly patients and cause more serious illnesses. The reasons for this are unclear. We noted previously that bacterial serum-sensitivity and induction of TNFalpha production in sera (iTNFsera) were associated with severe biliary infections. We examined the influence of age and these factors on illness severity. Three-hundred and forty patients were studied. Gallstones and bile were cultured. Illness was staged as none (no clinical infection or inflammation), SIRS (fever, leukocytosis), severe (cholangitis, abscess, empyema), or MODS (bacteremia, hypotension, organ dysfunction/failure). Bacterial serum-sensitivity and TNFalpha induction were measured. Younger (< 70 years) and elderly (> or = 70 years) patients were compared. Biliary bacteria were more common in elderly (64% vs 41%, P < .0001). Among patients with biliary bacteria, the elderly had more serious illnesses: none: 44% younger, 19% elderly; SIRS: 16% younger, 22% elderly; severe: 22% younger, 21% elderly; MODS 18% younger, 38% elderly (P = .003). Bacteria from elderly patients induced more TNFalpha (580 vs 310 pg/ml, P = .023). In both groups, serum-sensitive bacteria caused infectious manifestations and induced abundant TNFalpha; however, serum-resistant bacteria from elderly usually (69%) caused infectious manifestations and abundant TNFalpha, while serum-resistant bacteria from younger patients rarely (8%) caused infectious manifestations and minimal TNFalpha. Elderly patients with high iTNFsera bacteria had more severe illnesses. Biliary bacteria were more common in elderly patients and produced more serious illnesses. Many younger patients with biliary bacteria displayed no infectious manifestations. Elderly patients harbored more virulent bacteria, and had a heightened response to high iTNFsera bacteria, as well as bacteria largely tolerated by younger patients.
    Surgery 02/2008; 143(1):103-12. · 3.37 Impact Factor
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    ABSTRACT: Several methods of treatment for hepatocellular carcinoma (HCC) are often used in combination for either palliation or cure. We established a multidisciplinary treatment team (MDTT) at the San Francisco Veterans Affairs Medical Center in November 2003 and assessed whether aggressive multimodality treatment strategies may affect survival. A prospective database was established and follow-up information from patients with presumed HCC was collected up to November 2006. Information from the American College of Surgeons (ACS) cancer registry from January 2000 to November 2003 identified patients with HCC that were evaluated at the same institution prior to the establishment of the MDTT. The establishment of a MDTT resulted in the doubling of patient referrals for treatment. Significantly more patients were evaluated at earlier stages of disease and received either palliative or curative therapies. The overall survival (p<0.0001) and length of follow-up (p<0.05) were significantly improved after the establishment of the MDTT. Stage-by-stage comparisons indicate that aggressive multimodality therapy conferred significant survival advantage to patients with American Joint Commission on Cancer (AJCC) stage II HCC (odds ratio 15.50, p<0.001). Multidisciplinary collaboration and multimodality treatment approaches are important in the management of hepatocellular carcinoma and improves patient survival.
    HPB 01/2008; 10(6):405-11. · 1.94 Impact Factor
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    ABSTRACT: The clinical significance of bacteria in the pigment centers of cholesterol stones is unknown. We compared the infectious manifestations and characteristics of bacteria from pigment stones and predominantly cholesterol stones. Three hundred forty patients were studied. Bile was cultured. Gallstones were cultured and examined with scanning electron microscopy. Level of bacterial immunoglobulin G (bile, serum), complement killing, and tumor necrosis factor-alpha production were determined. Twenty-three percent of cholesterol stones and 68% of pigment stones contained bacteria (P < 0.0001). Stone culture correlated with scanning electron microscopy results. Pigment stone bacteria were more often present in bile and blood. Cholesterol stone bacteria caused more severe infections (19%) than sterile stones (0%), but less than pigment stone bacteria (57%) (P < 0.0001). Serum and bile from patients with cholesterol stone bacteria had less bacterial-specific immunoglobulin G. Cholesterol stone bacteria produced more slime. Pigment stone bacteria were more often killed by a patient's serum. Tumor necrosis factor-alpha production of the groups was similar. Bacteria are readily cultured from cholesterol stones with pigment centers, allowing for analysis of their virulence factors. Bacteria sequestered in cholesterol stones cause infectious manifestations, but less than bacteria in pigment stones. Possibly because of their isolation, cholesterol stone bacteria were less often present in bile and blood, induced less immunoglobulin G, were less often killed by a patient's serum, and demonstrated fewer infectious manifestations than pigment stone bacteria. This is the first study to analyze the clinical relevance of bacteria within cholesterol gallstones.
    Journal of Gastrointestinal Surgery 10/2007; 11(10):1298-308. · 2.36 Impact Factor
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    ABSTRACT: Gallstone bacteria provide a reservoir for biliary infections. Slime production facilitates adherence, whereas beta-glucuronidase and phospholipase generate colonization surface. These factors facilitate gallstone formation, but their influence on infection severity is unknown. Two hundred ninety-two patients were studied. Gallstones, bile, and blood (as applicable) were cultured. Bacteria were tested for beta-glucuronidase/phospholipase production and quantitative slime production. Infection severity was correlated with bacterial factors. Bacteria were present in 43% of cases, 13% with bacteremia. Severe infections correlated directly with beta-glucuronidase/phospholipase (55% with vs 13% without, P < 0.0001), but inversely with slime production (55 vs 8%, slime <75 or >75, P = 0.008). Low slime production and beta-glucuronidase/phospholipase production were additive: Severe infections were present in 76% with both, but 10% with either or none (P < 0.0001). beta-Glucuronidase/phospholipase production facilitated bactibilia (86% with vs 62% without, P = 0.03). Slime production was 19 (+/-8) vs 50 (+/-10) for bacteria that did or did not cause bacteremia (P = 0.004). No bacteria with slime >75 demonstrated bacteremia. Bacteria-laden gallstones are biofilms whose characteristics influence illness severity. Factors creating colonization surface (beta-glucuronidase/phospholipase) facilitated bacteremia and severe infections; but abundant slime production, while facilitating colonization, inhibited detachment and cholangiovenous reflux. This shows how properties of the gallstone biofilm determine the severity of the associated illness.
    Journal of Gastrointestinal Surgery 09/2007; 11(8):977-83; discussion 983-4. · 2.36 Impact Factor
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    ABSTRACT: The major technical challenge of liver surgery is controlling bleeding during transection of the parenchyma. The Gyrus hand piece (GHP) is a bipolar diathermy pulsation instrument that is similar in design to a large hemostat (Péan) clamp that divides tissue while the clamp remains closed. We retrospectively analyzed the peri-operative data from 10 patients with early cirrhosis (stage 1-4) who underwent liver resection for hepatocellular cancer between February 2004 and July 2005. Five consecutive patients who underwent resection using the GHP were compared to five other patients who underwent resection using the traditional "crush clamp technique" (CCT). Six patients underwent minor hepatectomy (<3 segments) and four underwent major hepatectomy (>3 segments). When the GHP was used, the mean Pringle time was 13 +/- 5 min, mean blood loss was 520 mL +/- 118, and mean operative time was 252 +/- 15 min. When the CCT was used, the average Pringle time was 13 +/- 3 min, mean blood loss was 630 +/- 67 mL, and mean operative time was 312 +/- 29 min. There were 2 major complications in the GHP group and 3 in the CCT group. Major complications included transient hepatic failure (i.e., ascites/encephalopathy) and biloma formation. One patient from each group suffered a minor wound complication. The average hospital stay was 8 days (range, 6-9) for the GHP group, and 8 days (range, 7-10) for CCT group. The operative mortality rate was 0%. Our preliminary results demonstrate that GHP provides an excellent and safe alternative to CCT for dividing the liver parenchyma in cirrhotic patients.
    Journal of Surgical Research 01/2007; 136(2):182-6. · 2.02 Impact Factor
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    ABSTRACT: Bacteria cause pigment gallstones and can act as a nidus for cholesterol gallstone formation. Bacterial factors that facilitate gallstone formation include beta-glucuronidase (bG), phospholipase (PhL), and slime. The current study sought to determine whether bacterial factors influence the path of gallstone formation. A total of 382 gallstones were cultured and/or examined using scanning electron microscopy (SEM). Bacteria were tested for bG and slime production. Gallstone composition was determined using infrared spectrography. Ca-palmitate presence documented bacterial PhL production. Groups were identified based upon bacterial factors present: slime and bGPhL (slime/bGPhL), bGPhL only, and slime only. Influence of bacterial stone-forming factors on gallstone composition and morphology was analyzed. Bacteria were present in 75% of pigment, 76% of mixed, and 20% of cholesterol stones. Gallstones with bGPhL producing bacteria contained more pigment (71% vs. 26%, P < .0001). The slime/bGPhL group was associated (79%) with pigment stones, bGPhL was associated (56%) with mixed stones, while slime (or none) only was associated (67%) with cholesterol stones (P < .031, all comparisons). Bacterial properties determined the path of gallstone formation. Bacteria that produced all stone-forming factors promoted pigment stone formation, while those that produced only bGPhL promoted mixed stone formation. Bacteria that only produced slime lacked the ability to generate pigment solids, and consequently were more common in the centers of cholesterol stones. This shows how bacterial characteristics may govern the process of gallstone formation.
    American journal of surgery 11/2006; 192(5):598-603. · 2.36 Impact Factor
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    ABSTRACT: There is no consensus on the appropriateness of local resection for ampullary tumors, because malignant recurrence of what were thought to be benign tumors has been reported. This study examined the role of local resection in the management of ampullary tumors. Thirty patients (mean age 66 years) had transduodenal local resections performed at UCSF-Moffitt Hospital or the San Francisco VA Medical Center (February, 1992 to March, 2004). Mean follow-up time was 5.8 years. Preoperative biopsies (obtained in all patients) showed 18 adenomas, four adenomas with dysplasia, five adenomas with atypia, one adenoma with dysplasia and focal adenocarcinoma, and two tumors seen on endoscopy, whose biopsies showed only duodenal mucosa. In comparison with the final pathology findings, the results of frozen section examinations for malignancy in 20 patients, during the operation, were false-negative in three cases. The final pathologic diagnosis was 23 villous adenomas, six adenocarcinomas, and one paraganglioma. On preoperative biopsies, all patients who had high-grade dysplasia and one of five patients with atypia turned out to have invasive adenocarcinoma when the entire specimen was examined postoperatively. Two (33%) adenocarcinomas recurred at a mean of 4 years; both had negative margins at the initial resection. Among the 23 adenomas, three (13%) recurred (all as adenomas) at a mean of 3.2 years; in only one of these cases was the margin positive at the time of resection. Tumor size did not influence recurrence rate. Ampullary tumors with high-grade dysplasia on preoperative biopsy should be treated by pancreaticoduodenectomy because they usually harbor malignancy. Recurrence is too common and unpredictable after local resection of malignant lesions for this to be considered an acceptable alternative to pancreaticoduodenectomy. Ampullary adenomas can be resected locally with good results, but the recurrence rate was 13%, so endoscopic surveillance is indicated postoperatively. Frozen sections were obtained during the operation, but they were less reliable than expected. No adenomas recurred as carcinomas, suggesting that local resection is appropriate for these tumors in the absence of dysplasia or atypia on preoperative biopsies.
    Journal of Gastrointestinal Surgery 01/2006; 9(9):1300-6. · 2.36 Impact Factor
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    ABSTRACT: Elderly male patients are thought to have a higher incidence of biliary infections. This demographic is common among veterans, so we analyzed the spectrum of gallstone disease in a large veteran population. A total of 285 patients with gallstone disease were studied. There were 27 women and 258 men, with an average age of 62 years. Gallstones, bile, and blood (as indicated) were cultured. Illness severity was staged as none (no clinical infection), moderate (fever, leukocytosis), or severe (cholangitis, bacteremia, abscess, hypotension, organ failure). Gallstones were grouped by appearance. Three bacterial groups were defined: EK (Escherichia coli or Klebsiella species), N (Enterococcus), or Oth (all other species). Biliary bacteria were present in 145 (51%) patients. Bacterial presence by patient age was 33% for those less than 50 years, 48% for those 50 to 70 years, and 65% for those more than 70 years (P <.02 vs. others). Bacterial presence by stone type was as follows: cholesterol, 11%; mixed, 51%; pigment, 71% (P <.01 vs. others). Illness severity by stone type was as follows for cholesterol: none, 73%; moderate, 27%; severe, 0%; for mixed: none, 62%; moderate, 25%; severe, 13%; for pigment: none, 41%; moderate, 17%; severe, 41% (P <.0001 vs. others). Illness severity by bacterial group was as follows for sterile: none, 77%; moderate, 23%; severe, 0%; for the Oth group: none, 57%; moderate, 22%; severe, 20%; for the N group: none, 32%; moderate, 16%; severe, 52%; for the EK group: none, 18%; moderate, 22%; severe, 60% (P <.0001 vs. sterile/Oth, P = .126 vs. N). Bacterial biliary tree colonization is prevalent in the veterans' population, it increases with age, and is more common with pigment stones. But not all bacterial species cause infectious manifestations. Patients with E coli and/or Klebsiella species commonly showed infectious manifestations, patients with Enterococcus were in an intermediate range, and those with other species had few infectious manifestations.
    The American Journal of Surgery 12/2005; 190(5):746-51. · 2.52 Impact Factor
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    ABSTRACT: To apply human performance concepts in an attempt to understand the causes of and prevent laparoscopic bile duct injury. Powerful conceptual advances have been made in understanding the nature and limits of human performance. Applying these findings in high-risk activities, such as commercial aviation, has allowed the work environment to be restructured to substantially reduce human error. The authors analyzed 252 laparoscopic bile duct injuries according to the principles of the cognitive science of visual perception, judgment, and human error. The injury distribution was class I, 7%; class II, 22%; class III, 61%; and class IV, 10%. The data included operative radiographs, clinical records, and 22 videotapes of original operations. The primary cause of error in 97% of cases was a visual perceptual illusion. Faults in technical skill were present in only 3% of injuries. Knowledge and judgment errors were contributory but not primary. Sixty-four injuries (25%) were recognized at the index operation; the surgeon identified the problem early enough to limit the injury in only 15 (6%). In class III injuries the common duct, erroneously believed to be the cystic duct, was deliberately cut. This stemmed from an illusion of object form due to a specific uncommon configuration of the structures and the heuristic nature (unconscious assumptions) of human visual perception. The videotapes showed the persuasiveness of the illusion, and many operative reports described the operation as routine. Class II injuries resulted from a dissection too close to the common hepatic duct. Fundamentally an illusion, it was contributed to in some instances by working too deep in the triangle of Calot. These data show that errors leading to laparoscopic bile duct injuries stem principally from misperception, not errors of skill, knowledge, or judgment. The misperception was so compelling that in most cases the surgeon did not recognize a problem. Even when irregularities were identified, corrective feedback did not occur, which is characteristic of human thinking under firmly held assumptions. These findings illustrate the complexity of human error in surgery while simultaneously providing insights. They demonstrate that automatically attributing technical complications to behavioral factors that rely on the assumption of control is likely to be wrong. Finally, this study shows that there are only a few points within laparoscopic cholecystectomy where the complication-causing errors occur, which suggests that focused training to heighten vigilance might be able to decrease the incidence of bile duct injury.
    Annals of Surgery 05/2003; 237(4):460-9. · 6.33 Impact Factor
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    ABSTRACT: In previous studies we noted that biliary bacteria produce slime and possess P1-fimbriae. The presence of gram-negative bacteria killed by complement correlated with serious biliary infections and induced more tumor necrosis factor-alpha (TNF-alpha) production in sera, suggesting a role for cytokine production and complement activation in biliary sepsis. This study examined bacterial virulence factors that facilitate cholangiovenous reflux (CVR) and TNF-alpha production in a rat model. Twenty-one biliary bacteria and two stool isolates were tested for slime production, sensitivity to complement killing, and hemolysin production. 10(7) Bacterial colony-forming units/ml (or saline control) were injected retrograde into the common bile ducts of Sprague-Dawley rats at a pressure of 30 cm H(2)O. Blood was obtained at 5 and 60 minutes after infusion for bacterial culture and TNF-alpha assay, respectively. The magnitude of slime production correlated inversely with the magnitude of bacterial CVR. Average bacterial colony-forming units were 1.4 x 10(5), 6.8 x 10(4), or 2.1 x 10(3) for bacteria with slime production 0 to 10, 11 to 99, or more than 100, respectively (P < 0.0001, analysis of variance). CVR was greater for serum-resistant bacteria (1.2 x 10(5) vs. 5.5 x 10(4) [P = 0.007, resistant vs. sensitive]), but TNF-alpha production was greater in serum-sensitive bacteria. TNF-alpha production as a function of bacterial reflux followed a logarithmic curve (R(2) = 0.75) for serum-sensitive bacteria but was linear (R(2) = 0.60) for serum-resistant bacteria. These data show how specific virulence factors explain why some bacterial species colonize without causing illness, whereas others colonize and cause sepsis. Although slime production was necessary for colonization, too much slime inhibited CVR. Although complement killing cleared bacteria from the circulation, it was also associated with increased TNF-alpha production, which can lead to septic manifestations. The most virulent bacterial species (from patients with sepsis) were killed by complement, but they still had significant CVR and were associated with increased TNF-alpha production.
    Journal of Gastrointestinal Surgery 03/2003; 7(2):191-8; discussion 198-9. · 2.36 Impact Factor

Publication Stats

664 Citations
109.80 Total Impact Points

Institutions

  • 2002–2012
    • San Francisco VA Medical Center
      San Francisco, California, United States
    • San Francisco State University
      San Francisco, California, United States
  • 1995–2012
    • University of California, San Francisco
      • Department of Surgery
      San Francisco, CA, United States
  • 2003
    • Oregon Health and Science University
      Portland, Oregon, United States