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Vascular and Interventional Radiology |
1 From the Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, 1 Deaconess Rd, Boston, MA 02215. From the 2002 RSNA scientific assembly. Received January 23, 2003; revision requested April 11; final revision received July 7; accepted August 22. Address correspondence to R.A.K. (e-mail: rkane@bidmc.harvard.edu).
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTS DISCUSSIONREFERENCES |
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MATERIALS AND METHODS: Between February 1997 and August 2002 at one institution, 112 patients underwent US-guided percutaneous cholecystostomy (59 men, 53 women; average age, 69.3 years). All US images were scored on a defined semiquantitative scale according to preset parameters: (a) gallbladder distention, (b) sludge and/or stones, (c) wall appearance, (d) pericholecystic fluid, and (e) common bile duct size and/or choledocholithiasis. Separate and total scores were generated. Retrospective evaluation of (a) the bacteriologic growth of aspirated bile and its color and (b) clinical indices (fever, white blood cell count, bilirubin level, liver function test results) was conducted by reviewing medical records. For each patient, the clinical manifestation was classified into four groups: (a) localized right upper quadrant symptoms, (b) generalized abdominal symptoms, (c) unexplained sepsis, or (d) sepsis with other known infection. Logistic regression models, exact Wilcoxon-Mann-Whitney test, and the Kruskal-Wallis test were used.
RESULTS: Forty-seven (44%) of 107 patients had infected bile. A logistic regression model showed that wall appearance, distention, bile color, and pericholecystic fluid were not individually significant predictors for culture-positive bile, leaving sludge and/or stones (P = .003, odds ratio = 1.647), common bile duct status (P = .02, odds ratio = 2.214), and total score (P = .007, odds ratio = 1.267). No US covariates or clinical indices predicted clinical outcome. Clinical manifestation was predictive of clinical outcome (P = .001) and aspirating culture-positive bile (P = .008); specifically, 30 (86%) of 35 patients with right upper quadrant symptoms had their condition improve, compared with one (7%) of 15 asymptomatic patients with other known causes of infection.
CONCLUSION: US variables can be used to predict culture-positive bile but not patient outcome. Clinical manifestation is important because patients with right upper quadrant symptoms have the best clinical outcome.
© RSNA, 2004
Index terms: Cholecystitis, 762.285 • Gallbladder, calculi, 762.285 • Gallbladder, interventional procedures, 762.12985, 762.12986 • Gallbladder, US, 762.12985, 762.12986
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTS DISCUSSIONREFERENCES |
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Acalculous cholecystitis may cause sepsis of unknown origin in critically ill patients, especially patients in the intensive care unit, and mortality rates as high as 41% have been documented after cholecystectomy (10–12). In these patients, the acalculous cholecystitis is believed to be caused by inflammation and ischemia of the gallbladder that are not related to cystic duct obstruction by a stone, but rather to intravesicular hemorrhage or inspissated bile that produces cystic duct obstruction, leading to infection and inflammation (13). Diagnosis of this condition in patients in the intensive care unit is difficult because such patients often are insensitive to pain or have decreased sensation caused by medications. In addition, these patients may have hypoalbuminemia or congestive heart failure and may be fed parenterally, conditions that may cause gallbladder wall thickening and distention. Fever and leukocytosis are common in this group, with many potential sources of infection, which are often multiple and confounding.
Surgical cholecystostomy (14,15) was the method of choice for gallbladder decompression for more than a century until laparoscopic techniques were adopted in the late 1980s. Percutaneous cholecystostomy, a minimally invasive method of removing gallbladder contents when surgery is not desired or is risky, consists of percutaneous placement of a catheter, with imaging guidance, into the lumen of the gallbladder. Drainage of the gallbladder with ultrasonography (US)-guided percutaneous cholecystostomy has been used for many years (16–24).
Clearly, many patients benefit from percutaneous cholecystostomy but not all to the same extent. Hence, clinical and imaging findings that predict which patients will benefit from percutaneous cholecystostomy would be helpful in triaging the appropriate patients for this procedure, to maximize the therapeutic benefits and minimize the procedure-related complications. We hypothesized that several US and clinical parameters could potentially be used to predict the positive or negative response in the condition of a patient. Thus, the purpose of this study was to assess sonographic and clinical features that might be used to predict infected bile and/or patient outcome from US-guided percutaneous cholecystostomy.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTS DISCUSSIONREFERENCES |
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US-guided cholecystostomy was performed (a) in the US suite (64 patients, 57%) if the general status of the patient permitted or (b) at bedside in the intensive care unit (48 patients, 43%) if the condition of the patient was unstable. The procedure was performed by board-certified interventional abdominal radiologists with experience ranging from 6 to 23 years (J.S., 6 years; J.B.K., 13 years; S.N.G., 10 years; R.A.K., 23 years). A needle (20–22-gauge Chiba) was inserted through the guiding device with the tip of the needle continuously monitored as it approached and penetrated the gallbladder through the bare area of the liver, to minimize the risk of bile leak. The procedure was performed with local anesthesia and was augmented with conscious sedation except when performed in the intensive care unit in sedated patients. The transhepatic route was considered appropriate for insertion and placement of the catheter into the gallbladder by using the trocar method (Navarre 8-F universal drainage catheter; Bard, Covington, Ga) because the liver serves as a tamponade against bile leakage into the peritoneum, and the transhepatic approach was used in 108 (96%) of 112 patients (9). A technical success was defined as placement of a pigtail catheter into the lumen of the gallbladder, with aspiration of bile.
US Evaluation
All sonograms were obtained by using standard techniques implemented by qualified technologists, and all sonographic studies were supervised and interpreted by board-certified radiologists with experience ranging from 3 to 23 years. The US images obtained during US-guided percutaneous cholecystostomy or in the 24 hours preceding the procedure were reevaluated. Some of the images obtained during the procedure were not diagnostic but rather included a limited number of images required for documentation. In such cases, the diagnostic study performed within 24 hours was used for reevaluation. The sonograms were subsequently reevaluated by two experienced abdominal radiologists blinded to the outcome (J.B.K., R.A.K.) and were scored by consensus according to preset parameters by using a semiquantitative grading system: (a) gallbladder distention (scored 1–5), (b) sludge and/or stones (scored 1–5), (c) wall appearance (scored 1–4), (d) fluid around the gallbladder (scored 1–3), and (e) common bile duct dilatation and/or choledocholithiasis (scored 1–4). Possible total US scores ranged from 5 to 21 (Figs 1, 2). From the original US report, data on bile color was retrieved by a single author (J.S.). This report of color was grouped into (a) normal bile (yellow-green), (b) dark bile (including black and brown), or (c) purulent bile.
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1.5 mg/dL [26 µmol/L] or >1.5 mg/dL [>26 µmol/L]); (c) liver function tests, including alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase levels (normal or elevated); and (d) body temperature (38°C or >38°C). Microbiologic records were evaluated for the presence and type of bacterial growth.
Outcome
The information about the outcome of the hospitalization during which US-guided percutaneous cholecystostomy was performed was gathered by a single author (J.S.) from the medical records at 48 hours after the procedure, and outcomes were grouped into three categories: (a) objective improvement in symptoms to include resolution of symptoms, reduction in body temperature of at least 1°C, and reduction in white blood cell count of more than 25% within 48 hours after the procedure; (b) unchanged symptoms; or (c) death related to the procedure or caused by the underlying medical conditions.
Statistical Analysis
Correlation of individual US parameters and bile color with the rate of culture-positive bile and with patient outcome was assessed. Cutoff levels of total US scores (<10, 10–15, and >15) were assessed for the rate of positive bile cultures. A logistic regression model was used (SAS version 6.12) for evaluation of the separate US findings and the total US score to predict positive bile culture and patient outcome. An exact Wilcoxon-Mann-Whitney test was used to test for differences in total US score between subjects with positive and negative cultures. An exact Kruskal-Wallis test was used to test for differences in clinical outcome or presence of infected bile between subjects within each subset of clinical manifestation. A P value less than .05 was considered to indicate a significant difference.
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTS DISCUSSIONREFERENCES |
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US Findings and Positive Bile Culture
Information on bile culture was available in 107 patients (96%), 47 (44%) of whom had infected bile, 10 (9%) with multiple organisms. In five cases, the culture results could not be retrieved from the database of the hospital. The mean scores for each parameter are presented in Table 2. A logistic regression model showed that wall appearance, gallbladder distention, and pericholecystic fluid were not individually significant predictors for culture-positive bile. However, the presence of sludge and/or stones (P = .003, odds ratio = 1.647) and the status of the common bile duct (P = .02, odds ratio = 2.214) were individual significant predictors of positive bile culture. The best-fit formula was the following: logit (positive culture) = -2.945 + 0.499 (sludge and/or stones score) + 0.795 (status of common bile duct score).
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Of the 107 patients with bile culture results available, 10 patients (9%) had a total US score that was less than 10, with only two (20%) of them having cultures that were positive. Twelve patients (11%) had a total US score greater than 15, with 67% (eight patients) of them having positive cultures. The vast majority (79%, 85 patients) of the 107 patients with available results had total US scores ranging from 11 to 15, and of these 85 patients, 44% (37 patients) had positive cultures (Table 3).
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Bile Culture Status and Patient Outcome
The subset of 83 subjects with complete data regarding outcomes was used in this analysis. An exact Kruskal-Wallis test was used to test for differences in clinical outcome between groups of patients with each bile culture status (positive or negative). The exact P value is .001, which is suggestive of a significant difference in clinical outcome between groups of subjects with and without culture-positive bile.
Type of Clinical Manifestation and Culture-Positive Bile
An exact Kruskal-Wallis test was used to test for differences in culture-positive bile status between subjects with each clinical manifestation. For this analysis, 103 patients with complete data were used. Of this group of 103 patients, 27 (66%) of the 41 patients with local symptoms, eight (36%) of the 22 patients with generalized abdominal symptoms, nine (38%) of the 24 patients with unexplained sepsis, and one (6%) of the 16 patients with another known source of infection had culture-positive bile. The exact P value was .008, which was suggestive of a significant difference in the rate of culture-positive bile among subjects on the basis of clinical manifestation.
Type of Clinical Manifestation and Outcome
The 83 patients with complete data were used in this analysis. Of these 83 patients, 35 patients (42%) had local symptoms, 15 patients (18%) presented with generalized abdominal symptoms, 18 patients (22%) had unexplained sepsis, and 15 patients (18%) had another known source of infection. An exact Kruskal-Wallis test was used to test for differences in clinical outcome between groups of subjects with each clinical manifestation (Table 4). Thirty patients (86%) of the 35 patients with local symptoms, seven patients (47%) of the 15 with generalized abdominal symptoms, and five patients (28%) of the 18 with sepsis had their condition improve, compared with one patient (7%) of the 15 known to have another source of infection. The exact P value was .001, which is suggestive of a significant difference in clinical outcome among groups of patients with each clinical manifestation.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTS DISCUSSIONREFERENCES |
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The reasons and rationale for percutaneous cholecystostomy must be clarified to assess appropriately the therapeutic effectiveness of this procedure in patients with complex medical conditions. The questions that need to be addressed are the selection of the appropriate patients and the end points for evaluation of outcome. Specifically, after percutaneous cholecystostomy, is clinical improvement in 24–48 hours the only indication of effectiveness? Is the lack of improvement or death of a patient an inevitable evidence of failure? Is the exclusion of bile infection in the intensive care unit setting important? (23). These key questions are still ill defined, and hence additional data are required to help optimize the selection and care of patients. Our intention was to determine whether there are reliable US and clinical predictors for assessing the benefit of percutaneous cholecystostomy to the patient.
In an attempt to be as thorough as possible, and unlike prior studies in which binary scoring systems were used (25), we used a US scoring system that included five parameters assessed in evaluation of the right upper quadrant (distention, stones and/or sludge, wall appearance, fluid around the gallbladder, and common bile duct status). In an attempt to evaluate different criteria, we used not only the clinical end points but also the rate of positive bile culture. Our findings indicate that many US findings (wall appearance, distention, and pericholecystic fluid) are not reliable predictors of culture-positive bile, leaving sludge and/or stones and the status of the common bile duct as the two significant predictors of positive bile culture. Better yet, a combined US score of all variables was also a significant predictor of positive bile culture. In patients with total US scores less than 10, only 20% had bile cultures that were positive, while patients with total US scores greater than 15 had a 67% chance of positive bile cultures. However, the vast majority (80%) of patients have total US scores ranging from 11 to 15. Hence, only in a minority of patients could we judge a priori the probability of infected bile.
The color of aspirated bile was also not a reliable indicator and could not be used as an interim decision point in determining whether to continue with placing a catheter or to stop after a diagnostic aspiration of the bile from the gallbladder. Indeed, there was no significant correlation between bile color and culture-positive bile. Clinical indices such as fever, leukocytosis, elevated results of liver function tests, and hyperbilirubinemia also do not show evidence of being predictive of clinical outcome or bile culture status. This has practical implications. In contrast with abscess drainage, for which we usually inquire about white blood cell count and fever, there is a limited role for taking into account these findings and the bilirubin level when deciding to perform percutaneous cholecystostomy, probably because of the complex nature of the condition of these patients, many of whom have multiple comorbid disease processes and are receiving antibiotic therapy.
In addition, although some US findings were predictive of culture growth, no individual US variables or combined imaging findings were significant for predicting clinical outcome. This differs from the results of England et al (25), who found such a correlation. It is likely that differences in the patient population may account for these findings.
The analysis of the four categories of clinical manifestation (local right upper quadrant symptoms, generalized abdominal symptoms, unexplained sepsis, and other known cause of infection) shows that patients with right upper quadrant symptoms benefit to the greatest extent from percutaneous cholecystostomy, followed by patients with generalized abdominal symptoms. Those with unexplained sepsis and those known to have another source of infection have much less likelihood of benefiting. The same trend was noted for culture-positive bile, with 66% of the cultures being positive in patients with local symptoms, compared with 6% of the cultures in patients with another known source of infection elsewhere. It seems that when there is a lack of localized symptoms and a known infection elsewhere, percutaneous cholecystostomy may not be effective. On the other hand, for patients with sepsis of unknown origin, we were able to clear the gallbladder as the source of infection in more than 60% because only 37% of the cultures were positive in these patients.
In some recent studies, investigators advocate the use of aspiration of the gallbladder instead of catheter placement in patients in noncritical condition (29). Other investigators advocate a conservative approach in this population (26). Indeed, no significant difference existed between the clinical outcomes of high-surgical-risk patients with acute cholecystitis treated with gallbladder aspiration or those treated with percutaneous cholecystostomy in a retrospective study conducted by Chopra et al (29). In light of our results, we wonder whether diagnostic aspiration may be helpful in asymptomatic patients with documented sepsis because in most of these patients, the culture will be negative, and the prognosis of the patient will not be affected by catheter placement. An aspiration procedure might be diagnostic as well as therapeutic. Further randomized prospective studies are needed to assess this approach.
The limitations of our study include its retrospective nature, which resulted in incomplete data acquisition for some of the patients. Indeed, our data on laboratory values were limited, making the generalization of them more difficult. A bias might also have been caused by the type of patients treated at our institution, which is a tertiary center with a large population of elderly patients with advanced cardiovascular diseases. Although we used a semiquantitative scaling system, we believe the definition of the different parameters was precise enough not to skew the results and to permit the US scoring to be reproducible. The use of clinical data from patients with multiple medical problems may be problematic when trying to find which parameter is a reliable predictor of outcome. This limitation is inherent in the study population. We also did not take into account sex or age as potential variables in the outcome analysis. We believe that this would not undermine our results because the underlying disease is most probably related to the ultimate outcome.
In summary, in this large cohort of patients from a single institution, US-guided percutaneous cholecystostomy was a safe procedure, with a 100% technical success rate. US variables can be used to predict culture-positive bile but not necessarily to predict final patient outcome. In particular, sludge and/or stones and the status of the common bile duct appear to be of particular importance, as well as the total US abnormality score, for predicting positive bile culture. Patients with right upper quadrant symptoms have the best clinical outcomes after percutaneous cholecystostomy. However, percutaneous cholecystostomy may be much less helpful in patients with a known source of infection elsewhere. In addition, the clinical indices and bile color do not show evidence of being predictive of clinical outcome or culture status.
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FOOTNOTES |
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REFERENCES |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTS DISCUSSIONREFERENCES |
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This article has been cited by other articles:
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  E. A. Smith, J. R. Dillman, K. M. Elsayes, C. O. Menias, and R. O. Bude Cross-Sectional Imaging of Acute and Chronic Gallbladder Inflammatory Disease Am. J. Roentgenol., January 1, 2009; 192(1): 188 - 196. [Abstract] [Full Text] [PDF]
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