Treatment of pyogenic liver abscess: Prospective randomized comparison of catheter drainage and needle aspiration
2004; Lippincott Williams & Wilkins; Volume: 39; Issue: 4 Linguagem: Inglês
10.1002/hep.20133
ISSN1527-3350
AutoresSimon C.H. Yu, Simon Ho, Wan Yee Lau, Deacons T.K. Yeung, Edmund H.Y. Yuen, Paul S.F. Lee, Constantine Metreweli,
Tópico(s)Gallbladder and Bile Duct Disorders
ResumoHepatologyVolume 39, Issue 4 p. 932-938 Liver Failure & Liver DiseaseFree Access Treatment of pyogenic liver abscess: Prospective randomized comparison of catheter drainage and needle aspiration Simon C.H. Yu, Corresponding Author Simon C.H. Yu simonyu@cuhk.edu.hk Department of Diagnostic Radiology and Organ Imaging, Prince of Wales Hospital, Hong Kong, China fax: +852-264-84122Prince of Wales Hospital, Diagnostic Radiology and Organ Imaging, 30-32 Ngan Shing Street, Shatin, New Territories, Hong Kong, China===Search for more papers by this authorSimon S.M. Ho, Simon S.M. Ho Department of Diagnostic Radiology and Organ Imaging, Prince of Wales Hospital, Hong Kong, ChinaSearch for more papers by this authorWan Y. Lau, Wan Y. Lau Department of Surgery, Prince of Wales Hospital, Hong Kong, ChinaSearch for more papers by this authorDeacons T.K. Yeung, Deacons T.K. Yeung Department of Diagnostic Radiology and Organ Imaging, Prince of Wales Hospital, Hong Kong, ChinaSearch for more papers by this authorEdmund H.Y. Yuen, Edmund H.Y. Yuen Department of Diagnostic Radiology and Organ Imaging, Prince of Wales Hospital, Hong Kong, ChinaSearch for more papers by this authorPaul S.F. Lee, Paul S.F. Lee Department of Diagnostic Radiology and Organ Imaging, Prince of Wales Hospital, Hong Kong, ChinaSearch for more papers by this authorConstantine Metreweli, Constantine Metreweli Department of Diagnostic Radiology and Organ Imaging, Prince of Wales Hospital, Hong Kong, ChinaSearch for more papers by this author Simon C.H. Yu, Corresponding Author Simon C.H. Yu simonyu@cuhk.edu.hk Department of Diagnostic Radiology and Organ Imaging, Prince of Wales Hospital, Hong Kong, China fax: +852-264-84122Prince of Wales Hospital, Diagnostic Radiology and Organ Imaging, 30-32 Ngan Shing Street, Shatin, New Territories, Hong Kong, China===Search for more papers by this authorSimon S.M. Ho, Simon S.M. Ho Department of Diagnostic Radiology and Organ Imaging, Prince of Wales Hospital, Hong Kong, ChinaSearch for more papers by this authorWan Y. Lau, Wan Y. Lau Department of Surgery, Prince of Wales Hospital, Hong Kong, ChinaSearch for more papers by this authorDeacons T.K. Yeung, Deacons T.K. Yeung Department of Diagnostic Radiology and Organ Imaging, Prince of Wales Hospital, Hong Kong, ChinaSearch for more papers by this authorEdmund H.Y. Yuen, Edmund H.Y. Yuen Department of Diagnostic Radiology and Organ Imaging, Prince of Wales Hospital, Hong Kong, ChinaSearch for more papers by this authorPaul S.F. Lee, Paul S.F. Lee Department of Diagnostic Radiology and Organ Imaging, Prince of Wales Hospital, Hong Kong, ChinaSearch for more papers by this authorConstantine Metreweli, Constantine Metreweli Department of Diagnostic Radiology and Organ Imaging, Prince of Wales Hospital, Hong Kong, ChinaSearch for more papers by this author First published: 25 March 2004 https://doi.org/10.1002/hep.20133Citations: 163 AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract This study aims to compare the therapeutic effectiveness of continuous catheter drainage versus intermittent needle aspiration in the percutaneous treatment of pyogenic liver abscesses. Over a 5-year period, 64 consecutive patients with pyogenic liver abscess were treated with intravenous antibiotics (ampicillin, cefuroxime, and metronidazole) and randomized into two percutaneous treatment groups: continuous catheter drainage (with an 8F multi-sidehole pigtail catheter); and intermittent needle aspiration (18G disposable trocar needle). There was no statistically significant difference between the two groups regarding patient demographics, underlying coexisting disease, abscess size, abscess number, number of loculation of abscess, the presenting clinical symptoms such as fever, abdominal pain, and pretreatment liver function test. Although not statistically significant, the duration of intravenous antibiotics treatment before percutaneous treatment was longer with the catheter group, and the change of antibiotics after the sensitivity test was more frequent with the needle group. The needle group was associated with a higher treatment success rate, a shorter duration of hospital stay, and a lower mortality rate, although this did not reach statistical significance. In conclusion, this study suggests that intermittent needle aspiration is probably as effective as continuous catheter drainage for the treatment of pyogenic liver abscess, although further proof with a large-scale study is necessary. Due to the additional advantages of procedure simplicity, patient comfort, and reduced price, needle aspiration deserves to be considered as a first-line drainage approach. (HEPATOLOGY 2004;39:932–938.) Prior to the availability of percutaneous drainage, pyogenic liver abscesses used to carry a high mortality despite medical treatment and surgical drainage.1-3 Since the first description of closed aspiration as a form of treatment for pyogenic liver abscesses half a century ago,4 imaging-guided percutaneous drainage has gained increasing acceptance as an integral part of treatment. Despite the challenge from a number of small series about the necessity5 and effectiveness6 of percutaneous drainage—the former showed success with medical treatment alone (9 out of 10), while the latter showed a poor response rate to antibiotics and percutaneous drainage (2 out of 13)—the combination of systemic antibiotics and percutaneous drainage has become the treatment of choice for the management of pyogenic liver abscesses in most centers.7-31 In general, surgical drainage has been reserved for patients who fail to respond to treatment with percutaneous drainage and antibiotics or who have concurrent intraabdominal pathology which requires surgical management.6, 13, 22, 23, 27, 28 Although mortality figures have improved over the last two decades, pyogenic liver abscesses still demonstrate a significant mortality—figures of 6–14% are typical of the more recent studies.22, 26, 27, 29 Continuous catheter drainage has been the more widely accepted technique for draining pyogenic liver abscesses,7-19 while intermittent needle aspiration has been preferred by some centers, including our institution.20-25 Although both techniques have been shown to be effective and safe, there has been no prospective randomized study directly comparing the two techniques in the treatment of pyogenic abscesses. To our knowledge, there has been one previous randomized study7 comparing the catheter drainage technique with needle aspiration in the treatment of liver abscesses. However, both amoebic and pyogenic abscesses were included in that study, with only 11 of 50 (22%) of the cases confirmed pyogenic abscesses. Moreover, the number of aspirations in that study was limited to two sessions and the failure rate of aspiration was higher than that of the other published studies.4, 20-25 The current article reports a randomized controlled trial in which continuous catheter drainage and intermittent needle aspiration were directly compared for the treatment of pyogenic liver abscesses. Patients and Methods Patient Inclusion Criteria and Randomization. This study was approved by the local ethics committee. Eight-three consecutive patients who had a diagnosis of pyogenic liver abscess made on the basis of clinical and imaging findings with ultrasound or computed tomography between November 1994 and November 1999 were assessed for eligibility for the study. Patients included for randomization had begun intravenous antibiotic treatment at presentation with ampicillin 500 mg 6 hourly, cefuroxime 750 mg 8 hourly, and metronidazole 500 mg 8 hourly and had idiopathic or biliary causes for their liver abscesses. The abscesses were at least 3 cm. Patients with short life expectancy of less than 2 months from terminal disease/malignancy, with uncertain diagnosis or initially treated with other antibiotic combinations were excluded from the study. Informed consent was obtained from all participating patients. Sixty-four patients fitting the inclusion criteria were randomly allocated to two percutaneous intervention groups, for either continuous catheter drainage or intermittent needle aspiration. The randomization process was executed by a secretary by selection of sealed and numbered envelopes which contained instructions for intervention options. The allocation of intervention option to each numbered envelope was computer-generated and blinded to all those participating in treatment. Antibiotics Policy. At presentation, all patients had been treated with intravenous ampicillin, cefuroxime, and metronidazole. The antibiotics therapy was adjusted according to the results of culture and sensitivity test of pus aspirated at the time of the drainage procedure. Antibiotics adjustment was done immediately when the sensitivity test was available. Patients with negative culture results were continuously treated with a combination of ampicillin, cefuroxime, and metronidazole. The antibiotic regime was not changed for patients with poor treatment response; follow-up sonography and repeat aspiration or drainage were provided to these patients. Intravenous antibiotic therapy was continued for a minimum of 7 days and until fever had subsided for at least 48 hours. The patients were then put on the appropriate oral antibiotics for a total treatment period of 6 weeks. Intervention. All percutaneous interventions were performed under ultrasound guidance with an Aloka SSD-650 machine and a 3.5 MHz curvilinear transducer (Aloka, Tokyo, Japan). A free-hand technique using an 18G disposable trocar needle (Cook, Bloomington, IN) of varying lengths (10–20 cm) was employed for puncturing the abscesses. A sample of pus was routinely taken and sent for microbiological analysis including microscopy, culture, and antibiotic sensitivity tests. Continuous Catheter Drainage. Under fluoroscopic control, 2–5 ml of undiluted contrast media was instilled slowly into the abscess cavity through the 18G needle to guide insertion of a 0.038″ Amplatz extra-stiff into the liver abscess. After serial dilatation, an 8F multi-sidehole pigtail catheter (Angiomed, Karlsruhe, Germany) was inserted into the largest cavity of the abscess. Aspiration was then performed with the catheter until no more pus could be removed. The catheter was then secured to the skin for continuous external drainage and the patient was sent back to the ward. When catheter output had stopped for 24 hours, a follow-up sonography was performed. If an abscess cavity was absent, the catheter was removed. If a residual cavity was present, the catheter was flushed with saline and aspirated until the return was clear. Residual loculations of abscess were treated with catheter repositioning and aspiration. Further sonography was performed 3 days later and the catheter was removed if the catheter had remained unproductive. Otherwise, the catheter was left in situ until catheter output had stopped. Sonography was repeated every 3 days until the cavity had either disappeared or had shown reduction or stasis in size with clinical recovery. A final sonogram was performed 2 weeks later to exclude recurrence. Intermittent Needle Aspiration. Complete evacuation of pus from each cavity was attempted with the 18G disposable trocar needle (Cook). The needle tip was inserted into the various locules of a multi-loculated abscess for complete pus removal. Sonography was performed every 3 days and the size of the abscess(es) was recorded. Aspiration was repeated if there was either no clinical improvement or no reduction in size of the abscess cavity/cavities. The end-point of sonography and the timing of the final sonography were the same as those for the continuous catheter drainage group. Patient Follow-up and Outcome Measures. The patients were assessed clinically until they were discharged from the hospital or dead. Patients' response to treatment in terms of clinical symptoms and laboratory tests was monitored. The criteria of successful percutaneous intervention was defined as adequate drainage of abscess to allow resolution of infection without the need for surgical drainage and with subsequent discharge of patient from the hospital. Patient outcomes, including the duration of hospital stay, procedure-related complications, treatment failure, and death, were recorded. The patients were discharged from hospital when the infection had subsided clinically and there was sonographic evidence of abscess resolution such as disappearance of abscess cavity or static or decrease in size of abscess cavity. Afterwards, the patients were followed-up in the out-patient clinic biweekly until the course of oral antibiotics was completed without evidence of recurrent infection. Statistics. Continuous variables were compared using the Mann-Whitney test while categorical variables were compared using the chi-squared test and Fisher's exact test. The G power statistical program was used in post hoc mode to calculate the statistical power of the study. Choosing α = 0.05 as per convention and a large effect size d of 0.8, with 32 subjects in each study limb gives a power of 0.88. Results Between November 1994 and November 1999, 83 patients were assessed for eligibility for participation in the study. Nineteen were excluded due to unmatched antibiotics combination, leaving a total of 64 patients to be randomized into the two percutaneous treatment groups. None was excluded due to short life expectancy from terminal diseases or malignancy. None was lost to follow-up or had their treatment discontinued. The 64 patients included in the study were diagnosed to have pyogenic liver abscess, commenced on ampicillin, cefuroxime and metronidazole, and had liver lesions greater than or equal to 3 cm in diameter. Thirty-two patients were randomized into each of the catheter drainage and needle aspiration groups. There was no statistically significant difference in patient demographics and coexisting underlying disease of the two groups (Table 1). The clinical characteristics and laboratory results of the 64 patients at inclusion were studied. Features such as incidence of fever, incidence of chills and rigor, body temperature of those patients with fever, incidence of epigastric or right upper quadrant abdominal pain, incidence of leucocytosis and white blood cell count in patients with leucocytosis, incidence of hyperbilirubinaemia and bilirubin level in patients with hyperbilirubinaemia, serum level of alkaline phosphatase, which is commonly elevated in patients with liver abscess, prothrombin time, and activated partial thromboplastin time were analyzed. There was no statistically significant difference between the two groups identified in any of these items (Table 2). Table 1. Patient Demographics Needle Aspiration Catheter Drainage P-Value Sex Male:Female 19:13 19:13 1.0000** Fisher's exact test. Age (years) Valid N 32 32 0.811†† Mann-Whitney test. Median 57.00 60.00 Percentile 25 44.00 51.00 Percentile 75 75.00 72.00 No. of patients with co-existing disease Diabetes 10 9 0.6798‡‡ Chi-square test. Carcinoma 4 8 History of gastrointestinal surgery 9 8 Cholangitis 1 2 Cholecystitis 0 1 CBD stone 1 0 Colitis 1 0 * Fisher's exact test. † Mann-Whitney test. ‡ Chi-square test. Table 2. Clinical Feature and Laboratory Results Needle Aspiration Catheter Drainage P-Value No. of patients with fever 27 26 1.0000** Chi-square test. No. of patients with chills and rigor 8 8 1.0000†† Fisher's exact test. No. of patients with epigastric or right upper quadrant abdominal pain 10 5 0.1401** Chi-square test. No. of patients with leucocytosis 29 28 1.0000†† Fisher's exact test. No. of patients with hyperbilirubinaemia 21 19 0.6056** Chi-square test. Temperature of patients with fever (Degree Celsius) Valid N 26 25 0.107‡‡ Mann-Whitney test. Median 38.0 38.5 Percentile 25 37.58 38 Percentile 75 38.50 39.05 White blood cell count in patients with leucocytosis (109/L) Valid N 29 28 0.107‡‡ Mann-Whitney test. Median 14.80 16.85 Percentile 25 12.70 13.55 Percentile 75 21.25 22.55 Bilirubin level in patients with hyperbilirubinaemia (umol/L) Valid N 21 19 0.706‡‡ Mann-Whitney test. Median 25.00 25.00 Percentile 25 19.50 18.00 Percentile 75 38.50 33.50 Alkaline phosphatase level (IU/L) Valid N 32 32 0.978‡‡ Mann-Whitney test. Median 244.50 223.50 Percentile 25 141.25 153.75 Percentile 75 356.25 303.75 Prothrombin time (seconds) Valid N 32 32 0.995‡‡ Mann-Whitney test. Median 13.15 13.05 Percentile 25 11.25 11.80 Percentile 75 15.63 14.48 Activated partial thromboplastin time (seconds) Valid N 32 32 0.963‡‡ Mann-Whitney test. Median 34.30 34.20 Percentile 25 30.70 31.65 Percentile 75 37.80 38.38 * Chi-square test. † Fisher's exact test. ‡ Mann-Whitney test. Frank pus was yielded from the abscesses in all 64 patients. There was no statistical difference in abscess characteristics in the two groups, including the size of abscess, the number of abscesses in each patient, the morphology or loculation of abscess, and the rate of positive pus culture from the abscess (Table 3). The details of pathogenic organisms identified from pus culture, of which all were pyogenic organisms, are shown in Table 4. The duration of intravenous antibiotics administered to the patients before and after the commencement of percutaneous intervention was compared between the two groups, with no statistical difference detected (Table 5). It was noted that negative pus culture from the abscess was more common in the catheter drainage group (14 vs. 12) (Table 4) and that the number of patients with antibiotics changed after pus culture and sensitivity test was fewer in the catheter drainage group (7 vs. 11) (Table 5). The change of antibiotics included ceftazidime (n = 12), penicillin (n = 4), imipenem (n = 1), and netromycin (n = 1). Table 3. Abscess Characteristics Needle Aspiration Catheter Drainage P-Value Size (cm) Valid N 32 32 0.436** Mann-Whitney test. Median 5.55 6.15 Percentile 25 4.53 4.63 Percentile 75 7.10 8.07 No. of patients with abscess no. 1:2:3 27:3:2 29:2:1 0.7496†† Chi-square test. No. of patients with abscess morphology Uniloculation : multi-loculation 22:10 23:9 0.784†† Chi-square test. No. of patients with positive pus culture 20 18 0.611†† Chi-square test. * Mann-Whitney test. † Chi-square test. Table 4. Results of Pus Culture From the Two Percutaneous Treatment Groups Pathogenic Organism Needle Aspiration (n = 32) Catheter Drainage (n = 32) Negative pus cultures 12 14 Klebsiella 9 11 E. coli 2 1 Staphylococcus 1 0 Streptococcus milleri 1 1 Combination of Klebsiella, E. coli, Staphylococcus, Streptococcus milleri 4 3 Enterobacter species 0 1 α-hemolytic streptococcus 1 0 Bacteroides fragilis 1 1 Gram negative cocci 1 0 Table 5. Patients Treatment Needle Aspiration Catheter Drainage P-Value Days of parenteral antibiotics before drainage Valid N 32 32 0.942** Mann-Whitney test. Median 3.50 3.00 Percentile 25 1.00 1.00 Percentile 75 6.00 6.75 Days of parenteral antibiotics after onset of drainage Valid N 31 28 0.033** Mann-Whitney test. Median 8.50 12.00 Percentile 25 4.25 8.75 Percentile 75 12.00 17.50 Number of patients with antibiotics changed after sensitivity test 11 7 0.264†† Chi-square test. Total volume of pus drained from each patient in the first treatment (ml) Valid N 32 32 0.778** Mann-Whitney test. Median 38.50 37.50 Percentile 25 20.75 16.25 Percentile 75 97.50 84.25 * Mann-Whitney test. † Chi-square test. The number of aspirations required in the needle aspiration group was once in 13 patients (41%), twice in 13 patients (41%), and three times or more in 6 patients (18%). The total duration of catheter insertion for each patient in the catheter drainage group ranged from 4–52 days, with a median of 13 days and an average of 16.9 ± 11.3 days. The abscess cavity was found to be absent in the final sonogram in half of the patients (50%) in both groups. The patients' response to treatment in terms of the time required for fever to subside and the time required for leucocytosis, hyperbilirubinemia, and alkaline phosphatase level to become normalized in both groups were compared, with no statistical significance (Table 6). The patient outcome parameters in terms of length of hospitalization, treatment failure requiring surgical drainage, procedure-related complication, and patient death are summarized in Table 7. There was no procedure-related complication such as hemorrhage of any degree of severity, or septicemia, in either group of patients. Hemorrhage unrelated to the procedure did not occur. There was one patient in the catheter drainage group who required surgery due to inadequate drainage and persistent sepsis. No statistically significant difference was seen in the main procedure outcome measures in either group of patients. The causes of death and clinical details of the five deaths (four from the continuous catheter drainage group and one from the intermittent needle aspiration group) are summarized in Table 8. All four patients who resulted in death in the continuous catheter drainage group had underlying malignancies. Table 6. Treatment Response Aspiration Needle Catheter Drainage P-Value Time for fever to subside (days) Valid N 27 24 0.595** Mann-Whitney test. Median 5.00 6.00 Percentile 25 4.00 2.00 Percentile 75 15.00 13.00 Time for leucocytosis to become normalized (days) Valid N 28 24 0.247** Mann-Whitney test. Median 6.00 11.00 Percentile 25 2.75 4.50 Percentile 75 15.00 19.00 Time for hyperbilirubinaemia to become normalized (days) Valid N 21 16 0.728** Mann-Whitney test. Median 2.50 2.50 Percentile 25 1.00 1.00 Percentile 75 12.75 10.50 Time for alkaline phosphatase level to become normalized (days) Valid N 31 28 0.341** Mann-Whitney test. Median 4.00 6.00 Percentile 25 2.00 3.50 Percentile 75 19.50 18.00 * Mann-Whitney test. Table 7. Patient Outcome Needle Aspiration Catheter Drainage P-Value Length of hospitalization (days) Valid N 32 32 0.120** Mann-Whitney test. Median 11.0 15.0 Percentile 25 5.25 9.50 Percentile 75 19.0 22.00 No. of patients with inadequate drainage requiring surgery 1 1 1.0000†† Fisher's exact test. No. of patients with procedure related complication 0 0 1.0000†† Fisher's exact test. No. of patient death 1 4 0.355†† Fisher's exact test. No. of patients with successful treatment 30 27 0.426†† Fisher's exact test. * Mann-Whitney test. † Fisher's exact test. Table 8. Cause of Death Patient Age/Sex Presentation Associated Pathology No. of Abscess Size of Abscess Cause of Death Remarks 1 83/F Shortness of breath, wheeze, fever, vomiting Chronic obstructive airway disease 1 6.5cm Uncontrolled sepsis Died 3 months after aspiration. 2 77/M Fever, cough Inoperable cholangiocarcinoma, cholangitis 1 4cm Uncontrolled sepsis Died 5 weeks after catheter drainage. 3 74/F Fever, chills, rigor Adenocarcinoma of unknown primary cholangitis 1 5.6cm Uncontrolled sepsis Died 4 weeks after catheter drainage. 4 77/F Fever, abdominal pain Ca thyroid 1 9cm Pulmonary embolism, acute myocardial infarction Operated for uncontrolled sepsis 4½ weeks after catheter drainage. Died 3 days after surgery. 5 78/M Fever Diabetes mellitus, inoperable cholangiocarcinoma, cholangitis 1 6cm Cholangitis Biliary endoprosthesis inserted via ERCP. Died 2 weeks after catheter drainage. Discussion This study is a prospective randomized trial comparing continuous catheter drainage and intermittent needle aspiration in the treatment outcome of pyogenic liver abscess. Rajak et al.7 did randomize 50 patients with liver abscesses into a needle aspiration group and a catheter drainage group and showed a significantly higher success rate in the catheter drainage group. However, they included patients with both amoebic and pyogenic liver abscesses, and only 11 of their 50 patients had a confirmed diagnosis of pyogenic liver abscess. In addition, they had limited their aspiration attempts to two times, which is likely to reduce the overall success rate of needle aspiration (60%) compared with catheter drainage (100%). Most previous reports have been retrospective analysis of data collected over 2–13 years and the sample sizes have typically ranged from 15–115.7-26, 28-31 A sample size of 64 from 5 years of data collection would seem reasonable compared with previously published work. Different authors tended to have favored either continuous catheter drainage7-19 or intermittent needle aspiration,20-25 while others left the choice of drainage method to the radiologists who performed the procedure.26, 27, 29 Our institution and others have advocated the use of intermittent aspiration in combination with intravenous antibiotics as the first-line treatment for pyogenic liver abscesses,22 and the current study adds further support to this management strategy. The observed high treatment success rate (97%) and low mortality (3%) rate from the current study and previous ones suggest that intermittent needle aspiration is a safe and effective procedure in the treatment of pyogenic liver abscesses. There was no statistically significant difference between the two groups in patient demographics, underlying coexisting disease, abscess characteristics, clinical presentation, and laboratory tests, indicating that the extent of abscess and the severity of infection at the time of inclusion were similar in both groups (Table 2). The fact that negative pus culture from the abscess was more common in the catheter drainage group (14 vs. 12) (Table 4) and that the number of patients with antibiotics changed after pus culture and sensitivity test was less in the catheter drainage group (7 vs. 11) (Table 5) indicates that the infection in patients of the catheter drainage group was probably better controlled with the regime of triple antibiotics administered before percutaneous intervention. Although not achieving statistical significance, all three outcome measures of this study—hospital stay duration, treatment success rate, and mortality rate—favored the intermittent needle aspiration group. Previous studies have shown the presence of coexisting malignancies of biliary origin28, 29 to be poor prognostic factors in patients with pyogenic liver abscesses, which may explain the higher observed death rate in the continuous catheter drainage group. Theoretically speaking, it would of course be ideal to recruit a large enough population to detect small differences that may exist between the two techniques, but taking into account the clinical reality, such an endeavor would not be feasible without a large-scale multicenter involvement. Using the G power statistical program for sample size calculation in the a priori mode, a study that can defect a small difference of effect size (d = 0.2 as per convention) with α = 0.05 and power set at 0.8 as per convention would require a sample size of 620, which would take ∼50 years for a single center like ours to collect. The result of the present study suggests that both techniques are probably equally effective and safe and further implies that it is justifiable to undertake a multicenter study on the subject to provide a definitive answer. Meanwhile, intermittent needle aspiration with an 18G metallic needle deserves to be considered as a first-line drainage approach for pyogenic liver abscess because it offers many advantages over continuous catheter drainage. First, the 18G metallic needle, which has been considered adequate for drainage of collections that are drainable, is smaller in caliber than an 8F catheter, and is therefore less traumatic to the liver. Second, it is more steerable and is abler to cross septae between locules of an abscess. This is of particular value for treatment of multiple or multi-loculated abscesses. Third, obviating the need for an indwelling catheter is not only more acceptable for patients in terms of comfort, it also reduces the chance of procedure-related sepsis and eliminates such problems as catheter blockage and dislodgment. Some authors have advocated early catheter removal within 72 hours to minimize the problems associated with continuous catheter drainage,9 but this is still substantially different from having no indwelling catheter at all. Finally, the 18G metallic needle is cheaper than the standard guide-wire, dilator, and 8F catheter required for continuous catheter drainage, and the use of the former can represent a significant cost saving. The main disadvantage of the needle aspiration technique is that multiple sessions may be required, but even the use of continuous catheter drainage does not guarantee a single session successful outcome.9, 12, 14, 17, 21 The experience from our institution shows that the majority of patients only require one to two sessions of aspiration (73–82%), with around a fifth to just over a quarter of patients requiring three of more sessions (18–26.7%).22 The current study and our previous work22 have shown no significant increase in morbidity or mortality from the repeat aspiration sessions. In conclusion, the current study represents an attempt to compare continuous catheter drainage and intermittent needle aspiration in the treatment of pyogenic liver abscesses in a 5-year prospective randomized trial. 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