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Endoscopic ultrasound-guided drainage to abdominal abscess: A systematic review and meta-analysis
Sifan Liu, Zibin Tian, Yueping Jiang, Tao Mao, Xueli Ding, Xue Jing
Department of Gastroenterology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong Province, China
|Date of Submission||15-Nov-2021|
|Date of Decision||18-Feb-2022|
|Date of Acceptance||01-Mar-2022|
|Date of Web Publication||20-Jul-2022|
Department of Gastroenterology, The Affiliated Hospital of Qingdao University, 16 Jiangsu Road, Qingdao 266003, Shandong Province
Source of Support: None, Conflict of Interest: None
Background: Ultrasound (US)- or computed tomography-guided drainage for abdominal abscess is currently the first-line options for drainage, but both options have disadvantages. Patients without adequate windows for drainage mostly undergo surgical drainage. However, surgical drainage is invasive and expensive. Endoscopic US (EUS)-guided drainage is a minimally invasive alternative for abdominal abscess, but there is less consensus on its efficacy, safety and complications. This meta-analysis aims to evaluate EUS-guided drainage for abdominal abscess.
Materials and Methods: We retrieved relevant papers on EUS-guided drainage for abdominal abscess from the PubMed, Cochrane Library, Web of Science and EMBASE databases. Each paper was reviewed, and data were extracted. We used R software version 3.6.3 to perform the meta-analysis. Fixed effects models were used for merging data.
Results: A total of 11 papers met the inclusion criteria, with a total sample population of 264 patients. The meta-analysis showed that the pooled clinical success rate was 90% (95% confidence interval [CI], 0.85–0.95), the technical success rate was 99% (95% CI, 0.97–1.00) and the recurrence rate was 1% (95% CI, 0.00–0.03). Three studies reported the complications, including perforation, bleeding and stent migration; none of the other eight studies reported complications. There were no significant differences between subgroups. There was no publication bias in either the clinical or the technical success rates.
Conclusions: This meta-analysis showed that EUS-guided drainage for abdominal abscess was effective and safe, with an excellent technical success rate. In addition, EUS-guided drainage could be used for abscesses with complex anatomy. Nevertheless, complications and stent type should be considered.
Keywords: Abdominal abscess, drainage, endoscopic ultrasound, meta-analysis
|How to cite this URL:|
Liu S, Tian Z, Jiang Y, Mao T, Ding X, Jing X. Endoscopic ultrasound-guided drainage to abdominal abscess: A systematic review and meta-analysis. J Min Access Surg [Epub ahead of print] [cited 2022 Aug 14]. Available from: https://www.journalofmas.com/preprintarticle.asp?id=351252
| ¤ Introduction|| |
Abdominal abscess is usually a consequence of surgery, inflammatory bowel disease, diverticulum abscess or ischaemic colitis. It is a condition with high rates of morbidity and mortality. Antibiotics combined with drainage are the current primary treatment. Ultrasound (US)- or computed tomography (CT)-guided percutaneous drainage (PCD), transrectal drainage and transvaginal drainage are the first-line drainage treatments that can be performed without general anaesthesia or longer hospitalisation. When patients lack adequate windows for drainage, they usually receive surgical drainage instead. However, surgical drainage is invasive and often has a high complication rate. Recently, endoscopic US-guided drainage (EUS-D) has come to be used successfully for the collection of peripancreatic fluid, hepatic abscesses,,,, and surgical intra-abdominal fluid.,, Its safety and efficacy in abdominal abscess have gained a great deal of attention.
EUS-D is a minimally invasive procedure that does not require general anaesthesia or longer periods of hospitalisation. In addition, as an internal modality of drainage, it does not cause self-removal of tubes or patient discomfort, and it has the advantage of real-time access to the abscess cavity. However, the effectiveness and safety of EUS-D are still uncertain. In this meta-analysis, we attempted to assess the effectiveness and safety of EUS-D.
| ¤ Materials and Methods|| |
We used the search terms 'abdominal abscess', 'intra-abdominal abscess', 'intraperitoneal abscess', 'endoscopic ultrasound', 'endosonography', 'EUS' and 'drainage' to search papers in the PubMed, Web of Science, Cochrane Library and EMBASE databases. The retrieval type was '((((('Abdominal Abscess' [MeSH]) OR 'intra-abdominal abscess' [Title/Abstract]) OR 'intraperitoneal abscess' [Title/Abstract])) AND ((('endoscopic ultrasound' [Title/Abstract]) OR endosonography [Title/Abstract]) OR EUS [Title/Abstract])) AND drainage [Title/Abstract]'.
Inclusion criteria were published papers investigating EUS-D for abdominal abscess that discussed the safety and effectiveness of EUS-D for this purpose and that provided complete, clear and reliable statistics. We prioritised higher quality papers among those covering the same subjects. Papers with less complete statistics, duplications and published in the language of Chinese were excluded.
Literature screening and assessment of quality
Two investigators independently extracted data from each study according to the selection criteria; any disagreement was resolved by a third reviewer. Blinding was used to ensure quality. The following information was extracted from papers: first author, country, year, patients' demographic characteristics (number, gender, age), study duration, diagnosis, locations and sizes of abscesses, drainage path, stent types, hospitalisation and follow-up time, clinical success rate, technical success rate, complications and recurrence rate. Main outcomes included clinical success rate (complete resolution of clinical symptoms, with lesions disappearing or decreasing by ≥50% in size as shown by at least one imaging technique) and technical success rate (ability to access and drain the abscess through placement of a drain with purulent fluid flowing through it). Secondary outcomes included complications (according to the American Society for Gastrointestinal Endoscopy [ASGE] lexicon's severity grading system) and recurrence rate (appearance of a new abdominal abscess in patients who had achieved clinical success). We used the methodological index for non-randomised studies criteria to evaluate literature quality. The registration number is INPLASY202050056. The DOI number is 10.37766/inplasy2020.5.0056.
We used R software version 3.6.3 (R Development Core Team, Auckland, New Zealand). Through heterogeneity testing, we applied the fixed-effects model for merging clinical success rate, technical success rate and recurrence rate and to obtain their cumulative 95% confidence interval (CI). Final data were subdivided into subgroups for statistical analysis according to country, abscess location, drainage approach and stent type. We created funnel plots and Egger's tests to test publication bias.
| ¤ Results|| |
Basic information and quality assessment
A total of 197 papers were retrieved from PubMed (52), Cochrane Library (79), Web of Science (2) and EMBASE (64). We included 176 papers after removing duplicates. Then, we excluded 122 papers with irrelevant subjects, leaving 54 papers. Ultimately, 11 papers were included, representing 264 abdominal-abscess patients who received EUS-D treatment. The paper screening process is illustrated in [Figure 1]. The basic information of the included papers is shown in [Table 1].
Meta-analysis of rates in endoscopic ultrasound-guided drainage for abdominal abscess
R software was used to perform the meta-analysis and calculate the merge rates. We tested heterogeneity for the clinical and technical success rates and the recurrence rate, and the results were, respectively, I2 = 0.16, P = 0.30; I2 = 0, P = 0.94 and I2 = 0, P = 0.74. We introduced fixed effects models to merge the data for meta-analysis, as shown in the forest plots. In addition, we performed subgroup analysis, created funnel plots and ran Egger's tests.
As shown in the forest plots in [Figure 2] and [Figure 3], the pooled clinical success rate and technical success rate were 90% and 99%, respectively, using fixed effects models, with 95% CIs and respective ranges of 0.85–0.95 and 0.97–1.00.
|Figure 2: Forest plot for clinical success rate and confidence intervals in each study and overall prevalence in the meta-analysis|
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|Figure 3: Forest plot for technical success rate and confidence intervals in each study and overall prevalence in the meta-analysis|
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All the included papers counted the number of complications, and several mentioned specific complications according to the ASGE lexicon's severity grading system [Table 2]. Only three studies showed complications, including perforation, bleeding and stent migration. The forest plot of the recurrence rate showed a pooled rate of 1% using a fixed effects model (95% CI, 0.00–0.03) in [Figure 4].
|Figure 4: Forest plot for recurrence rate and confidence intervals in each study and overall prevalence in the meta-analysis|
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Subgroup analysis was based on country, abscess location, drainage path and stent type. The clinical, technical success rate and complication rate were, respectively, 95% and 100%, 0 in Asian countries (95% CI, 0.80–1.00, 0.89–1.00, 0.00–0.11); 81%, 96% and 9% in European countries (95% CI, 0.72–0.91, 0.91–1.00, 0.00–0.20) and 93%, 100% and 1% in North American countries (95% CI, 0.88–0.99, 0.97–1.00, 0.00–0.04), as shown in [Table 3]. Clinical technical success rates and complication rates were, respectively, 93%, 96% and 5% in hepatic abscess (95% CI, 0.83–1.00, 0.88–1.00, 0.00–0.16); 76%, 96% and 13% in pancreatic abscess (95% CI, 0.62–0.91, 0.86–1.00, 0.00–0.43) and 92%, 100% and 1% in pelvic abscess (95% CI, 0.87–0.98, 0.97–1.00, 0.00–0.03). Drainage through the upper digestive tract had respective clinical, technical success rates and complication rates of 90%, 94% and 2% (95% CI, 0.81–0.99, 0.87–1.00, 0.00–0.09); through the lower digestive tract, these rates were, respectively, 90%, 100% and 1% (95% CI, 0.83–0.97, 0.97–1.00, 0.00–0.06). The results showed that there were more complications in pancreatic abscess, which may be due to the severity of pancreatic disease.
|Table 3: Clinical success rate and technical success rate of endoscopic-ultrasound-guided drainage for abdominal abscess in different subgroups|
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According to stent type, the clinical and technical success rates using a double-pigtail stent (DPS) were 89% and 100% (95% CI, 0.83–0.96, 0.97–1.00), the rates using the fully covered self-expanding metal stent (FCSEMS) were 71% and 100% (95% CI, 0.38–1.00, 0.83–1.00) and the clinical and technical success rates using both the FCSEMS and the DPS were 94% and 94%, respectively (95% CI, 0.83–1.00, 0.83–1.00). The results showed that the plastic stents were used more often in papers published before 2015, while FCSEMS and lumen-opposing stents were used in the past 5 years.
In the 11 included papers, three had complications. Two papers showed that EUS-D using DPS had stent migration and bleeding separately, and one paper showed that EUS-D using both FCSEMS and DPS had bleeding and perforation. The complication rates of EUS-D using DPS or FCSEMS were 1% and 0, respectively (95% CI, 0.00–0.03, 0.00–0.17). When EUS-D used both DPS and FCSEMS, the complication rate was 10% (95% CI, 0.00–0.32).
Publication bias refers to the fact that statistically significant studies were more likely to be published than non-statistically significant studies; this bias can be tested using funnel plots and Egger's tests. [Figure 5] shows that the included papers were symmetrical with the relatively narrow top and wide bottom of the clinical success rate. However, the funnel plot of the technical success rate was asymmetrical [Figure 6]. We performed more-accurate Egger's tests, which showed no publication bias for either the clinical or the technical success rate (P = 0.1364, P = 0.2204, respectively).
| ¤ Discussion|| |
This meta-analysis demonstrated that EUS-D had an excellent technical success rate, as well as a good clinical success rate and a low recurrence rate and complication rate.
Compared with EUS-D, studies of PCD showed that PCDs technical success rate ranged from 79% to 95%. However, US- or CT-guided drainage does not apply to all draining abscesses. Giovannini et al. pointed out that US-guided transvaginal drainage can only be used to biopsy solid lesions or to drain cystic lesions that can be completely aspirated. Two papers comparing EUS-D and US- or CT-guided drainage found that 10 patients had abscess relapses in the PCD group, but there were no relapses in the EUS-D group. In terms of adverse events, there were 0 and 3 in the EUS-D group and 4 and 13 in the PCD group, respectively. US- or CT-guided drainage can be self-removed and even fall off the tube easily; there are also some limitations in the ambulance and patients may require bed rest. Furthermore, repositioning can cause discomfort or pain for patients. In addition, long duration of drainage catheter placement leaves patients prone to infection and might predispose them to fistula formation.
Compared with US- or CT-guided drainage, EUS-D has many more advantages. First, it uses internal drainage, which does not have the adverse effects such as tube self-removal, infection, discomfort and pain. The abscessed sites can be seen clearly through endosonography and the contrast medium injected. Second, EUS-D is simple and convenient; it can be performed within 30 min and at bedside, which is beneficial for critically ill patients. Third, stents such as plastic DPS or FCSEMS can be applied during drainage and can minimise patient discomfort and shorten hospital stay. One study shows that time to resolution of pelvic abscess was 8 days using PCD versus 3.2 days using EUS-D. EUS-D is seen as a choice for patients without access to US- or CT-guided drainage. In clinic, the site in the closest apposition to the abscess collection with no intervening vessel is the most appropriate one under endoscopic guide. When it is difficult to localise the site, fluoroscopy such as US or CT combined with endoscopy is used to finish the localisation and evaluation.
The transrectal or transvaginal drainage can ruin surrounding vessels or organs, and some areas with complex anatomies cannot be reached. Conventionally, when patients lacked adequate windows for drainage, they received surgery, which is invasive and expensive. For patients without access to US- or CT-guided drainage, EUS-D is a good choice for abdominal abscess. For liver abscess, EUS-D is a better choice than US- or CT-guided PCD and surgery, due to the latter's success rate of only 79%–95%, numerous risks and expense. Right lobe hepatic abscess is harder to puncture for its difficult anatomies. [Table 4] shows only 3 papers reported right lobe hepatic abscess with clinical success rates of 100%, 100%, 80%, technical success rates of 100%, 100%, 80%, recurrence rates and complications of 0. For pancreatic pseudocysts or abscesses, EUS-D as internal drainage is safe and effective. For pelvic abscess, EUS-guided drainage without fluoroscopy is safe and feasible for patients and can reduce surgical intervention. EUS-D drainage can also easily reach abscesses that are anatomically difficult to access, such as caudate and subphrenic abscesses, and thereby avoid ruining surrounding vessels and organs.
|Table 4: Clinical success rate and technical success rate of right lobe hepatic abscesses in reported papers|
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In addition, placement of a transrectal drainage catheter and a stent under EUS guidance is a modified technique that is safe and effective for pelvic abscess. Reported studies show that as a standard approach, plastic stents are frequently complicated by migration, stenosis and revision. The novel FCSEMS is safer and more effective than plastic stents. Our findings showed that the clinical success rate of the plastic-stent subgroup was 89%, higher than that of the FCSEMS subgroup (71%); however, both groups had technical success rates of 100%. The combination of plastic stents and FCSEMS had a 94% clinical success rate, higher than those of the two subgroups, but the technical success rate was lower (94%). DPS and FCSEMS subgroups had complication rates of 1% and 0%, respectively. In the DPS and FCSEMS subgroup, the complication rate was 10%, which was higher than the above two subgroups. Possible explanations are that only one paper including 13 patients used FCSEMS; the sample size was small, and larger sample size studies are needed. Furthermore, for the combination subgroup, it was harder to place two types of stents simultaneously, and using two types of stents may cause more complications than using one type of stent. Considering its high clinical success rate, plastic stents combined with FCSEMS can be used in the actual procedure but should be carefully placed. Imaging is carried out when drainage is <25 ml/day to reposition the stent or removing it in case no fluid content existing. In addition, when the content of the abscess is viscous, only a single PS placement is hard to reach sufficient drainage, thus multiple PCs or even external naso-abscess drainage catheters are temporarily placed together with the internal plastic stent.
However, as an endoscopic procedure, EUS-D can bring complications such as perforation, bleeding and stent migration,, and sometimes even infection. In our findings, only three studies had complications, the rates of which were 4%, 5% and 31%; they included perforation, bleeding and stent migration. In actual clinical practice, EUS-D is limited by the available window from the gastric view, which makes it difficult for surgeons to obtain a clear and complete view of the abscess site. In addition, EUS-D drainage is excellent for liver abscess in a single cell, while it is not effective enough for honeycomb-like liver abscesses. This may result in inadequate drainage.
This study included abdominal abscesses in different sites drained with various approaches and stents. Our study was comprehensive, and heterogeneity was low. There was no publication bias in the clinical or technical success rate and no significant differences between subgroups. However, the study also has several limitations. Included papers had small sample sizes, and they spanned significant periods of time in which drainage methods and clinician experience varied greatly. In the future, large sample, multicentre studies involving clinicians at similar levels of technical expertise should be performed.
| ¤ Conclusions|| |
EUS-D proved to be effective and safe for abdominal abscess, with superior clinical and technical success rates, a low recurrence rate and rare complications. Nonetheless, surgeons should be aware of complications and stent types during surgery. For anatomically difficult abscesses, EUS-D is a good choice.
We would like to thank LetPub (www.letpub.com) for providing linguistic assistance during the preparation of this manuscript.
Financial support and sponsorship
This work was supported by the China Postdoctoral Science Foundation (Grant No. 2019M652332).
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
[Table 1], [Table 2], [Table 3], [Table 4]