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Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet]. York (UK): Centre for Reviews and Dissemination (UK); 1995-.

Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet].

Duplex ultrasound and contrast-enhanced ultrasound versus computed tomography for the detection of endoleak after EVAR: systematic review and bivariate meta-analysis

TA Mirza, A Karthikesalingam, D Jackson, SR Walsh, PJ Holt, PD Hayes, and JR Boyle.

Review published: 2010.

Link to full article: [Journal publisher]

CRD summary

This review concluded that unenhanced ultrasound had poor sensitivity for endoleak detection following endovascular aneurysm repair. Contrast-enhanced ultrasound was a highly sensitive modality. As acknowledged by the authors, these conclusions should be interpreted with some caution.

Authors' objectives

To determine the diagnostic accuracy of duplex ultrasound and contrast enhanced ultrasound (CEUS) to detect endoleak following endovascular aneurysm repair (EVAR).


MEDLINE and EMBASE were searched from 1996 to March 2009. Search terms were reported. Abstracts of the meetings of the Vascular Society of Great Britain and Ireland (1989 to 2008), International Congress on Endovascular Interventions (1996 to 2009), Society for Vascular Surgery (2005 to 2009) and Peripheral Vascular Surgery Society (1998 to 2009) were handsearched. Bibliographies of retrieved articles and Current Controlled Trials, DARE and Cochrane Central Register of Controlled Trials (CENTRAL) were screened for additional studies. Only English-language studies were included.

Study selection

Studies that assessed endoleak using ultrasound and computed tomography (CT) in more than 10 unselected patients after EVAR were eligible for inclusion. Included studies were required to report sufficient data to populate 2x2 contingency tables (numbers of true positive, false negative, false positive, and true negative test results).

Ultrasound criteria for a positive test, type of CT scanner used to confirm diagnosis and type of endograft all varied widely across the included studies; details were reported in the paper.

The authors did not state how many reviewers selected studies for inclusion.

Assessment of study quality

Methodological quality of included studies was independently assessed by two reviewers who used the 14-item QUADAS tool; disagreements were resolved by discussion with a third reviewer. Overall quality scores (maximum 14) were calculated.

Data extraction

Data to populate 2x2 contingency tables were extracted. Sensitivity and specificity values were calculated for each study.

The authors did not state how many reviewers performed data extraction.

Methods of synthesis

The bivariate model was used to generate pooled point estimates for sensitivity and specificity

with 95% CIs, together with a hierarchical summary receiver operating characteristic (SROC) curve. Between-study heterogeneity was assessed using the I2 statistic. Funnel plots were constructed to assess evidence of publication bias.

Results of the review

Twenty-one studies (data for 2,895 scan pairs) were included in the review. Overall quality scores ranged from 11 to 14. Items that scored no or unclear were blinded interpretation of the index test and/or reference standard (four studies) and avoidance of differential verification bias (one study).

Pooled sensitivity for unenhanced duplex ultrasound (n=2,610) was 0.77 (95% CI 0.64 to 0.86, I2=82%). Pooled specificity was 0.94 (95% CI 0.88 to 0.97, I2=90%).

Pooled sensitivity for contrast-enhanced ultrasound (n=285), was 0.98 (95% CI 0.90 to 0.99; I2=32%). Pooled specificity was 0.88 (95% CI 0.78 to 0.94, I2=67%).

Sensitivity analysis that excluded the study with the lowest quality score did not change results. There was no evidence of publication bias.

Authors' conclusions

This study confirmed that unenhanced duplex ultrasound had poor sensitivity for endoleak detection. CEUS was a highly sensitive modality. These results should be interpreted with some caution due to heterogeneity in the analysed trials.

CRD commentary

The review stated a clear objective and defined appropriate inclusion criteria. A range of sources were searched for relevant studies. The restriction to studies in English raised the possibility of language bias and omission of relevant studies. Measures to minimise error and/or bias were applied to the quality assessment of included studies; it was unclear whether similar methods were used for study selection and data extraction. The methodological quality of included studies was assessed and reported in full. Meta-analytic methods were appropriate, but could have been expanded to explore potential sources of heterogeneity.

The authors' conclusions reflected the data presented, but language restrictions, heterogeneity of included studies and some weaknesses in the review process mean that they should be interpreted cautiously.

Implications of the review for practice and research

Practice: The authors stated that duplex ultrasound was unsuitable for sole use in endoleak detection after EVAR, but contrast-enhanced ultrasound offered promise as a safe and sensitive modality for endoleak detection.

Research: The authors stated that further research was required to evaluate the clinical safety of CEUS and its utility in the direction of post-EVAR re-intervention before it could be recommended as the sole imaging modality after EVAR.


None stated.

Bibliographic details

Mirza TA, Karthikesalingam A, Jackson D, Walsh SR, Holt PJ, Hayes PD, Boyle JR. Duplex ultrasound and contrast-enhanced ultrasound versus computed tomography for the detection of endoleak after EVAR: systematic review and bivariate meta-analysis. European Journal of Vascular and Endovascular Surgery 2010; 39(4): 418-428. [PubMed: 20122853]

Indexing Status

Subject indexing assigned by NLM


Aneurysm /surgery; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation /adverse effects /instrumentation; Contrast Media /diagnostic use; Evidence-Based Medicine; Humans; Postoperative Complications /etiology /radiography /ultrasonography; Predictive Value of Tests; Prosthesis Failure; Sensitivity and Specificity; Tomography, X-Ray Computed; Treatment Failure; Ultrasonography, Doppler, Duplex



Database entry date


Record Status

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.

CRD has determined that this article meets the DARE scientific quality criteria for a systematic review.

Copyright © 2014 University of York.

PMID: 20122853

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