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Retroperitoneal versus transperitoneal approach for elective open abdominal aortic aneurysm repair.

BACKGROUND
There has been extensive debate in the surgical literature regarding the optimum surgical access approach to the infrarenal abdominal aorta during an operation to repair an abdominal aortic aneurysm. The published trials comparing retroperitoneal (RP) and transperitoneal (TP) aortic surgery show conflicting results. This is an update of the review first published in 2016.


OBJECTIVES
To assess the effectiveness and safety of the retroperitoneal versus transperitoneal approach for elective open abdominal aortic aneurysm repair on mortality, complications, hospital stay and blood loss.


SEARCH METHODS
The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase and CINAHL databases and the World Health Organization International Clinical Trials Registry Platform and the ClinicalTrials.gov trials registers to 30 November 2020. The review authors searched the Chinese Biomedical Literature Database and handsearched reference lists of relevant articles to identify additional trials.


SELECTION CRITERIA
We included randomized controlled trials (RCTs) that assessed the RP approach versus the TP approach for elective open abdominal aortic aneurysm (AAA) repair. There were no restrictions on language or publication status.


DATA COLLECTION AND ANALYSIS
Two review authors independently extracted data from the included trials. We resolved any disagreements through discussion with a third review author. Two review authors independently assessed the risk of bias in included trials with the Cochrane risk of bias tool. For dichotomous outcomes, we calculated the odds ratio (OR) with the corresponding 95% confidence interval (CI). For continuous data, we calculated a pooled estimate of treatment effect by calculating the mean difference (MD) and standard deviation (SD) with corresponding 95% CIs. We pooled data using a fixed-effect model, unless we identified heterogeneity, in which case we used a random-effects model. We used GRADE to assess the overall certainty of the evidence. We evaluated the outcomes of mortality, complications, intensive care unit (ICU) stay, hospital stay, blood loss, aortic cross-clamp time and operating time.


MAIN RESULTS
We identified no new studies from the updated searches. After reassessment, we included one study which had previously been excluded. Five RCTs with a combined total of 152 participants are included. The overall certainty of the evidence ranged from low to very low because of the low methodological quality of the included trials (unclear random sequence generation method and allocation concealment, and no blinding of outcome assessors), small sample sizes, small number of events, high heterogeneity and inconsistency between the included trials, no power calculations and relatively short follow-up. There was no evidence of a difference between the RP approach and the TP approach regarding mortality (odds ratio (OR) 0.32, 95% CI 0.01 to 8.25; 3 studies, 110 participants; very low-certainty evidence). Similarly, there was no evidence of a difference in complications such as hematoma (OR 0.90, 95% CI 0.13 to 6.48; 2 studies, 75 participants; very low-certainty evidence), abdominal wall hernia (OR 10.76, 95% CI 0.55 to 211.78; 1 study, 48 participants; very low-certainty evidence), or chronic wound pain (OR 2.20, 95% CI 0.36 to 13.34; 1 study, 48 participants; very low-certainty evidence) between the RP and TP approaches in participants undergoing elective open AAA repair. The RP approach may reduce ICU stay (mean difference (MD) -19.02 hours, 95% CI -30.83 to -7.21; 3 studies, 106 participants; low-certainty evidence); hospital stay (MD -3.30 days, 95% CI -4.85 to-1.75; 5 studies, 152 participants; low-certainty evidence); and blood loss (MD -504.87 mL, 95% CI -779.19 to -230.56; 4 studies, 129 participants; very low-certainty evidence). There was no evidence of a difference between the RP approach and the TP approach regarding aortic cross-clamp time (MD 0.69 min, 95% CI -7.23 to 8.60; 4 studies, 129 participants; very low-certainty evidence) or operating time (MD -15.94 min, 95% CI -34.76 to 2.88; 4 studies, 129 participants; very low-certainty evidence).


AUTHORS' CONCLUSIONS
Very low-certainty evidence from five small RCTs showed no clear evidence of a difference between the RP approach and the TP approach for elective open AAA repair in terms of mortality, or for rates of complications including hematoma (very low-certainty evidence), abdominal wall hernia (very low-certainty evidence), or chronic wound pain (very low-certainty evidence). However, a shorter intensive care unit (ICU) stay and shorter hospital stay was probably indicated following the RP approach compared to the TP approach (both low-certainty evidence). A possible reduction in blood loss was also shown after the RP approach (very low-certainty evidence). There is no clear difference between the RP approach and TP approach in aortic cross-clamp time or operating time. Further well-designed, large-scale RCTs assessing the RP approach versus TP approach for elective open AAA repair are required.