Background
There has been a lot of debate in the surgical literature about the best way to surgically access the infrarenal abdominal aorta during an operation to repair an abdominal aortic aneurysm (AAA: a ballooning of an artery (blood vessel) which occurs in the major artery in the abdomen (aorta)). Two approaches are commonly used: the retroperitoneal (RP) approach and the transperitoneal (TP) approach. Both approaches appear to have advantages and disadvantages. Many trials comparing RP and TP aortic surgery have been published, with conflicting results. The aim of this Cochrane Review is to assess the effectiveness and safety of the RP versus TP approach for planned surgical open AAA repair, taking into account mortality, complications, hospital stay and blood loss. This is an update of the review originally published in 2016.
Key results
We found no new studies from the updated searches. After reassessment, we included one study which had previously been excluded. Therefore, the review includes five small randomized controlled trials (RCTs), including 152 participants. The evidence in this Cochrane Review is current to 30 November 2020. There were no clear differences between RP and TP for the outcome of death. Similarly, there was no clear evidence that RP might increase complications such as hematoma (swelling of clotted blood), chronic wound pain and abdominal wall hernia compared with TP, but there were variations between the included trials. We found that RP might result in shorter hospital stay and intensive care unit (ICU) stay and less blood loss compared with TP. There were no clear differences between the two approaches for operating time and aortic cross-clamp time (length of time that a surgical instrument, used to clamp the aorta and separate the circulation from the outflow of the heart, is used).
Reliability of the evidence
Four of the five included trials had methodological weaknesses - such as unclear randomization methods, and no reporting of blinding of the people assessing the outcome - which compromised the value of their results. In addition, the included trials only included a small number of people, few outcomes were reported, participants were followed up for a relatively short time, and there were inconsistencies between the included trials, resulting in evidence of very low to low certainty. More large-scale RCTs of the RP approach versus the TP approach for planned surgical open AAA repair are needed.
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.
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.
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.
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.
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.
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.
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).