Renal Arterial Variations in Humans: A Systematic Review and Meta-Analysis of Global Anatomical and Radiological Evidence

Background: Renal arterial variation is a frequently encountered anatomic variation that has a significant impact on the transplantation, nephrectomy, partial nephrectomy and endovascular procedures. The reported prevalence however, ranges widely from one cadaveric to another radiology studies and a comprehensive global synthesis is not available. This systematic review and meta-analysis determined the overall renal arterial variant prevalence and described renal arterial variant patterns.

Materials and methods: A systematic review and a meta-analysis was performed based on PRISMA guidelines. The cadaveric, angiographic, and cadaveric plus CT angiography (CTA/MDCT) studies of the renal arteries were searched using electronic databases. Samples for eligible studies were drawn for the number of samples, variants, design of study and geographic location. A random-effects model was used to calculate pooled prevalence. Subgroup comparisons were carried out with respect to study methodology (cadaveric versus radiological) and geographical location. The level of heterogeneity was evaluated with the I² statistic and sensitivity analysis was performed following the leave-one-out approach. Funnel plot visualization and Egger's regression test were used for the assessment of publication bias.

Results: 21 studies with 9929 participants were included. The combined prevalence of renal arterial variations was 0.308 (95% CI: 0.274–0.344) including accessory renal arteries being the most common variant. The prevalence estimates obtained by radiological (CTA/MDCT) studies were slightly higher than those obtained by cadaveric studies. However, the prevalence was found to be variable in the different geographic regions with higher figures being reported among African people. Results from the studies were somewhat heterogeneous (I² > 75%) but stable when assessed by sensitivity analyses of the pooled estimates. No evidence of significant publication bias was obtained by funnel plot inspection or via Egger's test.

Conclusion: Renal artery anatomy differs significantly and is very common with its variation being present in about one-third of the world's population. They are seen in a wide range of populations and study designs, thus demonstrating their clinical relevance. High-resolution imaging is crucial for the identification and surgical management of complications that occur prior to a surgical procedure, with the ultimate goal of optimizing surgical outcomes, especially in renal surgery and transplantation.

Keywords: Renal artery variations, accessory renal artery, CT angiography, cadaveric study, renal transplantation, vascular anatomy, renal vascular anatomy.