Worldwide Incidence and Morphology of Accessory Renal Arteries

Accessory renal arteries (ARAs) arise when more than one artery supplies a kidney, usually as persistent lateral mesonephric arteries that fail to regress during renal ascent. Classic cadaveric work from South Africa reported additional renal arteries in 23% of individuals (n = 130), demonstrating that multiple arteries are a common, not exceptional, pattern.¹ Subsequent regional cadaveric and radiological series have shown similar or higher rates, often approaching one-quarter to one-third of studied populations across Africa, Asia and Europe.²

Modern CT angiography (CTA) and multidetector CT (MDCT) allow high-resolution mapping of the renal vasculature and have refined estimates of ARA prevalence. A 1000-patient CTA cohort from Turkey reported accessory or multiple renal arteries in roughly one-quarter of individuals, while Brazilian MDCT/CTA series documented renal arterial variations, including accessory and polar vessels, in around 30–31% of patients.^{4, 8} A CTA study from Nepal showed renal arterial variants in 32% of subjects, again reinforcing a cluster around the 25–30% range.⁷

Clinically, ARAs complicate renal transplantation, donor nephrectomy, stent-graft placement for juxtarenal aneurysms, renal denervation and segmental ablative procedures. Inferior polar ARAs may compromise ureteric drainage or predispose to hydronephrosis, while failure to re-anastomose a major polar vessel can produce segmental infarction in a transplanted kidney.^{5, 9} This review adopts a meta-analysis–style approach to summarise global incidence, regional patterns, laterality and morphology of ARAs, integrating cadaveric and imaging data with recent classification proposals.

This synthesis draws on cadaveric studies, CTA/MDCT series and systematic reviews that explicitly reported the presence of accessory or multiple renal arteries. Classic cadaveric work by Satyapal et al. in South Africans and Khamanarong et al. in Thai specimens provided early large-sample prevalence estimates, while more recent Australian, Spanish and South Asian series contributed mixed cadaveric–radiological and purely CTA perspectives.^{1, 2}

Imaging-based estimates relied predominantly on contrast-enhanced CTA or MDCT, including a 1000-patient cohort from Turkey, donor CTA from New Zealand and Brazilian CTA work that characterised normal and variant renal vasculature.^{4, 8} Additional data on multiple renal arteries and polar versus hilar entry were obtained from an Australian mixed cadaveric/CT analysis and a CT-based classification study from Spain.^{6, 8}

Where possible, prevalence values were stratified by region (Africa, South/East Asia, Europe, South America, Middle East), laterality (right, left, bilateral) and morphology (hilar, superior polar, inferior polar). Because study designs and definitions varied, exact numerical pooling was avoided; instead, representative values from the largest or methodologically strongest series in each region were used to construct summary figures and maps.

Global patterns from cadaveric and CTA studies

The earliest large cadaveric series by Satyapal et al. reported additional renal arteries in 23% of South African subjects, providing one of the most frequently cited anchors for global ARA prevalence.¹ Thai cadaveric work has described comparable or slightly higher rates in the mid-20% range, reinforcing that multiple renal arteries are common in diverse populations.²

CTA-based studies consistently yield prevalence figures at the upper end of this spectrum. A 1000-patient cohort from Turkey found that approximately one-quarter of individuals had more than one renal artery, while Brazilian CTA series reported anatomical variations of the renal arteries, including accessory and polar vessels, in about 30–31% of patients.⁴⁸ A hospital-based CTA study from Nepal demonstrated renal arterial variations, including accessory polar and hilar arteries, in 32% of patients.⁷

These findings are congruent with broader narrative and systematic reviews, which typically quote 20–30% of individuals as having multiple renal arteries, with ARAs representing the dominant variant type.⁹ For graphical purposes, a representative global prevalence of 28% is used as a midpoint of the most robust CTA series.

Graph explanation: Figure 1 illustrates a representative global prevalence of 28% for accessory renal arteries, approximating the midpoint of high-quality CTA series from Turkey, Brazil and Nepal that report values between about 24% and 33%.^{47, 8} The remaining 72% of individuals demonstrate a single renal artery per kidney, underscoring that while the classical pattern is still more common, ARAs are far from rare.

Prevalence across major world regions

Regional data show that the prevalence of ARAs is not uniform worldwide. South African cadaveric work documented additional renal arteries in approximately 23% of individuals, representing a robust African reference point.¹ In contrast, Brazilian CTA series reported anatomical variations of the renal arteries, including accessory and polar vessels, in about 31% of patients, suggesting a higher prevalence in South American cohorts.⁸

European and Mediterranean-region imaging studies report broadly similar or slightly lower figures. Turkish MDCT work and donor CTA from New Zealand have both described multiple renal arteries in roughly 22–27% of cases, whereas a Spanish mixed cadaveric and CT analysis reported multiple arteries in 22% of subjects.^{46, 8} Middle Eastern CTA series, including work from Saudi Arabia and neighbouring populations, frequently quote prevalence in the high-teens to low-20% range, at the lower end of the global spectrum.¹⁰

In South and East Asia, CT-based prevalence appears consistently high: Indian and Nepalese CTA and cadaveric studies report renal arterial variations in approximately 30–33% of individuals, with accessory polar arteries dominating the variant spectrum.²⁷ These data collectively support a genuine geographic pattern, with South America, South/East Asia and parts of Europe showing higher rates than many Middle Eastern and some African populations.

Graph explanation: Figure 2 summarises representative regional prevalence values, using South African cadaveric data as an African reference, Brazilian CTA for South America, Indian/Nepalese datasets for South/East Asia and Turkish–Spanish work for Europe.^{14, 8} Middle Eastern values cluster around 18–20%, yielding a visibly lower bar. The chart emphasises that ARAs approach or exceed 30% in many South American and Asian cohorts while remaining lower but still frequent in African and Middle Eastern series.

To provide a more intuitive overview of geographic variation, representative country-level prevalence values from the strongest available datasets are plotted on a world choropleth map. Only countries with relatively large cadaveric or CTA series are displayed, and values are rounded to whole percentages for visual clarity.

Graph explanation: Figure 3 visualises representative prevalence values for several well-studied countries. Darker shading in Brazil, India and Nepal reflects prevalence around or above 30%, based on CTA and cadaveric series, while lighter shading in Saudi Arabia and South Africa reflects values in the high-teens to mid-20% range.^{17, 8} The map underlines that high ARA prevalence is not confined to a single region but appears across multiple continents.

Laterality Patterns of Accessory Renal Arteries

Many large series report ARA prevalence separately for right, left and bilateral presentations. Cadaveric and CTA work from South Africa, India and Australia consistently demonstrate that unilateral variants are more common than bilateral, usually in a ratio of about 4:1 to 5:1.¹⁶ Left kidneys tend to show slightly higher rates of multiple arteries than right kidneys, a finding attributed to subtle differences in ascent and rotation.

The Australian mixed cadaveric–CT study by Tardo et al. found multiple renal arteries in 22% of subjects, with unilateral involvement in 17% and bilateral in 3%, and a small excess of variations among males.⁶ A CTA study from Nepal reported unilateral renal arterial variations in 72% and bilateral in 28% of affected individuals, again with a predominance of polar accessory arteries.⁷ These proportions support a general pattern in which left-sided and unilateral ARAs are most frequent, with a smaller but clinically important fraction of bilateral cases.

Graph explanation: Figure 4 presents a representative distribution in which left-sided ARAs slightly exceed right-sided in both sexes, while bilateral ARAs remain less frequent but clearly present. The approximate values mirror patterns reported in Australian and Nepalese CTA datasets, where unilateral, particularly left-sided, variants dominate but bilateral multiple arteries still account for about one-quarter of affected individuals.⁶⁷

Morphological types of accessory renal arteries

Several classification systems distinguish accessory renal arteries by their site of entry into the kidney (hilar versus polar) and by their origin (directly from the aorta versus from the main renal artery). Mixed cadaveric–CT work from Spain and Australia identified aortic hilar arteries as the most common variant type, with upper and lower polar arteries forming smaller but clinically important subgroups.^{6, 8}

In the Spanish series by Cases et al., aortic hilar arteries accounted for roughly 80–90% of variant arteries, whereas upper and lower polar arteries together represented approximately 10–12% of variants, with a slight predominance of upper polar types.⁸ By contrast, South Asian cadaveric and CTA cohorts frequently emphasise inferior polar arteries as clinically important vessels because they may cross anterior to the ureter and contribute to ureteropelvic junction obstruction when compromised or compressed.² Across these reports, inferior polar and hilar accessory arteries together make up the bulk of clinically relevant ARAs.

Graph explanation: Figure 5 summarises the morphological spectrum using three categories: inferior polar, superior polar and hilar accessory arteries. The proportions reflect the dominance of hilar and inferior polar branches reported in Spanish and South Asian classification studies, with superior polar arteries consistently forming the smallest fraction of variants.²⁸

Number of accessory renal arteries per kidney

Most individuals with variant renal vasculature harbour a single accessory renal artery rather than multiple additional vessels. The Australian mixed-sample study found that of all subjects with multiple renal arteries, 93% had only one variant vessel, 6% had two and around 1% had three, a pattern mirrored in other large series.⁶⁸ Similar proportions have been documented in South Asian CTA datasets, where double and triple ARAs occur but remain rare compared with single-vessel variants.⁷

From a clinical standpoint, however, even infrequent multiple ARAs are highly relevant: donor kidneys with more than one accessory artery require additional anastomoses, increase cold ischaemia time and may show higher rates of segmental infarction if small polar branches are missed.⁵

Graph explanation: Figure 6 shows that single ARAs dominate the numerical spectrum of variants, constituting over 90% of cases with multiple renal arteries in Australian and Spanish mixed datasets.⁶⁸ Double and triple accessory arteries form a small tail of the distribution but carry disproportionate weight in transplant and aortic surgery because each additional vessel demands separate consideration during reconstruction.

Transplantation, aortic surgery and endovascular procedures

Renal transplantation literature consistently highlights that donor kidneys with multiple arteries remain safe for transplantation but require meticulous arterial reconstruction to avoid segmental infarction or ureteric complications.⁵⁹ Pre-operative CTA in potential donors is now routine in many centres and reliably delineates ARAs and early branching patterns, reducing the risk of unexpected intra-operative findings.¹⁰

Endovascular and open aortic procedures must also respect ARA anatomy. Inferior polar arteries may arise close to the level of juxtarenal aneurysms, and inadvertent coverage by stent-grafts can precipitate segmental ischaemia or renovascular hypertension.⁹ Similarly, renal denervation and selective embolisation procedures must account for polar branches to ensure complete and safe treatment.¹⁶

This synthesis confirms that accessory renal arteries are among the most frequent vascular variants in the human body, with global prevalence anchored by cadaveric data around 23–26% and CTA series commonly reporting rates up to 30–33%.^{17, 9} Differences between cadaveric and imaging estimates likely reflect both methodological factors and the ability of modern CTA to detect small polar branches that may be missed at routine dissection.

Geographic comparisons demonstrate that high ARA prevalence is not confined to a single region: South American, South/East Asian and several European cohorts consistently show values near 30%, whereas African and Middle Eastern series tend to cluster in the low- to mid-20% range.^{18, 10} Whether these differences are driven predominantly by genetic, developmental or sampling factors remains uncertain, but for clinicians the practical inference is clear—variant renal vasculature should be anticipated in any population.

The dominance of single accessory arteries, with double and triple ARAs forming only a small minority, is a consistent finding across Australian, Spanish and South Asian series.⁶⁸ Yet even rare multiple-artery patterns have outsized consequences in renal transplantation and complex aortic repair. Transplant studies emphasise that meticulous reconstruction of all significant ARAs is essential to avoid segmental ischaemia, and outcome data suggest that when this is achieved, graft survival approximates that of single-artery kidneys.⁵⁹

Limitations of the underlying literature include heterogeneity in terminology (e.g. “accessory”, “multiple”, “polar” arteries), variable thresholds for defining clinically significant vessels, and a relative paucity of true population-based studies that integrate imaging, intra-operative findings and long-term clinical outcomes.⁹¹⁵ Recent systematic reviews and classification papers have begun to standardise definitions, but further prospective work is needed, particularly in under-represented regions such as sub-Saharan Africa and parts of the Middle East.

Accessory renal arteries are common anatomical variants with a global prevalence centred around one-quarter to one-third of individuals, depending on method and population. Regional data show higher prevalence in South American and South/East Asian cohorts, but significant rates are recorded on every continent studied to date.¹⁸ Unilateral, often left-sided, single accessory arteries dominate the variant spectrum, while multiple ARAs are less frequent but critical in surgical and endovascular planning.

For transplant surgeons, vascular and endovascular specialists, and interventional radiologists, pre-procedural CTA or equivalent cross-sectional imaging should be regarded as essential when operating near the renal vasculature. For anatomists and educators, the data argue for teaching the renal arterial tree not as a single, fixed pattern but as a spectrum of common configurations with well-defined clinical implications. Future research should focus on harmonised classification, true meta-analytic pooling and linkage of detailed anatomical patterns with robust long-term clinical outcomes.⁹¹⁵