Prevalence of variants in gonadal vessels: a systematic review with meta-analysis

Abstract

Gonadal arteries (GAs) and gonadal veins (GVs) display substantial anatomical variation, which has direct implications for surgical procedures, radiological interpretation, and fertility management. This study aimed to systematically review and meta-analyze the prevalence, origin, course, and drainage patterns of gonadal vessels in human anatomy. A systematic review and meta-analysis were conducted in line with current Evidence-Based Anatomy and PRISMA 2020 guidelines. A comprehensive search of major databases and anatomical journals yielded 31 eligible studies, comprising data on 2,875 gonadal vessels. The typical GA anatomy (single artery arising from the abdominal aorta) was observed in 98.72% of cases. Accessory GAs were found in 1.12%, most commonly arising from the renal artery (5.52%), with rare origins (<0.01%) from the accessory renal or suprarenal arteries. A normal arterial course was present in 90.24%, while an arched course occurred in 9.76%. The typical GV pattern (single vein draining into the inferior vena cava [IVC] or renal vein) was seen in 94.97%, and accessory GVs in 5.03%. The right GV drained into the IVC in 96.51%, with aberrant drainage to the right renal vein in 4.41%. The left GV drained into the left renal vein in 95.35%, with aberrant IVC drainage in 4.17%. Although the typical gonadal vascular anatomy predominates, variants, especially in GA origin and GV drainage, are not rare and must be recognized. These findings underscore the clinical importance of anatomical awareness in surgical planning, radiological evaluation, and the management of urological and reproductive conditions.

Introduction

Gonadal arteries (GAs)—testicular arteries (TAs) in males and ovarian arteries (OAs) in females—typically originate from the abdominal aorta (AA). The right GA passes anterior to the inferior vena cava (IVC), while the left GA courses posterior to the inferior mesenteric vein. Both arteries extend anterior to the psoas major muscle and cross the midsection of the ureter, which they often supply [1].

The OA, a long, paired vessel, arises from the anterolateral aspect of the AA below the renal arteries (RAs) and above the inferior mesenteric artery (IMA), near the L2/L3 level. It traverses the abdomen and pelvis, terminating at the suspensory ligament of the ovary. After crossing the pelvic brim, the OA travels within the suspensory ligament toward the ovary, accompanied by the ovarian veins (OVs). Along its path, it gives off ureteric, tubal, and ovarian branches [1].

The male counterpart, the TA, enters the deep inguinal ring, running anterior to the genitofemoral nerve, ureter, and external iliac artery. It passes through the inguinal canal with the spermatic cord, giving rise to branches that supply the perinephric fat, ureter, epididymis, and occasionally accessory TAs [1]. At the testis, TA branches enter through the mediastinum, spread within the tunica vasculosa, and support spermatogenesis. The TA also plays a role in testicular thermoregulation through its interaction with a specialized venous network—an essential function for fertility [2].

Variations in GAs, especially TAs, are common. Studies in fetuses show TA variants in about 8.8% of cases. Due to the wide variation in number, origin, and course, identifying a single dominant pattern is difficult [3]. Accessory gonadal arteries (AGAs) may arise not only from atypical AA levels but also from the RA, suprarenal artery (SRA), superior mesenteric artery, or an accessory renal artery (ARA) [4].

Gonadal veins (GVs) also show asymmetry in drainage. About 15–20 small veins emerge from the testis and epididymis, forming a pampiniform plexus that drains into 3–4 veins within the inguinal canal. These merge into a single testicular vein (TV). The right TV typically drains into the IVC or, less commonly, the right renal vein (RRV). The left TV terminates in the left renal vein (LRV). The left gonadal vein (LGV) is more frequently associated with venous incompetence [5].

Given their clinical relevance, variations in GAs and GVs—especially AGAs and AGVs—have been extensively studied. While several reviews and meta-analyses exist [2, 3, 6], this systematic review with meta-analysis aims to quantify the pooled prevalence of these variations, including variant numbers, origins, and terminations, with particular focus on symmetrical and asymmetrical patterns.

Materials and Methods

Search strategy

This systematic review and meta-analysis followed the Evidence-Based Anatomy (EBA) Workgroup guidelines for anatomical meta-analysis [7] and adhered to the PRISMA 2020 standards for reporting systematic reviews [8].

A comprehensive literature search was conducted across four major databases: PubMed, Google Scholar, Scopus, and Web of Science. Search terms included various combinations of: “gonadal artery,” “gonadal vein,” “testicular artery,” “testicular vein,” “ovarian artery,” “ovarian vein,” “variation,” “cadaveric study,” “imaging study,” and “surgical study.” Reference lists of selected studies were also screened for relevant sources. In addition, grey literature was reviewed, and a manual search was performed in key anatomical journals, including Annals of Anatomy, Clinical Anatomy, Journal of Anatomy, Anatomical Record, Surgical and Radiological Anatomy, Folia Morphologica, European Journal of Anatomy, Anatomical Science International, Anatomy and Cell Biology, and Morphologie.

Inclusion criteria: studies reporting the prevalence of GA or GV variations, as well as human-based cadaveric, imaging, or surgical studies.

Exclusion criteria: case reports, conference abstracts, animal studies, and studies lacking relevant or sufficient data.

Two independent reviewers (IP, VE) performed the screening and data extraction using Microsoft Excel. Any discrepancies were resolved through discussion with the remaining authors. The risk of bias for each included study was assessed using the Anatomical Quality Assurance tool developed by the EBA Workgroup [9].

Statistical analysis

Statistical meta-analysis was conducted using R (version 4.3.2) and RStudio, employing the “meta” and “metafor” packages. All analyses were performed by a single reviewer (GTr). For proportions (prevalence) meta-analysis, pooled prevalence was calculated using the inverse variance method under a random-effects model. The Freeman-Tukey double arcsine transformation was applied to stabilize variance. Between-study variance (tau²) was estimated using the DerSimonian-Laird method, and Jackson’s method was used to calculate confidence intervals for tau and tau². Subgroup analyses were conducted to explore the influence of factors such as geographic distribution and study type on pooled prevalence estimates. For means (e.g., vessel diameter) meta-analysis, raw (untransformed) means were used. The restricted maximum likelihood method was applied to estimate tau², with Q-profile confidence intervals used for tau and tau². A P-value <0.05 was considered statistically significant. To assess heterogeneity, Cochran’s Q statistic was used to test its presence (significance set at P<0.10). Higgins’ I² statistic was used to quantify its extent: 0%–40%, not important; 30%–60%, moderate heterogeneity; 50%–90%, substantial heterogeneity; and 75%–100%, considerable heterogeneity. Potential small-study effects were evaluated using the DOI plot and the LFK index, specifically for the prevalence of meta-analyses [10].

Results

Studies identification

The initial database search yielded 4,331 articles, which were imported into Mendeley (version 2.10.9; Elsevier) for screening. After removing duplicates and excluding irrelevant studies based on title and abstract, 87 full-text articles were assessed for eligibility. Of these, 25 studies met the inclusion criteria. An additional eight studies were identified through secondary sources, including reference list screening, grey literature, and manual searches of anatomical journals. In total, 31 studies were included in this systematic review and meta-analysis. The study selection process is illustrated in Fig. 1, following the PRISMA 2020 guidelines.

Fig. 1.

The flow diagram of the detailed literature search.

Characteristics of the included studies

A total of 31 studies were analyzed, comprising 2,875 gonadal vessels. Among them, 28 were cadaveric studies, and five utilized imaging modalities. The mean number of vessels per study was 87.12. Geographical distribution of the studies was as follows: Asia, 22 studies; Americas, 4 studies; Europe, 4 studies; Africa, 3 studies. Detailed characteristics of the included studies are presented in Table 1 [6, 11-40].

Table 1.

The characteristics of the included studies

Study	Year	Population	Study type	No of specimens	Age group	Risk of bias
Adebisi and Singh [17]	2000	Africa	Cadaveric	82	NR	High
Ahlberg et al. [18]	1966	Europe	Cadaveric	84	Adults	High
Anson and Kurth [19]	1955	America	Cadaveric	60	NR	High
Ali et al. [11]	2020	Asia	Cadaveric	25	Adults	High
Asala et al. [20]	2001	Africa	Cadaveric	150	NR	High
Balci et al. [21]	2021	Asia	Imaging	732	Adults	Low
Barber et al. [22]	2012	Europe	Imaging	106	Adults	Low
Cauldwell and Anson [23]	1943	America	Cadaveric	300	Adults	Low
Ciçekcibaşi et al. [24]	2002	Asia	Cadaveric	90	Fetuses (13–40 postmenstrual week)	High
Daripelli et al. [6]	2023	Asia	Cadaveric	35	Adults	High
Farhan [25]	2009	Asia	Cadaveric	20	NR	High
Farris et al. [26]	2022	America	Cadaveric	58	NR	High
Favorito et al. [15]	2007	America	Cadaveric	124	Adults and fetuses (20–35 weeks)	Low
Ghosh and Chaudhury [27]	2019	Asia	Cadaveric	47	Adults	High
Grine and Kramer [13]	1981	Africa	Cadaveric	123	Adults	Low
Gupta et al. [28]	2015	Asia	Cadaveric	60	NR	High
Kara et al. [29]	2012	Asia	Imaging	101	Adults	Low
Kotian et al. [30]	2016	Asia	Cadaveric	42	Adults	High
Kumar et al. [31]	2016	Asia	Cadaveric	40	Adults	High
Lalwani et al. [32]	2017	Asia	Cadaveric	35	Adults	High
Mamatha et al. [33]	2015	Asia	Cadaveric	40	NR	High
Mohandas et al. [34]	2014	Asia	Cadaveric	40	Adult	High
Mpekethu et al. [12]	2019	Africa	Cadaveric	100	Adult	Low
Nordmark et al. [35]	1977	Europe	Imaging	32	Children & adults	High
Pai et al. [36]	2008	Asia	Cadaveric	34	Adults	High
Petru et al. [37]	2007	Europe	Cadaveric	16	Adults & fetuses (5–8 months)	High
Prasad et al. [38]	2021	Asia	Cadaveric	40	Adults	High
Shoja et al. [14]	2007	Asia	Imaging	50	Adults	High
Dey et al. [16]	2018	Asia	Cadaveric	67	NR	High
Terayama et al. [39]	2021	Asia	Cadaveric	54	Adults	High
Wadhwa and Soni [40]	2010	Asia	Cadaveric	30	Adults	High

NR, not reported.

Variations of the gonadal artery

The pooled prevalence of a typical GA, defined as a single vessel originating from the AA, was 98.72% (95% CI: 97.59–99.56). Bilaterally typical GAs were present in 97.65% of cases (95% CI: 95.58–99.18). Subgroup analysis showed that nationality, study type, sample size, and laterality did not significantly influence these prevalence estimates (Table 2). The LFK index from the DOI plot was –0.43, indicating no small-study effect. This analysis affirms that while GA patterns are largely consistent, geography can influence vascular anatomy, especially concerning variant origins.

Table 2.

Subgroup analysis of gonadal artery variants by geographic distribution, study type, sample size, and side

Parameters	Typical GA (%)	P-value	GA aorta origin (%)	P-value	GA renal origin (%)	P-value	Accessory GA (%)	P-value
Africa	98.19	0.9153	95.68	0.0028*	1.62	0.0634	1.82	0.8721
Asia	99.06		92.41		6.14		0.77
America	97.93		96.96		4.63		2.07
Europe	96.49		81.24		17.52		3.51
Cadaveric	98.60	0.5464	93.48	0.5026	5.56	0.9112	1.21	0.6396
Imaging	99.25		91.58		5.87		0.75
Left	98.95	0.4259	94.95	0.1315	3.62	0.2082	0.91	0.4512
Right	98.26		91.81		6.08		1.53

GA, gonadal artery. *Statistically significant result.

AGAs defined as two arteries originating from the AA—had a pooled prevalence of 1.12% (95% CI: 0.36–2.18). No cases involving more than two GAs per side were reported. Bilateral AGAs were found with a pooled prevalence of 0.60% (95% CI: 0.00–2.51). Again, subgroup factors (nationality, study type, sample size, and laterality) were not statistically significant. However, the LFK index was –2.65, suggesting possible small-study effects for AGAs.

Regarding arterial origin, the AA was the most common source of GA, with a pooled prevalence of 93.29% (95% CI: 90.81–95.43). The RA was the second most frequent origin at 5.52% (95% CI: 3.58–7.82). Other less frequent origins included:

• ARA: 0.65% (95% CI: 0.03–1.76)

• SRA: <0.01% (10 cases)

• Other variant origins: <0.01% (8 cases)

No subgroup factor was statistically significant for the prevalence of GA origin. The LFK index was +0.68 for AA origin and –0.25 for RA origin, both indicating no small-study effect. Regarding the arterial course, the GA followed a typical anatomical path in 90.24% of cases, while an arched course was observed in 9.76% of cases.

Variations of the gonadal vein

The pooled prevalence of a typical GV—defined as a single vessel terminating in the LRV or the right IVC—was 94.97% (95% CI: 90.48–98.17). Bilateral typical GVs were reported in 91.56% of cases (95% CI: 88.62–95.52). Subgroup analysis revealed nationality as a significant factor (P=0.0018), while study type, sample size, and laterality were not significant (Table 3). The LFK index was +0.96, suggesting no small study effect.

Table 3.

Subgroup analysis of gonadal vein variants based on geographic distribution, type of study, sample size, and sides

Parameters	Typical GV (%)	P-value	Accessory GV (%)	P-value
Africa	90.67	0.0018*	9.33	0.0016*
Asia	93.00		7.00
America	91.88		8.12
Europe	99.58		0.42
Cadaveric	94.15	0.4656	5.85	0.4756
Imaging	97.77		2.23
Left	92.53	0.0669	7.47	0.0703
Right	97.70		2.30

GV, gonadal vein. *Statistically significant result.

Accessory gonadal veins (AGVs) had a pooled prevalence of 5.03% (95% CI: 1.83–9.52). Bilateral occurrence was not reported in the included studies. Specifically, a single AGV was found in 4.82% (95% CI: 1.75–9.14), two AGVs in <0.01% (2 cases), and three AGVs in <0.01% (2 cases).

As with typical GVs, nationality significantly influenced AGV prevalence (P=0.0018), while study type, sample size, and side did not. The LFK index for AGVs was –0.96, indicating the absence of a small-study effect.

The RGV drained into the IVC with a pooled prevalence of 96.51% (95% CI: 93.24–98.85). An aberrant termination into the RRV was observed in 4.41% (95% CI: 1.93–7.67). The LGV terminated into the LRV in 95.35% of cases (95% CI: 82.29–100). Aberrant drainage into the IVC was noted in 4.17% (95% CI: 0.00–16.92).

Discussion

This meta-analysis focused on the prevalence and anatomical patterns of GAs and GVs, including their typical forms and variations. We investigated laterality, origin, number, and course of GAs and AGAs, as well as GV configurations, laterality, and termination points.

The typical GA anatomy (Fig. 2)—a single artery originating from the AA was found in 98.88% of cases. AGAs were identified in 1.12% of the population, with no significant difference between left and right sides [41]. Although some studies, such as Mpekethu et al. [12], have reported a higher incidence of right-sided AGA origin, our meta-analysis did not support this finding.

Fig. 2.

Three-dimensional rendering of the renal and gonadal vessels. Anterior view. 1, inferior vena cava; 2, aorta; 3, celiac trunk; 4, superior mesenteric artery; 5, inferior mesenteric artery; 6, right renal artery; 7, right inferior phrenic artery; 8, right renal vein; 9, right superior polar branches; 10, right gonadal vessels; 11, left renal vein; 12, accessory superior left renal artery; 13, inferior suprarenal artery; 14, left superior polar branch; 15, hilar branch; 16, primary branches of the short left renal artery; 17, left gonadal vessels.

The most common origin for both typical GAs and AGAs was the AA (93.29%), followed by the RA (5.52%). Less frequent sources included the ARA (0.65%) and the SRA (<0.01%). Bergman’s Comprehensive Encyclopedia of Anatomic Variations also documents rare origins, including the lumbar, common or internal iliac, and superior epigastric arteries [11].

Regarding arterial course, the GA followed a typical path in 90.24% of cases. An arched course was present in 9.76% of cases. Although some studies suggest that an arched course is more common in males [12], our analysis found no significant sex-based or side-based difference.

Shoja et al. [14] proposed that the presence of AGAs may be linked to ARAs, likely stemming from shared embryological origins. They theorize that genetic factors, chemical influences, and growth regulators contribute to the persistence of these vascular channels during development. However, the precise embryological signals that underlie this relationship remain unclear.

In terms of GV anatomy, the typical configuration—draining into the LRV or right IVC was observed in 94.97% of cases, and bilaterally in 91.56%. AGVs were present at 5.03%, with one AGV in 4.82%, and two or three AGVs being exceedingly rare (<0.01% each, 2 cases). Nationality emerged as a significant factor, though side, study type, and sample size were not. GV termination patterns aligned with classical anatomy in most cases: the RGV drained into the IVC in 96.51%, the RGV drained into the RRV (variant) in 4.41%, the LGV drained into the LRV in 95.35%, and the LGV drained into the IVC (variant) in 4.17%. Although Favorito et al. [15] reported that AGVs are more commonly left-sided, and GV drainage variations more often occur on the right, our pooled analysis did not confirm these findings. Overall, Table 3 reinforces that GV variation is modest but influenced by geography and laterality, with clinical implications for procedures such as varicocele repair, nephrectomy, and vascular reconstructions [6, 15, 16, 18, 32]. An unusual case of triplication was identified by Nayak and Kodimajalu Vasudeva [42] during cadaveric dissection. Moreover, another interesting case was recorded by the same research group, where they identified an interconnection between the GV and the suprarenal vein [43].

Concurrent variations of the GA and GV have been previously observed. Nayak [44] reported the concomitant duplication of the GA and triplication of the GV. All vessels passed through the deep inguinal ring area, creating a unique anatomical pattern that could be of particular challenge intraoperatively.

Daripelli et al. [6] explained that GV drainage anomalies likely stem from complex embryological venous development, particularly dysplasia of subcardinal veins during the 7th–8th week of gestation. These early variations can produce persistent anastomoses and abnormal termination routes.

The clinical relevance of these vascular variants is considerable. In surgical contexts, particularly renal, urological, and gynecological procedures, unrecognized GA or GV anomalies can lead to complications such as hemorrhage, ischemia, or infertility. Variants in the GA origin or course are significant in renal surgeries due to their proximity to RAs. Misidentifying or damaging these vessels may result in conditions such as varicocele, nephroptosis, renal hypertension, testicular atrophy, or kidney infarction [6]. In male patients, TA variations affect procedures like orchidectomy and are associated with hydronephrosis, varicocele, and male infertility. TAs are also essential for testicular thermoregulation during spermatogenesis, further emphasizing their role in fertility [2, 3, 6]. In female patients, OA anomalies can complicate uterine artery embolization, potentially leading to ovarian failure, early menopause, or infertility if ovarian blood supply is compromised [17].

GV variations also bear significant surgical relevance, especially in kidney transplantation, where the GV may be harvested for vascular reconstruction or RV elongation. Additionally, understanding GV anatomy is vital for treating varicocele and for planning abdominal procedures involving the GVs or RVs [18].

In urology and andrology, treating varicocele, especially left-sided, necessitates understanding the LGV’s drainage patterns. Conditions like duplication or drainage into the IVC may lead to recurrent varicoceles if not identified during surgery [15, 16]. Misidentifying these patterns can cause incomplete ligation during varicocelectomy, resulting in surgical failure. Additionally, managing orchiectomy and testicular torsion involves careful consideration of TA variations, including accessory arteries, in radical inguinal orchiectomy to prevent ischemic injury to the testis and damage to surrounding structures [7, 11]. In nephrology and renal surgery, nephrectomy can complicate renal hilum dissection due to AGAs from the RA, increasing the risk of intraoperative bleeding or inadvertent testicular infarction if ligated mistakenly [3, 5]. In kidney transplantation, the GV is often used for vascular reconstruction or RV elongation, especially for short or anomalous donor RVs, making preoperative mapping of GV anatomy crucial [16]. In gynecology, OA anomalies can affect uterine artery embolization outcomes, particularly in postpartum hemorrhage or uterine fibroids. If the OA provides significant collateral flow, failing to embolize it may lead to treatment failure or fibroid revascularization [45]. Surgical procedures like oophorectomy, salpingectomy, or tubal ligation risk damaging the OA if variants are not anticipated, possibly resulting in ovarian failure or infertility.

Computed tomography and magnetic resonance angiography must consider common and rare GA/GV variants to avoid misinterpreting vascular anomalies as pathological conditions (e.g., lymphadenopathy and varices) [22, 29]. In interventional radiology, not recognizing variant gonadal vasculature can lead to non-target embolization or incomplete occlusion, compromising patient outcomes. TAs are crucial for thermoregulation, essential for spermatogenesis. Disruptions can cause subclinical hypoperfusion or temperature dysregulation, impacting male fertility—an increasingly relevant concern in andrology and reproductive endocrinology [2, 7]. Additionally, compromised ovarian blood flow from anatomical variants or injury can impede follicular development or trigger early menopause, affecting assisted reproductive outcomes. Anatomical variants reflect developmental changes in the subcardinal, supracardinal, and mesonephric venous systems. Recognizing these patterns helps clinicians differentiate congenital anomalies from acquired conditions, like gonadal vein thrombosis or retroperitoneal fibrosis [6, 14].

A few limitations of the present evidence-based meta-analysis should be considered. Several results showed substantial heterogeneity, the pooled prevalence estimates depicted asymmetry on their LFK index, and few studies were “high” on the risk of bias assessment. Firstly, these findings are common between anatomical systematic reviews with meta-analysis [5, 8]. Secondly, they could be attributed to the wide geographical distribution of the studies, the difference between the population demographics, as well as the different type of study (imaging and cadaveric). This is also depicted by the subgroup analyses (Tables 2 and 3), where few results were statistically significant. However, these should be taken into careful consideration because some parameters did not have the minimum of 3 studies, proposed for subgroup analyses [5, 8].

In conclusion, this comprehensive systematic review and meta-analysis assessed the prevalence, number, origin, and anatomical course of GAs, as well as the number, origin, and drainage patterns of GVs. Our findings confirm that the typical GA anatomy is present in 98.72% of cases, with AGAs occurring in 1.12%. The most common variant origin was from the RA (5.52%), while other origins were exceedingly rare (<0.01%). An arched arterial course was present in 9.76% of individuals, with the typical course observed in 90.24%. For GVs, the typical venous anatomy was identified in 94.97%, while AGVs were observed in 5.03%, most commonly presenting as a single accessory vein (4.82%). Multiple AGVs (two or three) were extremely rare (<0.01%).

In terms of venous drainage, the RGV drained into the IVC in 96.51% of cases, with an aberrant route into the RRV in 4.41%. The LGV typically drained into the LRV in 95.35%, while aberrant drainage into the left IVC occurred in 4.17% of individuals. Understanding these variations is essential for anatomists, radiologists, and surgeons, especially in the context of kidney transplantation, varicocele repair, and retroperitoneal surgeries. Awareness of these variants can help prevent iatrogenic injury, optimize surgical planning, and enhance diagnostic accuracy through the use of appropriate imaging techniques.