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Cadaveric Study of Mode of Termination of Gonadal Veins: Implications for Procedures Utilizing Terminal Ends of Gonadal Veins as Entry Portals

IntroductIon There is renewed interest in gonadal venous anatomy due to its potential use for renal vein lengthening in live donor kidney transplantation.[1,2] Gonadal veins also serve as an entry portal for newer techniques used for treating varicocele such as percutaneous retrograde varicocele occlusion and laparoscopic varicocelectomy in males and pelvic congestion disease in females.[3,4] While phlebography visualization of vessels precedes such procedures, Letcher et al.[5] observed that gonadal phlebography is technically not feasible in some cases and it did not correlate exactly with operative findings.


IntroductIon
There is renewed interest in gonadal venous anatomy due to its potential use for renal vein lengthening in live donor kidney transplantation. [1,2] Gonadal veins also serve as an entry portal for newer techniques used for treating varicocele such as percutaneous retrograde varicocele occlusion and laparoscopic varicocelectomy in males and pelvic congestion disease in females. [3,4] While phlebography visualization of vessels precedes such procedures, Letcher et al. [5] observed that gonadal phlebography is technically not feasible in some cases and it did not correlate exactly with operative findings.

MaterIals and Methods
Thirty-five adult formalin-fixed cadavers (23 male and 12 female) from the collection of the department of anatomy, over period of 4 years were used in this study. The abdominal and peritoneal cavity was opened by standard anatomical dissection. After the removal of gut and mesentery from the abdominal cavity, the retroperitoneum and gonadal veins were dissected and were carefully cleaned. The mode of termination of gonadal veins (within 1 cm of termination) was observed under the following study variables: (a) number, (b) locale of termination, and (c) termination angle, and the variations were documented.

results
Variations in study parameters were observed in eight sides of seven cadavers (seven unilateral and one bilateral).
Number: The termination of the vein was mostly as a single vein. Double termination was observed in seven cadavers (10% of cases). The testicular vein duplicated before termination in six cases (one right and five left). Ovarian vein also showed duplication in single case on the left side.
Locale of termination was mostly into the inferior vena cava (IVC) on the right side and into the renal vein on the left side. Anomalous drainage was observed in only three cases: i. Termination of the right testicular vein in right renal vein [ Figure 1] ii. Termination of the left testicular vein into IVC [ Figure 2].
Such anomalous drainage occurred in cases of double veins only iii. In one case (left side), the ovarian vein ascended in front of the left renal vein to join the left suprarenal vein [ Figure 3].
Angle of termination was observed to be acute on the right side in all cases and perpendicular on the left side except in three cadavers where it was variable. The following variations were observed: i. Left testicular vein joined IVC at an acute angle [ Figure 2] ii. Left testicular vein (double at termination) ran parallel to the left renal vein and draining at its anterior and posterior surface, respectively [ Figure 4] iii. Left ovarian vein ascended anterior to the left renal vein to drain in left suprarenal vein just before the latter joined the left renal vein [ Figure 3].

dIscussIon
Venous variations are a rule rather than exception, and veins are the most variable structures in the human body. In dissection-based studies, single testicular vein termination is reported in 78-85% of cases; [5,21] however, we observed single testicular vein termination in 90% of the cadavers studied. This difference may be due to inclusion of ovarian veins in the present study, which are relatively less variable. Interestingly, double termination of gonadal veins was reported in 12.9% of cases in a computed tomography-based study, [24] which is comparable to our observations.
The locale of termination of testicular veins was also variable in some cases. Such variability was observed to be double termination. Several case reports have also documented drainage of the right gonadal vein into right renal vein [6,7,25] and termination of left gonadal vein into IVC. [10] Interestingly, termination of the left gonadal (ovarian) vein in left suprarenal vein as observed in the present study is not described before. In a previous report, right ovarian vein draining into right renal vein  instead of IVC was observed in 10% of cases; [26] however, we did not find any anomalous drainage in ovarian veins on the right side.
Anatomical variations in gonadal vein terminations and its implications to clinical procedures have been emphasized during presurgical evaluation of varicocele cases and were such variations lead to poor treatment outcomes. [19] More recently, percutaneous embolization techniques for treatment of varicocele are also performed. In this, the right femoral vein is punctured to insert an angiocatheter to gain access to the internal spermatic vein via the IVC and the left renal vein.
Although widely used, this technique has high unperformable rates (8-30%) due to the venous anatomical variations leading to difficulties in gaining proper venous access. [3] Hence, a study of anatomical variations in gonadal veins in different population groups is justified and necessary to improve the success of clinical procedures involving access to these veins. Specifically, in recent times, utility of gonadal veins for lengthening short renal vessels in cases of live donor transplant is also reported. [1,2] conclusIon We report here the variations in terminal ends of gonadal veins in the Indian population. The variations were observed in about 11% of cases with preponderance on the left side. Testicular veins were relatively more variable as compared to ovarian veins. We believe our observations will be useful to radiologist, urologist, and urosurgeons for planning of operative procedures and to decrease the rate of failures especially in cases of varicocele.

Financial support and sponsorship
Nil.

Conflicts of interest
There are no conflicts of interest.