|Year : 2018 | Volume
| Issue : 3 | Page : 139-145
A cadaveric study of anatomical variations of testicular veins
Anly Antony1, J Sujitha Jacinth2
1 Assistant Professor, Dept. of Anatomy, Government Medical College, Manjeri, Kerala, India
2 Assistant Professor, Dept. of Anatomy, Rajah Muthiah Medical College and Hospital, Annamalai University, Chidambaram, India
|Date of Submission||20-Mar-2018|
|Date of Acceptance||06-Apr-2018|
|Date of Web Publication||10-Sep-2020|
Dept of Anatomy, Govt. Medical College, Manjeri, Kerala
Source of Support: None, Conflict of Interest: None
Background: Infertility is considered a major public health issue. A multicentric WHO study showed increased frequency of varicocele in infertile couples to vary geographically from 6% to 47%. Some theorize, varicocele results due to anatomical differences between the right and left testicular veins. This disparity is believed, leads to increase in hydrostatic pressure of the left testicular vein, which is subsequently transferred to the venous plexus, causing dilation. Hence knowledge of testicular venous pattern and its variations takes paramount importance. Aims: To study anatomy of testicular veins with focus on: a] normal and occurrence of varying number and patterns of testicular veins b] to find explanations for incidence of some anomalies c] to consider surgical significance of such variations and d] to compare the results of the present study with previous studies. Materials and methods: The study material comprised of 25 embalmed, adult human male cadavers of south Indian origin. Systematic dissection was carried out following the guidelines of Cunningham” s Manual of Practical Anatomy. Results: On five sides, four testicular veins were found at the deep inguinal ring. On the left side, all testicular veins terminated in the left renal vein with some showing duplication. Variations in the terminations of testicular veins were seen in three of the right sides, which included termination in the right renal vein, junction of the inferior vena cava with the right renal vein and in one case following duplication, veins terminated on the anterior and lateral wall of the inferior vena cava. Conclusion: Termination of testicular veins followed standard text book pattern on the left side, however a slight increase in the duplication of veins was observed on this side. On the right side, testicular veins showed variations in the site of termination and also duplication. Knowledge of these findings can be of importance in clinical practice related to the problems of the testis.
Keywords: testicular vein variations, south Indian origin, cadavers
|How to cite this article:|
Antony A, Jacinth J S. A cadaveric study of anatomical variations of testicular veins. Natl J Clin Anat 2018;7:139-45
| Introduction|| |
The fundamental process that allows living organisms preserve their progeny and evolve by transmitting genes is reproduction. The testis is an important reproductive organ for the very survival of the human species. Testicular veins play a significant role in the thermoregulation of this organ which is imperative for spermatogenesis.
Normally there is one testicular vein on each side draining the testis through pampiniform plexus. While on the right side the testicular vein drains directly into the inferior vena cava, on the left side, the testicular vein first opens into the left renal vein and then the left renal vein passes in front of the aorta to drain into the inferior venacava.
Anatomy of the gonadal vessels has attracted attention of vascular surgeons, general surgeons, traumatologists, urologists and radiologists due to the advent of new operative techniques for conditions like varicocele and undescended testes. It’s incumbent upon them to carefully preserve gonadal vessels in order to prevent any vascular complications of the gonad during laparoscopic surgery, due to unfamiliar anatomy in the operative field. Thus in order to attain correct diagnosis during radiologic procedures and to perform complication free surgery, knowledge of the anatomy and congenital anomalies of these vessels is important.
Variations in the origin, number and course of the testicular veins are of significant practical importance in clinical practice particularly surgery and radiology. Ignorance of variation, in the pattern of these vessels can lead to incorrect interpretation of angiographic images. Furthermore, nescience of varied pattern in relation to kidney, ureter and other structures in the posterior abdominal and pelvic walls can be consequential in abdominopelvic surgical procedures such as renal transplantations, renal and gonadal surgeries, uroradiology, gonadal / testicular colour Doppler imaging and other retroperitoneal therapeutic and diagnostic procedures. Therefore knowledge of variations in the origin, course and relations of structures in this region for accurate diagnosis, has become obligatory.
| Materials and methods|| |
The present study was carried out at the Department of Anatomy, Jubilee Mission Medical College and Research Institute, Kerala and the Division of Anatomy, Rajah Muthiah Medical College and Hospital, Annamalai Nagar, Tamil Nadu over a period of three years from 2012-2015. The material used for this study comprised of 25 well embalmed, adult human male cadavers who had died of natural causes. All cadavers were of South Indian origin. They were serially numbered from 1-25. Gross dissection of the abdominal wall and cavity followed by removal of abdominal viscera was carried out as per the guidelines of Cunningham’s Manual of Practical Anatomy. The connective tissue surrounding the great vessels, their branches and tributaries was dissected and removed to provide a clear field of vision. The abdominal aorta and the inferior vena cava were cleaned along their entire length, parietal peritoneum on posterior abdominal wall reflected and the gonadal vessels exposed and cleaned.
The following observations were made regarding the testicular veins:
- Number of the testicular veins at the deep inguinal ring were observed.
- Course of the testicular veins, from the inguinal canal into the abdominal cavity till the point of termination.
- Mode of termination of the testicular veins was ascertained by following their course to the inferior vena cava on the right side and the left renal vein.
- Point of termination of the testicular veins in relation to the renal veins was measured in the following way: On the right side, it was measured along the right wall of the inferior vena cava, from the level of the right renal vein to the termination of the right testicular vein. On the left side, it was measured from the left wall of the inferior vena cava to the termination of the left testicular vein.
- Duplication of the testicular veins, if any.
The data was arranged in tabular form and values were compared with data cited in literature.
| Results|| |
1] Number of testicular veins at deep inguinal ring
At the deep inguinal ring, the number of testicular veins on 45 sides followed the standard text book pattern of being two in number. However on five sides [two right and three left] the number of testicular veins at the deep inguinal ring were four [see [Figure 1]A& [Figure 1]B.
2] Mode of termination of testicular veins
On the right side, in 23 instances veins terminated directly into the inferior vena cava, below the level of renal vein, whereas in two instances veins [see [Table 2] terminated in a different manner: One concluded in the right renal vein. The other drained into the junction of the inferior vena cava with the right renal vein see [Figure 2]A & [Figure 2]B. In all instances testicular veins on the left side, terminated directly into the left renal vein.
3] Duplication of testicular veins
No duplication of veins was observed in 92% of the sides [see [Table 3] however, on four sides [three on the left and one on the right] duplication was observed see [Figure 3]A&[Figure 3]B,
3] Duplication of testicular veins
[Table 3] clearly shows that duplication of veins was not observed in 92% of the sides though, on four sides [3 on the left and 1 on the right] duplication was observed as shown in [Figure 3]A & [Figure 3]B
| Discussion|| |
The testicular veins are responsible for venous return from the testes. Variations in gonadal venous arrangements are of immense clinical importance as it may influence blood flow, temperature and spermatogenesis of the testes resulting in pathological conditions like varicocele, which are regarded as one of the causes of male infertility.
Anatomically, the testicular veins originate from the pampiniform plexus which is formed by the union of small veins from the testis and epididymis. The pampiniform plexus surrounds the testicular artery, proceeds cranially and unites to form two or three venous trunks at the level of the deep inguinal ring. At the lumbar region, the venous trunks coalesce generally to form a single testicular vein that courses ventral to the ureter and accompanies the artery of the same name to ascend. The right testicular vein usually drains into the inferior venacava, and the left testicular vein joins the left renal vein.
However, the number, course and drainage of these veins are sometimes different from the usual pattern. Duplication, unusual course and atypical drainage of the testicular veins have been reported in previous studies. These anatomical variations of the testicular veins are occasionally found in routine dissection and radiological studies of the retroperitoneal region.
Pollak et al observed that variations of the testicular veins are more common on the right side in contrast to Asala et al who reported variations to be more frequent on the left side. Surucu et al reported a case of double inferior venacava with left supra-renal vein draining into left inferior venacava and right testicular vein draining into right renal vein. In another case, left testicular vein and left supra-renal veins united inferior to superior mesenteric artery, coursed anterior to the abdominal aorta and drained into inferior vena cava. They found only two cases of right gonadal vein draining into right renal vein out of 150 cadavers dissected. Biswas et al in their study, reported an additional right renal vein into which the right testicular vein terminated. During endo-urological procedures, anatomical variations of renal and gonadal veins are of immense significance. Accidental injury of these veins during surgery may cause severe bleeding, during and after surgery. Hoeltl et al opines that these variations remain clinically silent and go unnoticed, until discovered during operation or autopsy. In the present study as far as mode of termination was concerned, variations were more on the right side which included testicular veins terminating either into the right renal vein or into the confluence of the inferior vena cava with the right renal vein [8%] as shown in [Figure 2]A & [Figure 2]B, whereas the remaining [92%] testicular veins terminated in the inferior venacava. All testicular veins on the left side, concluded in the left renal vein.
Congenital variations of the testicular veins also include variations in the number of veins. In a radiological study of the testicular veins, twin termination of a unilateral testicular vein on the right and left margins of the inferior vena cava were identified by Bensussan and Huguet. Three left gonadal venous trunk terminations on the ipsilateral renal vein were reported in another study by Lechter et al with an incidence of 1% in the cases investigated. In their study Asala et al stated that bilaterally, duplicated testicular veins appeared as an incomplete duplication and complete duplication of veins was detected only unilaterally. Xue et al reported a case of duplication of testicular veins in which, the right testicular vein was composed of the medial and lateral testicular veins. The medial testicular vein drained into the inferior venacava, whereas the lateral testicular vein drained into the confluence of the inferior venacava and right renal vein. Several anastomosing branches were seen between the medial and lateral testicular veins. The left testicular vein was formed after the medial and lateral venous trunks joined and drained into the ipsilateral renal vein. Yang et al reported a case in which the right testicular vein was a completely duplicated vein. The right lateral testicular vein drained into the right renal vein, whereas the right medial testicular vein drained into the left aspect of the inferior venacava. The left testicular vein consisted of three venous trunks. Three left testicular veins indicated a nearly equal width and terminated on the left renal vein, respectively. Since the testicular vein is closely related to the inferior venacava in embryogenesis, variations of the testicular veins often accompany abnormalities of the inferior venacava such as duplication of the inferior venacava. But in the case by Yang et al, no variations of the inferior venacava were observed. In the present study, duplication of testicular veins were present in one cadaver on the right side which terminated on the anterior and lateral walls of the inferior venacava as shown in [Figure 3]A & [Figure 3]B and in three cadavers on the left side which drained in the left renal vein. 92% of the veins showed no duplication.
Awareness of the possible presence of variations in the gonadal veins is very important. Variations of the testicular vein may result in persistence of varicocele. Though bilateral incidences of varicocele range from 15% to 50% Ranade et al opine that left sided varicoceles are presumably more frequent. Shafik and Bedeir remark isolated right varicoceles are fairly rare. This is affirmed by Morag et al who observed occurrence of palpable unilateral varicocele on the left side in 85% - 90% of the cases. Kass and Reitelman attributed the following causes for high incidence of varicocele on the left side, compared to that on the right side:
- Left testicular vein joins left renal vein at a right angle, while the right testicular vein joins the inferior venacava at an acute angle. The left testicular vein is a few centimeters higher than the right one with higher hydrostatic pressure.
- The left testicular vein is longer than the right testicular vein, as the left testis is at a lower level. Hence, it has to bear a larger column of blood and therefore more pressure.
- The loaded pelvic colon compresses the left testicular vein causing back pressure.
- The left renal vein may be sandwiched between the abdominal aorta and trunk of the superior mesenteric vessels, increasing the pressure in the left renal vein with consequent dilatation of the left testicular vein. This theory is called “nutcrackerphenomenon”.
- The testicular artery may arch over the left renal vein and cause compression of the left renal vein.
Also variations in the number and unusual course of the testicular veins may increase the complexity of varicocelectomy or retroperitoneal vascular operations. Atypical drainage of the testicular veins may increase the risk of renal transplantation and abdominal aortectomy. Therefore, multiple variations of the testicular veins would affect the approach to surgical procedures and lead to a higher percentage of operative failures in the retroperitoneal region. Anatomical knowledge of testicular venous variations and their special relations to adjacent vessels are indispensable for urologists and vascular surgeons to recognize the causes of urinary and genital disorders and avoid complications of the retroperitoneal operations and radiological examinations.
During the 5th week of development, three pairs of major veins can be distinguished - Vitelline system drain GIT and gut derivatives, Umbilical system - carry oxygenated blood from placenta, Cardinal system - drain head, neck and body wall. All the three systems are bilaterally symmetrical and converge on the right and left horns of sinus venosus. However, the shift of systemic venous return to the right atrium, initiates radical remodelling that reshapes these systems to yield the adult pattern”.
Prima facie, morphological variations are commonly ascribed embryologic origins. During development of inferior vena cava, the “renal collar” forms a circum aortic venous ring, being contributed anteriorly by subcardinal veins, posteriorly by supracardinal veins and on each side by supracardinal - subcardinal anastomosis. The subcardinal system drains the structure of the median dorsal body wall, principally kidney and gonads. The bilaterally symmetrical cardinal venous system converts into unilateral right - sided inferior venacava at around 8 wks. IVC is thus established in the right of aorta consequent to this “venous shift”.
Testicular vein develops from caudal part of subcardinal vein and drains into the supra-subcardinal anastomosis. In the right side, this supra-subcardinal anastomosis and also a small portion of subcardinal vein are incorporated into the formation of inferior vena cava, so right gonadal vein usually drains into the inferior venacava. If this fails, a part of right renal vein will be formed by right supra-subcardinal anastomosis and hence receives the right testicular vein. In the left side, this supra-subcardinal anastomosis forms part of left renal vein where the left gonadal vein drains. Sometimes, there may be doubling of mesonephric and subcardinal veins which give rise to two pairs of renal and testicular veins respectively.
Thus morphological variations of testicular veins are attributed to their embryologic origin. Anatomical knowledge of these variations and their special relations to adjacent structures become indispensible to various walks of the medical fraternity during the management of clinical conditions associated with testis.
| Conclusion|| |
Terminations of the testicular veins on the left side, followed standard text book pattern except for a few that showed duplication and terminated at two sites of the left testicular vein. Testicular veins on the right side, showed variations in the terminating site in addition to duplication. This knowledge is quintessential in many dimensions of the medical field especially surgical exposure of adjacent structures.
Conflicts of interest : None
Financial support : None
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]