Blood Supply of Testis
The internal spermatic artery originates from the abdominal aorta just below the renal artery. Embryo- logically, the testicles lie opposite the second lumbar vertebra and keep the blood supply that is acquired during the ﬁrst weeks of life as they descend into the scrotum. The internal spermatic artery joins the spermatic cord above the internal inguinal ring and lies adjacent to the testicular veins (pampiniform plexus) to the testis mediastinum. Inferior to the scrotal pampiniform plexus, the spermatic artery is highly coiled and branches before entering the testis. Extensive interconnections, especially between the internal spermatic and deferential arteries, allow maintenance of testis viability even after division of the internal spermatic artery. A single artery enters the testis in 56% of cases; two branches enter in 31% of cases and three or more branches in 13% of testes. In men with a single testicular artery, its interruption can result in testicular atrophy. The testicular arteries penetrate the testis tunica albuginea and travel inferiorly along its posterior surface and penetrate into the parenchyma. Individual arteries to the seminiferous tubules, termed centrifugal arteries, travel within the septa between tubules. Centrifugal artery branches give rise to arterioles that become individual intertubular and peritubular capillaries.
The deferential artery (artery of the vas deferens) originates from either the inferior or superior vesical artery (see Plate 2-6) and supplies the vas deferens and the cauda of the epididymis. Near the testis, the internal spermatic artery and the deferential artery anastomose. A third artery, the external spermatic artery (cremasteric artery), arises from the inferior epigastric artery from within the internal inguinal ring, where it enters the spermatic cord. This artery forms a network over the tunica vaginalis and usually anastomoses at the testicular mediastinum with the internal spermatic and deferential arteries. The external spermatic artery also forms anastomotic patterns that supply the scrotal wall. The veins of the spermatic cord emerge from the testis mediastinum to form the extensive pampiniform plexus. These veins gradually coalesce and, in 60% of cases, form a single trunk within the inguinal canal. The pampiniform plexus consists of three groups of freely anastomosing veins: (1) the internal spermatic vein group that emerges from the testicle and accompanies the spermatic artery to enter the vena cava; (2) the deferential group that accompanies the vas deferens to veins within the pelvis; and (3) the external spermatic (cremasteric) group that follows a course along the posterior spermatic cord. The latter group empties into branches of the superﬁcial and deep inferior epigastric veins and into the superﬁcial external and deep pudendal veins. These groups of veins afford routes of collateral circulation for blood return from the testicles.
The right internal spermatic vein enters the inferior vena cava obliquely below the right renal vein, whereas the left internal spermatic vein terminates in the left renal vein at a right angle, apparently without natural valve formation. These differences in drainage patterns likely explain the fact that 95% per cent of varicoceles occur on the left side, where natural resistance to increased abdominal pressure on retrograde ﬂow through these veins is lower.
With varicocele formation, blood ﬂow in the internal spermatic vein is reversed. With varicocelectomy, all veins except the deferential veins are ligated to reverse this process and improve pain or testis function. The deferential vein affords a sufﬁcient avenue for blood return. When performed in the retroperitoneum (Palomo or laparoscopic), varicocele recurrence rates after surgery are higher than when performed inguinally or subinguinally because of more complete ligation of all suspicious contributing veins observed more distally. Because of the increased number of pampiniform plexus veins subinguinally and the potential lack of a sufﬁciently collateralized arterial supply, varicocelectomy at this anatomic level is performed microscopically.