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Clinical Anatomy 24:988–990 (2011) COMPENDIUM OF ANATOMICAL VARIANTS Variable Course and Drainage Pattern of the Right Testicular Vein: Embryological Aspects GEORGE K. PARASKEVAS* AND ORESTIS IOANNIDIS Department of Anatomy, Medical School of Aristotle University of Thessaloniki, Thessaloniki, Greece Varicocele of the testicular vein (TV) is the major contributor to ipsilateral testicular atrophy and decreased fertility (Zini et al., 1998). Variation in testicular vein (TV) design can result in persistence of the varicocele (Gat et al., 2004). Thus, when performing varicocele operations, surgeons must have an understanding of TV variation to successfully eliminate the varicocele. TV variation has been reported not only to be more common on the left (Asala et al., 2001; Rai and Ranade, 2007), but also very rare on the right (Nayak, 2008). Variation in the anatomical design of the right testicular vein (TV), however, may be underestimated because TVs are most commonly observed during varicocele surgeries, and varicoceles are much more common on the left than on the right. In light of the above, we present a cadaveric case of an incomplete triple right TV, with an unusual course and drainage. To our knowledge, this variant has not been described previously. We also suggest how it developed embryologically. An incomplete, right triple TV was encountered during a routine dissection of the formalin-embalmed cadaver of a 78-year-old male who had died of lung cancer. We found a right TV in the normal position, the so-called typical right TV (TRTV). The TRTV ascended to drain into the right margin of the inferior vena cava (IVC), 1.5 cm below the drainage site of the right renal vein. An atypical right testicular vein (ARTV) was also present, coursing somewhat parallel, but lateral to the TRTV. As it ascended, the ARTV bifurcated into a medial component and a lateral component. The medial component coursed ventrally to the right kidney to drain into the IVC, 2 cm proximal to the drainage site of the right renal vein. The lateral component, by contrast, coursed medially to open into the right subcostal vein (Fig. 1). No other pathological conditions such as portal hypertension or obstruction to ﬂow from regional masses effect were present or evidence of surgical procedures on the abdomen. Variations in the right TV design include: (a) drainage into the right renal vein in from 1.25% (Asala et al., 2001) to 5% (Bensussan and Huguet, 1984) of the population, (b) drainage into the left aspect of the IVC, (c) drainage into the right renal vein or into the conﬂuence of right renal vein with IVC with co-existence of double IVC (Davis et al., 1958), (d) the existence of medial and lateral comC 2010 V Wiley Periodicals, Inc. ponents that drain into the IVC and the right renal vein (Bergman et al., 1988), the right and left margins of the IVC (Bensussan and Huguet, 1984), or the IVC and the right subcostal vein (Tubbs et al., 2005), (e) drainage into the IVC at a level lower than usual in cases of preureteric IVC (Adachi, 1940), (f) the presence of a completely duplicated TV (Wishahi, 1991; Asala et al., 2001; Yang et al., 2008), (g) the formation of a common trunk by the right TV and the right renal vein (Bensussan and Huguet, 1984), and (h) the presence of intercommunicating venous trunks some of which may open into the common iliac vein (Poynter, 1923). A thorough search of the relevant literature revealed no report of the presence of two distinct right TVs, with the lateral ARTV divided into two components. Moreover, no description was found of the medial component draining into the prerenal segment of the IVC. Rather, only the generally accepted drainage pattern for double TVs is described, which is one TV draining into the right renal vein and the other TV draining into the IVC (Diamond et al., 1977; Shaﬁk et al., 1990; Wishahi, 1991). The pattern we present here differs from this accepted design in that the right TVs drain into the prerenal and renal segments of the IVC, and into the subcostal vein. This variant illustrates the complex embryogenesis of venous channels in the retroperitoneal region. The caval system is known to form between the 6th and 10th weeks of gestation and is derived from the modiﬁcation of three parallel sets of veins: subcardinal, supracardinal, and postcardinal (Milloy et al., 1962; Babaian and Johnson, 1979). Anastomoses between the supracardinal veins and the subcardinal sinus are important for TV formation. Congenital anomalies of the TVs are caused by dys- *Correspondence to: Dr. G.K. Paraskevas, Assistant Professor of Anatomy, Department of Anatomy, Medical School of Aristotle University of Thessaloniki, P. O. Box: 300, Thessaloniki, 54124 Greece. E-mail: [email protected] Received 24 August 2010; Revised 19 September 2010; Accepted 25 September 2010 Published online 10 November 2010 in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ca.21084 Right Testicular Vein Fig. 1. A: Photograph of the incomplete right testicular vein. (ARTV, atypical right testicular vein; TRTV, typical right testicular vein; LC, lateral component; MC, medial component; SV, subcostal vein; RV, renal vein; Fig. 2. A: Primitive veins of the abdomen of a human embryo at 8 weeks (modiﬁcation from Arey, 1960). B: Hypothesized embryogenesis of the present case. (1: postcardinal vein, 2: supracardinal vein, 3: prerenal segment of IVC derived from subcardinal vein, 4: subcardinal sinus, 5: renal segment of IVC derived from sub-supracardinal anastomosis, 6: testicular vein, 7: postrenal segment of IVC derived from supracardinal vein, 8: subcardinal vein, 9: anastomosis of supracardinal vein with the ARTV, 10: ARTV). plasia of the caval system during the 7th–8th weeks (Carlson, 1988). The supracardinal veins are thought to anastomose with various regions of the subcardinal sinus. Most supracardinal veins anastomose with the subcardinal sinus at, or caudal to, the level of the renal vein (Itoh et al., 2001). Although Itoh et al. (2001) claimed that TV formation is somewhat uncertain, Arey (1960) demonstrated that the right TV is derived from the caudal portion of the right subcardinal vein that typically drains into the region of subsupracardinal anastomosis. Collins (1995) claimed that the right subcardinal vein is in part incorporated in the right TV and partly disappears. We propose 989 IVC, inferior vena cava; RK, right kidney; U, ureter). B: Schematic representation of the variants encountered in our specimen. [Color ﬁgure can be viewed in the online issue, which is available at wileyonlinelibrary.com.] that the triple right TV in our case originated from the failure of the numerous channels in the anastomosis sites between the subcardinal sinus and the right supracardinal vein to regress. Furthermore, we hypothesize that the drainage of the ARTV medial component into the prerenal segment of the IVC is due to the persistence and shift in position of the channel that connects the caudal end of the prerenal segment of the IVC to the most caudal portion of the right subcardinal vein. We further hypothesize that the lateral ARTV component drainage into the subcostal vein, which is a tributary of the azygos vein, originated from an anastomosis of the atrophied proximal segment of the right supracardinal vein with the ARTV (Fig. 2). We feel that by presenting this variant, albeit rare, light may be shed on TV embryogenesis, and that surgeons can take advantage of this knowledge when ligating the TV, thereby reducing the chances that a varicocele will re-occur postoperatively. REFERENCES Adachi B. 1940. Das Venensystem der Japaner. Bd 1. Tokyo: Kenkyusha. p 216–266. Arey LB. 1960. Developmental Anatomy: A Textbook and Laboratory Manual of Embryology. 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