2314582

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
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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.
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