Download Arteries of the scrotum

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Reconstructive and Paediatric Urology
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ARTERIES OF THE SCROTUM
CARRERA
et al.
BJUI
Arteries of the scrotum: a microvascular study
and its application to urethral reconstruction
with scrotal flaps
BJU INTERNATIONAL
Anna Carrera, Alfredo Gil-Vernet*, Pau Forcada, Rosa Morro, Manuel Llusa
and Octavio Arango†
Department of Human Anatomy, Faculty of Medicine, University of Barcelona, * Department of Urology, Centro
Médico Teknon, and †Department of Urology, Hospital del Mar, Barcelona, Spain
Accepted for publication 10 July 2008
Study Type – Aetiology (case series)
Level of Evidence 4
cases to evaluate the number, distribution
and anastomosis of the cutaneous arteries
of the scrotum.
OBJECTIVE
RESULTS
To study scrotal microvascularization and
apply the findings to the design of reliable
skin flaps for reconstructive surgery of
complex urethral or panurethral stenoses.
Scrotal skin is irrigated by two main vascular
systems, through the inferior external
pudendal arteries and the perineal arteries,
which branch into multiple scrotal arteries.
These arteries are distributed in three
cutaneous territories, two lateral and one
central, which are widely inter-anastomosed.
Each lateral territory receives an inferior
external pudendal artery which accesses
at the midpoint of the scrotal root and fans
out to cover the entire corresponding
hemiscrotum. The central cutaneous
territory is vascularized through the
branches of two main scrotal arteries which
are a continuation of the perineal arteries
and which access via the posterior face,
running deeply on both sides of the septum.
CONCLUSIONS
MATERIALS AND METHODS
In 15 cryopreserved male cadavers, scrotal
skin vascularization was explored using
macro- and microdissections, and the scrotal
sac made transparent using the Spalteholtz
method. A meticulous descriptive analysis of
the arterial network was conducted out in all
INTRODUCTION
In any reconstructive surgery, axial flaps are
more reliable than grafts, as the blood supply
is always guaranteed when vascular
continuity is well preserved [1]. Many penile
and scrotal skin flaps to reconstruct complex
urethral stenosis have been described, but
most were not supported by previous
microvascular studies, which could explain
their variable outcomes.
Scrotal skin is well vascularized due to the
confluence of two main arterial systems,
the external iliac and the internal iliac, as
described in classic anatomical texts and
atlases [2–7], and specialized books and texts
on microvascular anatomy [8–10]; however,
recent and well-detailed descriptions are
scarce or unavailable. Our aim was to study
the arterial microvascular distribution of the
820
scrotum and apply the findings to improving
the results of complex urethral surgery.
MATERIALS AND METHODS
Fifteen cadavers of men aged 53–92 years,
cryopreserved and with arterial black latex
injected through the internal and external
iliac arteries, were studied using a
combination of different techniques.
The bilateral inguinal regions and the
perineoscrotal area were dissected to identify
the origin of the main arterial vessels that
vascularize the scrotum.
Microdissections of scrotal cutaneous arteries
using magnifying lenses (×2.5) were carried
out from inside and outside the scrotal wall,
with each layer identified and raised
successively.
The special anatomical distribution of scrotal
branches stemming from perineal arteries
enables the construction of adequate reliable
longitudinal median island scrotal flaps for
the reconstructive surgery of panurethral
stenosis, as profuse axial vascularization is
ensured.
KEYWORDS
arteries, blood supply, scrotum, surgical
flaps, urethral stricture, urethroplasty
To evaluate specific characteristics,
disposition and anastomosis of the
skin arteries, the scrotum was made
transparent using the Spalteholtz
technique [11] in which tissue is cleared
by alcohol dehydration and impregnation
with benzyl benzoate/methyl salicylate
mixture. Sections were made in the frontal or
sagittal planes in some of these preparations
to attain better visualization of the vascular
disposition.
RESULTS
Scrotal blood supply from the external iliac
system: Two external pudendal arteries
(superior and inferior) were found stemming
from the femoral artery at a mean distance of
5 cm below the inguinal ligament in 95% of
cases. One arterial trunk dividing into these
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ARTERIES OF THE SCROTUM
FIG. 1. Dissection of the inguinal region. 1. Femoral
artery. 2. Superior external pudendal artery. 3.
Inferior external pudendal artery. 4. Femoral vein. 5.
Great saphenous vein. 6. Inguinal ligament.
FIG. 2. Spalteholtz technique. A, Lateral view of
scrotal sac. Scrotal arteries are long, tortuous and
follow a descending course in scrotal layers. They
fan out into branches emerging at acute angle from
the main trunk. B, Superior view of the scrotal sac
after removing the testes. Anastomosis is visible
between great branches of scrotal vascularization
from the external iliac and internal iliac systems. 1.
Inferior external pudendal artery. 2. Great branch of
perineal artery. 3. Corpus spongiosum.
A
FIG. 3. Landmarks of the emergence point of the
perineal artery (lithotomy position). A, As indicated
with the red ellipse, 75% of perineal arteries emerge
at the middle third of the line between median raphe
and ischial tuberosity. The remaining arteries
emerge in the lateral third of this line but with a
clear tendency to move away from the ischial
tuberosity, as indicated by the green circle. B,
Dissection of the course of perineal arteries to the
scrotum. During their course, these arteries give
off branches towards neighbouring anatomical
structures. In the root of the scrotum, both perineal
arteries are attached to the septum. 1. Perineal
artery. 2. Superficial transverse perineal muscle. 3.
Ischiocavernosus muscle. 4. Bulbospongiosus
muscle.
A
two branches was found in 65% of cases
(Fig. 1).
B
Scrotal vascularization was exclusively
through branches of the inferior external
pudendal artery in 89.5% of cases. Both
external pudendal arteries or a single
external pudendal artery were responsible for
scrotal blood supply in the remaining cases.
These arteries enter the scrotal sac laterally
at the mid-point of its base or root, then
bifurcate and are distributed throughout the
entirety of the skin of each hemi-scrotum
(Fig. 2).
Scrotal blood supply from the internal iliac
system: A perineal artery (superficial perineal
artery) branching from the internal pudendal
artery was located bilaterally in the perineal
area in all cases. All these vessels gain access
in the perineal region, perforating the perineal
membrane in the triangular space formed
in front of the superficial transverse
muscle of the perineum, and between the
ischiocavernosus and bulbospongiosus
muscles. This emergence point was found
at a mean distance of 1.9 cm lateral to the
median perineal raphe, along the line joining
the two ischial tuberosities passing through
the anterior margin of the anal orifice. In
depth, the arterial emergence point was at a
mean of 4.5 cm from the cutaneous surface.
Both superficial perineal arteries traced an
anterosuperior route towards the rear face
of the scrotum (lithotomy position), being
located deep in the space between the
ischiocavernosus and bulbospongiosus
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B
muscles (Fig. 3). At the root of the scrotum,
each perineal artery splits into fine branches
that are distributed in the skin of this area,
and a main branch, of larger diameter, which
continues a deep course towards the interior
of the scrotal sac (Fig. 4). This main branch
runs ventrally along the urethral corpus
spongiosum at each side of the scrotal
septum insertion, following an anterior
direction, and branching out into several
arteries that descend obliquely over the
septum (Fig. 5). When these septal arteries
reach the superficial end of the septum, they
turn towards the skin of each hemiscrotum at
the median line where they are distributed
(Figs 6,7).
In addition, in 70% of cases the skin of the
superolateral region of the scrotum had
supplementary irrigation from a lateral
artery originating in the medial femoral
circumflex artery (83% of cases) or in
the obturator artery (17%). There were
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C A R R E R A ET AL.
FIG. 4. The great branch of the perineal artery only gives off small, scant branches to the skin of the scrotal
root. A, Microdissection of the posterior aspect of the scrotum (lithotomy position). All the skin has been
removed laterally to the scrotal raphe. B, Spalteholtz technique. Posterior view of the scrotum. C, Spalteholtz
technique. Frontal section and internal view of the posterior aspect of the left hemiscrotum. 1. Great branch
of perineal artery on its route inside scrotal sac. 2. Branches of perineal artery to the skin of the scrotal root.
3. Scrotal septum. 4. Corpus spongiosum. 5. Skin.
A
B
FIG. 5. A, Internal microdissection of scrotal sac. The
scrotal septum and skin are in the same plane.
Scrotal arteries run at different levels of the
subcutaneous tissue of the scrotum. B,
Transillumination of scrotal septum in the internal
microdissection of the scrotal sac. C, Spalteholtz
technique and frontal section of scrotum. The
scrotal septum has two arterial planes with fine,
scant communications between them. 1. Great
branch of perineal artery. 2. Septal arteries. 3.
Branches from inferior external pudendal artery. 4.
Corpus spongiosum. 5. Scrotal septum.
A
C
B
The use of scrotal and penile skin flaps in
reconstructive surgery of bulbar urethral
stenosis has declined since the advent of
free buccal mucosa grafts. However, there
are cases of complex bulbar stenosis (very
extensive, multi-operated and with chronic
urinary infection) or panurethral disease in
which reconstruction with a scrotal skin
flap is an option to be considered before a
definitive perineal urethrostomy.
suitability and reliability. As classically
described, scrotal skin has a dual blood supply
through branches from the external and
internal iliac systems, respectively, distributed
in anterior and posterior faces of the
scrotum [2,3,8]. However, our results show
the existence of three cutaneous territories;
two lateral and one central (Fig. 8). Classically
and in recent texts, perineal arteries were
considered to only irrigate the posterior
face of the scrotum [9,10,16]; however,
the present study showed that all the skin
from the scrotal midline to its insertion
into the mid penile raphe receives its
vascularization via the perineal arteries and
their branches.
Different urethroplasty techniques with
scrotal flaps have been described [12–16];
however, the design of most was based on
the understanding of classical anatomy
and not on microvascular studies, which
might support the existence of axial-type
vascularization and thus assure their
Understanding of the exact anatomical
location of these vessels is necessary to
ensure their inclusion in the skin flap and
avoid surgical manoeuvres that could harm
them. In this respect, several surgical
landmarks should be considered throughout
their route.
anastomoses between the arteries of each
scrotal vascular region.
DISCUSSION
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C
Regarding the exit point of these arteries in
the perineal region, incisions at the base of a
flap of the scrotal midline must move away
laterally from ischial tuberosities to avoid
injury. Fortunately, the characteristic deep exit
site of both perineal arteries prevents them
from being injured in their main trunk when a
superficial skin incision is made.
To ensure inclusion in the scrotal flap of
the main trunk of both perineal arteries
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ARTERIES OF THE SCROTUM
FIG. 6. Spalteholtz technique. A, Cutaneous surface of the scrotal midline. B,C, Frontal section of the scrotal
septum and midline skin. Anastomoses are visible between vessels from septal arteries and vessels from
inferior external pudendal artery. There are many vessels in the midline skin of the scrotum. 1. Septal arteries.
2. Branches from inferior external pudendal artery. 3. Septum.
A
FIG. 7. Spalteholtz technique. Inferior view of
scrotum. Anastomoses are apparent among the
arterial territories of the scrotum. 1. Branches from
inferior external pudendal artery. 2. Branches from
septal arteries.
B
C
FIG. 8. Vascular scrotal territories. Branches from
inferior external pudendal artery (in red) and
branches from septal arteries (in orange). A, Anterior
face of scrotum. B, Posterior face of scrotum.
situated between the ischiocavernosus
and bulbospongiosus muscles, it will be
necessary to raise them within the plane of
the fascia of these muscles or, even more
safely, subfascially, while taking special care in
the intermuscular space, as indicated in a
perineally based scrotal flap urethroplasty
[15].
The particular ventral route of both
perineal arteries with respect to the corpus
spongiosum of the urethra and exit of
its branches towards the scrotal septum,
advocate the routine inclusion of the septum
in scrotal flap construction, and thus preserve
this important vascularization. However,
anatomical findings have shown that
perineally based flaps of the scrotal midline
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can be adequately designed in length and
width without their vascularization being
compromised.
As the median line of scrotal skin, on the
posterior and anterior faces, depends on
vascularization through perineal arteries,
posterior scrotal midline flaps are not limited
in length and could be raised, with no risk, up
to the anterior face of the scrotum. Thus, this
permits long cutaneous island flaps to be
obtained that can be moved and sutured free
from tension.
Confirmation of the existence of anastomosis
between the arteries of the two lateral arterial
territories with a central territory, forming
a true scrotal network as described by
several authors [8–10], permits the design
of flaps of the scrotal central line with
variable amplitude, without endangering
the vascularization of their lateral zones.
Finally, direct connections between the
arteries of the right- and left-hand sides at
the level of the scrotal skin of the median line
could ensure vascularization of the whole flap
in the event of lesions to the vascular supply
of one of the sides of the septum.
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C A R R E R A ET AL.
Some authors have described flaps for
complex urethral reconstruction based on the
distribution of perineal artery branches in
other territories [14,16,17] or exclusively on
the septal blood supply [13]. Without doubt,
according to our results, a raised flap in the
posterolateral scrotal skin is vascularized by
fine branches of the ipsilateral perineal artery
that are distributed in the area. Such a flap
must be considered as a ‘random’ flap,
given that it will remain nourished through
arterial interconnections of the dartos, but
will not count on an axial vessel making its
vascularization totally predictable. Septum
pedicled scrotal skin flaps are randomly
vascularized by fine septal arteries that can be
easily damaged when surgical incisions are
deepened in the scrotal septum to obtain an
adequate mobilization of the flap.
the base of the penis) and variable width,
thereby guaranteeing axial vascularization.
The surgical execution of these flaps must
respect certain important surgical landmarks
and preferentially include the septum.
8
ACKNOWLEDGEMENTS
10
The authors thank Christine O’Hara for
valuable help with the English version of the
manuscript.
11
9
CONFLICT OF INTEREST
12
None.
13
REFERENCES
In no case did we find a distribution of
perineal artery branches in the superficial
fascia of the internal thigh laterally
contiguous to the inguinal fold, as described
in diagrams of a urethroplasty technique for
complex cases [16,17].
In conclusion, the scrotum receives a good
arterial supply from two main arterial
systems that determine the existence of
three cutaneous territories; two lateral, each
dependent on an inferior external pudendal
artery, and one central, dependent on perineal
arteries, which includes the anterior and
posterior faces and the septum. The three
territories are widely interconnected by a
veritable scrotal arterial network.
Microvascular anatomical study of the
distribution of scrotal branches of the
perineal artery permits the design of
skin flaps of the central scrotal territory,
sufficiently long (from the scrotal root to
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Correspondence: Anna Carrera Burgaya,
Department of Human Anatomy, Faculty of
Medicine, University of Barcelona, Calle
Casanova, 143, 08034 Barcelona, Spain.
e-mail: [email protected]
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