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58 Toldt’s fascia
Mesorectal (Toldt’s) fascia
tum
(i.e
(a)
(b)
Mesorec
Mesorectal
., Toldt’s)
fascia
Left mesocolic
fascia
Right
mesocolic
fascia
Mesosigmoid
fascia
Mesorectal
fascia
Figure 5.1 (a) Intraoperative photomicrograph demonstrating Toldt’s fascia. (b) 2.5D snapshot of 3D model demonstrat-
ing the fascia (green) associated with mesentery distal to the duodenojejunal exure. The right and left mesocolic fascia,
mesosigmoid, and mesorectal fascia are demonstrated. These represent different regions of the same overall structure,
that is, Toldt’s fascia.
DEMONSTRATION OF TOLDT’S FASCIA
living anatomy. Finally, histologic and scanning electron
microscopic photomicrographs are included to complete a
Given variability in fascial composition, the fascia is
comprehensive visual appraisal of the fascia [2].
best portrayed using a number of modalities. Schematic
diagrams derived from 3D digital sculptures enable
demonstration of the relationship of the fascia to adjacent
structures (Figure 5.1). In the following, schematic dia-
TOLDT’S FASCIA: REGIONAL ANATOMY
Mesorectal fascia
grams are juxtaposed with cadaver-derived screenshots
[1,3,10,11]. Intraoperative images (from both open and laparoscopic cases) are also included as the high magnication and resolution of these provide unsurpassed views of
Starting in the pelvis, Toldt’s fascia occurs between the mesorectum and the bony pelvis. Here, bers are areolar, resembling “angel hair” or “candy oss” (Figure 5.3)[12,13]. Several
Toldt’s fascia: Regional anatomy 59
mesocolic
fascia
Mesosigmoid
Distribution of Toldt’s fascia
Right
fascia
Small intestine
and mesentery have
been removed
Toldt’s fascia
Transverse colon and
mesocolon have
been removed
Left
mesocolic
fascia
fascia
Mesorectal
Figure 5.2 Schematic illustration showing the distribution of Toldt’s fascia as originally described by Toldt. With minor
exceptions the distribution closely mirrors that seen in Figure 5.1b. (Courtesy of CCF. Copyright 2010.)
terms have been used in reference to the mesorectal region
of Toldt’s fascia. ese include the retrorectal and endopelvic
fascia. Deep in the pelvis, the mesorectum tapers dramatically creating a posterior space in which Toldt’s fascia gathers. In this region, it is referred to as Waldeyer’s fascia [13].
Itoccurs circumferentially at all mesorectal levels. Deep to
the peritoneal reection, it oen coalesces with the anterior
cu of mesorectum to form Denonvillier’s fascia. As this
component of the mesorectum (i.e., the anterior cu) is not
always well developed, Denonvillier’s fascia is not an anatomic constant. However, the fascia is universally constant.
e fascia is dicult to identify laterally, where the meso-
rectum apposes with the fat of the pelvic sidewall. ese are
the “zones of adherence” or “lateral ligaments” and careful
dissection here may reveal fascia, even in cases of extreme
adiposity. In general however, it seems that at the zone of
adherence the fascia is interrupted and regathers around it.
thin here, it is easily disrupted. Not surprisingly, the mesosigmoidal fascia is obliterated by solutions used for preservation. is eect may explain its omission from most
reference anatomic texts with the singular exception of the
most recent edition of Gray’s anatomy [2,14–17]. In turn, it
may also explain how the right and le mesocolon could,
with few exceptions, be perceived as absent, obliterated,
or vestigial [10,14–21]. is is explained as follows. If the
fascia is lost, then one has the impression of a single body
of fat. If the fascia is retained, then the mesocolon can be
observed as separate from the retroperitoneum. It is likely
that this phenomenon explains persistence of the concept
that the right and le mesocolon are absent in the adult. It
also explains why the attached component of the mesosigmoid was not acknowledged up to recently [17]. As demonstrated in Chapter 2, the mesosigmoid comprises attached
and mobile regions. Toldt’s fascia separates the attached
region from the underlying retroperitoneum [1,3,17].
Mesosigmoidal fascia
Left mesocolic fascia and the white line
Once it has been identied, it is possible to trace Toldt’s
fascia out of the pelvis, proximally under the mesosigmoid
and the le mesocolon and thereaer under the pancreas.
Beneath the mesosigmoid, the mesosigmoidal region of
Toldt’s fascia is areolar (Figure 5.4) [1,13]. As it is extremely
ofToldt
e composition of Toldt’s fascia changes beneath the proximal mesosigmoid (i.e., where the mesosigmoid and le
mesocolon are contiguous). Here, the fascia (i.e., the le
60 Toldt’s fascia
Mesorectal (Toldt’s) fascia
Mesorec
ritoneal
(b) (c)
Posterior
mesorectum
(a)
Rectum
Mesorectal
fascia
Legend
Mesentery
Fascia
Colon
Peritoneum
Mesorectum
Toldt’s
fascia
tum
Figure 5.3 (a) Cadaveric example of Toldt’s fascia posterior to the mesorectum (i.e., the mesorectal or endopelvic fascia).
(b) Intraoperative image of Toldt’s fascia surrounding the mesorectum. (c) (See also QR 3/2.) 2.5D snapshot of 3D model
demonstrating the relationship of the fascia, mesorectum, and peritoneal reections.
mesocolicfascia) comprises multiple lamellae of connective
tissue (Figure5.5). As a result, it loses the areolar appearance
and becomes moredense and somewhat lmy [1]. is prop-
erty facilitates its observation, provided of course one is deliberately looking for it in the rst instance. e fascia here can
be excellently demonstrated during laparoscopic and robotic
colorectal surgery, where the surgeon relies on twenty-fold
magnication and high-resolution digital imagery to dierentiate it from adjacent structures [22,23]. During this surgery, the mesocolon is detached from the retroperitoneum by
separating it from the underlying fascia. is technical activity exposes a white line at the interface between the fascia and
Mesorectal fascia
mesocolon, that is, the white line of Toldt [23]. If this process
of separation is continued underneath the le mesocolon
toward the transverse mesocolon, the inferior border of the
pancreas comes into view. e fascia envelops the pancreas
on both anterior and posterior surfaces [1,4–6].
Laterally, the fascia continues under the le colon and
terminates at the le peritoneal reection, where it forms
a white line of Toldt. Although this arrangement can be
demonstrated at open surgery, it is easier demonstrated
with magnication aorded by laparoscopic and robotic
surgery [23]. e white line of Toldt is evident at the le
colic but not at sigmoidal level. is is due to dierences in
Pe
re˜ec tion
Toldt’s fascia: Regional anatomy 61
Mesosigmoid fascia
(c)
Mesosigmoid
(b
Mesosigmoid
Mesosigmoid
fascia
Legend
Mesentery
(a)
Mesosigmoid
Mesosigmoid
fascia
)
Figure 5.4 (a) Cadaveric example of Toldt’s fascia beneath the mesosigmoid (i.e., the mesosigmoidal fascia). Here, the
fascia is areolar and easily disrupted or missed. (b) Intraoperative image of Toldt’s (mesosigmoidal) fascia interposed
between the mesosigmoid and underlying retroperitoneum. (c) (See also QR 2d/1.) 2.5D snapshot of 3D model demonstrating the relationship of the fascia to the mesosigmoid. Note that the lateral limit of the fascia occurs where the mesosigmoid changes fromattached to mobile (i.e., at the peritoneal reection).
Mesosigmoid
fascia
Fascia
Colon
Peritoneum
the composition of the fascia at both levels. e le mesocolic fascia is dense and forms a discrete line where it fuses
with the peritoneal reection. In contrast, the mesosigmoidal fascia is areolar and does not form a distinct line where
it meets the peritoneal reection. is is clinically relevant
as it is oen easier to commence mobilizing the le colon
by identifying the white line of Toldt. As the white line is
not present at the sigmoidal level, commencement of mobilization here is more dicult [22,23].
Right mesocolic fascia and the white line
ofToldt
On the right side, Toldt’s fascia occurs between the right
mesocolon and underlying retroperitoneum. Here, it is
thicker than on the le side, which reects increases in
collagen lamellae (Figure 5.6). As on the le, the fascia
continues under the right colon (forming a colofascial
plane) until it reaches the right peritoneal reection with
62 Toldt’s fascia
Left mesocolic fascia
Le
mesocolon
(b) (c)
Left mesocolon
Left mesocolic fascia
(a)
ft mesocolon
(undersurface)
White line
of Toldt
Figure 5.5 (a) Cadaveric example of Toldt’s fascia beneath the left mesocolon (i.e., the left mesocolic fascia). Here, the fascia is lamellated, thick, and thus more easily identied compared with beneath the mesosigmoid. (b) Intraoperative image
of Toldt’s (mesocolic) fascia interposed between the left mesocolon and underlying retroperitoneum. (c) (See also QR 6/2.)
2.5D snapshot of 3D model demonstrating the relationship of the fascia to the mesocolon.
Left mesocolic
fascia
Legend
Mesentery
Fascia
Colon
Peritoneum
Left
Left mesocolic fascia
(Toldt’s fascia)
which it coalesces at the white line of Toldt. Medially, the
right mesocolon is contiguous with the small intestinal
mesentery. In keeping with this, Toldt’s fascia continues
medially until the small intestinal peritoneal reection, at
which its distribution again ceases [3].
Fascial continuity
Although the fascia is contiguous, it is interrupted at points
where vessels enter or leave the mesentery. Here, it coalesces
with mesenteric connective tissue, to form a perivascular collar of connective tissue. e latter contributes to the adventitia
of the vessel in question, a property that has been discussed in
Chapter 4. e fascia also interrupted at the peritoneal reec-
tion, the dierent regions of which serve as a mechanical barrier to its further spread (see Chapter2). Finally, the fascia is
disrupted at the zones of adherence around which it regathers.
HISTOLOGY
e fascia is comprised of collagen, with occasional cell bodies interspersed between collagen bundles [2]. Lymphatic
vessels are present in one-third of individuals. ey have a
Right mesocolic fascia
Right
(b) (c)
mesocolon
(a)
Undersurface of
right mesocolon
Function of Toldt’s fascia 63
Right colon
Toldt’s
fascia
Legend
Mesentery
Fascia
Colon
Peritoneum
Right
mesocolon
Right mesocolic fascia
still attached to
right mesocolon
Figure 5.6 (a) (See also QR 2/4.) Intraoperative example of Toldt’s fascia beneath the right mesocolon (i.e., the right mesocolic
fascia). (b)Intraoperative image of Toldt’s (mesocolic) fascia interposed between the right mesocolon and underlying retroperitoneum. (c) (See also QR 6/4.) 2.5D snapshot of 3D model demonstrating the relationship of the fascia to the mesocolon.
radius of diusion of 174.72 ± 97.68 µm. is means a lymphatic vessel can be expected every 174 µm [24]. e origin
of these, as well as their termination, is as yet unknown and
could be of oncologic signicance.
At points of vascular contiguity (i.e., the origin of the
middle colic or inferior mesenteric vessels), the fascia
coalesces around vessels where it encases these. From these
points, the connective tissue of the fascia continues into the
body of the mesentery as the mesenteric connective tissue
lattice [1,2]. e relevance of this relationship, in relation
Right mesocolic fascia
(Toldt’s fascia)
Right mesocolic fascia
mobilized o˜ right
mesocolon
to disease spread, is discussed in Chapter 7 (i.e., diseases
involving the mesentery).
FUNCTION OF TOLDT’S FASCIA
It is likely that the fascia assists in maintaining attachment
between the overlying mesentery and underlying retroperitoneum. e elucidation of function in general is aided by
the identication of states in which the structure in question is absent and extrapolation of related observations.
64 Toldt’s fascia
Appendix
Normal gastromesenteric confirmation Confirmation as seen in malrotation model
(c)
isincludes nonrotation of the intestinal tract. In nonrotation (see below), the small intestinal mesentery is fully mobile
and positioned in the right paracolic gutter (Figure 5.7). e
right mesocolon and foreshortened transverse mesocolon are
adherent to the retroperitoneum. e absence of attachment
of the small intestinal mesentery can be associated with a devastating volvulus around the mesenteric root region, at the
superior mesenteric vascular pedicle. is is the commonest
life-threatening abdominal emergency in the rst year of life.
In adulthood, incomplete attachment of the right mesocolon
is associated with volvulus of the ileocecal region (Figure5.7).
Similarly, incomplete attachment of the mesosigmoid is
associated with volvulus of this. Finally, it is suggested that
incomplete xation of the le and right mesocolon may cause
diculty during endoscopic negotiation of the colon [25–28].
Toldt’s fascia may also provide a barrier function. Rarely
in colorectal cancer does one observe spread of a colon cancer through the fascia into the retroperitoneum. Even where
the mesocolon has been directly involved, spread through
the fascia is unusual (Figure 5.8a) [13].
A further function may relate to uid absorption. In
patients with uid overload, the fascia increasesdramatically
(a) (b)
Intraoperative nonrotation
Mesoappendix
Figure 5.7 (a) Overview of normal gastromesenteric anatomy. (b) Overview of gastromesenteric anatomy in mal or nonro-
tation. The small intestine and associated mesentery are positioned to the right. The left colon and mesentery are to the
left and the right gastromesenteric complex is located between. (c) Given the central positioning of the right colon in mal
or nonrotation, the appendix can occupy variable positions.
Right mesocolon and Toldt’s fascia
mesocolon
Mass in
(b)
cecum
Function of Toldt’s fascia 65
Right
mesocolon
Toldt’s fascia
Right mesocolic fascia
(a)
Transverse mesocolon
Left
Mass in right
mesocolon
Anterior renal (Toldt’s) fascia
Splenic ˜exur e
mesentery
Descending
colon
Anterior
renal
(Toldt’s )
fascia
Figure 5.8 (a) Axial computerized tomography demonstrating a lesion in the right colon. There is a right mesocolic lesion
with involvement of the underlying fascia. Intraoperatively the patient has a T4 adenocarcinoma that had invaded locally
through the mesentery and into the underlying fascia. (b) Axial computerized tomography demonstrating fascial thickening in a patient with congestive cardiac and renal failure.
in width (Figure 5.8b). is suggests that it provides a means
of uid absorption and retention [29].
Elucidation of the function of Toldt’s fascia is dicult in
view of the absence of appropriate animal models. In general in
experimental science, animal models used are either murine,
porcine, or rodent in nature. In these, the intestinal tract is
highly mobile and the associated mesentery does not become
apposed to the abdominal wall. At present, a species has yet
to be identied for which the mesenteric attachment equates
with to that observed in Homo sapiens. e identication of
66 Toldt’s fascia
Fascia and related structures
l
T
Ureter
Gonada
vein
oldt’s
fascia
Figure 5.9 Intraoperative photomicrograph demonstrating the glistening fascia with the ureter and gonadal vessels
located immediately underneath Toldt’s fascia.
one such species, and the development of this as a model system, represents an area of future research in this eld.
e lack of representative animal models is in itself
informative. It is possible that attachment of the mesentery
to the posterior abdominal wall may well be anatomically exclusive to H. sapiens and other higher order species
(i.e.,apes). Absence of attachments, would mean that aer
standing upright, the entire gastromesenteric complex would
collapse into the pelvis, and function would be impaired.
it can be dicult to visualize because it is translucent and
inmany regions extremely thin (Figures 5.3, 5.4, and 5.9).
Notsurprisingly, the fascia is dicult to visualize in radiologic contexts, unless it is thickened due to a pathologic
process (Figure 5.8). Recent advances in radiologic interpretation of computerized tomographic imaging have led
to increased rates of identication of the fascia [35]. is
is dealt with in greater detail in Chapter 8. In keeping with
this, what was previously referred to as the “anterior pararenal fascia” is now increasingly recognized as representing a
SURGICAL IMPLICATIONS
OF TOLDT’S FASCIA
region of Toldt’s fascia[35].
e development of the Visual Human Project (VHP)
is also likely to further improve our understanding of the
Toldt’s fascia is of crucial technical importance in resectional
colorectal surgery. Together with the mesocolon (or colon), it
generates an interface that must be disrupted in order to free
these structures from the posterior abdominal wall and allow
their resection (Figure 5.9). It thus contributes an anatomic
roadmap that is of fundamental importance in safe surgery.
Digression from this anatomic roadmap into the retroperito-
fascia [36]. In the VHP, a full color dataset enables one look
at subtle structures in their undisturbed and insitu format.
is represents an exciting opportunity, and it is through
the identication of undisturbed fascial layers that we are
likely to better understand the relationship between Toldt’s
fascia, the overlying mesenteric organ, and associated peritoneal reections [35,36].
neum is associated with damage to ureters, gonadal vessels, and
duodenum. Digression from the roadmap into the mesentery is
associated with damage to the latter and extensive hemorrhage.
By adhering to the planar roadmap provided by the fascia, surgeons achieve a mesenteric and intestinal resection with minimal blood loss or tissue damage in general [1,2,24,30–34].
ADHESIONS AND TOLDT’S FASCIA
ere is a striking similarity between adhesions and Toldt’s
fascia. Just as the fascia can be lmy or areolar in appearance, so too can adhesions. is similarity points to an
overlap in the cellular and molecular processes involved in
TOLDT’S FASCIA AND RADIOLOGIC
IMPLICATIONS
formation of both. Considered in this manner, it is feasible
that adhesion formation is not a pathologic process per se,
but rather a fundamentally important embryologic process
e anatomic properties of the fascia render it dicult to
visualize out with the surgical context. Even intraoper atively,
that ensures attachment and normal function of the gastromesenteric complex.
References 67
FUTURE DIRECTIONS
Experimental and clinical interest in the composition and
distribution of Toldt’s fascia is increasing. e absence of an
animal model in which the mesentery has attached to the
posterior abdominal wall has been discussed and deserves
particular emphasis. Currently, eorts are focused at articially stimulating fascial development in the rodent or porcine context by suturing mesentery to the retroperitoneum.
e identication of lymphatic vessels in the fascia
prompts further investigation of this. In general, operative surgery involves leaving the fascia behind. However,
malignant cells are known to utilize lymphatic channels in
spreading from a primary tumor. e question thus arises
as to whether the fascia should also be resected or not. e
origin and termination of fascial lymphatics should be
determined to partly address this question.
SUMMARY
Toldt’s fascia is continuous from the root region of the mesentery at the superior mesenteric artery, to the anorectal
junction, where it both expands and condenses to form
Waldeyer’s fascia. is continuity is disrupted only at the
peritoneal reections, the zones of adherence in the pelvis, and where major vessels enter or leave the mesentery.
e right mesocolic fascia, the le mesocolic fascia, and the
mesosigmoidal and mesorectal fascia are dierent regions
of the same contiguous structure. Macroscopically, it resembles adhesions that may arise aer abdominal surgery.
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