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Applied Peritoneal Anatomy - A Pictorial review.
Poster No.:
C-1925
Congress:
ECR 2011
Type:
Educational Exhibit
Authors:
R. Patel, I. Beal, K. Planche; London/UK
Keywords:
MR, CT, Anatomy, Abdominal wall, Abdomen
DOI:
10.1594/ecr2011/C-1925
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Page 1 of 54
Learning objectives
•
To review and simplify the complex anatomy of the peritoneum, its
attachments and reflections forming the peritoneal boundaries.
•
To describe normal anatomy using schematic illustrations with
corresponding CT and MRI images including CT peritoneograms.
•
Furthermore, to demonstrate how understanding the relevant peritoneal
and extraperitoneal anatomy allows the diagnosis of different pathological
processes.
Background
Primary abnormalities of the peritoneum are rare but involvement of the peritoneal
cavity secondary to infections, malignancy and trauma are common. Detailed anatomical
knowledge of the peritoneum spaces allows more accurate localisation of pathology to
enable the radiologist to narrow the differential diagnoses.
Peritoneal Anatomy
The peritoneum is the largest and most complex serous membrane of the body. It consists
of two, transparent layers which are continuous with each other. The parietal peritoneum
lines and attaches, in places, to the internal surface of the abdomino-pelvic cavity. The
visceral peritoneum invests and covers the external surface of viscera.
Page 2 of 54
Fig.: Sagittal CT peritoneogram with diagram
References: R. Patel; Radiology, Royal Free Hospital, London, UNITED KINGDOM
Terminology
Strictly speaking there are no organs within the peritoneal cavity itself which normally
only contains peritoneal fluid. Instead intraperitoneal organs invaginate and are almost
completely covered by the visceral layer.
Extra- or retroperitoneal organs also lie outside the peritoneal cavity, either exterior or
posterior to the parietal peritoneum. These organs are usually only partially covered by
peritoneum.
Various terms are used to describe parts of the peritoneum that connect organs with
other organs or to the abdominal wall.
•
A mesentery suspends the small and large bowel from the posterior
peritoneal cavity by way of a double layer of peritoneum. It acts as a conduit
Page 3 of 54
•
•
for neurovascular and lymphatic structures between the organ and posterior
abdominal wall.
A ligament is also formed by two layers of the peritoneum, it supports a
structure within the peritoneal cavity and is named according to the the
structures it connects.
An omentum refers to a double-layered extension of ligaments of the
peritoneum joining the stomach and proximal duodenum to other adjacent
structures, the greater and lesser omentum extending from the greater and
lesser curvatures of the stomach respectively.
Fig.: Sagittal view from CT peritoneogram showing the greater and lesser omenta.
Peritoneal spaces and ligaments
The boundaries of the peritoneal spaces are formed by the mesenteries and ligaments.
A basic knowledge of peritoneal embryological development is required to understand
the formation of the communicating peritoneal spaces.
Page 4 of 54
In the developing foetus, the peritoneal cavity is divided into right and left peritoneal
cavities by the ventral and dorsal mesenteries of the primitive gut. Many of the ligaments
and mesenteries are formed from remnants of the ventral and dorsal mesenteries.
Fig.: Schematic diagram demonstrating the formation of the peritoneal spaces.
Above the transverse mesocolon, the ventral mesentery contains the liver bud and the
dorsal mesentery contains the splenic bud. As development continues, these organs
migrate anticlockwise taking the attached mesenteries with them. This migration divides
the right peritoneal cavity into the perihepatic space and the lesser sac. The left peritoneal
space forms the left subphrenic space.
Page 5 of 54
Fig.: Diagram demonstrating peritoneal spaces
Page 6 of 54
Fig.: Schematic illustration of peritoneal spaces and ligaments correlated with axial CT
peritoneogram.
Remnants of the dorsal mesentery form the gastrocolic, gastrosplenic, gastrophrenic,
gastropancreatic ligaments forming part of the greater omentum. The splenorenal and
phrenicocolic ligaments also arise from the dorsal mesentry.
The ventral mesenteric remnant give rise to the faciform ligament, (dividing the
supramesolic compartment, which contains the stomach, liver and spleen, into left and
right), the gastrohepatic and hepatoduodenal ligament, the latter two form part of the
lesser omentum.
The inframesocolic compartment lies posterior to the greater omentum, below the
transverse mesocolon but medial to the ascending and descending colon. It contains
the small bowel and ascending and desending colon. It is divided in right and left by
the oblique small bowel mesentery. Both the transverse mesocolon and the small bowel
mesentery are remnants of the foetal dorsal mesentery, as is the sigmoid mesentery and
the mesoappendix. The ventral mesentery regresses below the transverse mesocolon.
Page 7 of 54
Fig.: Diagram illustrating the omenta, mesenteries and spaces
Lateral to the ascending and descending colons are the right and left paracolic gutters.
The right paracolic gutter is continous with the right perihepatic space. Conversely on the
left, the phrenicocolic ligament prevents direct communication between the left paracolic
gutter and the left subphrenic space.
Page 8 of 54
Fig.: Coronal CT peritoneogram showing peritoneal spaces
Page 9 of 54
Fig.: Coronal and sagittal CT peritoneograms showing peritoneal spaces
The urogenital peritoneum reflects over the pelvic organs to form most of the pelvic
ligaments and mesenteries. These include the broad and round ligaments of the uterus
and the median, medial and lateral umbilical folds creating the midline recto-vesical pouch
in a male and the recto-uterine pouch in a female and the paravesical fossae.
Page 10 of 54
Fig.: Sagittal and coronal views from CT peritoneogram demonstrating pelvic
peritoneal folds and spaces.
Peritoneal Circulation
The peritoneal cavity normally contains only a thin film of fluid. This fluid is continually
produced, circulated and resorbed. The direction of flow is determined by diagphragmatic
movement, bowel peristalsis and limitations imposed by peritoneal attachments and
ligaments. The fluid takes the path of least resistance which involves flow up the right
paracolic gutter which is wider and more dependant then the left. The majority of the fluid
is resorbed via lymphatics in the subphrenic space.
Page 11 of 54
Fig.: Coronal CT peritoneogram demonstrating regions of fluid stasis correlated with
diagram
Fluid flow and stasis is dependent on gravity, changes in intra-abdominal pressure and
peritoneal reflections. Areas of preferential fluid stasis include the Pouch of Douglas, the
right lower quadrant at the termination of the small bowel mesentery, superior aspect of
the sigmoid mesentery and the right paracolic gutter (*). These are the first sites to be
involved in peritoneal spread of infections and metastases.
Images for this section:
Page 12 of 54
Fig. 1: Sagittal CT peritoneogram with diagram
Page 13 of 54
Fig. 2: Sagittal view from CT peritoneogram showing the greater and lesser omenta.
Page 14 of 54
Fig. 3: Schematic diagram demonstrating the formation of the peritoneal spaces.
Page 15 of 54
Fig. 4: Diagram demonstrating peritoneal spaces
Page 16 of 54
Fig. 5: Schematic illustration of peritoneal spaces and ligaments correlated with axial CT
peritoneogram.
Page 17 of 54
Fig. 6: Diagram illustrating the omenta, mesenteries and spaces
Page 18 of 54
Fig. 7: Coronal CT peritoneogram showing peritoneal spaces
Page 19 of 54
Fig. 8: Coronal and sagittal CT peritoneograms showing peritoneal spaces
Page 20 of 54
Fig. 9: Sagittal and coronal views from CT peritoneogram demonstrating pelvic peritoneal
folds and spaces.
Page 21 of 54
Fig. 10: Coronal CT peritoneogram demonstrating regions of fluid stasis correlated with
diagram
Page 22 of 54
Imaging findings OR Procedure details
•
Schematic diagrams with corresponding CT (including CT peritoneograms)
are used to illustrate peritoneal anatomy and different pathological
processes affecting various peritoneal spaces.
Supramesocolic compartment
•
The subphrenic space is divided into right and left by the falciform ligament.
Fig.: Axial views from CT peritoneogram demonstrating peritoneal spaces in the upper
abdomen. Correlated with schematic diagram
•
The right subphrenic space communicates freely with the perihepatic and
subhepatic spaces, including Morison's pouch, which communicates with the
lesser sac via the epiploic foramen (foramen of Winslow).
Page 23 of 54
Fig.: Coronal and sagittal view from CT peritoneogram demonstrating upper
abdominal peritoneal spaces.
•
These supramesocolic spaces are preferential sites for peritoneal fluid stasis
and therefore are common sites to detect ascites, abcesses and peritoneal
spread of metastases.
Page 24 of 54
Fig.: Hydatid cysts in the subhepatic, right paracolic gutter and pelvis on sagittal and
coronal MR.
Page 25 of 54
Page 26 of 54
Fig.: Coronal CT demonstrating hydatid disease in intraperitoneal regions of peritoneal
fluid stasis.
•
The lesser sac communicates with the other peritoneal spaces via the
epiploic foramen. By way of the greater and lesser omentum (and the
ligaments that constitute them) and the transverse mesocolon, which all
form the lesser sac boundaries, pathological involvement can also be
seen in the anterior pararenal space, mesenteric root and and along the
transverse colon.
•
For example, gastric neoplasms can spread to involve the the superior
border of the transverse colon, and vice versa. Similar patterns of spread
can also be seen with pancreatic pathology with preferential involvement of
the inferior border of the colon
Page 27 of 54
Fig.: Axial CT demonstrating peripancreatic collections involving the lesser sac, left
anterior pararenal space, mesenteric root and transverse mesocolon.
Inframesocolic compartment
•
The supramesocolic compartments communicates with the inframesocolic
compartments by way of the right paracolic gutter. Free communication
between the left paracolic gutter and left subphrenic space is prevented by
the phrenicocolic ligament.
Page 28 of 54
Fig.: Coronal CT peritoneogram demonstrating peritoneal spaces. Note, free
communication between the subphrenic and paracolic spaces is prevented on the left
by the phrenicocolic ligament.
Page 29 of 54
Fig.: Coronal CT demonstrating malignant ascites within all the intraperitoneal spaces.
Perforation
•
The location of free gas within the peritoneal spaces shows the likely site of
perforation. If there is a perforated duodenal ulcer, free gas will travel along
the hepatoduodenal ligament to collect in the ligamentum teres fissure. This
may be the only manifestation of pneumoperitoneum.
Page 30 of 54
Fig.: Coronal and axial CT in a patient with a perforated duodenal ulcer demonstrating
the location of free gas.
Page 31 of 54
Fig.: Coronal CT demonstrating the distribution of free gas following a perforated
duodenal ulcer.
•
If there is perforation of the colon, most commonly from sigmoid diverticulitis,
free gas will initially pass along the sigmoid mesentery to collect in the
peritoneal spaces, primarily inferiorly.
Page 32 of 54
Fig.: Axial CT in patient with perforated diverticulits showing extensive free gas
spreading along mesenteric planes
Page 33 of 54
Fig.: Axial and coronal CT in patient with perforated diverticulits showing extensive
free gas spreading along mesenteric planes
Pelvis
•
•
The broad ligament is a peritoneal reflection forming the mesentery for the
ovaries, fallopian tubes and posterior myometrium. It also drapes over the
ureters and round ligament of the uterus.
These ligaments and mesenteries act as a pathway for local spread
between structures.
Page 34 of 54
Fig.: Axial and coronal CT peritoneogram demonstrating pelvic peritoneal
reflections and spaces.
References: R. Patel; Radiology, Royal Free Hospital, London, UNITED
KINGDOM
•
The recto-uterine (females) and rectovesical (males) are the most
dependent regions within the pelvis resulting in fluid stasis and therefore,
these are common sites for abscesses, fluid collections and metastases.
Page 35 of 54
Fig.: Top right: Sagittal schematic diagram of pelvic peritoneal spaces
Bottom left and right: sagittal CT peritoneogram and MR demonstrating the
recto-vesical space and recto-uterine space, respectively. Top right: sagittal
MR demonstrating hydatid disease within this dependent pelvic space.
References: R. Patel; Radiology, Royal Free Hospital, London, UNITED
KINGDOM
Extraperitoneal spaces
•
The small bowel mesentery divides the inframesocolic compartment into
right and left. Fluid collections between the leaves of the mesentery, and
therefore extraperitoneal, are often triangular shaped.
•
Fluid from bowel injuries, as opposed to solid organs injury, may initially
bleed between mesenteric folds. Fluid/blood is not seen in the paracolic
gutters or pelvis. Conversely, solid organ injury will initially bleed around the
injured organ. Fluid/blood then extends down the paracolic gutters and into
the pelvis. Only once these readily accesible spaces are filled will fluid/blood
extend between the mesenteric leaves.
Page 36 of 54
Fig.: Coronal CT demonstrating a triangular shaped pocket of fluid between the leaves
of the small bowel mesentery.
Page 37 of 54
Fig.: Left: Axial CT demonstrating fluid between leases of mesentery following bowel
injury. Right: pattern of free fluid pooling following solid organ injury,in this case
traumatic splenic injury.
•
Retroperitoneal fluid can sometimes be difficult to distinguish from
intraperitoneal fluid.
Page 38 of 54
Fig.: Axial CT demonstrating intra- and retropeitoneal fluid.
•
Some fluid collections or heamatomas are easily identified as being
retroperitoneal.
Page 39 of 54
Fig.: Coronal CT demonstrating retroperitoneal bleed from right kidney following
trauma. 25 year old man kicked by a horse.
Extraperitoneal rupture of the bladder shows a typical appearance with fluid seen in the
perivesical space giving a classic 'molar tooth' appearance.
Page 40 of 54
Fig.: Axial CT image showing extraperitoneal fluid following bladder rupture.
Images for this section:
Page 41 of 54
Fig. 1: Axial views from CT peritoneogram demonstrating peritoneal spaces in the upper
abdomen. Correlated with schematic diagram
Page 42 of 54
Fig. 2: Coronal and sagittal view from CT peritoneogram demonstrating upper abdominal
peritoneal spaces.
Page 43 of 54
Fig. 3: Hydatid cysts in the subhepatic, right paracolic gutter and pelvis on sagittal and
coronal MR.
Page 44 of 54
Fig. 4: Coronal and axial CT in a patient with a perforated duodenal ulcer demonstrating
the location of free gas.
Page 45 of 54
Fig. 5: Axial and coronal CT in patient with perforated diverticulits showing extensive free
gas spreading along mesenteric planes
Page 46 of 54
Fig. 6: Axial and coronal CT peritoneogram demonstrating pelvic peritoneal reflections
and spaces.
Page 47 of 54
Fig. 7: Top right: Sagittal schematic diagram of pelvic peritoneal spaces Bottom left and
right: sagittal CT peritoneogram and MR demonstrating the recto-vesical space and rectouterine space, respectively. Top right: sagittal MR demonstrating hydatid disease within
this dependent pelvic space.
Page 48 of 54
Fig. 8: Coronal CT demonstrating a triangular shaped pocket of fluid between the leaves
of the small bowel mesentery.
Page 49 of 54
Fig. 9: Left: Axial CT demonstrating fluid between leases of mesentery following bowel
injury. Right: pattern of free fluid pooling following solid organ injury,in this case traumatic
splenic injury.
Page 50 of 54
Fig. 10: Axial CT demonstrating intra- and retropeitoneal fluid.
Page 51 of 54
Fig. 11: Axial CT image showing extraperitoneal fluid following bladder rupture.
Page 52 of 54
Conclusion
•
A thorough understanding of peritoneal anatomy and physiology can aid
radiological interpretation and narrow the differential diagnosis of a wide
variety of pathological processes including perforations, trauma, infections
and spread of malignancy.
•
Using CT (including CT peritoneograms) and MR we have demonstrated
how the peritoneal anatomy determines involvement of the intra- and extraperitoneal spaces following various pathological processes.
•
A thorough understanding of peritoneal anatomy and physiology results in
more accurate radiological interpretation.
Personal Information
Dr. Roopal R. Patel
Specialist Registrar in Radiology
Royal Free Hospital Radiology Scheme, London
Email: [email protected]
Dr Isobel Beal
Radiology Consultant
Royal Free Hospital, London
Dr Katie Planche
Radiology Consultant
Royal Free Hospital, London
Email: [email protected]
References
Page 53 of 54
1. Angela D Levy. Peritoneum and Mesentery - part I Anatomy. Radiology Assistant 2009.
2. Morton A Meyers. Dynamic Radiology of the Abdomen.
3. Yoo et al. Greater and Lesser Omenta: Normal anatomy and pathologic processes.
Radiographics 2007;27: 707-720
4. DeMeo et al. Anatomic CT Demonstration of the peritoneal spaces, ligaments and
mesenteries: Normal and pathologic processes. Radiographics 1995; 15: 755-770.
5. Elsayes et al. MRI of the peritoneum: Spectrum of abnormalities. AJR 2006; 186:
1368-1379.
6. Moore KL and Dalley AF. Clinically Orientated Anatomy. 1999. Fourth edition: 209-218.
Page 54 of 54

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