Mesentry and omenum.pptx

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Mesentry and omentum
Anatomy and Surgical Disorders

Anatomy of omentum
1- Omenta :
Broad peritoneal sheet associated
with stomach are termed omemta.
Two omenta
Lesser omentum
Greater omentum

-
Lesser omentum
Two-layered fold of peritoneum
Passes from the lesser curvature of the
stomach
and first part of the duodenum
to the inferior surface of the liver.
Extends from porta hepatis,
fissure of ligamentum venosum
and the diaphragm to lesser curvature
of stomach and superior part of
duodenum
•

Lesser omentum
• Hepatogastric ligament from
porta hepatis to lesser curvature
of stomach
• Hepatoduodenal ligament
- Extends from porta hepatis
to superior part of
duodenum,
- at its free margine enclose 3
structures(3 key structures)
common bile duct Ant.
proper hepatic a At the Lt. of the
common bile duct
portal v post.

-
• Blood vessels Rt. & Lt. gastric vessels
• Lymph nodes & lymphatic vessels
• Fat
• Autonomic N.S sympathetic +
parasympathetic (vagus nerve)
Contents of lesser omentum

-
Greater omentum
- It is the largest peritoneal fold.
- It consists of a double sheet, folded on
itself so that it is made up of four layers.
- The anterior two layers descend from the
greater curvature of stomach and superior
part of duodenum and hangs down like an
apron in front of coils of small intestine
- then turn up on the back of itself, and
ascend to the transverse colon .
- the two layers are separated to cover the
anterior and posterior surfaces of
transverse colon. Then they form the
transverse mesocolon

-
• The upper part of the greater
omentum which extends
between the stomach and the
transverse colon is termed the
gastrocolic ligament.
• In adult, the four layers of
greater omentum are
frequently adhered together,
and are found wrapped about
the organs in the upper part of
the abdomen

-
Contents of Greater omentum (between
the descended layers)

-
Contents of Greater omentum (between
the descended layers)
• Gastroepiploic vessels
• Lymph nodes & lymphatic vessels
• Fat
• Autonomic N.S sympathetic +
parasympathetic (vagus nerve)

-
Functions of greater omentum

-
• ① protective function: The greater omentum contains
numerous fixed macrophages, which performs an
important protective function.
• ② storehouse for fat: The greater omentum is usually thin,
and presents a cribriform apperarance, but always contains
some adipose tissue, which in fatty people is present in
considerable quantity.
• ③ migration and limation: The greater omentum may limit
spread of infection in the peritoneal cavity. Because it will
migrate to the site of any inflammation in the peritoneal
cavity and wrap itself around such a site, the greater
omentum is commonly referred to as the “policeman” of
the peritoneal cavity.
Functions of greater omentum

MESENTERY
•Mesentery = double layer of peritoneum created by invagination
of peritoneum by an organ
•Is the continuity of visceral and parietal peritoneum
•Provides a pathway for neurovascular communication between
organ and body wall
•Contains lymph nodes and variable amounts of fat
•The mesentery is the mesentery of the small intestine
•The mesocolon is the mesentery of the large intestine
• Transverse mesocolon
• Sigmoid mesocolon

-
1- Mesentery of small intestine
-suspends the small intestine from
the posterior abdominal wall
-Broad and a fan-shaped
• Root of mesentery
– 15 cm long
– Directed obliquely from left
side of L2 vertebra to right
sacroiliac joint

-Mesentery of small
intestine….cont
Contents of the mesentery
- the jejunal and ileal
branches of the superior
mesenteric artery &veins
- nerve plexuses
- lymphatic vessels
- the lymphatic nodes,
- connective tissue
- fat

-
2- Mesoappendix
• Triangular mesentery－
extends from terminal part
of ileum to appendix
• Appendicular artery runs in free
margin of the mesoappendix

- 3. The transverse mesocolon
- It is a broad fold
- Connects the transverse colon
to the anterior border of the
pancreas.
• Contents
• - The blood vessels
• - Nerves
• - lymphatic's of the transverse
colon.

-4- Sigmoid mesocolon
• - It is a fold of peritoneum
- attaches the sigmoid colon to
the pelvic wall.
• Contents
- The sigmoid vessels
- Lymphatic vessels
- Nerves
- The left Ureter descends into
the pelvis behind its apex.

-
-
A wound of the mesentery can follow a severe abdominal contusion and is a cause of
haemoperitone um.
Conditions of the mesentery
Traumatic tears
Torsion
•Embolism/thrombosis
•Acute non-specific adenitis
•Tuberculosis adenitis
•Cysts
•Neoplasms - benign and malignant
•

Acute non-specific ileocaecal mesenteric
adenitis
• Aetiology
• very much more common than the tuberculous variety.
• aetiology often remains unknown,
• although some cases are associated with Yersinia
infection of the ileum.
• In other cases, an unidentified virus is blamed.
• In about 25% of cases, a respiratory infection precedes an
attack of non-specific mesenteric adenitis.
• This self-limiting disease is never fatal but may be
recurrent.

Pathology
• small increase in amount of peritoneal fluid.
• ileocaecal mesenteric lymph nodes are enlarged
• In very acute cases - distinctly red, many of them are size of a
walnut.
• Nodes nearest the attachment of the mesentery are the largest.
• Not adherent to their peritoneal coats, and if a small incision is
made through the overlying peritoneum a node is extruded
easily.

• During childhood, acute non- specific common condition.
• unusual after puberty
• sometimes seen in teenage girls.
• Typical history is one of short attacks of central abdominal pain
lasting from 10 to 30 minutes, and associated with circumoral pallor.
• They tend to come on when the patient is tired.
• Vomiting is common but there is no alteration of bowel habit.
• If vomiting is absent, it is more likely to be a case of mesenteric
adenitis than appendicitis.

History
• Onset and progression may be insidious or sometimes dramatic. Clinical
features of associated organ involvement, such as enterocolitis or ileitis
in Yersinia infection, may be present.
Clinical presentations include the following:
• Abdominal pain - Often right lower quadrant (RLQ) but may be more diffuse
• Fever
• Diarrhea
• Malaise
• Anorexia
• Concomitant or antecedent upper respiratory tract infection
• Nausea and vomiting (which generally precedes abdominal pain, as compared
to the sequence in appendicitis)
• History of ingestion of raw pork may be obtained in areas with
endemicYersinia (eg, Belgium).

Physical
• No set of physical findings is pathognomonic of mesenteric
lymphadenitis.
• Fever (38-38.5°C)
• Flushed appearance
• RLQ tenderness - Mild, with or without rebound tenderness
• Voluntary guarding rather than abdominal rigidity
• Rectal tenderness
• Rhinorrhea
• Hyperemic pharynx
• Toxic appearance
• Associated peripheral lymphadenopathy (usually cervical) in 20% of
cases

• Differential Diagnoses
• Appendicitis
• Benign Neoplasm of the Small Intestine
• Cholecystitis
• Chronic Mesenteric Ischemia
• Ectopic Pregnancy
• Inflammatory Bowel Disease
• Pyelonephritis, Acute
• Salpingitis
• Urinary Tract Infection, Females
• Urinary Tract Infection, Males

Laboratory Stud
• CBC count: Leucocytosis with WBCs exceeding 10,000/µL occurs in at least 50%
of cases.
• Chemistries: - Findings are generally within reference ranges except in patients
with severe nausea and vomiting who may present with metabolic alkalosis and
azotemia.
• Serology can be supportive in diagnosis of etiologic agents such as
Y enterocolitica.
Serological tests tend to be delayed, and several antigens may have to be tested.
• Urinalysis may be useful to perform when the diagnosis is unclear and to exclude
urinary tract infection.
• In patients who present with diarrheal symptoms, stool cultures should be
performed.
• Blood culture: This is performed prior to prescribing antibiotics and in patients who
have features of septicemia. Isolation of the organism from blood, lymph nodes, or
other body fluids will help define appropriate therapy and guide further evaluation.

Imaging Studies
• Contrast computed tomography (CT) demonstrates enlarged
mesenteric lymph nodes, with or without associated ileal or
ileocecal wall thickening, and a normal appearing appendix.
• In mesenteric adenitis, lymph nodes tend to be larger, greater
in number, and more widely distributed than in appendicitis.
Rao et al specified the criterion of
• 3 or more nodes with a short-axis diameter of at least 5
clustered in the right lower quadrant.
• CT scanning is also important to exclude other differential
diagnoses, especially acute appendicitis.

• Abdominal ultrasound scanning with Doppler
scanning is a useful adjunct for excluding other
differential diagnoses.
• For instance, ultrasonic demonstration of mural
thickening of the terminal ileum plus mesenteric
thickening is indicative of regional enteritis. Focal
abdominal tenderness in response to transducer
pressure is common. Ultrasound is often the
preferred initial diagnostic procedure, especially in
children with uncomplicated abdominal pain.

Tuberculosis of the mesenteric
lymph nodes

Tuberculosis of the mesenteric
lymph nodes
Tuberculous mesenteric lymphadenitis
• less common than acute non-specific lymphadenitis.
Tubercle bacilli, usually, but not necessarily,
• bovine, are ingested and enter the mesenteric lymph nodes
by way of Peyer's patches.
• It is possible for one draught of raw milk to start the
infection; it is equally possible that a toddler can become
infected with human tubercule bacilli by placing one dust-
covered small object in its mouth. Sometimes only one
lymph node is infected; usually there are several;
occasionally massive involvement occurs

Tuberculosis of Mesenteric Lymph
Nodes
• Isolated involvement of the mesentry in tuberculosis is
uncommon.
• Usually there is concomitant involvement of the bowel or
peritoneum, or more commonly, both.
• The patient will give a history of previous pulmonary
tuberculosis or is currently on treatment.
• Ingested tubercle bacilli reach the Peyer's patches in the bowel
and involvement of bowel.
• This gives rise to the involvement of the mesenteric nodes.
• Usually several lymph nodes are involved.
• Involvement of the bowel and the peritoneum is also seen.

Clinical presentation
• Asymptomatic:
The patient is asymptomatic with a calcified lymph node seen on X-ray.
• Toxemia:
The patient presents with symptoms of tubercular toxemia with evening pyrexia,
pallor, and anorexia and weight loss.
Very often, abdominal pain is present due the the involvement of the bowel.
• Abdominal mass:
Several matted lymph nodes in the right iliac fossa will give the appearance of a mass.
This may be confused with an appendicular mass or a carcinoma.
• Intestinal obstruction:
Subacute obstruction may be present due to the involvement of the ileocecal region of
the bowel.
•

Investigations
• Plain X-ray of the abdomen:
• It may show a calcified opacity similar to a
ureteric calculus.
• US abdomen should be performed in the
presence of a mass in the right iliac fossa.
• Multiple matted lymph nodes are clearly seen.
• In cases of involvement of the bowel, dilated
and thickened loops may be demonstrated.
•

• Barium meal follow-through:
When bowel involvement is suspected, the
patient presents with subacute obstruction.

T/t
• Anti-tubercular treatment (ATT):
Treatment is by a full course of antituberculosis chemotherapy.
ATT should be started with four antituberculous drugs for two months
(HRZE) and at least two of these (HR) are continued for at least 4
months.
• Laparotomy:
It is indicated in the presence of subacute intestinal obstruction due to
involvement of the ileocecal region.
Sometimes, the matted loops may cause a compression over the ileocecal
region along with contiguous involvement. In such case, an
ileotransverse anastomosis may be performed.
• Any adhesions are lysed and limited right hemicolectomy is performed
for involvement of the ileocecal region.

Mesenteric Trauma (Tears)
• Mesenteric vessels injured by penetrating or
blunt trauma of the abdomen.
Tear of the mesentery with laceration of the
vessel.
• In penetrating injuries of the mesenteric
vessels, associated injury to other organs is
frequent.
• Transverse tears carry more morbidity as they
often lead to damage of vascularity of the
bowel unlike longitudinal tears.

Clinical features
• The patient will present with
• shock,
• abdominal pain,
• tenderness
• distention.
This depends on the severity of injury and
associated injuries.

-
• -Treatment Exploratory laparotomy
• Gunshot wounds of abdomen most stab wounds should be explored early.
• Longitudinal tears are apposed after securing hemostasis but
• Transverse tears often require resection and anastomosis of a segment of the bowel
due to devitalization.
• Lacerations of the mesenteric veins can be ligated.
• Injury to the main trunk of the superior mesenteric artery, primary
suture or interposition of a vascular graft between the severed ends of
the vessel should be attempted.

-mesentric cyst
• Mesenteric cysts can occur anywhere in the
mesentery of gastrointestinal tract from
duodenum to rectum,
may extend from the base of the mesentery into the
retroperitoneum.
• 60% in the small-bowel mesentery,
• 24% in the large-bowel mesentery,
• 14.5% in the retroperitoneum.
• They most commonly occur in the ileal
mesentery of the small bowel or the sigmoid
mesentery of the colon.

Mesenteric cysts are of following type
a) Chylolymphatic (most common)
b) Enterogenous
c) Urogenital remnant
d) Dermoid (teratomatous cyst)

Chylolymphatic cyst
Usually are congenital, resulting from developmental sequestration of lymphatics.
• It is found most frequently in the mesentery of the ileum.
• Cyst wall is thin, made up of connective tissue; lacks the muscular wall of
enteric duplication cyst
• Cyst is not lined by mucosa.
• It is filled with clear lymph or chyle.
• A chylolymphatic cyst is almost invariably solitary, although in
extreme rare cases, multiple cyst may be seen. Cyst is more often
unilocular than multilocular.
• A chylolymphatic cyst has a blood supply independent of that of the
adjacent intestine, and thus enucleation
• (resection) is possible without the need for resection of gut.

Enterogenous Cyst
• Believed to be derived either from a diverticulum of the
mesenteric border of the intestine which has become
sequestered from the intestinal canal during embryonic
life or from a duplication of the intestine.
• An enterogenous cyst has thicker wall than a chylolymphatic
cyst, and it is lined by mucous membrane, sometimes
ciliated.
• The content is mucinous
• The enterogenous cyst and the adjacent bowel wall has a
common blood supply therefore enucleation of the cyst is
always done along with resection of the related portion of
intestine followed by anastomosis.

Clinical features
• a) a painless abdominal swelling, the swelling
moves freely in a plane at right angles to the
attachment of the mesentry.
• b) recurrent attacks of abdominal pain with or
without vomiting due to obstructive symptoms.
• c) acute abdominal pain due to torsion of the
mesentry containing cyst rupture of cyst
• haemorrhage into the cyst infection of the cyst

t/t
• Enucleation ls the t/t of choice.
Associated segment of bowel is removed
along with enterogenous cyst. Other tit
• modalities i.e. marsupialization, internal
drainage, or aspiration are suboptimal
and are almost always followed by
recurrence.

Acute Mesenteric ischemia
• This pt. is having ischemia of various
organs due to atherosclerotic narrowing
of arteries.
• • Ischemia of Brain ----->
CVA (stroke)
• • Ischemia of Heart ----->
Myocardial infarction
• • Ischemia of Intestines ----->

Etiology-
(A) Sudden Occlusion of the superior mesentric artery (50%)* Cause
• - Atherosclerosis * (90%)*
• Embolism *
• Vasculitis (PAN) *
• Fibromuscular dysplasia of mesentric artery*
(B) Mesentric vein occlusion (25%)
Cause -
• Thrombosis in hypercoaguable states such as polycythemia vera, *
OCp* use
• Infiltration by malignant neoplasm.
(C) Nonocclusive infarction (25%)
• Intestinal infarction may occur without physical obstruction of the
mesentric arteries in severe shock where there is prolonged
vasoconstriction in the intestinal arterial circulation.

• Pathology:
• Transmural necrosis of the intestinal wall.
This is rapidly followed by bacterial infection from
the lumen and acute inflammation leading to
wet gangrene*.
Both arterial and venous occlusion lead to
haemorrhagic infarction" and distinction cannot
be made on examination of bowel.

Clinical features
• AMI is characterized by a sudden onset of severe
abdominal pain (often colicky and periumbilical at the onset
,later becoming diffuse and constant ).
• fever; anorexia,vomiting and constipation frequent.
• Examination of abdomen may reveal tenderness & abdominal
distention.
• There is functional intestinal obstruction with absent
bowel sounds. Bloody diarrhoea may occur.
• • The disease progresses very rapidly with shock and
peritonitis due to bacterial permeation of the necrotic
bowel wall.
• • Without operation there is 100% mortality. Even with

• Abdominal plain films –reveal air – fluid
levels and distension.
• Barium study of small intestine-non specific
dilation,poor motility,evidence of thick
mucosal folds.
• Arteriography is diagnostic.
• Embolectomy is t/t

Omental Cysts
Cysts of the omentum are rare.
•True cysts:
These are caused by obstruction of lymphatic channels.
They may be unilocular or multilocular and contain serous fluid.
True cysts have an endothelial lining and may assume large sizes.
•Dermoid cysts
are uncommon and are lined with squamous epithelium and may contain
hair, teeth, and sebaceous material.
• False cysts:
Pseudocyst of the omentum result from fat necrosis, trauma with
hematoma, or foreign-body reaction. These have a fibrous and
inflammatory lining and usually contain cloudy or blood-tinged fluid.

• Abdominal mass: Large cysts present as a palpable
abdominal mass or produce diffuse abdominal swelling.
The uncomplicated omental cyst usually lies in the lower
midabdomen and is freely movable, smooth, and
nontender. These may cause symptoms of heaviness or
pain or manifestations of possible complications of
omental cysts such as torsion, infection, rupture, or
intestinal obstruction.

Investigations
• Plain X-ray of the abdomen:
It may show a soft tissue haziness.
The presence of bone or teeth is diagnostic of dermoid cyst.
• Barium meal follow-through:
It will demonstrate a displacement of bowel loops.
• Ultrasound or CT scan:
It shows a fluid-filled mass that often contains internal
septations.

Treatment
laparotomy and excision of the cyst should be
performed.

-Torsion of Omentum
uncommon condition
in which the organ twists on its long
axis, causing vascular compromise.
This may vary from
mild vascular constriction to
complete strangulation
leading to frank gangrene.

-ETIOLOGY
• The omentum twists around a fixed point
commonly due to adhesions of the free end of
the omentum due to
1.postoperative wounds,
2.scarring
3. internal or external hernias.

- Clinical features
Pain is the initial and predominant symptom.
The onset of pain is sudden and constant and
increases in severity.

Investigations
• CT scan may be of some use in diagnosing omental
pathology.

Treatment
• It consists of resection of the involved
omentum.
• In patients with torsion, the underlying
condition (hernia, cysts, adhesions,) should
be corrected.

Uses of Omentum
Intraabdominal:
• Repair of vesicovaginal and vesicocolic
fistulas
• Augmentation of bowel anastamoses
• Augmentation of wound closures involving
the urinary bladder
• Repair of defects of the abdominal wall

Uses of Omentum
Extraabdominal :
Support of primary suture lines of the
esophagus
• Closure of full-thickness defects of the
esophagus
• Repair of thoracic wall defects
• Palliation of lymphedema of an extremity
• Revasularization of tissue that is ischemic
• -brain of stroke victims
• -myocardial ischemia

Uses of Omentum
Extraabdominal : contd.
• Resurface scalp defects
• Reconstruct facial deformities
• Repair of bronchopleural fistulas

MCQ
1..Which one of the following is not correct regarding
chylolymphatic cyst ? (UPSC/03)
(a) It does not contain chyle very frequently
(b) Enucleation is impossible because blood supply is same
as that of the adjacent intestine
(c) It is the commonest mesenteric cyst
(d) It is lined by endothelium and has no different lymphatic
communications

1..Which one of the following is not correct regarding
chylolymphatic cyst ? (UPSC/03)
(a) It does not contain chyle very frequently
(b) Enucleation is impossible because blood supply is same
as that of the adjacent intestine
(c) It is the commonest mesenteric cyst
(d) It is lined by endothelium and has no different lymphatic
communications

2.Most common type of mesenteric cyst is:
(AIIMS 93 ,KARNATAKA 2008)
(a) Enterogenous
(b) Chylolymphatic
(c) Dermoid
(d) Urogenital remnant

2.Most common type of mesenteric cyst is:
(AIIMS 93, KARNATAKA 2008)
(a) Enterogenous
(b) Chylolymphatic
(c) Dermoid
(d) Urogenital remnant

3.Which is mesenteric cyst whose removal
entrails removal of part of gut:
(a) Chylolymphatic cyst
(b) Enterogenous cyst
(c) Dermoid
(d) All

3.Mesenteric cysts A/E (DNB Dec 07)
A. Chylolymphatic
B. Urogenital remnant
C. Dermoid cyst
D. Calcified lesion

4.All the following are feature of Mesenteric
cyst except (JI P -1993)
(a) common in infants
(b) swelling near umbilicus
(c) painless swelling
(d) can present as acute abdomen

4.All the following are feature of Mesenteric
cyst except (JIP -1993)
(a) common in infants
(b) swelling near umbilicus
(c) painless swelling
(d) can present as acute abdomen

5.True about mesenteric cyst: (PGI 97)
(a) Enterogenous cyst is the most common
variety
(b) Mesenteric cyst are usually multiple
(c) Enucleation is the treatment of choice of
chylolymphatic cyst
(d) Recurrence is common after enucleation

6.Mesenteric cyst" (AI 98)
a)Moves parallel to the mysentery
b)Moves perpendicular to the mesentery
c)Is secondary tumour
d)Is fixed and immobile

7.Commonest cuase of acute mesentric
adenitis is (JIPMER 81, AMU87)
a) Tuberculosis
b) Brucellosis
c) Pneumococcal infection
d) Idiopathic

8.Most common cause of mesenteric
ischemia? (AIIMS Nov 08)
• A. Embolism
• B. Non-occlusive ischemia
• C. Arterial thrombosis
• D. Venous thrombosis

9.True about mesenteric vein
thrombosis - (PGI DEC 2000)
a)Peritoneal signs are always present
b)Invariably involves long length of bowel
c)I.V. Heparin is the treatment of choice
d)Surgery can lead to short-bowel syndrome

10.Mesenteric tumors are
a) Usually solid.
b) Usually cystic
c) Highly malignant.
d) Highly vascular

• 10.Mesenteric tumors are
a) Usually solid.
b) Usually cystic
c) Highly malignant.
d) Highly vascular

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