Omental and Mesenteric
Conditions
Omentum
I. Anatomy
- double sheet of flattened endothelium
- epiploic vessels, lymphatics, nerves,
and fatty areolar tissue pass in
between
- hangs as a double fold between the
greater curve of the stomach to the
transverse colon, with the right side
usually longer and larger
- size depends on the amount of fat
- usually underdeveloped in innfants
II. Physiology
- “Policeman of the abdomen”; helps in
walling of inflammatory conditions
- areolar tissue is rich in inflammatory
conditions
III. Pathology
A. Torsion – twisting along its long axis
causing vascular compromise
* requirements for torsion
- redundant segment
- a fixed point
1. Etiology
a. Primary
- with predisposing factors such
as projections from the edge of
the omentum, obesity, and
venous redundancy
b. secondary
- associated with another
pathology such as omental cysts,
tumors, inflammatory conditions
or hernias
2. Pathology
a. twists in a clockwise direction
b. right side twists more
frequently
3. Clinical manifestations
a. pain
- sudden, constant, increasing in
intensity
b. nausea and vomiting
c. peritonitis
d. mass
4. Diagnosis
- laparotomy
5. Treatment
- resection
B. Idiopathic Segmental Infarction – acute vascular
occlusion not accompanid by torsion, intraabdominal
conditions, trauma, or cardiac disease
1. Etiology – thrombosis of the omental veins
secondary to endothelia injury
- usually involves the right side
2. Clinical manifestions – pain which is
gradual in onset, usually on the right
side
3. Diagnosis – CT scan which will show
a “smudged” appearance
4. Treatment – excision
C. Cysts
1. Pathology
a. obstructed lymphatic channels
b. growth of congenitally
misplaced lymphatic tissue
2. Clinical manifestations – palpable
mass
3. Diagnosis
a. x- ray – can diagnose dermoid
cyst
b. ultrasound
c. CT scan
4. Treatment – excision
D. Solid tumors
1. Pathology
a. metastatic carcinoma – most
common
b. hemangiopericytoma and
leiomyosarcoma – most common
primary tumors
2. Diagnosis
a. ultrasound
b. CT scan
3. Treatment – excision of the primary
tumor if possible and omentum
Mesentery
I. Anatomy
- a reflection of the posterior
peritoneum
- connects the intestines to the
posterior abdominal wall and carries
blood vessel and nerves
- root of the mesentery extends from
the ligament of Treitz at the level of L2
and is approximately 6 inches
- Mesocolon – suspensory ligament of
the transverse and sigmoid colon
- Space of Riolan – avascular space to
the left of the middle colic artery
- Mesenteric circulation
B. Pathology
1. Acute Occlusion of the SMA
a. embolism
- sudden occlusion of the main
branch of the SMA
- produces ischemia of the entire
small bowel distal to the ligament
of Treitz and proximal half of the colon
b. thrombosis
- occurs in an artery partially
occluded by atherosclerosis
- slowly developing stenosis may
allow time for collaterals to
develop
2. Pathology
- sudden complete occlusion first
causing an ischemic infarct in
which the bowel is pale
- later stages will show
hemorrhagic infarction
3. Clinical Manifestations
- surgical emergency with
extreme abdominal pain
- P.E. is not proportional to the
pain the patient perceives
- unresponsive to narcotics
- mottled, cyanotic abdomen
- absent bowel sounds
4. Diagnosis
a. arteriogram
b. WBC – leukocytosis
c. hct – hemoconcentration
d. metabolic acidosis
e. FPA – dilated bowel loops
5. Treatment
a. embolectomy
b. resection
c. antibiotics
d. anticoagulation
e. NGT
B. Non- occlusive Mesenteric Infarction
1. Etiology – low cardiac output from
MI, septic shock, arrythmia
2. Diagnosis – arteriography
3. Treatment
a. correct hypotension
b. vasodilators
c. antibiotics
CHF,
C. Chronic Occlusion of Visceral Arteries
1. Etiology – “intestinal angina”
- ischemia without infarction
- food pain sequence
2. Pathology – occlusion secondary to
atherosclerosis
3. Clinical Manifestation – crampy
abdominal pain when eating with
weight loss
4. Diagnosis – arteriogram
5. Treatment
a. arterial reconstruction
b. thromboendarterectomy
c. synthetic vein graft
d. resection
D. Occlusion of Mesenteric Veins
1. Etiology – usually secondary to thrombosis
2. Pathology – hyperemia, edema, subserosal
hemorrhage
3. Clinical Manifestations – vague discomfort,
severe abdominal pain
4. Treatment – resection, antibiotics, anticoagulant