Omental and Mesenteric Conditions

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Omental and Mesenteric Conditions
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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

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• - 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

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• III. Pathology
• A. Torsion twisting along its long axis
  causing vascular compromise
• requirements for torsion
• - redundant segment
• - a fixed point

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• 1. Etiology
• a. Primary
• - with predisposing factors such as
  projections from the edge of the omentum,
  obesity, and venous redundancy

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• 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

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• 3. Clinical manifestations
• a. pain
• - sudden, constant, increasing in intensity
• b. nausea and vomiting
• c. peritonitis
• d. mass

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• 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

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• - 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

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• 4. Treatment excision
• C. Cysts
• 1. Pathology
• a. obstructed lymphatic channels
• b. growth of congenitally misplaced
  lymphatic tissue

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• 2. Clinical manifestations palpable mass
• 3. Diagnosis
• a. x- ray can diagnose dermoid cyst
• b. ultrasound
• c. CT scan

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• 4. Treatment excision
• D. Solid tumors
• 1. Pathology
• a. metastatic carcinoma most common
• b. hemangiopericytoma and
  leiomyosarcoma most common primary
  tumors

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• 2. Diagnosis
• a. ultrasound
• b. CT scan
• 3. Treatment excision of the primary tumor
  if possible and omentum

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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

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• - Mesocolon suspensory ligament of the
  transverse and sigmoid colon
• - Space of Riolan avascular space to the
  left of the middle colic artery
• - Mesenteric circulation

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• 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

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• b. thrombosis
• - occurs in an artery partially occluded by
  atherosclerosis
• - slowly developing stenosis may allow time
  for collaterals to develop

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• 2. Pathology
• - sudden complete occlusion first
• causing an ischemic infarct in which the
  bowel is pale
• - later stages will show hemorrhagic
  infarction

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• 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

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• 4. Diagnosis
• a. arteriogram
• b. WBC leukocytosis
• c. hct hemoconcentration
• d. metabolic acidosis
• e. FPA dilated bowel loops

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• 5. Treatment
• a. embolectomy
• b. resection
• c. antibiotics
• d. anticoagulation
• e. NGT

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• B. Non- occlusive Mesenteric Infarction
• 1. Etiology low cardiac output from CHF, MI,
  septic shock, arrythmia
• 2. Diagnosis arteriography
• 3. Treatment
• a. correct hypotension
• b. vasodilators
• c. antibiotics

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• C. Chronic Occlusion of Visceral Arteries
• 1. Etiology intestinal angina
• - ischemia without infarction
• - food pain sequence
• 2. Pathology occlusion secondary to
  atherosclerosis

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• 3. Clinical Manifestation crampy abdominal
  pain when eating with weight loss
• 4. Diagnosis arteriogram

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• 5. Treatment
• a. arterial reconstruction
• b. thromboendarterectomy
• c. synthetic vein graft
• d. resection

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• 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