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Omentum:
Good Cop or Bad Cop?
Omentum – Purpose?
• Hippocrates: formation and absorption of fluid
• Aristotle: protects the intestine against cold
• Vesalius: fixation ligament for the transverse
colon
• Ross (1890’s): protects the intestine against
injury “It is like a man-of-war ready to
sail to any port in which there is impending
trouble”
Sir Rutherford Morison
British Medical Journal 1906
• “A special protective agency…the
abdominal policeman. It travels
around the abdomen with
considerable activity, and is attracted
by some sort of information to
neighborhoods in which mischief is
brewing”
OmentumThe Policemen of the Abdomen
Omentum:
Good Cop or Bad Cop?
Omentum
• What is it and why does it exist?
• How does it work:
How does it move ?
How does it adhere ?
What is its role in malignancies ?
What is its role in bowel obstruction?
• What good is it?
Omentum
• How can we use it:
• Should we remove it?
Omentum - Structure
J. Pathology 1926 Florey, Walker and
Carleton
“The question of omental reaction resolves
itself into two questions: (1) through what
agency does the omentum get into contact
with an injured area or foreign body, and (2)
how does it attach itself thereto?”
How Does It Move?
• Intrinsic omental movement
o “chemiotaxis”
o Morison – moves like a jelly fish
o Cantacuzene – differences in electric potential
o Hertzler – leukocyte dependent “an individual’s
omentum is as smart as their leukocytes”
• Passive movement
– Diaphragmatic motion
– Peristalsis
– Gravity
Omentum - movement
Movements of the omentum were randomAllen MS, Surgery 1954
Omentum - Attachment
Omentum - Attachment
?
Omentum – What is its
function?Activated by:
– Infection
– Trauma
– Ischemia
– Foreign bodies
– Obesity
– Tumor metastases
Activation of the Omentum
One week after activation with foreign body:
• Milky spots expand 15 to 20-fold
• Blood vessel density increases 3-fold
• Increased production of:VEGF P-/ E- selectin bFGF
• Increased progenitor cells, marked by: – SDF-1α
– CXCR-4
– WT-1
Litbarg et al. Cell Tissue Res 2007
Boston: Officer O’mently
To The RescueSurgical Utility of Omentum
Plastic Surgical Applications
“The omental free flap is a valuable option
for reconstructive efforts in nearly all
anatomic regions. This is a result of its
inherent anatomy and vascularity, and its
angiogenic, immunogenic, and lymphatic
properties” Mazzaferro et al., J Reconstr
Microsurg 2018
Wound Bed Preparation
Omentum as Healer
• Vascularized Omental Lymphatic Transfer
(VOLT)
Omentum as Healer
• Anastomotic augmentation
– Duodenum
– Colon
– Esophagus
– Bronchus
Graham Patch
for perforated ulcer
Anastomotic Augmentation
Does Omentum Improve
Anastomotic Healing?• Dai et al. Surgery 2011 Prospective
randomized study esophageal cancer resections
(n=255)
– Anastomotic leaks:
• 1% with omentum wrap
• 6% w/o omentum wrap p< 0.05
– Strictures:
• 6% with omentum wrap
• 16% w/o omentum wrap p< 0.05
Does Omentum Improve
Anastomotic Healing?• Wiggins et al. Surgical Oncology 2015
Meta-analysis of esophageal and
colorectal anastomoses ( 9 studies, n= 2296)
– Esophageal leaks:
• 2.9% with omentum wrap
• 10.5% w/o omentum wrap p< 0.0001
– Colorectal leaks:
• 5.0% with omentum wrap
• 8.4% w/o omentum wrap NS
No difference in stricture or mortality
Anastomotic Healing
Bronchus in lung transplantation or lung
resection?
How Does Omentum Augment
Anastomotic Healing?• Neovascularity
– VEGF?
• Improved control of infection/ inflammation
– Milky spots
• Structural integrity
Omentum
Anastomotic Healing
Bronchus in lung transplantation or lung
resection?
Dog studies: omentum increases
capillary ingrowth to bronchus after auto-
transplantation
Early years of lung transplantation;
routinely used omental wraps -> now rarely
Anastomotic Healing
Bronchus in lung transplantation or lung
resection?
Pancreatic fistula prevention?
Meta analysis w/ 2971 patientsTian Y et al. Hepatogastroenterology 2015
No reduction
Omentum as Healer
Subtotal nephrectomy model
Rat model of 5/6 nephrectomy
Control animals had omentectomy
Experimental animals polydextran gel
particles injected to activate omentum
Omentum as Healer
• After 12 weeks:
– Experimental rats had lower creat, BUN, less
glomerulosclerosis, thinner basement
membrane
– Stem cell Antigen-1, WT-1, and CD34
expression at the renal-omentum interface
Omentum slowed the progression of CKD, and
the repair of the injured kidney was associated
with stem cell activity derived from the omentum
Omentum as Healer
Subtotal nephrectomy model
Activated omentum preserves renal function
Intra-abdominal fistula management
Reduction of femoral artery aneurysm after
axillary- bifemoral by-pass
Myocardial perfusion
Neural injury/ scarring/ ischemia
©2005American Society of Plastic Surgeons. Published by Lippincott Williams & Wilkins, Inc. 2
Fig. 3
s of the Wrist: A Long-Term Follow-Up.Gbert; Steichen, James
Plastic & Reconstructive Surgery. 115(1):163-171, January 2005.DOI: 10.1097/01.PRS.0000138808.77038.D7
Fig. 3 . Omentum placed around the median nerve and microvascular anastomosis performed in the distal forearm.
Omentum as Healer- Infection
• Omental flaps for:
– Mediastinitis
– Vascular graft infections
65 patients 93% survival
Frautschi RS et al. Ann Plast Surg 2017
– Infected AAA
Infected Abdominal Aortic
Aneurysm
Omentum as Healer
• Treatment for CNS disease:
– Spinal cord injury
– TIA
– Stroke
– Alzheimer’s Disease?
Neurotrophic factors
Improved neovascularization – esp. MMD
Konieczny MJ et al. World Neurosurgery 2016
Omental Transposition for
Alzheimer’s Diseaes• Hypothesis: Decreased cerebral blood
flow is a cause of AD, not a consequence
of AD
• 9 of 25 patients treated with OT had
reversal of symptoms
• Theory: improved blood flow & VEGF,
stem cells, nerve growth factors
Omentum as Safe Harbor
• Tissue engineering “incubator”
Porcine Engineered Intestine
Grikscheit, CHLA
Engineered Intestine
Courtesy of T.
Grikscheit, CHLA
Omentum as Source of
Problems• Cysts
• Torsion
• Site of metastases
• Adhesive bowel obstruction
• Spontaneous bleeding
• “Engine of obesity”
Omentum - Obesity
Omentum: Role in Obesity
Omentum in Obesity
• Produces adipokines:
Resistin Adiponectin
MIP MCP-1
IL-6 TNFα
GRO TIMP-1
• Omental fat effects myometrial artery
contraction
Omentectomy as Rx for Obesity
• 2002 – 50 patients randomized to
omentectomy vs. no omentectomy with
adjustable gastric banding.
– Omentectomy associated with significantly
improved insulin sensitivity and glucose
tolerance at 2 years
• 2017 – 49 patients randomized to gastric
by-pass with and w/o omentectomy
– No significant improvement on weight, insulin
sensitivity, or hemodynamic profile
Omentum - metastases
• Intra-abdominal malignancies
Ovarian, gastric, colon
• Adipocytes: micro-environment favorable
to metastases
Omentum - metastases
• Intra-abdominal malignancies
Ovarian, gastric, colon
• Adipocytes: micro-environment favorable
to metastases
Chemokines Adhesion molecules
Growth factors
Omentum – To keep or
remove?• David Tapper – “get rid of that (damn)
omentum. If you don’t, it will always
(mess) you up.”
• “The greater omentum, a useless and
hazardous organ for the patient and
surgeon. Advantages of omentectomy in
all abdominal operations” Yodice in El Dia
Medico, 1963
Omentum – Role in Adhesions
Injury
Inflammation -> Fibrinous exudate
Decrease of t-PA
Overaccumulation of fibrin exudates
Increase of PAI-1
and PAI-2
Omentum – To keep or remove?
Peritoneal dialysis
Retention of omentum:
? Increased filtration
? Improved immunologic protection
? Increased obstruction
Phan et al.
J Ped Surg 2013: Lack of omentectomy associated
with 2-fold increased risk of infection and malfunction, and
higher mortality
Omentum – To keep or
remove?Ariake et al. Int. J. Surg 2015
Case:control study of 113 patients w/ ASBO
18 developed recurrence
95 no recurrence
Multivariate analysis: Omentectomy was
associated with 3-fold risk of recurrent
ASBO
Omentum – Good Cop or Bad
Cop?
Omentum
• Simple structure -> complex physiology
• Provides protection
• Versatile applications
• Central role in obesity
Must be treated with respect!
Omentum – Good Cop or Bad
Cop?
Good
Bad