Transcript THE PANCREAS - Orange Coast College

THE PANCREAS
I. Introduction/General Information
A. Located in epigastric & left
hypochondriac regions
B. Dimensions:
1. 5 - 6” length x
2. 1-1/2” width x
3. 1/2 - 1” thick
C. Lies retroperitoneally at ~T-12/L-1
to L-3
The Pancreas in situ
Right lobe of liver
Falciform ligament
Gallbladder
Pancreas
Duodenum
L-3
Pancreas, Introduction, continued …
D.
Head fills concavity of duodenum
E.
Body crosses left kidney
F.
Tail reaches hilus of the spleen
G. Related anteriorly to transverse
colon
Pancreas in situ
Duodenum
Head of Pancreas
Pancreas, Introduction, continued …
H. Aorta, IVC lie posterior
I.
Uncinate process:
a. Lies posterior to SMA and SMV
b. Lies anterior to aorta
J.
Neck lies anterior to SMV, with
pylorus just above
Venous Drainage of the Pancreas
IVC
SMV
Introduction, continued
L. Body related
posteriorly to left
crus, left adrenal,
left renal vein, and
splenic vein
K. Celiac Axis
(trunk, artery) lies
superior to body
II. Detailed Anatomy
A. Landmark structures
1. Splenic Artery:
a. Branch of celiac
trunk
b. passes right to
left
c. Course is along
upper margin of
body and tail
Detailed Anatomy, con’t…
2. Hepatic Artery:
a. Branch of celiac trunk
b. courses left to right
c. along upper margin of neck and
head
3. Superior Mesenteric Artery: at its
origin from aorta, points at body of
pancreas
Arterial Supply to Pancreas
Proper Hepatic
Artery
Common Hepatic
Artery
Superior
Mesenteric Artery
Landmark structures, continued …
4. Splenic Vein:
a. runs parallel
to artery
b. on posterior
surface of
pancreas
c. Terminates in
portal vein
Landmark structures, continued …
5. Superior & Inferior
Mesenteric Veins:
a. pass (inferior to
superior) deep
to pancreas
b. merge with splenic
vein
c. Terminate in portal
vein
Landmark structures, continued …
6. Common Bile Duct:
a. passes behind first portion of
duodenum
b. then through head of pancreas
c. Terminates at ampulla of vater
Detailed Anatomy continued …
B. Head of Pancreas
1. Important clinically because:
a. Numerous ducts and vessels traverse it
b. Carcinoma usually located here
Head of Pancreas, Detailed Anatomy, continued …
2. Tumor will compress surrounding
structures
a. First indication may be jaundice
b. Tumor may compress
duodenum
c. May involve local vessels
*Metastases may spread through these vessels*
Head of Pancreas, Detailed Anatomy, continued …
3. Lymphatics from head of pancreas
a. Drain to celiac nodes
b. metastases may follow lymph
c. Metastases may spread via
lesser omentum to liver
d. Some terminate in lumbar nodes
Head of Pancreas, Detailed Anatomy, continued …
4. Vessels supplying head of pancreas
a. Superior & inferior
pancreaticoduodenal arteries
b. Both divide into two parallel
vessels
c. one anterior and one posterior to
head
Head of Pancreas, Detailed Anatomy, continued …
1. Anterior branch of
pancreaticoduodenal
artery
a. superior branch:
anterior superior
pancreaticoduodenal
artery
b. inferior branch:
anterior inferior
pancreaticoduodenal
artery
Head of Pancreas, Detailed Anatomy, continued …
2. Posterior branch of
pancreaticoduodenal
artery
a. superior branch:
posterior superior
pancreaticoduodenal artery
b. inferior branch:
posterior inferior
pancreaticoduodenal artery
**extensive blood supply**
Anterior Pancreaticoduodenal Artery
•Branches are
continuous with
one another
•Superior
branches
originate from the
GDA
•Inferior branches
originate from the
SMA
Detailed Anatomy, continued …
C. Body & Tail of Pancreas:
1. Supplied by splenic artery
2. Have three surfaces:
a. Anterior surface
1. Concave
2. Deep to stomach
3. Separated from stomach by
lesser sac of peritoneum
(aka omental bursa)
Anterior surface of pancreas
Epiploic
foramen
Anterior surface
of pancreas
Lesser sac, continued …
4. Lesser sac bounded by:
a. Liver, superiorly
b. Below, extends to
greater omentum
c. Anteriorly: lesser
omentum, stomach,
greater omentum
Lesser sac, continued …
d. Posteriorly: greater
omentum
transverse colon,
transverse mesocolon
e. Laterally:
1. Foramen of Winslow on
right
2. Spleen on left
Detailed Anatomy, continued …
f. Foramen of Winslow (AKA: Epiploic
Foramen):
1. Lies between greater & lesser
sacs of peritoneum
2. posterior to free edge of
lesser omentum
3. close to porta hepatis
Three Surfaces, continued …
2. Posterior surface:
a.
b.
c.
d.
e.
f.
separated from vertebrae by
Aorta
Splenic vein
Left kidney and renal vessels
Left adrenal gland
Left Crus of diaphragm
SMA and SMV
Three surfaces, continued …
3. Inferior surface of Pancreatic body:
a. Rests on duodeno-jejunal flexure
b. Left extremity (tail)
1. Rests on splenic flexure
2. Abuts hilus of spleen
Detailed Anatomy, continued …
D. Pancreatic Duct System
1. Pancreatic Duct (of Wirsung)
a. Course is left to right
b. Receives numerous small ducts
c. @ neck of pancreas, duct turns
inferior, posterior & to the right
d. AKA “main pancreatic duct’
Duct of Wirsung (Main pancreatic duct)
Pancreatic Duct System, continued …
d. joins CBD at Ampulla of Vater
3 - 4” below pylorus
e. results from fusion of ducts during
fetal development
1. One from ventral pancreas
2. One from dorsal pancreas
(see Netter’s Embryology, p. 142, for Pancreas
development)
Duct of Wirsung
Duct of
Wirsung
Pancreatic Duct System, continued …
2. Duct of Santorini:
a. accessory pancreatic duct
b. Not universally identified
c. joins duodenum @ minor papilla
d. part of duct from dorsal pancreas
Duct of Santorini
Pancreatic Duct System, continued …
3. In 10% of population
a. ducts fail to fuse
b. result is drainage of tail, body, &
most of head through minor papilla
c. Not pathological
III. Scanning Anatomy
A. Depends on recognition of pancreatic
margins
B. Sonography best used as screening
procedure
1. May be interference from bowel
gas (especially in tail region)
Scanning Anatomy, continued …
2. Extremely accurate in detection
of pseudocysts
3. U/S can show texture of organ
4. By ID-ing vessels, can delineate
head, portions of body
Scanning Anatomy, continued …
5. U/S can frequently detect dilation
of pancreatic duct
6. Splenic Vein: landmark vessel
a. usually seen along posterior
margin of body, tail
b. May be anterior (~30%)
Scanning Anatomy, continued …
C. Head:
1. SMV outlines medial head to neck
region
2. Duodenum & GB outline lateral
head
3. Superiorly, delineated by
gastroduodenal artery (GDA)
4. Inferiorly, bounded by CBD
Scanning Anatomy, continued …
D. Further delineation by vascular
landmarks:
1. SMA:
a. Lies immediately posterior to
body, points to it!
b. Recognized by echogenic fat
collar surrounding vessel
Vascular Landmarks of the Pancreas

Pancreatic
sonography
depends largely
on identifying
surrounding
landmark vessels
Scanning Anatomy, continued …
2. SMV:
a. Delineates medial head
b. Larger diameter than SMA
c. Lies to right of SMA
d. Uncinate process wraps it (and
SMA), lies posterior & medial
Vascular Landmarks of the Pancreas

Venous
landmarks of the
pancreas
include the SMV
and renal veins
Scanning Anatomy, continued …
3. Left Renal Vein:
a. as it enters IVC
b. head & uncinate process should
lie within 1 – 2 cm
c. Landmark vessel posterior
to body of pancreas
Scanning Anatomy, continued …
E. Tail of Pancreas
1. May be visualized through fluid-filled
stomach
2. Tail seen as 2-3 cm rounded
mass anterior to hilus of left kidney
IV. Pancreatic Disorders
A. Pancreatitis: diagnosis depends on
clinical evidence
1. Usually secondary to biliary tract
disease
2. Surgery of biliary tract or stomach,
alcoholism are other causes
Pancreatitis, Pancreatic Disorders, continued …
3. Infrequent causes:
a. Infectious diseases
b. Trauma
d. Drugs
e. Hyperparathyroidism
4. Inflammation may be diffuse or spotty
Pancreatitis, Pancreatic Disorders, continued …
5. Important factor is release of protein
kinins
a. Increase permeability of vessels
& cells
b. Releases tissue fluid
c. Edema may compress vessels
d. Tissue damage occurs
Pancreatitis, Pancreatic Disorders, continued …
6. WBC’s may increase to 20,000/ml
7. Increase in pancreatic enzymes
a. serum bilirubinase (by 25%)
b. serum amylase
c. serum lipase
Pancreatic Disorders, continued …
B. Pseudocysts:
1. “False” cysts that may arise
a. due to tissue necrosis
b. From enzymatic destruction
2. May persist after inflammation subsides
3. Usually near or in pancreas
Pancreatic Disorders, continued …
4. Rarely, may be elsewhere
a. in abdomen or pelvis
b. Rarely, mediastinum
5. Pseudocyst appearance
a. unilocular or multilocular
b. echoes from pus & cellular debris
Pancreatic Diseases, continued
C. Acute Pancreatitis
1. Diffuse enlargement
2. Less echogenic due
to edema
3. Echogenicity usually >
liver parenchyma
Pancreatic Diseases, continued …
D. Chronic Pancreatitis
1. organ usually appears as small,
atrophic
2. Contains scattered echoes from
calcifications
3. Primary cause is alcoholism
Pancreatic Diseases, continued …
E. Dilation of Pancreatic Duct
1. Seen in acute or chronic
pancreatitis
2. Frequently associated with
neoplasm of pancreas
3. Biliary tract problems
Pancreatic Diseases, continued …
F. Abscess or Hemorrhagic Pancreatitis
1. Similar in sonographic appearance
2. Hemorrhagic:
a. Mass with inhomogeneous texture
b. Acute hemorrhage: sonolucent to
echogenic
c. CT scan used for differentiation
Pancreatic Disorders, continued …
G. Pancreatic Tumors
1. Malignant tumors usually arise
as adenocarcinomas
2. In head of Pancreas: Sx
a. Painless jaundice
b. Anorexia
Pancreatic Tumors, In head, continued …
c. Nausea
d. Weight loss
e. Increased plasma amylase
f. Increased alkaline phosphatase
g. May involve compression of
pancreatic duct, CBD
Pancreatic Tumors in the Head

Tumors in the head
may compress
biliary ducts or
pancreatic ducts
Pancreatic tumors, continued …
3. In Body of Pancreas: Sx
a. Gnawing pain radiating to back
b. Pain increases after eating or
lying down
c. Weight loss, anorexia
d. Large tumor may compress IVC,
portal vein
Pancreatic tumors, continued …
4. In Tail of
Pancreas: Sx
a. Often silent until local
metastasis occurs
b. May metastasize to:
1. para-aortic lymph
nodes
2. spleen
Pancreatic tumors, continued …
5. Identified by organ enlargement,
subtle echo changes, irregular outline
6. Metastases to stomach, liver & lungs
are common
7. Often causes dilation of ducts
Pancreatic Disorders, continued …
H. Fibrocystic Disease
1. Result of cystic fibrosis
2. Diagnosed by methods other than
ultrasound
Pancreatic Disorders, continued …
I. Pancreaticolithiasis
1. Characteristic stone echoes in pancreatic duct
2. May see atrophied pancreatic parenchyma
3. Associated with chronic alcoholic pancreatitis
4. Contours of body, tail show irregularities
Pancreatolithiasis, continued …
5. Incidence slightly higher in head
6. Associated with occult pancreatic
carcinoma
a. Mass < 2mm diameter
b. Seen with dilation of pancreatic
duct or CBD