Diagnostic ultrasound ( PDFDrive )

CHAPTER 7 The Pancreas 219
D
IVC
A
Accessory
Santorini
Main
Wirsung
B
Functional description
Embryologic origin
FIG. 7.17 Pancreatic Ductal Anatomy. (A) Pancreatic head. Transverse sonogram shows the accessory pancreatic duct (white arrow). The main
pancreatic duct (yellow arrow) is seen dorsal and medial to the common bile duct (red arrow). D, Duodenum; IVC, inferior vena cava.
(B) Pancreatic ductal system, functional description. Accessory duct is shown in tan (black arrow) and the main duct in white (orange arrows). The
accessory duct persists in only a minority of individuals. (C) Pancreatic ductal system, embryologic origin. Dorsal component of main adult duct
and the accessory duct (black arrows, duct of Santorini, pink) both originate from the dorsal anlage. Ventral component of main duct (orange arrow,
duct of Wirsung, brown) in pancreatic head arises from the ventral anlage and usually fuses with main duct from pancreatic body (dorsal anlage).
C
(Fig. 7.20). his explains why luid in the stomach can sometimes
be helpful in sonographic visualization of the pancreas. he lesser
peritoneal sac is situated between the lesser omentum, greater
omentum, and the stomach anteriorly and the parietal peritoneum
and transverse mesocolon posteriorly (Fig. 7.21).
he antrum and duodenal bulb are intraperitoneal structures,
whereas the duodenal sweep (second and third parts of duodenum)
is retroperitoneal and hugs the pancreatic head. he
third portion of the duodenum is a useful landmark, deining
the caudal aspect of the pancreatic head. he transverse colon
and hepatic lexure oten overlie the pancreas, sometimes obscuring
direct visualization.
he transverse mesocolon arises from the anterior pancreas
and duodenum, formed by the parietal peritoneum that
invests the pancreas and duodenum. he transverse mesocolon
invests the transverse colon and forms part of the posterior limits
of the lesser peritoneal sac.
he tail of the pancreas lies within the splenorenal ligament
and contacts the let kidney, let colic (splenic) lexure, and the
hilum of the spleen posteriorly. hus a portion of the pancreatic
tail is intraperitoneal and somewhat mobile.
ACUTE PANCREATITIS
Acute pancreatitis is deined by the International Symposium
on Acute Pancreatitis (Atlanta, 1992) as “an acute inlammatory
process of the pancreas with variable involvement of other regional
tissues or remote organ systems associated with raised pancreatic
enzyme levels in blood and/or urine.” 27 More than 300,000 patients
are admitted to US hospitals annually with acute pancreatitis. 28
It is diicult to determine the prevalence of acute pancreatitis
because mild pancreatitis is oten missed. he annual incidence
of acute pancreatitis has been reported as 5 to 35 per 100,000
population. 29