Pancreas

CHAPTER 16
Pancreas


Firas Madbak


Test Taking Tip


• Neuroendocrine tumors of the pancreas are a favorite. Know the clinical presentation, diagnosis, and medical and surgical treatment particularly in conjunction with multiple endocrine neoplasia (MEN) syndromes.


ANATOMY/PHYSIOLOGY


What is the duct of Wirsung?


Major pancreatic duct that forms in the pancreatic head and descends inferiorly and joins the intrapancreatic portion of the common bile duct to form the common pancreaticobiliary channel proximal to the ampulla of Vater.


What is the duct of Santorini?


Accessory pancreatic duct that drains the anterior portion of the pancreatic head


Image


FIGURE 16-1. Arterial supply to the pancreas. Multiple arcades in the head and body of the pancreas provide a rich blood supply. The head of the pancreas cannot be resected without devascularizing the duodenum unless a rim of pancreas containing the pancreaticoduodenal arcade is preserved. (Reproduced from Brunicardi FC, Andersen DK, Billiar TR, et al. Schwartz’s Principles of Surgery. 9th ed. www.accessmedicine.com. Copyright © The McGraw-Hill Companies, Inc. All rights reserved.)


What is the blood supply to the head of the pancreas?


Anterior and posterosuperior pancreaticoduodenal arteries from the gastroduodenal artery that form collaterals with branches of the superior mesenteric artery (SMA) (inferoanterior and posterior pancreaticoduodenal arteries)


What is the venous drainage?


It parallels the arterial supply; drains into the portal system via the superior mesenteric and splenic veins.


Which enzyme is responsible for pancreatic necrosis in presence of bile?


Phospholipase A


What defines a high-output pancreatic fistula?


Output in excess of 200 mL/d


BENIGN PANCREATIC DISEASES


What are the etiologies of acute pancreatitis?


Gallstones and alcohol account for >90% of cases. Other causes include hyperlipidemia, hypercalcemia, trauma, pancreatic duct obstruction, ischemia, drugs, familial, and idiopathic.


What are some common medications implicated as possible etiologies of pancreatitis?


Azathioprine, furosemide, thiazides, sulfonamide, tetracycline, steroids, estrogens, ethacrynic acid, and H2 blockers


What metabolic conditions could cause pancreatitis?


Hyperlipidemia (types I, IV, and V have been implicated); hypercalcemia, which is most commonly found with hyperparathyroidism that could lead to intraductal precipitation of calcium


How is acute pancreatitis diagnosed?


The diagnosis of pancreatitis requires 2 of the following 3 features: abdominal pain characteristic of acute pancreatitis, a serum amylase or lipase level at least 3 times the upper limit of normal, and characteristic findings of acute pancreatitis on computed tomography (CT).


Which enzyme is implicated in etiology of pancreatitis?


Trypsin


Which serum enzyme rises within 2 hours of the onset of pancreatitis and peaks within 48 hours?


Amylase


What antibiotics are indicated for patients with mild pancreatitis?


None! Antibiotics neither improve the course nor prevent septic complications.


What CT scan findings are suggestive of chronic pancreatitis?


Dilated pancreatic duct, calcifications, and parenchymal atrophy


What are the early Ranson criteria (on admission)?


Glucose >200 mg/dL, Age >55, LDH >350 IU/L, AST >250 IU/L, WBC >16k


What are the late Ranson criteria (48 hours)?


Calcium <8.0 mg/dL, HCT drop >10%, PaO2 <60 mm Hg, BUN increase by 5 or more mg/dL, base deficit >4 mEq/L, fluid sequestration >6 L


How do Ranson criteria predict mortality?


0 to 2 signs, 2%


3 to 4 signs, 15%


5 to 6 signs, 40%


7 to 8 signs, ~100%


What are the indications for surgery in chronic pancreatitis?


Intractable abdominal pain, common bile duct obstruction, duodenal obstruction, persistent pseudocysts, pancreatic fistula or ascites, variceal hemorrhage secondary to splenic vein obstruction (treated by splenectomy), to rule out pancreatic malignancy, colonic obstruction


What are possible complications of pancreatitis?


Pancreatic necrosis, pseudocyst, pancreatic fistulas, hemorrhage, pancreatic ascites, abscess/sepsis


How does chronic pancreatitis present?


Abdominal pain, diabetes, steatorrhea, and pancreatic calcification. Amylase is not typically elevated in chronic pancreatitis


Initial management of pancreatic duct stricture from chronic pancreatitis:


Pancreatic duct stenting


What are some surgical procedures used in chronic pancreatitis?


Duval procedure (distal pancreatectomy with end-to-end pancreaticojejunostomy) Puestow procedure (lateral side-to-side pancreaticojejunostomy), which is most widely used and preferred; pancreatic resection, pancreatic denervation, islet cell transplantation (for type I diabetes mellitus)


Frey procedure (coring out of diseased portion of pancreatic head and then lateral pancreaticojejunostomy for chronic pancreatitis)


Beger procedure (duodenum-preserving pancreatic head resection)


When is a follow-up CT scan for pancreatitis indicated?


Clinical deterioration (pseudocyst, abscess, or necrosis)


Why does shock occur in severe pancreatitis?


Hypotension and subsequent shock are related to hemodynamic changes resembling sepsis rather than hypovolemia. Cardiac output is generally increased with decreased peripheral vascular resistance


What percentage of pseudocysts spontaneously resolve within 4 to 6 weeks?


50%


How are pseudocysts managed?


Expectant, supportive management for 4 to 6 weeks


If no resolution occurs, wait until a thick, fibrous wall has formed and perform internal cyst drainage via a cystgastrostomy, cystjejunostomy, or cystduodenostomy.


A biopsy should always be performed to rule out malignancy


External drainage may be pursued for infected pseudocysts or ones with immature walls


How long does it take a pseudocyst to mature?


4 to 6 weeks


Indication for surgical intervention for pancreatic pseudocysts:


Pseudocyst has not resolved by 6 weeks and also persistently greater than 6 cm


List the enteric methods of pseudocyst drainage:


Cystogastrostomy, cystoduodenostomy, and Roux-en-y cystojejunostomy, lateral pancreaticojejunostomy


Most common cause of pancreatic abscess:


Infection of pseudocyst


What is the usual time frame for development of pancreatic abscesses associated with acute pancreatitis?


2 to 4 weeks


What CT scan criteria are used for diagnosis of pancreatic necrosis?


Well-demarcated areas of nonenhancing pancreatic tissue >3 cm or occupying more than 30% of the gland


How is infected pancreatic necrosis diagnosed?


CT-guided percutaneous fine-needle aspiration


What antibiotics are indicated in pancreatic necrosis involving >30% of the gland?


Imipenem or meropenem


Aspiration of the necrotic pancreas is negative, now what?


Continue nonoperative management


How are pancreatic fistulas managed?


NPO, parenteral nutrition. Somatostatin has been showed to accelerate closure rate. If no resolution, an endoscopic retrograde cholangiopancreatography (ERCP) to evaluate anatomy and ultimate surgical internal drainage or distal resection.


How does hemorrhage manifest in the setting of pancreatitis?


It usually is due to erosion of an arterial pseudoaneurysm secondary to pseudocyst, abscess, or necrotizing pancreatitis. Diagnosis is by angiography. Immediate surgery is indicated should the patient become unstable. Selective embolization may be possible in stable patients.

Aug 13, 2019 | Posted by in ABDOMINAL MEDICINE | Comments Off on Pancreas
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