– Pancreas

Head (including uncinate), neck, body, and tail

Uncinate process – rests on aorta, behind SMV

SMV and SMA – lay behind neck of pancreas

Portal vein – forms behind the neck (SMV and splenic vein)

Blood supply

• Head – superior (off GDA) and inferior (off SMA) pancreaticoduodenal arteries (anterior and posterior branches for each)

• Body – great, inferior, and caudal pancreatic arteries (all off splenic artery)

• Tail – splenic, gastroepiploic, and dorsal pancreatic arteries

Venous drainage into the portal system

Lymphatics – celiac and SMA nodes

Ductal cells – secrete HCO₃⁻ solution (have carbonic anhydrase)

Acinar cells – secrete digestive enzymes

Exocrine function of the pancreas – amylase, lipase, trypsinogen, chymotrypsinogen, carboxypeptidase; HCO₃⁻

• Amylase – only pancreatic enzyme secreted in active form; hydrolyzes alpha 1–4 linkages of glucose chains

Endocrine function of the pancreas

• Alpha cells – glucagon

• Beta cells (at center of islets) – insulin

• Delta cells – somatostatin

• PP or F cells – pancreatic polypeptide

• Islet cells – also produce vasoactive intestinal peptide (VIP), serotonin

Islet cells receive majority of blood supply related to size

• After islets, blood goes to acinar cells

Enterokinase – released by the duodenum, activates trypsinogen to trypsin

• Trypsin activates other pancreatic enzymes including trypsinogen

Hormonal control of pancreatic excretion

• Secretin – ↑ HCO₃⁻ mostly

• CCK – ↑ pancreatic enzymes mostly

• Acetylcholine – ↑ HCO⁻ and enzymes

• Somatostatin and glucagons – ↓ exocrine function

• CCK and secretin – most released by cells in the duodenum

Ventral pancreatic bud

• Connected to duct of Wirsung; migrates posteriorly, to the right, and clockwise to fuse with the dorsal bud

• Forms uncinate and inferior portion of the head

Dorsal pancreatic bud – body, tail, and superior aspect of the pancreatic head; has duct of Santorini

Duct of Wirsung – major pancreatic duct that merges with CBD before entering duodenum

Duct of Santorini – small accessory pancreatic duct that drains directly into duodenum

ANNULAR PANCREAS

2nd portion of duodenum trapped in pancreatic band; can see double bubble on abdominal x-ray; get duodenal obstruction (N/V, abdominal pain)

Associated with Down syndrome; forms from the ventral pancreatic bud from failure of clockwise rotation

Tx: duodenojejunostomy or duodenoduodenostomy; possible sphincteroplasty

• Pancreas not resected

PANCREAS DIVISUM

Failed fusion of the pancreatic ducts; can result in pancreatitis from duct of Santorini (accessory duct) stenosis

Most are asymptomatic; some get pancreatitis

Dx: ERCP – minor papilla will show long and large duct of Santorini; major papilla will show short duct of Wirsung

Tx: ERCP with sphincteroplasty; open sphincteroplasty if that fails

HETEROTOPIC PANCREAS

Most commonly found in duodenum

Usually asymptomatic

Surgical resection if symptomatic

ACUTE PANCREATITIS

Gallstones and ETOH most common etiologies in the United States

• Other etiologies – ERCP, trauma, hyperlipidemia, hypercalcemia, viral infection, medications (azathioprine, furosemide, steroids, cimetidine)

• Gallstones – can obstruct the ampulla of Vater, causing impaired extrusion of zymogen granules and activation of degradation enzymes → leads to pancreatic auto-digestion

• ETOH – can cause auto-activation of pancreatic enzymes while still in the pancreas

Symptoms: abdominal pain radiating to the back, nausea, vomiting, anorexia

• Can also get jaundice, left pleural effusion, ascites, or sentinel loop (dilated small bowel near the pancreas as a result of the inflammation)

Mortality rate 10%; hemorrhagic pancreatitis mortality 50%

Pancreatitis without obvious cause → need to worry about malignancy

Ranson’s criteria

• On admission → age > 55, WBC > 16, glucose > 200, AST > 250, LDH > 350

• After 48 hours: Hct ↓ 10%, BUN ↑ of 5, Ca < 8, PaO₂ < 60, base deficit > 4, fluid sequestration > 6 L

• 8 Ranson criteria met → mortality rate near 100%

Labs: ↑ amylase, lipase, and WBCs

Ultrasound – needed to check for gallstones and possible CBD dilatation

Abdominal CT – to check for complications (necrotic pancreas will not uptake contrast)

Tx: NPO, aggressive fluid resuscitation

• ERCP is needed in patients with gallstone pancreatitis and retained CBD stones → perform sphincterotomy and stone extraction

• Antibiotics for stones, severe pancreatitis, failure to improve, or suspected infection

• TPN may be necessary during recovery period

• Patients with gallstone pancreatitis should undergo cholecystectomy when recovered from pancreatitis (same hospital admission)

• Morphine should be avoided as it can contract the sphincter of Oddi and worsen attack

Bleeding

• Grey Turner sign – flank ecchymosis

• Cullen’s sign – periumbilical ecchymosis

• Fox’s sign – inguinal ecchymosis

15% get pancreatic necrosis – leave sterile necrosis alone

• Infected necrosis (fever, sepsis, positive blood cultures; may need to sample necrotic pancreatic fluid with CT-guided aspiration to get diagnosis) Tx: need surgical debridement

• Pancreatic abscesses → Tx: need surgical debridement

• CT-guided drainage of infected pancreatic necrosis or pancreatic abscess is generally not effective

• Gas in necrotic pancreas = infected necrosis or abscess (need open debridement)

Infection – leading cause of death with pancreatitis; usually GNRs

Surgery only for infected pancreatitis or pancreatic abscess

Obesity – most important risk factor for necrotizing pancreatitis

ARDS – related to release of phospholipases

Coagulopathy – related to release of proteases

Pancreatic fat necrosis – related to release of phospholipases

Mild ↑ amylase and lipase can be seen with cholecystitis, perforated ulcer, sialoadenitis, small bowel obstruction (SBO), and intestinal infarction

PANCREATIC PSEUDOCYSTS

Most common in patients with chronic pancreatitis

• Cysts not associated with pancreatitis – need to R/O CA (eg mucinous cystadenocarcinoma)

Symptoms: pain, fever, weight loss, bowel obstruction from compression

Often occurs in the head of the pancreas; is a non-epithelialized sac

Most resolve spontaneously (especially if < 5 cm)

Tx: expectant management for 3 months – (most resolve on their own; also allows pseudocyst to mature if cystogastrostomy is required)

• May need to place these patients on TPN if unable to eat

• Surgery only for continued symptoms (Tx: cystogastrostomy, open or percutaneous) or pseudocysts that are growing (Tx: resection to R/O CA)

Complications of pancreatic pseudocyst – infection of cyst, portal or splenic vein thrombosis

Incidental cysts not associated with pancreatitis should be resected (worry about intraductal papillary-mucinous neoplasms [IPMNs] or mucinous cystadenocarcinoma) unless the cyst is purely serous and non-complex

Non-complex, purely serous cystadenomas have an extremely low malignancy risk (< 1%) and can be followed

PANCREATIC FISTULAS

Most close spontaneously (especially if low output < 200 cc/day)

Tx: allow drainage, NPO, TPN, octreotide

• If failure to resolve with medical management, can try ERCP, sphincterotomy, and pancreatic stent placement (fistula will usually close, then remove stent)

PANCREATITIS-ASSOCIATED PLEURAL EFFUSION (OR ASCITES)

Caused by retroperitoneal leakage of pancreatic fluid from the pancreatic duct or a pseudocyst (is not a pancreatic–pleural fistula); majority close on their own