Postoperative Pancreas

Published on 19/07/2015 by admin

Filed under Radiology

Last modified 19/07/2015

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Small free fluid, edema, and fat stranding in surgical bed with reactive subcentimeter lymph nodes in mesentery

Mild biliary dilatation, gastrojejunostomy thickening, and pancreatic duct dilatation due to anastomotic edema

Pancreatic duct stent (thin linear radiodensity) often placed during surgery (traversing pancreaticojejunostomy) to ↓ risk of pancreatic fistula

• Common complications

Pancreatic fistula: Leakage of amylase-rich fluid from pancreatic duct

– Focal fluid collection, ectopic gas, or hematoma directly adjacent to pancreaticojejunostomy

Abscess: Can be intrahepatic, in pancreatic bed, or in subphrenic, subhepatic, or retroperitoneal spaces

Gastrojejunostomy and hepaticojejunostomy leaks: Suspect when focal fluid collection or ectopic gas in close contiguity to anastomosis

Postoperative pancreatitis: Fluid, edema, and stranding centered in pancreatic remnant

Liver infarct: Wedge-shaped areas of hypodensity at periphery of liver

Postoperative hemorrhage: May be due to bleeding from gastroduodenal artery stump or due to structural abnormality (e.g., pseudoaneurysm)

Portomesenteric venous thrombosis

Anastomotic strictures: Suspect when progressive biliary or pancreatic ductal dilatation without obstructing tumor at anastomotic site

Delayed gastric emptying: Gastric remnant markedly dilated with large retained ingested material and fluid

Tumor recurrence: Differentiate linear postoperative scarring from nodular, mass-like tumor recurrence

CLINICAL ISSUES

• Whipple procedure mortality has dramatically fallen (was once ∼ 25%, and is now 1-3%)

• Morbidity for Whipple procedure remains considerable, with complications in ∼ 20% of patients

(Left) Graphic shows the Whipple (pancreaticoduodenectomy) procedure. Note the common bile duct margin , the pancreatic margin , and the intestinal margins .

(Right) This graphic depicts Whipple anatomy: Pancreaticojejunostomy , choledochojejunostomy , gastrojejunostomy or duodenojejunostomy , and cholecystectomy . The pylorus may be removed or preserved, depending on extent of disease and surgeon preference. Note the ligated gastroduodenal artery .

(Left) Axial CECT demonstrates a collection of fluid and gas immediately adjacent to the pancreaticojejunostomy in a patient with an elevated drain amylase, compatible with pancreatic fistula. Note the presence of a pancreatic duct stent .

(Right) Axial CECT in a patient with a fever after Whipple procedure demonstrates a thick-walled fluid collection in the right liver lobe with an internal air-fluid level, compatible with a postoperative hepatic abscess.

TERMINOLOGY

Synonyms

Definitions

•

IMAGING

General Features

• Best diagnostic clue

Post Whipple resection: Expected findings include gas in biliary tree, jejunal loop anastomosed to pancreatic neck, gallbladder usually resected

Post distal pancreatectomy: Expected findings include absent body and tail of pancreas; spleen often resected

• Location

• Surgical procedure determined by location and type of pathology

Whipple procedure most commonly performed for tumors of pancreatic head, uncinate, and proximal neck

– Classic Whipple procedure (pancreaticoduodenectomy) involves surgical removal of pancreatic head, gastric antrum, proximal duodenum, and gallbladder

– Pylorus-sparing Whipple procedure, which may theoretically have lower risk of bile reflux, retains pylorus and short segment of duodenum with creation of duodenojejunostomy

– 3 anastomoses created: Hepaticojejunostomy, pancreaticojejunostomy, and gastrojejunostomy (classic) or duodenojejunostomy (pylorus-sparing)

Distal pancreatectomy performed for tumors of distal pancreatic neck, body, and tail

– May be performed with splenectomy

– Can be performed with en bloc celiac axis resection for some pancreatic body tumors that invade celiac or hepatic artery

Central pancreatectomy performed for low-risk lesions (low malignant potential) in pancreatic neck/body

– Not used for higher risk lesions due to inadequate lymphadenectomy and ↑ risk of pancreatic fistula

Enucleation performed for lesions with low malignant potential that are small and exophytic (often utilized for insulinomas)

Frey procedure and Puestow procedure are both utilized for treatment of chronic pancreatitis

– Both result in lateral side-to-side pancreaticojejunostomy, with additional resection of portions of pancreatic head in Frey procedure

Laparoscopic technique is increasingly utilized at high-volume surgical centers (distal pancreatectomy > Whipple procedure)

CT Findings

• Normal findings immediately after Whipple procedure

Small free fluid, edema, and fat stranding in surgical bed with reactive subcentimeter lymph nodes in mesentery

Pneumobilia is an expected finding after Whipple procedure due to hepaticojejunostomy

Mild biliary dilatation frequently present due to anastomotic edema at hepaticojejunostomy

Thickening at gastrojejunostomy due to edema

Mild pancreatic duct dilatation due to anastomotic edema at pancreaticojejunostomy

Pancreatic duct stent (thin linear radiodensity) often placed during surgery (traversing pancreaticojejunostomy) to ↓ risk of pancreatic fistula

– Will eventually pass into bowel over time on its own

Small free air expected for 14 days after surgery

• Complications

Pancreatic fistula

– Leakage of amylase-rich fluid from pancreatic duct (either at pancreaticojejunal anastomosis or at site of parenchymal injury)

– Should be suspected when focal fluid collection, greater than expected ectopic gas, or hematoma identified directly adjacent to pancreaticojejunostomy

Fluid and gas may be visualized in direct contiguity with suture line

Abscess

– Rim enhancing fluid collection ± internal ectopic gas

– Abscesses following Whipple may be intrahepatic, in surgical bed, or in subphrenic, subhepatic, or retroperitoneal spaces

– Abscesses following distal pancreatectomy are typically in left subphrenic or left subhepatic spaces

Gastrojejunostomy and hepaticojejunostomy leaks

– Both are uncommon complications, but hepaticojejunostomy leaks are more common

– Should be suspected in acute setting when focal fluid collection visualized in close contiguity to anastomosis (usually with greater than expected ectopic gas)