Complications of Pancreatitis

Pseudocysts

1. Definition and Pathogenesis
• localized collections of pancreatic secretions that lack an epithelial lining
• occur as a result of surrounding tissues walling off and containing a pancreatic duct disruption
• usually are located adjacent to the pancreas but may occur within the gland itself
• will persist for as long as the cyst and disrupted duct remain in continuity
• pseudocysts develop in 10% of patients after an attack of acute alcoholic pancreatitis and in 20% to 40% of patients with chronic pancreatitis
• fluid collections that occur within the first 4 weeks after an episode of acute pancreatitis are termed acute fluid collections and are not considered pseudocysts
• after an episode on necrotizing pancreatitis, an entity called walled-off pancreatic necrosis may develop, which must be distinguished from a pseudocyst







2. Clinical Manifestations
• abdominal pain is the most common symptom (80% to 90% of patients)
• nausea, vomiting, early satiety may occur as a result of gastric outlet obstruction
• pseudocysts in the head of the pancreas can cause biliary obstruction or gastric outlet obstruction
• on physical exam, abdominal tenderness is present in most patients; a palpable mass is present in ~50%


3. Diagnosis
• serum amylase level is often elevated
• imaging studies are required for definitive diagnosis


1. Contrast-enhanced CT Scan
1. Pseudocyst
• uniform, rounded, fluid-filled mass with a thickened, hyperdense capsule
• CT will show the relationship between the pseudocyst and surrounding structures
• CT may show evidence of hemorrhage from a pseudoaneurysm



2. Walled-Off Pancreatic Necrosis (WOPN)
• consists of fluid with solid matter and particulate debris




2. MRCP
• usually performed with secretin stimulation
• improves the differentiation between pseudocysts and cystic neoplasms
• detects solid debris consistent with WOPN
• delineates the anatomy of the pancreatic duct and its relationship to the pseudocyst



3. ERCP
• rarely used for diagnostic purposes since it may convert a sterile pseudocyst into an infected pseudocyst
• used therapeutically for sphincterotomy or stenting


4. Endoscopic Ultrasound (EUS)
• very useful in distinguishing a pseudocyst from a pancreatic cystic neoplasm by morphology or by cyst fluid aspiration
• fluid high in amylase suggests a pseudocyst; fluid high in CEA suggests a mucinous neoplasm


5. Ultrasound
• most useful in following the size of a known pseudocyst


4. Complications of Pseudocysts
1. Hemorrhage
• occurs in ~6% of patients
• results from erosion of the splenic or gastroduodenal arteries
• if the patient is stable, CT angiography is the initial diagnostic procedure
• if the bleeding vessel is seen, embolization can be performed in the IR suite
• if the patient is hemodynamically unstable, then an emergency laparotomy may be necessary (mortality rate ~ 30%)



2. Rupture
• free rupture into the peritoneal cavity may present as an acute abdomen
• treatment consists of irrigation of the peritoneal cavity and external drainage of the pseudocyst
• pseudocysts may also rupture into the GI tract (stomach, colon)


3. Infection
• diagnosed by CT findings and percutaneous cyst aspiration
• treatment is by percutaneous drainage



4. Obstruction
• pseudocysts may present with obstruction of the stomach or duodenum (gastric outlet obstruction) or with jaundice (common bile duct obstruction)


5. Management of Pseudocysts
1. Expectant Management
• truly asymptomatic pseudocysts can be safely observed and followed with serial CT scans or ultrasound
• even large pseudocysts (> 6 cm) can be managed successfully nonoperatively, although the eventual need for surgery increases with the size of the pseudocyst
• development of symptoms, complications, or increase in pseudocyst size are indications for intervention


2. Endoscopic Management
• often the first intervention chosen in tertiary referral centers
• if the pseudocyst communicates with the main pancreatic duct, and the remainder of the duct is normal, then ERCP/sphincterotomy or transpapillary stent placement has a high success rate



• if the pseudocyst does not communicate with the main pancreatic duct, then an endoscopic cystogastrostomy or cystoduodenostomy can be created
• tissue from the cyst wall must be sent to pathology to rule out a cystic neoplasm
• major complication is hemorrhage







3. Surgical Management
• indicated when endoscopic management has failed or is not available


1. Internal Drainage
• must biopsy the pseudocyst wall to exclude a pancreatic cystic neoplasm
• pseudocyst wall must be mature enough to hold sutures (at least 6 weeks old)
• internal drainage procedures do not correct an underlying duct disorder (obstruction)


1. Cystogastrostomy
• used for pseudocysts in the lesser sac that are adherent to the posterior stomach wall
• may be done laparoscopically and robotically, as well as open



2. Cystojejunostomy
• most versatile internal drainage procedure
• utilizes a Roux-en-Y limb of jejunum
• often used when the pseudocyst bulges through the transverse mesocolon and is not adherent to the posterior wall of the stomach
• other uses include draining multiple pseudocysts or performing a concomitant Puestow procedure in chronic pancreatitis



3. Cystoduodenostomy
• applicable for pseudocysts in the head of the pancreas adjacent to the duodenum
• performed in a similar manner as cystogastrostomy
• must take care to avoid the ampulla and common bile duct


2. Excision
• reserved for pseudocysts in the tail of the pancreas not amenable to internal drainage
• splenectomy is invariably required because of peripancreatic and pericystic inflammation
• if a duct stricture is present, it should be incorporated into the resection if possible; if the stricture is proximal, then the pancreatic stump should be incorporated into a Roux-en-Y pancreaticojejunostomy



3. External Drainage
• used in patients with infected pseudocysts, free rupture, or an immature cyst wall that will not hold sutures
• resulting pancreaticocutaneous fistula usually closes spontaneously
• persistent fistulas will require operative intervention


4. Percutaneous Drainage
• a one-time aspiration is ineffective because of an 80% to 90% recurrence rate
• primary role is in managing an infected pseudocyst
• has the same drawback as external surgical drainage: pancreaticocutaneous fistula


6. Management of Walled-Off Pancreatic Necrosis
• may resolve spontaneously over time
• drainage or debridement is required for infected necrosis or persistent unwellness
• multiple approaches are possible: open debridement via the lesser sac, transgastric approach (open, laparoscopic, or endoscopic), retroperitoneal approach (open or videoscopic), or percutaneous drainage
• choice of approach is dependent on the anatomy and distribution of necrosis, body habitus, and surgeon experience and preference