**9.4 Vascular complications**

Patients suffering from pancreatic pseudocysts can potentially develop vascular complications, such as pseudoaneurysm formation within the cyst, splenic and portal vein complications.

Formation of pseudoaneurysm inside the pancreatic pseudocyst is a rare pathology and life-threatening situation with high mortality rates. The exact mechanisms are still under investigation, but three possible mechanisms have been proposed. Firstly, inflammation in conjunction with pancreatic enzymes could lead to erosion of pancreatic or peripancreatic artery and consequently the formation of pseudoaneurysm; communication of a pancreatic pseudocyst with a vessel; and lastly a pseudocyst eroding the bowel wall with bleeding [39, 40]. The symptoms are nonspecific, and even on suspicion the patient must undergo a thorough examination to avoid any rupture resulting in severe bleeding. Contrast-enhanced CT or angiography if the

patient is stable is used for recognition of the vessel. In addition, angiography can be used for immediate angio-embolization after tracking the bleeding site. Endovascular interventions should be the first-line treatment [41]. In case of unsuccessful endovascular intervention, a surgical treatment should be performed. The general idea is drainage of the pancreatic pseudocyst and arterial ligation of the vessel that causes the pseudoaneurysm. Splenic artery is the most frequent vessel involved [42].

A pseudocyst can also be the cause of portal vein or splenic vein thrombosis. Pathophysiologically, local inflammation and complement system activation can contribute to thrombosis. In addition, pseudocyst can compress the portal or splenic vein leading to obstruction and consequently to portal hypertension. Treatment includes management of the pancreatic pseudocyst and its cause, e.g. lithrotripsy if choledocholithiasis exist, and management of the thrombosis. Anti-coagulation therapy, thrombolytic agents (urokinase), endovascular intervention (transjugular intrahepatic portosystemic shunt) as well as surgery have been described [43–45].

Last but not least, communication between the pseudoaneurysm and the pancreatic duct can result in severe bleeding to gastrointestinal tract through the ampulla of Vater. This life-threatening situation is called hemosuccus pancreaticus also known as wirsungorrhagia and pseudohemobilia. The most frequent clinical manifestation includes melena, hematochezia or hematemesis, symptomatic anemia, abdominal pain, nausea, and vomiting [46]. The "gold standard" diagnostic as well as therapeutic modality is the angiography identifying the causative vessel and applying the proper interventional method (stent placement and metallic coil embolization). In patients whose endoscopic intervention failed, or in those that are unstable, surgery is still an option without experiencing unwanted complications [47].

### **9.5 Splenic complications**

Splenic rupture in acute and chronic pancreatitis accounts for 9% of the atraumatic splenic ruptures [48]. Especially, if a pancreatic pseudocyst occurs at the tail of the pancreas, the pancreatic enzymes and the inflammation can erode the splenic parenchyma secondary to hematoma. The main etiological factor is excessive alcohol consumption, while the majority of patients are referring to abdominal pain, nausea, vomiting, and lumbar pain [49]. Early recognition of this complication with CT and/or angiography is important for the immediate therapeutic approach, which is consisted of conservative management, percutaneous drainage, splenic artery embolization (hematoma exists without rupture), and splenectomy (when a rupture occurs) [50–52].

Other splenic complications, such as splenic artery pseudoaneurysm and splenic vein thrombosis are described in the "vascular complications" session.

### **9.6 Local mass effect**

There have been reported cases in which the pancreatic pseudocyst caused compression to the adjacent viscera due to its huge size. Additionally, a big pancreatic pseudocyst can increase the intra-abdominal pressure leading to orthopnea, dyspnea, abdominal pain, and distention. Depending on the region of the cyst, the common bile duct and the poral vein or the splenic vein could be obstructed resulting in obstructive jaundice and portal hypertension (see session "vascular complications") accordingly [53, 54]. Endoscopic approach reducing the size of the cyst combined with stenting is the ideal treatment for this situation.
