Drainage procedures (anastomoses between the pancreas or a pseudocyst and a segment of intestine) are performed to relieve intra-pancreatic and ductal pressure, re-establish an adequate pancreatic juice outflow, and resolve pain. Internal drainage may be necessary to resolve symptoms caused by a large or infected pseudocyst.
DECOMPRESSION PROCEDURES FOR CHRONIC PANCREATITIS
A dominant component of chronic pancreatitis is the pancreatic duct hypertension, caused by fibrotic replacement of normal pancreatic tissue. Duct stenosis and hypertension are the basis of the duct pressure-pain hypothesis. Drainage operations are performed on the assumption that pain relief is obtained by drainage of the main pancreatic duct.
Longitudinal decompression of the main pancreatic duct (at the level of the body-tail) was proposed in the ’50s by Puestow and modified in 1960 by Partington and Rochelle (latero-lateral Wirsung-jejunostomy) became the first surgical treatment widely considered to be effective for pain in chronic pancreatitis. Briefly, after accessing the lesser sac, a ventral incision of the main pancreatic duct is made until the head of the pancreas, at the level of gastroduodenal artery. The Wirsung duct is then anastomosed with a Roux-en-Y loop. Only patients with dilated pancreatic duct are amenable of lateral pancreatico-jejunostomy. According to the current literature, the immediate success rate is about 80%, but 30% experience pain recurrence after 3-5 years, probably because of concomitant inflammatory mass in the head of the pancreas.
Izbicki et al. proposed a technical modification (pancreatic longitudinal excavation and lateral pancreatico-jejunostomy) to treat patients with small, non-dilated main pancreatic duct (< 5 mm).
In the early 1970s, it was observed that many patients with chronic pancreatitis had an inflammatory mass in the head of the pancreas. The three principal ductal systems (Wirsung duct, Santorini duct, and uncinate process duct) adjoin in the head of pancreas, that may represent the “core”in which the disease begins. Therefore, hybrid approaches that associate partial pancreatic head resection with drainage of the main pancreatic duct were proposed.
In 1972 Beger introduced the duodenum-preserving pancreatic head resection. By subtotal resection of the pancreatic head and by preserving the body and tail of the pancreas, pylorus, duodenum, and extra-pancreatic bile ducts, this operation preserves the normal anatomy of the upper gut and the normal passage of food. The intention of this operation is to treat only the enlarged pancreatic head. Reconstruction involves an end-to-side pancreaticojejunostomy and a side-to-side pancreaticojejunostomy. If necessary, the body and the tail can be drained via a longitudinal pancreaticojejunostomy. Immediate relieve of pain has been reported in 80% of patients.
Combining the surgical principles of drainage and organ-preserving resection, Frey introduced in 1987 a modification of the duodenum-preserving pancreatic head resection, the longitudinal pancreatojejunostomy with local pancreatic head resection. Key steps in the performance of the Frey procedure include preservation of the pancreatic neck as well as the capsule of the posterior pancreatic head. The ducts of Wirsung and Santorini are excised, and the excavation is created in continuity with the longitudinal dochotomy of the dorsal duct. The locally excised head of the pancreas is covered with the opened Roux-en-Y limb of jejunum in continuity with the opened main pancreatic duct in the body and tail of the pancreas. Results are similar to those of the Beger procedure.
INTERNAL DRAINAGE OF PSEUDOCYSTS
Drainage of pancreatic pseudocysts can be performed either percutaneously, endoscopically or surgically.
Percutaneous drainage of pseudocyst is the least employed technique. Endoscopic drainage is the treatment of choice if there is abutment of the pseudocyst against the stomach or duodenal wall. The procedure involves endoluminal ultrasonographically guided transgastric puncture of the pseudocyst, insertion of single or multiple stents, and – if necessary – transpapillary stenting of the pancreatic duct.
Surgical drainage is indicated when endoscopic drainage is not feasible (there is no abutment of the pseudocyst against the stomach or duodenum, there is extensive collateral circle) or after multiple endoscopic drainage failure.
The surgical approach involves a pseudocystogastrostomy on the posterior stomach wall (that can be fashioned via an anterior gastrotomy), or a pseudocystojejunostomy on a Roux-en-Y loop. The pseudocyst wall should be thick and solid enough to allow the fashioning of the anastomosis.