Extracorporeal shock wave lithotripsy (ESWL) for large pancreatic stones: are these shocks worth while?

Chronic pancreatitis is characterized by irreversible damage to the pancreas that leads to pain and/or exocrine and endocrine insufficiency [1–3]. Abdominal pain is the most common and distressing symptom and is the most common indication for endoscopic or surgical intervention [1, 4, 5]. One of the mechanisms responsible for pain in chronic pancreatitis is obstruction to the pancreatic duct by strictures or calculi and relief of this obstruction by surgical or endoscopic drainage relieves pain in a majority of patients [6–8]. Endoscopic drainage procedures for relief of pain include pancreatic sphincterotomy, dilation of pancreatic strictures, removal of pancreatic stones and the placement of pancreatic stents to overcome the obstruction [8]. On plain X-ray of the abdomen, pancreatic calcification can be seen in up to 30% of patients with chronic pancreatitis [4]. The advent of newer imaging modalities like computed tomography (CT) has improved the ability to detect pancreatic calcification [9]. Up to 70% of patients with alcohol-related chronic pancreatitis can have pancreatic calcification after 10 years of disease [10]. The calcification can be either due to parenchymal or ductal calculi. Pancreatic duct calculi have been reported in 50% to 90% of patients with chronic pancreatitis and there is higher incidence of ductal calculi in patients with tropical pancreatitis [2, 11]. The ductal calculi cause obstruction leading to an increase in intraductal as well as parenchymal pressure and ischemia, thus causing pain [12]. The factors correlating with pain are the stone size and the diameter of the pancreatic duct. The goal of endoscopic treatment for chronic painful pancreatitis with ductal calculi is complete clearance of calculi from the duct, thus relieving the obstruction and pain [13–16]. Endoscopic extraction of pancreatic duct calculi is usually more difficult than extraction of bile duct stones because pancreatic stones are generally spiculated, hard and multiple, and on many occasions are impacted behind strictures. Endoscopic sphincterotomy followed by balloon or Dormia-assisted stone extraction is usually successful when the stones are of small size and are located in the head or body of the pancreas, and there is no ductal stricture [17]. The presence of ductal stricture or large calculi creates difficulty in endoscopic clearance and requires either decrease in the size of calculi by breaking them into small pieces or enlarging the ampullary orifice so as to successfully deliver intact large stones. Endoscopic balloon sphincteroplasty of the papilla has been used to enlarge the papillary orifice and to successfully extract intact ductal calculi >1 cm, especially radiolucent stones [18]. However, this technique is technically demanding, and has potentially serious complications including bleeding, retroduodenal perforation and pancreatitis [18]. An alternative method is to break the large stones into small pieces so that they can be easily extracted through the papilla. This can be done by using mechanical lithotripsy, intraductal electrohydraulic lithotripsy (EHL) and extracorporeal shock wave lithotripsy (ESWL). Mechanical lithotripsy using a throughthe-scope mechanical lithotripter is technically difficult and is not successful in all cases with large pancreatic calculi, especially when there is difficulty in grasping large stones [19]. Intraductal EHL is cumbersome and requires specialized D. K. Bhasin : S. S. Rana Department of Gastroenterology, Post Graduate Institute of Medical Education and Research (PGIMER), Sector 12, Chandigarh 160 012, India