CASE REPORT

JOP. J Pancreas (Online) 2012 Jan 10; 13(1):101-103.

Laser Lithotripsy to Treat Basket Impaction during Mechanical Lithotripsy of a Pancreatic Duct Stone

Crystal Hlaing¹, Paul Tarnasky², David Hambrick²

¹Conroe Medical Education Foundation Family Medicine Residency. Conroe, TX, USA. ²Methodist Dallas Medical Center. Dallas, TX, USA

ABSTRACT

Context Though uncommon, pancreatic duct stones can cause significant discomfort and morbidity. Endoscopic removal of pancreatic stones may decrease intraductal pressure by augmenting ductal drainage. Endoscopy is shown to be most effective when used early in the course of the disease. Endoscopic methods such as mechanical lithotripsy are often successful in removing the majority of pancreatic stones. However, its complication rate is quite high, with basket malfunction being the one most frequently encountered. Case report We report a case of a patient with idiopathic chronic calcific pancreatitis presenting with symptomatic pancreatic duct stones. During one attempt of basket mechanical lithotripsy, the basket wires fractured. The basket and stone thus became entrapped in the patient’s pancreatic duct. Holmium laser lithotripsy was applied via the mother-baby system of the endoscope. The stone was crushed, and the basket and stone fragments were able to be removed. Conclusions To our knowledge, this is the first time laser lithotripsy has been employed to relieve basket impaction during attempted mechanical lithotripsy of a pancreatic duct stone. This method may be considered as a rescue technique by endoscopists encountering basket impaction in the future.

INTRODUCTION

Pancreatic duct stones occur most commonly in patients with chronic pancreatitis from long-term alcohol abuse [1]. Many of the methods used to remove biliary stones are also effective in removing pancreatic stones [2]. However, the latter are more difficult to access, due to the location and narrow diameter of the pancreatic duct. Complication rates for removal of pancreatic stones are higher than for biliary stones as well. For example, endoscopists face three times the number of complications during mechanical lithotripsy of pancreatic versus biliary stones [3]. Thus, removal methods have not been extensively attempted nor studied in patients with pancreaticolithiasis.

Nonetheless, numerous types of removal methods are available. The Puestow and Whipple procedures are the most common surgical methods used to remove pancreatic stones. Endotherapeutic options include: pancreatic sphincterotomy, stricture dilation, balloon catheter and basket extraction, extracorporeal shockwave lithotripsy (ESWL), and intracorporeal lithotripsy, which includes electrohydraulic (EHL), basket mechanical, and laser lithotripsy.

Balloon catheter and basket extraction are considered standard endotherapeutic techniques for pancreaticolithiasis. However, large stones often require lithotripsy fragmentation before ductal clearance is achieved. Currently, the most common type of lithotripsy used on pancreatic duct stones is mechanical [2]. When stones are too hard for the lithotripter to break, though, baskets and stones may become impacted in pancreatic ducts [3]. Surgery or a second form of lithotripsy is often required to relieve impaction. To date, the only types of lithotripsy reported to have been used for this purpose are ESWL and EHL.

CASE REPORT

A 76-year-old white male was referred to Methodist Dallas Medical Center with diarrhea and imaging consistent with chronic pancreatitis. The patient had no history of alcohol abuse. He was diagnosed with steatorrhea due to idiopathic chronic calcific pancreatitis. MRCP revealed pancreatic duct stones within a dilated duct. Initial ERCP confirmed obstruction due to large stones being in the distal pancreatic duct. Sphincterotomy and standard removal techniques were attempted, but they failed to remove the stones. Partial stone clearance was achieved via ERCP after two sessions of ESWL.

A residual 8 mm stone fragment was captured in a basket for mechanical lithotripsy. However, it was too hard for the metal sheath to crush. While attempting to crush the stone by applying traction, the basket wires fractured near the lithotripter handle outside the patient’s mouth. The stone and basket thus became impacted inside the patient’s pancreatic duct (Figure 1).

Figure 1. Basket impaction of pancreatic duct stone during mechanical lithotripsy.

The decision was then made to utilize the mother-baby system and insert a FCP-9P Therapeutic Choledochofiberscope (Pentax of America, Montvale, NJ, USA) baby scope alongside the duodenoscope’s mother/working channel. A laser lithotripter was introduced into the pancreatic duct via the baby scope. The stone fragment at the tip of the basket was easily visualized. It was then targeted for lithotripsy. Laser energy was applied at a level of 1 J and frequency of 10 Hz. This successfully fulgurated the stone (Figure 2).

Figure 2. Pancreatic stone pieces in basket after laser lithotripsy.

After fulguration of the stone, the basket and stone fragments were easily removed by applying gentle traction on the wires outside the patient’s mouth (Figure 3).

Figure 3. Relief of impacted basket after laser lithotripsy.

DISCUSSION

Due to the potential of causing persistent ductal obstruction and recurrent pancreatitis, it is recommended that all pancreatic duct stones found be removed, if possible [1]. Endoscopic sphincterotomy, balloon, and basket techniques are current standard removal methods. These succeed in 50-75% of cases of pancreatic duct stones [2]. Lithotripsy methods entail more risk and are thus less frequently employed. Due to its relative ease of use, mechanical lithotripsy is the most common type of lithotripsy used. For biliary stones, it has resulted in complete ductal clearance in about 80-90% of cases [3]. For pancreatic stones, the clearance rate is between 71-100% [4].

However, in one large, multi-center study, complications of mechanical lithotripsy occurred in 11.6% of pancreatic stone cases but in only 3.6% of biliary stone cases [3]. Although the number of pancreatic stones cases were much fewer than that of biliary stone cases, the complication rate being three times higher is still significant. The most common setback for pancreatic stone removal was basket-breaking (due to stones being too hard for the lithotripters’ metal sheaths to crush). Other complications included: cable or wire fracture (such as occurred with our patient), breakage of the device’s handle, and pancreatic duct leak.

Basket impaction usually occurs inside the pancreatic duct. Several salvage methods are available, including: open surgery, salvage lithotripters, sphincterotomy extension, stent placement, EHL, and ESWL. In the past, open surgery was the most frequently used salvage option [3]. However, mortality rates of open surgery for trapped baskets have been reported to be as high as 3% [5]. Now the most commonly used methods are ESWL and the Soehendra^® (Cook Endoscopy, Winston-Salem, NC, USA) salvage lithotripter [3]. ESWL (and EHL) usually requires multiple sessions to achieve complete ductal clearance. The Soehendra^® lithotripter consists of a metal sheath that is shorter and thicker than the one originally used during basket mechanical lithotripsy. The sheath is slid over the wires and then functions as the original lithotripter was supposed to. The difficulty with this method is that the endoscope must first be removed from the esophagus before the Soehendra^® can be inserted. Furthermore, if the wires are accidentally let go of while removing the endoscope, the new sheath becomes entrapped along with the original basket and wires.

Laser lithotripsy is a technique that was first used to crush kidney stones more than 40 years ago [6]. Endoscopists have since applied it to biliary and pancreatic stones, with an overall complication rate of 7-9% [3]. When compared to biliary stones, the use of laser lithotripsy on pancreatic stones is still in its infancy. Two reasons for this are: the pancreatic duct is more difficult to access due to angulation, and the diameter of the distal pancreatic duct is quite narrow compared to the bile duct [7]. Thus, as laser energy carries a substantially high risk of tissue injury and ductal perforation, endoscopists must demonstrate great precision when treating pancreatic stones. Furthermore, while laser lithotripsy has been performed under fluoroscopic guidance alone [6], ERCP is recommended, as it may decrease the risk of damaging surrounding tissues by allowing direct visualization and thus greater targeting accuracy of stones.

Laser lithotripsy has been used in multiple ways to treat pancreaticobiliary lithiasis, first as a primary method for removing stones [8, 9], second as a salvage method in cases of basket impaction of biliary stones [6]. There has been one report from Germany that laser lithotripsy was used as a salvage method for an impacted pancreatic stone [8]. However, a mother-baby endoscope system was not utilized; the endoscope first had to be disengaged from the patient and fluoroscopy employed for visualization. Only then could laser lithotripsy be performed. Our use of the mother-baby endoscope system seems to be a novel, safer salvage method utilizing laser lithotripsy for the case of basket entrapment of a pancreatic duct stone. Furthermore, presuming results would be similar to those of retained biliary stone cases, laser lithotripsy versus other salvage methods like ESWL and EHL would require less time to stone disintegration and a fewer number of treatment sessions [10].

Ideally no complications would occur during mechanical lithotripsy. However, until and unless technology improves (i.e., having stronger wires and metal sheaths better capable of crushing hard stones), endoscopists must still have salvage methods readily at hand. Soehendra^® lithotripters, EHL, and other devices have been used in the past. We were able to successfully use laser lithotripsy alongside a mechanical lithotripter when basket impaction occurred in our patient with stones from chronic calcific pancreatitis. To our knowledge, this is the first report of using laser lithotripsy as a salvage method for pancreatic stone basket impaction. As our patient tolerated the procedure well and suffered no complications from it, we propose that it may be tried in similar cases in the future. More studies have yet to be done to establish the efficacy, safety, and tolerability of laser lithotripsy in patients with pancreatic duct stones.

Received August 31^st, - Accepted December 20^th, 2011

Key words Calculi /complications; Cholangiopancreatography, Endoscopic Retrograde; Lithotripsy, Laser /methods; Pancreatic Diseases /therapy

Abbreviations EHL: electrohydraulic lithotripsy

Notification of conflicts of interest None

Correspondence
Paul Tarnasky
Methodist Dallas Medical Center
1441 N. Beckley Avenue
Dallas, TX 75203
USA
Phone: +1-214.947.8181
Fax: +1-214.943.5871
E-mail: paul.tarnasky@dhat.com

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