Fragmentation of difficult bile duct stones: Impact of Argon-Plasma-Coagulation (APC), Cryo- and WaterJet-technology

Aims: In case of bile duct stones, complete clearance of the bile duct by conventional endoscopic stone extraction methods is achievable in over 90% of cases. In patients with difficult and/or giant stones, additive endoscopic fragmentation techniques like laser or electrohydaulic lithotripsy are required. APC is a well-known thermal technology with devitalization and fragmentation effects in high temperatures. Cryo-technology utilizes the selective, controlled application of freeze-thaw cycles with low temperature (-89° to -196°C) in order to devitalize pathological tissue. The dissecting WaterJet (Erbe Waterjet Technology) uses the action of a thin laminar liquid jet. With its accurate method of operation it ensures a sensitive, precise, and safe dissection of tissues. AIM/

Methods: The feasibility of APC, Cryo-technology and dissecting WaterJet (all ERBE Elektromedizin GmbH, GER) as a treatment option for bile duct stones. In an in vitro bench study, we evaluated the fragmentation of 120 bile duct stones treated with each 3 technologies. The stones were differentiated in pigment, cholesterol and mixed stones. Minimum diameter of the stones was 1cm. Stones were positioned in a test tube surrounded by 0.9% NaCl-solution. Primary goal was the evaluation of the fragmentation rate and energy intake for each technology.

Results: Complete fragmentation was seen only in 10% of stones treated with Cryo-technology. All cholesterol based concrements were fragmented with APC at a power setting of 30–50 W. Hard pigment stones were resistant and demonstrated even at high energies of 100 W and long application time no satisfying results. This was related to the different melting temperature and the chemical compounds of the stones. With the WaterJet technology all 40 concrements (100%) were cracked effectively and completely with a pressure of 10–50bar. The highest local effect was seen when the WaterJet applicator had direct contact to the concrement.

Conclusion: In this first of its kind feasibility study, only the WaterJet technology demonstrated an efficient fragmentation of huge bile duct stones in vitro. APC- and Cryo-technology are not suitable for the treatment of bile duct stones. The fragmentation rate with these thermal technologies were inadequate.