Stenting and interventional radiology for obstructive jaundice in patients with unresectable biliary tract carcinomas

Together with biliary drainage, which is an appropriate procedure for unresectable biliary cancer, biliary stent placement is used to improve symptoms associated with jaundice. Owing to investigations comparing percutaneous transhepatic biliary drainage (PTBD), surgical drainage, and endoscopic drainage, many types of stents are now available that can be placed endoscopically. The stents used are classified roughly as plastic stents and metal stents. Compared with plastic stents, metal stents are of large diameter, and have long-term patency (although they are expensive). For this reason, the use of metal stents is preferred for patients who are expected to survive for more than 6 months, whereas for patients who are likely to survive for less than 6 months, the use of plastic stents is not considered to be improper. Obstruction in a metal stent is caused by a tumor that grows within the stent through the mesh interstices. To overcome such problems, a covered metal stent was developed, and these stents are now used in patients with malignant distal biliary obstruction. However, this type of stent has been reported to have several shortcomings, such as being associated with the development of acute cholecystitis and stent migration. In spite of these shortcomings, evidence is expected to demonstrate its superiority over other types of stent

Endoscopic and Percutaneous Preoperative Biliary Drainage in Patients with Suspected Hilar Cholangiocarcinoma

INTRODUCTION: Controversy exists over the preferred technique of preoperative biliary drainage (PBD) in patients with hilar cholangiocarcinoma (HCCA) requiring major liver resection. The current study compared outcomes of endoscopic biliary drainage (EBD) and percutaneous transhepatic biliary drainage (PTBD) in patients with resectable HCCA. METHODS: One hundred fifteen consecutive patients were explored for HCCA between 2001 and July 2008 and assigned by initial PBD procedure to either EBD or PTBD. RESULTS: Of these patients, 101 (88%) underwent PBD; 90 patients underwent EBD as primary procedure, and 11 PTBD. The technical success rate of initial drainage was 81% in the EBD versus 100% in the PTBD group (P = 0.20). Stent dislocation was similar in the EBD and PTBD groups (23% vs. 20%, P = 0.70). Infectious complications were significantly more common in the endoscopic group (48% vs. 9%, P < 0.05). Patients in the EBD group underwent more drainage procedures (2.8 vs. 1.4, P < 0.01) and had a significantly longer drainage period until laparotomy (mean 15 weeks vs. 11 weeks in the PTBD group; P < 0.05). In 30 patients, EBD was converted to PTBD due to failure of the endoscopic approach. CONCLUSIONS: Preoperative percutaneous drainage could outperform endoscopic stent placement in patients with resectable HCCA, showing fewer infectious complications, using less procedure

Forward-viewing versus oblique-viewing echoendoscopes in transluminal drainage of pancreatic fluid collections: a multicenter, randomized, controlled trial

EUS-guided drainage of pancreatic fluid collections (PFCs) is commonly performed with oblique-viewing echoendoscopes. However, accessing the PFC under an oblique angle can make drainage difficult. These difficulties might be overcome by using a forward-viewing echoendoscope

How to Get an Efficient yet Verified Arbitrary-Precision Integer Library

International audienceThe GNU Multi-Precision library is a widely used, safety-critical, library for arbitrary-precision arithmetic. Its source code is written in C and assembly, and includes intricate state-of-the-art algorithms for the sake of high performance. Formally verifying the functional behavior of such highly optimized code, not designed with verification in mind, is challenging. We present a fully verified library designed using the Why3 program verifier. The use of a dedicated memory model makes it possible to have the Why3 code be very similar to the original GMP code. This library is extracted to C and is compatible and performance-competitive with GMP

Automating the Verification of Floating-Point Programs

International audienceIn the context of deductive program verification, handling floating-point computations is challenging. The level of proof success and proof automation highly depends on the way the floating-point operations are interpreted in the logic supported by back-end provers. We address this challenge by combining multiple techniques to separately prove different parts of the desired properties. We use abstract interpretation to compute numerical bounds of expressions, and we use multiple automated provers, relying on different strategies for representing floating-point computations. One of these strategies is based on the native support for floating-point arithmetic recently added in the SMT-LIB standard. Our approach is implemented in the Why3 environment and its front-end SPARK 2014 for the development of safety-critical Ada programs. It is validated experimentally on several examples originating from industrial use of SPARK 2014