الفهرس 
INTRODUCTION.Only 14 pages are availabe for public view
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Abstract
Malignant biliary obstruction is a poor prognostic disease with serious consequences on the patient’s lifestyle and survival. At the time of diagnosis, the majority of these patients either have an advanced stage or unfit for surgical resection for other medical reasons making palliative treatments the only options.
Palliation of unresectable malignant biliary obstruction requires a multi-disciplinary approach including medical oncologists, radiation oncologists, gastroenterologists, hepato-biliary surgeons, and interventional radiologists.
Palliative therapy involves: Surgical bypass, endoscopic stenting, and percutaneous drainage and stenting. Sometimes a combined approach is needed.
Whatever the method of intervention chosen, the fundamental objectives of palliative biliary drainage are to prolong survival, improve quality of life, relieve the pain and prevent life threating complication including cholangitis, progressive renal and hepatic failure.
PBDS is an established method to palliatively treat malignant biliary obstruction. The major aim is to direct the bile into the small intestine to achieve a drainage resembling normal physiological drainage to maintain a normal entero-hepatic circulation.
PTBD can be achieved by means of: External drainage, internal-external drainage, plastic prosthesis implantation and metallic
biliary stenting. Each of these methods has its advantages and disadvantages.
Major categories of SEMSs include uncovered (USEMSs) and covered (CSEMSs) groups. The limitations found in each category of SEMSs make it difficult to use one type as the ideal stent for biliary stenting.
USEMSs have an open wire mesh design that allows drainage of biliary side-branches. The small surface area of the wire mesh reduces bacterial growth and encrustation. Also, USEMSs have a lower shortening rate, and deployment is easier compared with covered stents.
The mesh design of the USEMSs allows them to be embedded in the biliary duct wall but it also makes them susceptible to tissue ingrowth through the mesh, which can lead to occlusion leading to continuous re-admissions and re-interventions, increasing discomfort, and procedure cost.
CSEMSs were designed in the past 10 years to prevent tissue ingrowth, by sealing the metallic mesh with a membrane, which prevents tumor ingrowth through the stent, increasing patency rates, but because of this, they are known to have increased rates of migration.There has been theoretical concern that covering the cystic duct or pancreatic duct orifice might induce cholecystitis or pancreatitis.
The complication rate for PTBD can be substantial, and varies according to pre-procedure patient status and diagnosis. Complications are divided into immediate and late complications.
Immediate complications include pain at the site of puncture, bile leak, intra-hepatic and extra-hepatic bleeding, septicaemia, and catheter related problems of kinking or dislocation. Late complications include cholangitis, pancreatitis, liver abscess, septicaemia, drainage catheter or stent occlusion, and arterial or venous biliary fistula.
The mechanism of stent obstruction and/or recurrent biliary obstruction after placement of CSEMSs and USEMSs differs. For USEMS, tissue ingrowth through the mesh interstices at the level of the tumor remains the most likely source of occlusion. Other causes include sludge formation, proximal and distal tumour over-growth, and stone formation. For partially or fully covered SEMS, occlusion may occur due to stent migration, biliary sludge, overgrowth of tissue at the ends of the stent, or food debris.
Our prospective controlled randomized study was conducted in the National Liver Institute-Menoufia University, from March 2013 to December 2014. The study included 74 patients (58 male and 16 females) diagnosed with unresectable malignant biliary obstruction. The patients were randomly divided into two groups:- Group (A): Included 35 patients (29 males and 6 females), subjected to insertion of covered metallic stents and Group (B): Included 39 patients (29 males and 10 females), subjected to insertion of uncovered metallic stents.
The aim of our study is to compare between the percutaneous trans-hepatic covered and uncovered metallic biliary stents in the palliative treatment of malignant biliary obstruction regarding the technical success, clinical success, stent Patency, patient survival and complication rates.
In our study, the technical success was 100%. There was significant difference between both group regarding the clinical success at 3 months follow up (P=0.02) with no significant difference at one week (P=0.31), one month (P=0.32) and 6 months follow up (P=0.14). The explanation of the significant difference at 3 months follow up was that early stent dysfuction (< 3 months) occurred more in group A due to sludge formation and stent migration.
The mean primary stent patency duration was 114.6±81.5 days in group B and 99.1±92.03 days in group A. Uncovered stents were superior to covered stents in terms of stent patency with no significant difference between both groups (P=0.35).
The mean 6 month survival time was 149.549 days (SE=9.277 days) (95% confidence interval, 131.3–167.7 days) in group A and 162.992 days (SE=8.213 days) (95% confidence interval, 146.8–179.09 days) in group B with no significant difference between both groups (0.679). The mean 12 months survival time was 204.151 days (SE=30.220 days) (95% confidence interval, 144.9–263.3 days) in group A and 198.734 days (SE=16.841 days) (95% confidence interval, 165.8–231.6 days) in group B with no significant difference between both groups (0.750).
Complications were recorded in 16 patients (45.7%) in group A and 10 patients (25.6%) in group B, with no significant difference between both groups (p=0.07)