Plastic or metal stents for benign extrahepatic biliary strictures: a systematic review

  • Petra GA van Boeckel1Email author,

    Affiliated with

    • Frank P Vleggaar1 and

      Affiliated with

      • Peter D Siersema1

        Affiliated with

        BMC Gastroenterol20099:96

        DOI: 10.1186/1471-230X-9-96

        Received: 17 July 2009

        Accepted: 17 December 2009

        Published: 17 December 2009

        Abstract

        Background

        Benign biliary strictures may be a consequence of surgical procedures, chronic pancreatitis or iatrogenic injuries to the ampulla. Stents are increasingly being used for this indication, however it is not completely clear which stent type should be preferred.

        Methods

        A systematic review on stent placement for benign extrahepatic biliary strictures was performed after searching PubMed and EMBASE databases. Data were pooled and evaluated for technical success, clinical success and complications.

        Results

        In total, 47 studies (1116 patients) on outcome of stent placement were identified. No randomized controlled trials (RCTs), one non-randomized comparative studies and 46 case series were found. Technical success was 98,9% for uncovered self-expandable metal stents (uSEMS), 94,8% for single plastic stents and 94,0% for multiple plastic stents. Overall clinical success rate was highest for placement of multiple plastic stents (94,3%) followed by uSEMS (79,5%) and single plastic stents (59.6%). Complications occurred more frequently with uSEMS (39.5%) compared with single plastic stents (36.0%) and multiple plastic stents (20,3%).

        Conclusion

        Based on clinical success and risk of complications, placement of multiple plastic stents is currently the best choice. The evolving role of cSEMS placement as a more patient friendly and cost effective treatment for benign biliary strictures needs further elucidation. There is a need for RCTs comparing different stent types for this indication.

        Background

        Benign biliary strictures occur most frequently as a consequence of a surgical procedure of the gallbladder, mainly cholecystectomy, or common bile duct (CBD) [1]. Other causes include inflammatory conditions, such as chronic pancreatitis and sclerosing cholangitis [2]. In addition, cholelithiasis, sphincterotomy and infections of the biliary tract may also lead to a stricture [3]. Benign strictures of the biliary tract are associated with a broad spectrum of signs and symptoms, ranging from subclinical disease with mild elevation of liver enzymes to complete obstruction with jaundice, pruritus and cholangitis, and ultimately biliary cirrhosis [4].

        A bilio-digestive anastomosis, or a percutaneously or endoscopically performed dilation with or without stent placement are the most commonly used treatment options for benign biliary strictures[5]. Stent placement in the CBD is an increasingly being used alternative to surgery. Several reports on the nonsurgical management of benign biliary strictures with stents have shown results which are equal to those obtained by surgery [612]. The endoscopic management typically consists of dilation and insertion of one or more plastic stents followed by elective stent exchange every 3 months to avoid cholangitis caused by stent clogging [4, 13]. An increasing number of plastic stents will progressively dilate a stricture in the CBD or the papilla. The major disadvantages of this method are the need for multiple invasive procedures and the morbidity caused by stent dysfunction resulting in recurrent jaundice and cholangitis.

        In malignant biliary strictures, uncovered self-expanding metal stents (uSEMS) have been shown to have a longer stent patency than plastic stents, mainly because of their larger diameter [4, 14]. Nonetheless, long-term stent patency is a limiting factor with uSEMS as well, as these devices may obstruct due to epithelial hyperplasia and tissue ingrowth through the stent meshes [1517]. This process of epithelial hyperplasia causes embedding of the stent into the bile duct mucosa, making removal of uSEMS difficult or even impossible [18]. These drawbacks limit the use of uSEMS in the treatment of benign biliary strictures.

        Only limited data comparing the efficacy and safety of different biliary stent types for benign biliary strictures are available. We therefore performed a systematic review of the current literature to assess technical and clinical success, and complications of different stent types for this indication.

        Methods

        Systematic search

        A systematic search of PubMed between January 1966 and March 2008 and EMBASE between January 1980 and March 2008 was performed. In PubMed, the MeSH headings 'cholestasis' and 'obstructive jaundice' were used in combination with the MeSH heading 'stent'. In EMBASE a similar search using the same headings was performed. We detected 1051 abstracts in PubMed and 476 abstracts in EMBASE and these 1527 abstracts were evaluated. All studies reporting on biliary stent placement in patients with benign strictures were included. Non-English language studies, letters, editorials, reviews, animal studies, single case reports, studies with data on covered self-expandable metal stents (cSEMS), studies with results on intrahepatic strictures, studies with strictures of unknown origin and studies in patients with malignant strictures or children were excluded. This resulted in 51 abstracts being retrieved as full text. Thirteen studies were excluded because they were duplicates and 23 studies because they contained no data on stent placement for benign biliary strictures. Another 32 studies were added after manual searching of references in the selected studies. Finally, 47 studies were retrieved for data extraction (Figure 1).
        http://static-content.springer.com/image/art%3A10.1186%2F1471-230X-9-96/MediaObjects/12876_2009_Article_388_Fig1_HTML.jpg
        Figure 1

        Flowchart of search history on stents for benign extrahepatic biliary strictures.

        Data extraction

        Data on study design, number of patients, etiology and location of the stricture, route of stent placement, stent type, follow-up time, previous treatment, median stenting time, technical and clinical success rates, patency rate, complications, stricture recurrence and mortality were extracted.

        Definitions

        • Stenting time: the time between stent placement and removal. Stenting time in patients treated with uSEMS was defined as the time between stent placement and the moment that further treatment was indicated because of stent obstruction.

        • Technical success: technically successful stent placement.

        • Clinical success: no need for further treatment after stent placement, relief of symptoms and/or significant decrease in bilirubin level after stent placement.

        • Complication: adverse event after stent placement, such as cholangitis, pancreatitis, stent migration or hemorrhage.

        • Mortality: procedure-related and stent-related death.

        Statistics

        The following data were pooled using a fixed effect model: stenting time, technical success rate, clinical success rate, complications and mortality. The number of patients with a single plastic stent, multiple plastic stents and uSEMS were plotted against clinical and technical success rates, resulting in funnel plots, a statistical method used for assessing publication bias [19]. If publication bias is not present, a funnel plot is expected to be roughly symmetrical. The underlying idea is that studies with the largest number of patients estimate clinical and technical success rates more accurately than studies with fewer patients. As it may be difficult to establish publication bias by visual inspection [20], we used the Mann-Whitney U test and Spearman's rank correlation test to determine a correlation between technical and clinical success rates per stent type and the number of patients. A p-value < 0.05 was considered statistically significant. SPSS software, version 15, (Inc., Chicago, Illinois, USA) was used to perform the statistical analysis.

        Results

        Study types

        From the 47 selected studies, data on outcome of biliary stenting in 1116 patients were extracted (Table 1, 2). Of these, 24 studies reported on single plastic stents [2, 2142], 6 on multiple plastic stents [4348] and 17 on uSEMS [15, 16, 4963]. A single plastic stent was compared with multiple plastic stents in one non-randomized study [64]. The remaining studies were all case series, of which 33 were retrospective[16, 2129, 31, 3537, 39, 4144, 47, 4951, 5355, 59, 60, 62, 64] and 14 prospective in design[15, 30, 32, 34, 38, 40, 45, 48, 52, 5658, 61,63]
        Table 1

        Case series with uncovered SEMS (uSEMS) for benign biliary strictures

        Author

        Year

        N

        Age (years (range))

        Women

        Intervention

        Route

        Etiology stricture

        Location obstruction

        Prospective studies

                

        Yamaguchi et al [63]

        2006

        8

        median 65,7 (42-78)

        0

        Streckerstent (2)

        ERCP

        chronic pancreatitis

        CBD

        O Brien et al [58]

        1998

        8

        median 59 (26-88)

        unknown

        Wallstent

        ERCP

        postoperative/endoscopic (5)

        hilair (3)

               

        chronic pancreatitis (2)

        proximal (5)

               

        idiopathic (1)

         

        Deviere et al [15]

        1994

        20

        mean 45 (27-61)

        4

        Wallstent

        ERCP

        chronic pancreatitis

        CBD

        Mygind et al (75)

        1993

        2

        unknown

        2

        Z stent

        PTC

        post operative

        CBD (1)

                

        CBD and anastomosis (1)

        Maccioni et al [56]

        1992

        18

        mean 60 (22-76)

        8

        Z stent (17)

        PTC

        post operative

        anastomosis (13)

             

        Wallstent (1)

          

        CBD (5)

        Foerster et al [52]

        1991

        7

        median 60 (49-80)

        5

        Wallstent

        ERCP (6)

        postoperative

        anastomosis (2)

              

        PTC (1)

         

        CBD (5)

                

        hepatoduodenal fistel (1)

        Retrospective studies

                

        van Berkel et al [62]

        2004

        13

        mean 56 (40-79)

        4

        Wallstent

        ERCP

        chronic pancreatitis

        CBD

        Roumilhac et al [60]

        2003

        12

        unknown

        unknown

        Metal stent (12)

        ERCP

        post OLT

        anastomosis (11)

        Eickhoff et al [51]

        2003

        6

        median 38 (29-60)

        1

        Wallstent

        ERCP

        chronic pancreatitis

        CBD

        Kahl et al [55]

        2002

        3

        mean 48 (21-81)

        1

        Wallstent (3)

        ERCP

        chronic pancreatitis

        CBD

        Bonnel et al [49]

        1997

        25

        mean 64 (35-86)

        13

        Z stent

        PTC

        postoperative

        CBD (8)

                

        anastomosis (17)

        Rieber et al [59]

        1996

        8

        mean 42 (17-66)

        3

        Palmaz stent

        PTC

        post OLT

        anastomosis (5)

                

        nonanastomotis (3)

        Hausegger et al [53]

        1996

        20

        mean 62 (36-83)

        7

        Wallstent

        PTC

        chronic pancreatitis (7)

        anastomosis (4)

               

        fibrous papillary stenosis (2)

        CBD (16)

               

        psc (1)

         
               

        post operative (10)

         

        Chu et al [50]

        1994

        2

        unknown

        unknown

        Z stent

        PTC

        post operative

        hilair (1)

                

        CBD (1)

        Ivancev et al [54]

        1992

        2

        66 and 41

        2

        Z stent

        PTC

        post operative

        anastomosis (1)

                

        CBD (1)

        Rossi et al [16]

        1990

        17

        mean 60 (22-76)

        7

        Z stent

        PTC

        postoperative

        anastomosis (13)

                

        CBD (4)

        Table 2

        Case series with multiple plastic stents and single plastic stents for benign biliary strictures

        Author

        Year

        N

        Age (years (range))

        Women

        Intervention

        Route

        Etiology stricture

        Location obstruction

        Prospective studies

                

        Holt et al [32]

        2007

        53

        48,5 (37-61)

        32

        single plastic stent

        ERCP

        post OLT

        anastomosis

        Graziadei et al [30]

        2006

        84

        53,5

        21

        single plastic stent

        ERCP

        post OLT

        anastomosis (65)

                

        non anastomosis (19)

        Pozsar et al [48]

        2005

        20

        mean 61,3 (36-81)

        18

        multiple plastic stents

        ERCP

        post sphincterectomy

        distal CBD

        Kuzela et al [45]

        2005

        43

        mean 50,3 (37-82)

        25

        multiple plastic stents

        ERCP

        post operative

        hilair

        Kahl et al [34]

        2003

        61

        median 47 (21-81)

        15

        single plastic stent

        ERCP

        chronic pancreatitis (61)

        CBD

        Tocchi et al [38]

        2000

        20

        mean 57

        10

        single plastic stent

        ERCP

        post operative

        CBD (3)

                

        hilair (17)

        van Milligen et al [40]

        1997

        16

        median 43 (17-69)

        8

        single plastic stent

        ERCP

        psc

        CBD (10)

                

        hiliar (6)

        Retrospective studies

                

        Pasha et al [47]

        2007

        25

        mean 46,7 (28-59)

        4

        multiple plastic stents

        ERCP

        post OLT

        anastomosis

        Elmi et al [28]

        2007

        15

        52 year (42-68)

        9

        single plastic stent

        ERCP

        post OLT

        anastomosis

        Akay et al [21]

        2006

        11

        42 (17-60)

        6

        single plastic stent

        ERCP

        post OLT

        anastomosis

        Sharma et al [37]

        2006

        8

        median 42 (20-61)

        3

        single plastic stent

        ERCP

        idiopathic

        CBD (6)

                

        hilair (2)

        Alazmi et al [22]

        2006

        143

        unknown

        unknown

        single plastic stent

        ERCP

        post OLT

        anastomosis

        Zoepf et al [42]

        2005

        7

        median 55 (45-65)

        unknown

        single plastic stent

        ERCP

        post OLT

        anastomosis

        Cahen et al [25]

        2005

        58

        median 54 (19-85)

        10

        single plastic stent

        ERCP

        chronic pancreatitis

        CBD

        Catalano et al [64]

        2004

        46

        mean 48 (30-71)

        11

        1 plastic stent (34)

        ERCP

        chronic pancreatitis

        CBD

             

        multiple plastic stents (12)

           

        Morelli et al [46]

        2003

        25

        mean 48 (18-72)

        9

        multiple plastic stents

         

        post OLT

        anastomosis

        Hisatsune et al [31]

        2003

        19

        45 (14-67)

        9

        single plastic stent

        ERCP

        post OLT

        anastomosis

        Eickhoff et al [27]

        2001

        39

        mean 54,7 (32-81)

        7

        single plastic stent

        ERCP

        chronic pancreatitis (39)

        CBD

        Bourke et al [43]

        2000

        6

        mean 53 (20-64)

        3

        multiple plastic stents

        ERCP

        post sphyncterectomy

        ampullary

        Khandekar et al [44]

        2000

        17

        median 50 (17-68)

        13

        multiple plastic stents

        ERCP

        post sphyncterectomy (10)

        CBD (14)

               

        papillotomy (2)

        other (3)

               

        post operative (3)

         

        Vitale et al [41]

        2000

        25

        mean 46,7 (36-89)

        7

        single plastic stent

        ERCP

        chronic pancreatitis

        CBD

        Kiehne et al [35]

        2000

        14

        (36-89)

        2

        single plastic stent

         

        chronic pancreatitis

        CBD

        Farnbacher et al [29]

        2000

        31

        50 (24-71)

        3

        single plastic stent

        ERCP

        chronic pancreatitis

        CBD

        Rossi et al [36]

        1998

        15

        mean 44 (28-55)

        6

        single plastic stent

        ERCP

        post OLT (15)

        anastomosis

        De Masi et al [26]

        1998

        53

        unknown

        unknown

        single plastic stent

        ERCP

        iatrogenic (39)

        CBD (20)

               

        gallstones (8)

        hilair (30)

        Aru et al [23]

        1997

        8

        mean 44

        7

        single plastic stent

        ERCP

        post operative

        CBD (7)

                

        hilair (1)

        van Milligen et al [39]

        1996

        25

        median 42 (21-74)

        13

        single plastic stent

        ERCP

        psc

        CBD (19)

                

        hilair (3)

        Itani et al [33]

        1995

        5

        unknown

        unknown

        single plastic stent

        ERCP

        chronic pancreatitis

        CBD

        Barthet et al [24]

        1994

        19

        mean 49

        1

        single plastic stent

        ERCP

        chronic pancreatitis

        CBD

        Deviere et al [2]

        1990

        25

        mean 42 (34-69)

        1

        single plastic stent

        ERCP

        chronic pancreatitis

        CBD

        Patients

        Fourty seven studies evaluated 786 patients treated with a single plastic stent (7-11.5 Fr.), 148 with multiple plastic stents (10-11.5 Fr.) and 182 with uSEMS.

        Indications for stent placement included a biliary stricture secondary to liver transplantation (n = 417, 37%), chronic pancreatitis (n = 380, 34%), surgery (n = 170, 16%), and other causes (n = 149,13%).

        Most strictures were located in the CBD (47%), followed by anastomotic strictures (40%), hilar strictures (11%) and other locations (2%) (Table 3, 4).
        Table 3

        Results on route, previous treatment, treatment time, technical success, clinical success and complications in case series with uncovered SEMS (uSEMS) for benign biliary strictures

        Author

        Intervention

        Follow up (range)

        Previous treatment

        Technical success

        Clinical succes

        Treatment time Stentpatency

        Total complications

        Prospective studies

               

        Yamaguchi et al [63]

        Streckerstent (2)

        > 5 years (7.4 year)

        plastic stent placement

        100%

        62,50%

        unknown

        25%

         

        Wallstent (6)

              

        O Brien et al [58]

        Wallstent

        mean 64,5 months (26-81)

        plastic stent placement (5)

        100%

        unknown

        median 35 months (7-57)

        75

        Tesdal et al [69]

        Wallstent (11)

        mean 63,8 months

        balloon dilatation (19)

        100%

        unknown

        mean 30,2 months

        64,50%

         

        Palmazstent (9)

        median 80,5 (2-116)

             
         

        Streckerstent(4)

              

        Deviere et al [15]

        Wallstent

        mean 33 months (24-42)

        plastic stent placement (11)

        100%

        90%

        3 and 6 months (2/20)

        10

        Mygind et al (75)

        Z stent

        4 and 7 months

        balloon dilatation

        100%

        100%

        unknown

        unknown

        Maccioni et al [56]

        Z stent (17)

        mean 37 months (30-41)

        percutaneous dilatation

        83,30%

        55,50%

        unknown

        38,80%

         

        Wallstent (1)

              

        Foerster et al [52]

        Wallstent

        mean 32,7 weeks (21-53)

        laparotomy (2)

        100%

        100%

        8 months until now

        14%

        Retrospective studies

               

        van Berkel et al [62]

        Wall stent

        mean 50 months (6 d -86 months)

        none

        100%

        69%

        60 months

        15,40%

        Roumhilac et al [60]

        SEMS (12)

        median 37 months (18-53)

        plastic stent treatment for 1 year

        100%

        100%

        no stent obstruction

        unknown

        Eickhoff et al [51]

        Wallstent

        median 58 months (22-29)

        plastic stent placement

        100%

        unknown

        median 20 months (10-38)

        83,40%

        Kahl et al [55]

        Wallstent (3)

        median 37 months (18-53)

        plastic stent treatment for 1 year

        100%

        100%

        no stent obstruction

        unknown

        Bonnel et al [49]

        Z stent

        mean 55 months (9-84)

        surgery (17)

        18 one approach

        72%

         

        36%

           

        T tube (8)

        7 two approaches

           

        Rieber et al [59]

        Palmaz stent

        mean 18 months (1,5-43)

        balloon dilatation

        100%

         

        62% occlusion

         
           

        post PTBD

          

        occlussion time

        1,5-2,5-24 months

         

        Hausegger et al [53]

        Walsltent

        mean 31,2 months (3-78)

        balloon dilatation

        100%

        unknown

        73% (6 months)

        50,00%

              

        38% (36 months)

         
              

        19% (end follow up)

         
              

        3-3-3-4-5-11-24-2-36-55

         

        Chu et al [50]

        Z stent

        unknown

        plastic stents

        unknown

         

        0%

         
           

        PTBD

            

        Ivancev et al [54]

        Z stent (2)

        9 and 14 months

        balloon dilatation

        100%

        50%

        50% (5 months)

        50%

        Rossi et al [16]

        Z stent

        mean 8 months (4-12)

        baloon dilatition

        100%

        82,40%

        unknown

        11,80%

        Table 4

        Results on route, previous treatment, treatment time, technical success, clinical success and complications in case series with multiple plastic stents and single plastic stents for benign biliary strictures

        Author

        Intervention

        Follow up (range)

        Previous treatment

        Technical success

        Clinical succes

        Treatment time

        Stentpatency

        Total complications

        Prospective studies

               

        Holt et al [32]

        single plastic stent

        18 months

        balloon dilatation

        92%

        69%

        11,3 months (7-14)

        69,70%

        Graziadei et al [30]

        single plastic stent

        mean 39,8 (0,3-98)

        balloon dilatation

        unknown

        77% anastomosis

        unknown

        5-424 procedures

             

        0% non anastomosis

          

        Pozsar et al [48]

        multiple stent placement

        mean 61,3 (36-81)

        dilatation

        unknown

        90%

        median 9 months (3-22)

        37,70%

        Kuzela et al [45]

        multiple stent placement

        median 16 months (1-42)

        none

        100%

        100%

        1 year

        12%

          

        after stent placement

           

        (planned)

         

        Tocchi et al [38]

        single plastic stent

        mean 89,7 months

        none

        100%

        80%

        unknown

        0%

        Kahl et al [34]

        single plastic stent

        median 40 months (18-66)

        none

        100%

        31,1% (1 year)

        1 year (19)

        34,40%

             

        26,2% (40 months)

        rest unknown

         

        van Milligen et al [40]

        single plastic stent

        median 19 months (7-27)

        none

        100%

        81%

        median 9 days

        7%

        Retrospective studies

               

        Pasha et al [47]

        multiple plastic stent

        median 21,5 months (5,4-31,2)

        diliatation

        unknown

        88% (intend to treat)

        median 4,6 months (1,1-11,9)

        27%

        Elmi et al [28]

        single plastic stent

        535 days (22-1301)

        balloondilatation

        Unknown

        87%

        192 days (18-944)

        22,2% (procedure)

           

        sphincterectomy

            

        Akay et al [21]

        single plastic stent

        22 months (SD 13 months)

        balloondilatation

        75%

        55%

        3 months (6)

        12%

              

        6 months (1)

         
              

        9 months (1)

         
              

        12 months (3)

         

        Sharma et al [37]

        single plastic stent

        median 19 months (4-52)

        balloondilatation

        100%

        100%

        median 19 months

        18%

        Alazmi et al [22]

        single plastic stent

        mean 28 months (1-114)

        balloondilatation

        6,60%

        82%

        unknown

        unknown

        Zoepf et al [42]

        single plastic stent

        median 9,5 months (1-36)

        sometimes dilatation

        100%

        85,60%

        median 8 months (2-26)

        18,60%

        Cahen et al [25]

        single plastic stent

        median 45 months (0-182)

        sphincterectomy

        100%

        38%

        median 274 days (3-2706)

        52%

           

        pancreatic duct stenting

            

        Catalano et al [64]

        single plastic stent (34)

        mean 4,2 years (1 plastic stent)

        unknown

        100%

        24% 1 stent

        21 months

        42,7% (single plastic stent)

         

        multiple plastic stent (12)

        mean 3,9 years (mulitple stents)

          

        92% multiple stents

        14 months

        8,3% (multiple plastic stent)

        Morelli et al [46]

        multiple plastic stent

        mean 54 weeks (5 wks - 103 mo)

        diliatation

        88%

        90%

        unknown

        3,70%

        Hisatsune et al [34]

        single plastic stent

        mean 26 months(15-44)

        none

        79%

        93%

        mean 637 days (487-933)

        43%

        Eickhoff et al [31]

        single plastic stent

        median 58 months (2-146)

        balloon dilatation

        100%

        31%

        mean 9 months (1-144)

        43%

           

        nasobiliary drainage

            

        Bourke et al [43]

        multiple plastic stent

        median 26,5 months (24-32)

        dilatation

        unknown

        100%

        median 12,5 months

        33%

        Author

        Intervention

        Follow up (range)

        Previous treatment

        Technical success

        Clinical succes

        Treatment time

        Stentpatency

        Total complications

        Khandekar et al [44]

        multiple plastic stent

        median 720 days

        sometimes dilatation

        Unknown

        100%

        median 140 days (30-1080)

        unknown

        Vitale et al [41]

        single plastic stent

        32 months (13-76)

        balloon dilatation

        Unknown

        80%

        mean 13,3 months

        unknown

        Khiene et al [35]

        single plastic stent

        1-5 years

        none

        100%

        7,40%

        unknown

        85,70%

        Farnbacher et al [29]

        single plastic stent

        24 months (2-76)

        none

        100%

        13%

        24 months (2-76 months)

        72%

        Rossi et al [36]

        single plastic stent

        1 year

        dilatation

        100%

        83,30%

        1 year

        33,30%

        De Masi et al [26]

        single plastic stent

        6-84 months

        unknown

        Unknown

        71,40%

        24 months

        52,70%

        Aru et al [23]

        single plastic stent

        unknown

        unknown

        100%

        25%

        unknown

        unknown

        van Millegen et al [39]

        single plastic stent

        mean 29 months (2-120)

        dilatation

        nasobiliary drain

        84%

        76%

        1 stent period (17)

        30,5%(procedure)

              

        2 stent period (2)

         
              

        3 stent period (3)

         

        Itani et al [33]

        single plastic stent

        mean 7 months

        dilatation

        100%

        80%

        4 months (2)

        unknown

              

        1 change 4 months (2)

         
              

        15 months (1)

         

        Barthet et al [24]

        single plastic stent

        mean 18 months (13-48)

        none

        100%

        42%

        mean 10 months

        10,50%

        Deviere et al [2]

        single plastic stent

        mean 14 months (4-72)

        dilatation

        100%

        12%

        unknown

        72%

        In the majority of patients with chronic pancreatitis, a single plastic stent was placed (85%), followed by uSEMS (15%) and multiple plastic stents (0%). Similarly, single plastic stents were placed in 82% of patients with a biliary stricture after liver transplantation, followed by uSEMS (22%) and multiple plastic stents (13%). In patients with a biliary stricture after a surgical procedure uSEMS (50%) were placed most frequently followed by multiple plastic stents (35%) and a single plastic stent (15%).

        Comparison between different stent types

        The median stenting time was not different between multiple plastic stents (11.3 (range 4.6-13) months) and single plastic stents (10.5 (0.3-24) months). Median stenting time was 20 (4.5-60) months for uSEMS.

        The technical success rate was not different between different stent types (98,9% for uSEMS and 94.8% for single plastic stents, 94.0% for multiple plastic stents) (Figure 2).
        http://static-content.springer.com/image/art%3A10.1186%2F1471-230X-9-96/MediaObjects/12876_2009_Article_388_Fig2_HTML.jpg
        Figure 2

        Technical success of uncovered SEMS (uSEMS), multiple plastic stents and single plastic stents for benign biliary strictures.

        The clinical success rate for all patients was highest after placement of multiple plastic stents (94,3%) followed by uSEMS (79.5%) and single plastic stents (59,6%) (Figure 3). Clinical success rate in chronic pancreatitis patients was highest for uSEMS (80.4%) and lowest for single plastic stents (35.9%). Multiple plastic stents had the best clinical performance for strictures following liver transplantation (89.0%) and surgery (81.3%), whereas uSEMS (69% and 62.3%, respectively) showed the worst clinical results in these situations (Table 5).
        http://static-content.springer.com/image/art%3A10.1186%2F1471-230X-9-96/MediaObjects/12876_2009_Article_388_Fig3_HTML.jpg
        Figure 3

        Clinical success of uncovered SEMS (uSEMS), multiple plastic stents and single plastic stents for benign biliary strictures.

        Table 5

        Overview of technical and clinical success of uncovered SEMS (uSEMS), multiple plastic stents and single plastic stents for benign biliary strictures

         

        Single plastic stent

         

        USEMS

         

        Multiple plastic stents

         
         

        Technical success

        Clinical success

        Technical success

        Clinical success

        Technical success

        Clinical success

         

        (mean)

        (mean)

        (mean)

        (mean)

        (mean)

        (mean)

        All indications

        94,10%

        61.3%

        98,50%

        62,40%

        97,60%

        87,50%

        Post operative

        86,6,%

        64,90%

        97,60%

        59,60%

        100

        87,60%

        Chronic pancreatitis

        100%

        36,60%

        100%

        80,40%

        NA

        NA

        Post OLT

        97,20%

        81%

        100%

        50%

        88%

        89%

        Complications occurred most frequently with uSEMS (39.5%), followed by a single plastic stent (36.0%) and multiple plastic stents (20.3%) (Figure 4). The most frequently reported complications included cholangitis, pancreatitis, stent migration and hemorrhage.
        http://static-content.springer.com/image/art%3A10.1186%2F1471-230X-9-96/MediaObjects/12876_2009_Article_388_Fig4_HTML.jpg
        Figure 4

        Complications of uncovered SEMS (uSEMS), multiple plastic stents and single plastic stents for benign biliary strictures.

        No stent-related mortality was reported with placement of multiple plastic stents, whereas 7 (0.9%) patients died as a consequence of single plastic stent placement. Following uSEMS placement, 2 (1.1%) patients died of a stent-related cause. In all these cases, the cause of death was a septic complication due to cholangitis.

        Publication bias

        Plotting the total number of patients with uSEMS against technical and clinical success showed that publication bias was not present (Figure 5). This was confirmed with Spearman's rank correlation test for technical (r-0.218, p = 0.435) and clinical success (r-0.089, p = 0.796) against the number of included patients. The same was found when technical success and clinical success rates in publications with ≤ 8 or >8 patients were compared (p = 0.414 and p = 0.779, respectively).
        http://static-content.springer.com/image/art%3A10.1186%2F1471-230X-9-96/MediaObjects/12876_2009_Article_388_Fig5_HTML.jpg
        Figure 5

        Numbers of patients with a benign biliary stricture vs. reported results for technical success (a) and clinical success (b) of uncovered self-expanding metal stent placement.

        We also plotted the number of patients with a single plastic stent against technical and clinical success and again found no evidence of publication bias (Figure 6). Similarly, no evidence of bias was found when the clinical success in publications with ≤ 20 or >20 included patients were compared (p = 0.065). For clinical success, this was confirmed with Spearman's rank correlation test (r-0.343, p = 0.109). For technical success, however, Spearman's rank correlation test suggested publication bias (r-0.046, p = 0.109). On the other hand, no evidence of bias was found when publications with ≤ 20 or >20 patients were compared (p = 0.303).
        http://static-content.springer.com/image/art%3A10.1186%2F1471-230X-9-96/MediaObjects/12876_2009_Article_388_Fig6_HTML.jpg
        Figure 6

        Numbers of patients with a benign biliary stricture vs. reported results for technical success (a) and clinical success (b) of single plastic stent placement.

        As the number of publications on multiple plastic stents (n = 6) in benign biliary stricture was low, it was not possible to make funnel plots for this stent type.

        Discussion

        This review shows that the most optimal nonsurgical treatment of benign extrahepatic biliary strictures has been demonstrated with multiple plastic stent placement. These results confirm that dilation with a large diameter dilator, i.e. multiple plastic stents, for a prolonged period is the most effective way to relieve benign strictures. It is however important to note that these results were mainly based on case series with often small patient numbers included.

        Complication rates were also lowest for multiple plastic stents, followed by single plastic stents and uSEMS. The low complication rate of multiple plastic stents is most likely due to the practice of exchanging multiple plastic stents at 3-months intervals. This was found to be uncommon after single plastic stent placement. In the latter, cholangitis as a result of stent clogging occurred more frequently. Due to their larger luminal diameter, placement of uSEMS seems an attractive alternative for single or multiple plastic stents in benign biliary strictures, however uSEMS have the disadvantage that tissue hyperplasia through uncovered stent meshes may occur, leading to stent obstruction [15, 16, 65]. Based on clinical success and complication rates, placement of multiple plastic stents has therefore still the best treatment profile for treatment of benign biliary strictures.

        Our findings are in line with results of stent placement for specific causes of benign biliary obstruction, particularly those following liver transplantation or a surgical procedure. Only for patients with strictures due to chronic pancreatitis, uSEMS were found to give good results with regard to clinical success. The number of studies that included patients with this indication and were treated with multiple plastic stents was low. The reason for this is likely that biliary obstruction due to chronic pancreatitis often has a protracted course, requiring multiple procedures if plastic stents are used [66].

        An exception to the overall poor results of endoscopic treatment with single plastic stents in patients with chronic pancreatitis was reported by Vitale et al. [41], who achieved stricture resolution with single plastic stents in 80% of patients. Calcifications in the pancreatic head were found in only 4 of 25 patients in this study, which may well explain the high success rate. Calcifications in the pancreatic head have been suggested to be a strong predictor of failure of CBD stenting [34]. As these calcifications are often associated with a firm fibrotic component due to the inflammatory reaction in chronic pancreatitis [67], it can be expected that these strictures are more difficult to dilate. Patients with chronic pancreatitis but without calcifications are more likely to have a stricture secondary to edema and to have less pronounced fibrosis. These strictures may subside over time and therefore only require temporary treatment. This explains why single plastic stent placement for CBD strictures in this patient category was found to be successful (78).

        It should be noted that the disappointing results of uSEMS placement, particularly in patients with biliary strictures following liver transplantation or a surgical procedure, are probably affected by selection bias. In most studies, the included population consisted of patients in whom the initial treatment, mostly plastic stent placement, had already failed. As a consequence, these patients were probably more difficult to treat and less responsive to dilation.

        We found that the median stenting time was not different between multiple and single plastic stent placement (11.3 vs.10.5 months, respectively).uSEMS functioned clinically well for a median time of 20 months (0.5-60) before a reintervention, mostly for stent obstruction, was needed. Reported reinterventions included placement of a new stent within the occluded uSEMS, percutaneous biliary drainage, endoscopic removal of sludge, or surgical or endoscopic removal of the stent.

        A problem with uSEMS is that they tend to embed into the mucosa of the CBD, leading to mucosal hyperplasia. This is an unwanted side effect, as removal of uSEMS in this situation is difficult, if not impossible. Removal may however be indicated when uSEMS are malpositioned or obstructed, or have (partially) migrated [18, 68]. Recently, cSEMS have been introduced. These devices have the benefit that removal is possible as the risk of embedding into the biliary wall is reduced or even negligible. This capacity combined with the larger diameter of cSEMS makes stepwise dilation, as is performed with multiple plastic stents, unnecessary and may thus reduce the number of procedures [69]. The clinical experience with cSEMS for benign biliary strictures is until now only limited [66, 69, 69]. cSEMS can achieve a luminal diameter that is comparable to that of multiple plastic stents and uSEMS, but due to their covering have the advantage that fewer procedures for recurrent obstruction are required. In the future, cSEMS are likely to be a more patient-friendly and cost-effective treatment option for benign biliary strictures. Until now, cSEMS placement for benign biliary strictures is still associated with relatively high complication rates (39.6%) [66, 69, 69]. In our opinion, new covered stents and refinements of existing covered stents are needed before large scale introduction of cSEMS for this indication can be recommended.

        This review has several limitations which should be taken into account before concluding that a particular stent type is favorable in patients with a benign biliary stricture. First, no randomized trials and only one comparative trial have been conducted. This may be due to the fact that (multiple) plastic stents have an acceptable technical and clinical success rate in daily clinical practice. Moreover, uSEMS placement has not been shown to be more successful than multiple plastic stents in case series.

        Secondly, several types of plastic stents were used in different studies. Results on individual plastic stent types in patients with benign biliary strictures are not available. From trials in patients with malignant biliary strictures, it is however known that different plastic stents types have varying luminal patencies, due to the stent material and/or the stent diameter [7073]. Particularly, plastic stents with a diameter of 10 French (Fr.) have been shown to be remain patent for a significantly longer period than 8 Fr. stents (median 32 vs. 12 weeks) [71].

        Finally, there was a wide variety in treatment protocols in the various studies with plastic stents. In some studies, stent exchange was performed at 3-month intervals, while in other studies stents were only exchanged when they became occluded. Besides, the number of plastic stents used for multiple stenting varied between 2 and 4 among patients. This could both have affected clinical success rates, but also complication rates in patients treated with plastic stents.

        The strength of this review is that all available data on the use of plastic stents and SEMS for the treatment of biliary strictures was evaluated. To the best of our knowledge, this is the largest review on the use of different types of stents in patients with a benign biliary stricture, with pooled data on 1116 treated patients. We also showed that the reported results, particularly those of single plastic stents and uSEMS, were not affected by publication bias, making an overestimation of the clinical success rate and/or an underestimation of the complication rate of a particular stent type unlikely.

        Conclusion

        In conclusion, this systematic review shows that, based on clinical success and risk of complications, placement of multiple plastic stents is currently the best choice. The evolving role of cSEMS placement as a more patient friendly and cost effective treatment for benign biliary strictures needs further elucidation. There is a need for RCTs comparing different stent types for this indication.

        Declarations

        Authors’ Affiliations

        (1)
        Department of Gastroenterology and Hepatology, University Medical Center Utrecht

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        74. Pre-publication history

          1. The pre-publication history for this paper can be accessed here:http://​www.​biomedcentral.​com/​1471-230X/​9/​96/​prepub

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        © van Boeckel et al. 2009

        This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://​creativecommons.​org/​licenses/​by/​2.​0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.