Improved stent characteristics for prophylaxis of post-ERCP pancreatitis.

Abstract

Pancreatic stenting is an effective method to prevent post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis in high-risk patients. This retrospective study evaluated the impact of modified stent characteristics on the rate of post-ERCP pancreatitis, spontaneous stent dislodgment, and stent-related sequelae.
A total of 2283 patients underwent 2447 ERCPs over a 6-year period with placement of 3-4F diameter, unflanged pancreatic stents. The indication for stenting was pancreatitis prophylaxis predominantly in suspected sphincter of Oddi dysfunction (SOD), pancreas divisum therapy, and precut sphincterotomy. An abdominal radiograph was obtained 10-14 days later to assess spontaneous stent passage. Post-ERCP pancreatitis was defined according to established criteria. A total of 479 patients underwent repeat ERCPs after an initial ERCP with pancreatic stent placement. The prestenting pancreatogram was then compared with follow-up studies.
The pancreatitis rate with 3F, 4F, 5F, and 6F stents was 7.5%, 10.6%, 9.8%, and 14.6%, respectively (3F vs. 4F, 5F, 6F: P = 0.047). Spontaneous stent dislodgment was 86%, 73%, 67%, and 65%, respectively (3F vs. 4F, 5F, 6F: P < 0.0001). The frequency of ductal changes was 24% in patients with 3-4F stents compared with 80% with 5-6F stents. Ductal perforation from the stents occurred in 3 patients (0.1%).
Small diameter (3-4F), unflanged pancreatic stents are more effective than the traditionally used stents (5-6F) in preventing post-ERCP pancreatitis. Stent-induced ductal changes and the need for endoscopic removal are also significantly less with 3-4F stents. The 3F stent appears to be superior in all aspects studied. Additional studies are needed to define the ideal method to eliminate post-ERCP pancreatitis.

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Improved Stent Characteristics for Prophylaxis of Post-ERCP
Pancreatitis
ABDULLAH RASHDAN,* EVAN L. FOGEL,* LEE MCHENRY JR.,* STUART SHERMAN,*
M’HAMED TEMKIT,‡and GLEN A. LEHMAN*
*Division of Gastroenterology/Hepatology; and the‡Department of Biostatistics, Indiana University Medical Center, Indianapolis, Indiana
Background & Aims: Pancreatic stenting is an effective
method to prevent post–endoscopic retrograde cholan-
giopancreatography (ERCP) pancreatitis in high-risk pa-
tients. This retrospective study evaluated the impact of
modified stent characteristics on the rate of post-ERCP
pancreatitis, spontaneous stent dislodgment, and stent-
related sequelae. Methods: A total of 2283 patients
underwent 2447 ERCPs over a 6-year period with place-
ment of 3–4F diameter, unflanged pancreatic stents.
The indication for stenting was pancreatitis prophylaxis
predominantly in suspected sphincter of Oddi dysfunc-
tion (SOD), pancreas divisum therapy, and precut
sphincterotomy. An abdominal radiograph was obtained
10–14 days later to assess spontaneous stent passage.
Post-ERCP pancreatitis was defined according to estab-
lished criteria. A total of 479 patients underwent repeat
ERCPs after an initial ERCP with pancreatic stent place-
ment. The prestenting pancreatogram was then com-
pared with follow-up studies. Results: The pancreatitis
rate with 3F, 4F, 5F, and 6F stents was 7.5%, 10.6%,
9.8%, and 14.6%, respectively (3F vs. 4F, 5F, 6F: P ?
0.047). Spontaneous stent dislodgment was 86%, 73%,
67%, and 65%, respectively (3F vs. 4F, 5F, 6F: P <
0.0001). The frequency of ductal changes was 24% in
patients with 3–4F stents compared with 80% with 5-6F
stents. Ductal perforation from the stents occurred in 3
patients (0.1%). Conclusions: Small diameter (3–4F),
unflanged pancreatic stents are more effective than the
traditionally used stents (5–6F) in preventing post-ERCP
pancreatitis. Stent-induced ductal changes and the need
for endoscopic removal are also significantly less with
3–4F stents. The 3F stent appears to be superior in all
aspects studied. Additional studies are needed to define
the ideal method to eliminate post-ERCP pancreatitis.
P
(ERCP) pancreatitis in high-risk individuals is increas-
ingly applied in current clinical practice. In the recent
“NIH state of the science conference: ERCP for diagnosis
and therapy,” Freeman reviewed several randomized con-
trolled trials supporting the role of prophylactic pancre-
atic stenting in patients undergoing sphincterotomy (bil-
iary and/or pancreatic) for sphincter of Oddi dysfunction
lacement of pancreatic duct stents to limit post–
endoscopicretrogradecholangiopancreatography
(SOD), biliary balloon dilatation for stone extraction, and
precut sphincterotomy.1For these purposes, 5–7F poly-
ethylene pancreatic stents have been used the most
widely. However, studies from our group as well as
others have shown that their use may lead to pancreatic
ductal and parenchymal alterations mimicking chronic
pancreatitis.2–10Pancreatic duct changes from the stent is
an undesirable consequence because the majority of pa-
tients who undergo this protective technique have nor-
mal pancreatograms before stenting. One series reported
that in about one third of cases stent-induced ductal
changes were long lasting.2Furthermore, if the stent has
an intraductal flange then a repeat costly endoscopy often
is needed to remove the stent with the associated proce-
dure-related complications and missed work days. The
ideal stent should prevent pancreatitis, not damage the
pancreatic duct and spontaneously dislodge, avoiding the
need for upper endoscopy to remove the stent.
Theoretically, the use of smaller-diameter stents (3–4F)
may result in less ductal irritation, less ductal changes, and
may spontaneously dislodge more frequently than larger-
diameter ones. However, small luminal diameter stents
occlude sooner, compromising pancreatic duct drainage and
therefore may increase the risk for pancreatitis. In the late
1990s, our group made a transition away from 5F and 6F
prophylactic stents and used mostly 3F and 4F stents at the
discretion of the endoscopist.
The aim of our study was to compare the frequency of
post-ERCP pancreatitis, spontaneous stent dislodgment
rates, and the frequency of stent-induced ductal changes
in patients undergoing prophylactic pancreatic duct
stenting with modified 3–4F stents and 5–6F stents.
Materials and Methods
Small-diameter 3F and 4F polyethylene pancreatic
stents with a single duodenal pigtail (Wilson-Cook, Winston-
Abbreviations used in this paper: ERCP, endoscopic retrograde
cholangiopancreatography; SOD, sphincter of Oddi dysfunction.
© 2004 by the American Gastroenterological Association
1542-3565/04/$30.00
PII: 10.1053/S1542-3565(04)00062-X
CLINICAL GASTROENTEROLOGY AND HEPATOLOGY 2004;2:322–329

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Salem, NC) became commercially available in the 1990s. From
January 1997 to October 2002, 7383 consecutive patients
underwent 11,178 ERCPs at our institution. Of those, 2283
(31%) patients underwent 2447 ERCPs with placement of a
3F or 4F diameter, 4–12 cm long (median length ? 8 cm,
intraductal length ? 3–8 cm), three-quarter duodenal pigtail
polyethylene pancreatic duct stent at the discretion of the
endoscopist. The flange of the 4F stent was always removed.
The 3F stent had no internal flange (Figure 1). Indications for
stenting were predominantly for pancreatitis prophylaxis in
manometrically documented or suspected SOD dysfunction,
pancreas divisum therapy (minor papilla sphincterotomy), and
as a guide for needle-knife precut papillotomy or pancreatic
sphincterotomy (Table 1). The 3F and 4F stents were placed
predominantly over a 0.018-in diameter guidewire (Roadrun-
ner wire; Wilson-Cook). When a 0.025-in diameter guide wire
was used, a 4F diameter stent was necessary to accommodate
the larger guide wire. Patients only were observed overnight in
the hospital if there was a clinical suspicion of post-ERCP
pancreatitis, other complications, or if they were in the hos-
pital for ongoing treatment. A plain abdominal radiograph
(kidney ureters bladder [KUB]) was obtained for all patients
10–14 days after stent placement to ensure spontaneous pas-
sage of the stent. If the stent did not exit the pancreas,
endoscopic removal was undertaken. Follow-up pancreatogra-
phy at the time of stent removal was performed at the discre-
tion of the endoscopist.
The prospectively recorded ERCP database from January
1997 to October 2002 was reviewed regarding the frequency
and severity of post-ERCP pancreatitis in patients who under-
went prophylactic 3F or 4F stent placement, and was compared
with patients who had 5F or 6F stents. The diagnosis of
post-ERCP pancreatitis and the grading of its severity were
based on established criteria.11The occurrence of post-ERCP
pancreatitis and its severity was correlated with the prevalence
of SOD in the same population group.
Follow-up pancreatograms were available for review in 479
patients who previously had either a 3F or 4F stent placed. The
indications for repeat study were for stent removal if it failed
to dislodge spontaneously after 2 weeks of placement (mean ?
24 days; range ? 10–59 days), or for recurrent symptoms long
after the stent migration or removal (mean ? 14 mo; range ?
2–67 mo). Patients whose initial pancreatogram showed mod-
erate to severe pancreatitis, malignancy involving the pancreas,
or those patients who underwent interval pancreatic surgery
were excluded. Baseline pancreatograms were read and classi-
fied as normal or abnormal according to the Cambridge crite-
ria.12Ductographic abnormalities were recorded with empha-
sis on their location and type and degree of change. The
location of main pancreatic ductal changes was specified to the
stented portion of the duct (i.e., stented zone) or the upstream
duct (i.e., remote zone), and involvement of the pancreatic side
branches. The morphologic ductal changes were noted as duc-
tal irregularity, narrowing, or dilatation. The degree of nar-
rowing was graded subjectively as follows: grade I: ?20%
luminal narrowing; grade II: 20% to 50% luminal narrowing;
Figure 1. (A) Polyethylene duodenal pigtail pancreatic stents (Wilson-
Cook): 3F stent (top), 4F stent (middle), and 5F stent (bottom). (B)
Three-quarter duodenal pigtail stents, 3F stent (top), and 4F stent,
internal flange removed (bottom).
Table 1. Patient Data
Stentn M/F
Mean age
(range)
IndicationsPancreatic therapy
SODa
PDivCP Othersb
DES MiES Othersc
3F
4F
Total
1353
930
2283
293/1060
207/723
500/1783
47 (10–89)
45 (5–91)
994
656
1650
165
119
284
75
37
112
110
108
218
912
661
1573
174
130
304
167
139
306
CP, chronic pancreatitis; DES, dual (biliary and pancreatic) endoscopic sphincterotomy; MiES, minor papilla sphincterotomy; PDiv, pancreas
divisum.
aSphincter of Oddi dysfunction: basal sphincter pressure ? 40 mm Hg.
bNormal SOM, precut sphincterotomy, ampullary tumor resection.
cNo therapy, orifice (biliary/pancreatic) dilatation.
April 2004 STENTING FOR POST-ERCP PANCREATITIS PROPHYLAXIS323

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grade III: ?50% luminal narrowing (Figures 2–4). Ductal
perforations were recorded. The degree of resolution of stent-
induced changes was determined by comparing the latest
available pancreatograms with baseline study (Figure 5). All
studies were performed at our institution. Two endoscopists
experienced in ERCP who were blinded to the patient’s clin-
ical condition graded the pancreatograms. Differences in pan-
creatogram interpretation were resolved by mutual discussion
between the investigators. The frequency of stent-induced
changes was correlated with stent size, duration of follow-up,
patency of the removed stents, and whether or not the baseline
pancreatogram was normal or abnormal. This study was ap-
proved by the Institutional Review Board at Indiana Univer-
sity Medical Center.
Statistical Methods
Logistic analysis was used to model binary responses
such as severity of pancreatitis and stent-induced ductal
changes to examine the effects of different stent diameters on
these outcomes, with or without adjusting for other risk factors
and to conduct pairwise comparisons between the different
stent diameters after controlling for type I error. Pearson’s ?2
test and exact version of the Pearson’s ?2test when the sample
sizes were small were used to test for association between the
baseline pancreatogram and the development of stent-induced
ductal changes, as well as for association between different
stent diameters and stent spontaneous dislodgment. Statistical
tests with a P value ?0.05 were considered significant. Sta-
tistical analyses were performed using the statistical software
package SAS version 8.2 (SAS Institute, Cary, NC).
Results
Post-ERCP Pancreatitis
Overall, post-ERCP pancreatitis occurred in
7.5%, 10.6%, 9.8%, and 14.6% of patients stented with
3F, 4F, 5F, and 6F stents, respectively. Table 2 shows the
frequency and severity of post-ERCP pancreatitis corre-
Figure 2. (A) Baseline normal pancreatogram. A prophylactic 3F
10-cm pancreatic stent was placed. (B) Pancreatogram performed 9
months later for recurrent symptoms showing grade I narrowing in the
stented zone (arrow, ?20% luminal narrowing).
Figure 3. (A) Baseline normal pancreatogram. A prophylactic 4F 8-cm
pancreatic stent was placed. (B) Pancreatogram performed 4 months
later for persistent symptoms showing grade II narrowing in the
stented zone (arrow, 20%–50% luminal narrowing).
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lated with stent size. The frequency of post-ERCP pan-
creatitis was significantly lower with the 3F stent than
the 4F stent (P ? 0.0043). The 3F and the 4F stents were
associated with significantly lower post-ERCP pancreati-
tis rates than the 5F and 6F stents (P ? 0.0471).
However, when comparing the severity of pancreatitis
rates between 3F or 4F stents with 5F or 6F stents, the
difference was not statistically significant (P ? 0.19). Sev-
enty-five percent of patients with post-ERCP pancreatitis
and 93% of patients with moderate to severe post-ERCP
pancreatitis had manometrically documented SOD.
Stent Dislodgment
Data regarding the spontaneous dislodgment rate
of the 3–4F stents were tallied on 1371 patients and
were compared with our previous experience with the
5–6F stents (Figure 6).13,14The 3F stent had the highest
spontaneous passage rate (P ? 0.0001).
Figure 4. (A) Baseline normal pancreatogram. A prophylactic 3F 10-cm
pancreatic stent was placed. (B) Pancreatogram at stent removal show-
ing grade III narrowing in the stented zone (arrow, ?50% luminal narrowing).
Figure 5. (A) Baseline normal pancreatogram. A prophylactic 4F 8-cm
pancreatic stent was placed. (B) Pancreatogram at stent removal
showing grade I narrowing in the stented zone (arrow ?20% luminal
narrowing). (C) Resolution of the stent-induced changes seen on a
pancreatogram performed 8 months later (arrow, no residual narrow-
ing present).
April 2004 STENTING FOR POST-ERCP PANCREATITIS PROPHYLAXIS 325

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Ductographic Changes
Of the 479 patients who had serial pancreato-
grams available for review, 166 (24%) were found to
have morphologic changes of their pancreatic duct com-
pared with their baseline pancreatogram (Table 3). The
ductal changes were most commonly grade I (90%), and
were typically found within the stented zone. Involve-
ment of the remote zone and the side branches were seen
in patients with grade II or III ductal abnormalities.
These changes were seen more frequently during the
short-term follow-up period (i.e., at stent pull), but were
found less commonly on long-term follow-up evaluation
(i.e., recurrent symptoms). The 3F stents had signifi-
cantly less short-term as well as long-term stent-induced
morphologic changes (P ? 0.0006). At presentation,
355 (74%) patients had a normal pancreatogram, and
124 (26%) had features of mild chronic pancreatitis. Of
the patients with stent-induced ductal alterations, 99/
116 (85%) had a normal baseline pancreatogram,
whereas patients with underlying mild chronic pancre-
atitis were less prone to have stent-induced ductal
changes (17/116, 15%; P ? 0.002), as shown in Table 4.
All the stent-induced changes were grade I in patients
with baseline chronic pancreatitis. Correlation of stent-
induced changes between 3, 4, 5, and 6F stents is sum-
marized in Figure 7.
The degree of resolution of stent-induced changes was
assessed in 22 patients who had remote follow-up pan-
creatograms (Table 5). The indications for pancreatic
stent insertion in these patients were as follows: 11 SOD,
7 pancreas divisum, 3 chronic pancreatitis, and 2 amp-
ullary adenoma resections. The mean duration of fol-
low-up evaluation was 8.4 months, the range was 3–20
months. The indication for further follow-up ERCP in
this group was continuing or recurrent pain or pancre-
atitis and surveillance for ampullary tumor recurrence.
The degree of long-term resolution appeared similar in
patients with normal and abnormal baseline pancreato-
grams. Nine of the 22 patients (42%) had stent-induced
changes noted at the time of stent removal (failure to
dislodge spontaneously after 2 weeks of placement). Six
of the 9 patients (67%) had complete resolution of the
stent-induced abnormalities with longer follow-up eval-
uation. The remaining 13 patients (58%) had stent-
induced changes noted at long-term follow-up. There
was no significant difference seen in the mean follow-up
interval between the patients who had complete and
incomplete resolution. All 8 patients who had no im-
provement of their stent-induced ductal changes had
grade II–III changes of the stented zone, associated with
main duct and side branch dilatations at the remote zone.
One patient with grade III ductal changes had partial
resolution after repeated stenting and stricture dilation.
The remaining 13 patients with complete or partial
resolution had only mild ductal narrowing and irregu-
larity of the stented zone.
Three of the 2283 patients (0.1%) developed a perfo-
ration of the pancreatic duct at the intraductal stent tip
Figure 6. Spontaneous pancreatic polyethylene stents dislodgment
rates of various diameters (a vs. b, c, or d: P ? 0.0001).
Table 3. Characteristics of 3–4F Diameter Stent Induced Pancreatic Ductal Changes
Stent
Reason for repeat
pancreatogramN
Frequency of
stent-induced changes
Grade of stent-induced changes
III III
3F Stent pull
Symptomsb
Stent pull
Symptomsb
24
219
68
168
479
9 (37%)a
23 (10%)c
39 (57%)d
45 (26%)e
116 (24%)
9 (100%)
21 (91%)
35 (90%)
39 (87%)
104 (90%)
0
0
0
2 (9%)
2 (5%)
2 (4%)
6 (5%)
4F2 (5%)
4 (9%)
6 (5%) Total
NOTE. a vs. d: P ? 0.0006; c vs. e: P ? 0.0001.
bRefers to repeat pancreatograms for persistent and/or recurrent symptoms long after stent migration or removal.
Table 2. Post-ERCP Clinical Pancreatitis Rates
StentnMildModerateSevereTotal
3F
4F
5F
6F
1451
996
377
116
85 (6%)
80 (8%)
28 (7.4%)
14 (12%)
18 (1.3%)
20 (2%)
6 (1.6%)
2 (1.8%)
4 (0.2%)
6 (0.6%)
3 (0.8%)
1 (0.9%)
107 (7.5%)a
106 (10.6%)b
37 (9.8%)c
17 (14.6%)d
NOTE. a vs. b: P ? 0.0043; a vs. c: P ? 0.111; a vs. d: P ? 0.0058;
a or b vs. c or d: P ? 0.0471.
326RASHDAN ET AL.CLINICAL GASTROENTEROLOGY AND HEPATOLOGY Vol. 2, No. 4