3 | DISCUSSION
There are 3 reports in the literature on cases of CBD stones with distal
CBD strictures that were treated using CSEMS (Table 1). However, two
case series did not mention the details of the cases with CBD stones and
distal CBD strictures. A case series by Cerefice et al. targeted cases
with the CBD stones that were difficult to remove using conventional
endoscopic methods.8Another case series by García-Cano et al. targeted older patients who
had difficulty tolerating endoscopic lithotripsy due to the long
duration required by the
procedure.10
A case report by Okabe et al. described a case of CBD stones and distal
CBD stricture due to
CP.9 In that case, the
CBD stones remained in the biliary duct and the upper portion of the
CSEMS, and the distal biliary stricture did not improve despite CSEMS
placement for 14 days. On the contrary, the CBD stones had spontaneously
disappeared in our case and, the distal biliary stricture had also
slightly improved by the placement of the CSEMS for only 7 days. This
observation indicates that the new CSEMS BONASTENT M-intraductal
(Standard Sci Tech) has strong dilation ability. The stent’s dumbbell
shape was thought to slightly prevent stent migration and transmit
dilation forces to the CBD stricture.
The CSEMS should be placed for a longer duration to avoid recurrence of
the CBD stones. Although, CSEMS dilated the distal CBD stricture, the
distal CBD remained thin (Fig. 3c). In the past reports, variations were
seen in the duration and effectiveness of the CSEMS placement for CBD
strictures secondary to CP. Cahen et al. reported six cases that
received CSEMS for CBD stricture with
CP.20 They reported the
CSEMS removal time to be 3–6 months and that 66% of the CBD stricture
showed improvement. Lalezari et al. reported a case with CP in which the
CBD was dilated by
CSEMS.21 In this
report, the CSEMS was placed for 63 days, and the CBD stricture had
improved. Haapamäki et al. had conducted a randomized controlled study
on the effectiveness of multiple plastic stents versus the CSEMS in
treating biliary stricture with
CP.22 In this study,
CSEMS was removed 6 months after randomization, and the two-year
stricture-free success rate was 92% (24/26). Although, the targets were
not CP patients alone, Park et al. raised the duration of CSEMS
placement to ≥ 120 days as a factor for CBD stricture
resolution.23
However, complications such as migration and embedding have been
reported when the CSEMS was left in place for a longer
duration.10,20,23-25A new dumbbell-shaped CSEMS is thought to be useful in preventing
misregistration. The duodenal tip of the dumbbell shape can prevent the
embedding and migration into the biliary tract superiorly and while the
hilar tip can prevent duodenal migration. If the new dumbbell-shaped
CSEMS migrates into the biliary tract superiorly, removing the stent is
thought to be easier than removing other types of the CSEMSs, primarily
because the dumbbell-shaped CSEMS becomes narrower by pulling a string
that is attached at the duodenal tip (Figure 2). Park et al. described
that migration of the CSEMS is a risk factor that prevents benign CBD
stricture resolution.23Therefore, the dumbbell shape is expected to prevent misregistration and
dilate the CBD stricture effectively. In fact, in this case, the CBD
stricture was slightly dilated after CSEMS placement for only 7 days.
In conclusion, the new
dumbbell-shaped CSEMS is efficient in removing the CBD stones with CBD
strictures that occur due to CP. The stent might have the potential to
prevent positional displacement and contribute to improved CBD
stricture.