Review for 10.1186/s12876-022-02162-8 (2022)

Reviewer’s report
Title: 
Endoscopic ultrasound avoids adverse events in high probability
choledocholithiasis patients with a negative computed tomography
Version: 
1 
Date: 
01 Jan 2022
Reviewer's report:
The authors conduct a prospective study to elucidate the usefulness of EUS
before ERCP in high probability CBD stones with negative CT scan.
A total of 604 patients was screening and 104 patients were enrolled after
excluding malignant biliary obstruction, altered GI anastomosis, CBD stones on
CT scan. 44 patients in EUS first group and 60 patients in ERCP first group.
Lower complication rate and more cost-effectiveness were noted in EUS first
groups. This article had been reviewed and was re-summitted after replying
previous comments.
Followings are my comments:
1. ASGE high-risk criteria demonstrated >50% probability of the patient has
CBD stones but some patients would receive diagnostic ERCPs according to
ASGE guidelines. This study provides some evidences about benefits of EUS in
high risk patients with negative CT scan.
2. In previous literatures (Ref 3 and 4). ERCP adverse event rate is about 6.9-
12%. However, the ERCP adverse event rate is higher in this study (13 in 60
patients, 21.7% in ERCP group; 3 in 17 ERCP patients, 17.6% in EUS first
group). This study was conducted in high annular ERCP volume center. The
reason of high ERCP adverse event rate in choledocholithiasis?
3. 
In result section (Table 1), not all ERCP group patients are naïve papilla.
Seven patients had received previous ERCP procedure. These patients might
have lower post-ERCP adverse event rate than naïve papilla patient (but high
post-ERCP adverse event in this study as previous paragraph).
The methods to open papilla include EST, EPLBD, TPS, Pre-cut. Table 1
showed CBD diameter is 7.0mm (4.25-8.00) in EUS first group and 8.5mm (7.0-
11.0) in ERCP group. In previous literatures, EPLBD means dilation balloon size
more than 12mm (≥12mm). Generally, we would not inflate balloon size larger
than CBD diameter to avoid adverse event. In this study, 16 EPLBD procedures
were performed in ERCP group and largest CBD diameter was only 11mm. Is
EPLBD or EPBD was performed in this study?
In ERCP group, 10 pre-cut or TPS procedures were performed and seems higher
than previous literatures. Pre-cut and TPS might cause post-ERCP pancreatitis
and other post-ERCP adverse event. Does it associate with high adverse event
rate (bleeding and cholangitis) in this study?
4. About gallstones related discomfort, authors included biliary colic,
cholecystitis, cholangitis into methodology and table. Is gallstone related acute
pancreatitis should be included?
5. Is there any other formal term of gallstone related discomfort? such as
recurrent biliary events, recurrent biliary complication? I suggested authors
review other literatures and consider to revise this term. 
6. In result section (distribution of ASGE criteria and common risk factors for
choledocholithiasis), authors collected gallstones/CBD stones risk factors (forty,
fat, fertility and female). All enrolled patients had gallstones (most important
CBD stone risk factors). Is there any important role to compare these factors
between EUS first or ERCP group?
7. In discussion session (limitation section), author try to explain high post-
ERCP bleeding rate in this study. In 2020 ESGE guideline, post-EST bleeding
rate is 0.3-9.6% (much lower than this study). Is any other possible undetected
risk factors in this study?
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