Review for 10.1186/s12876-022-02196-y (2022)

Reviewer’s report
Title: 
Biliary balloon dilator impaction in a non-dilated bile duct with
anatomical variations: a case report
Version: 
0 
Date: 
07 May 2021
Reviewer's report:
I read with interest this manuscript describing a case report of a rare adverse
event of a balloon impacting inside the bile duct during ERCP. I have several
queries and issues with this manuscript - 
1. Why was the patient subjected to a percutaneous cholecystostomy instead of
cholecystectomy in the first place? She was 45 years old and unlikely to have
severe co-morbidities that precluded primary surgery. 
2. Percutaneous cholecystostomy resulted in a stone migrating across the cystic
duct into the CBD resulting in secondary cholangitis. In my opinion, the issue
could have been entirely avoided by primary cholecystectomy. 
3. The appearance of the ERC cholangiogram suggests that the stone is impacted
at the junction of the long cystic duct and CBD - Mirrizzi syndrome. It was for
this reason that the stone could not be retrieved using a basket or stone extractor
balloon. 
4. Biliary dilatation balloons are not designed to be used for stone extraction. In
fact, their shape and design cannot grasp and trawl the stone effectively. Also,
the balloon is significantly longer so I cannot imagine why such a balloon was
used in the first place for stone extraction? Or did the authors use the balloon to
attempt dilatation of the distal bile duct as there appears to be some relative
narrowing distally? Please clarify. 
5. The appearance of the MRCP and ERC images are classical of stone impacted
at the cystic duct - CBD junction. Such stones are invariably associated with
distal narrowing and can almost never be retrieved by standard ERCP
techniques. 
6. The safest step to be done in such a situation should have been to place a
biliary stent in the CBD. Stone fragmentation using cholangioscopy guided laser
or electrohydraulic lithotripsy can be attempted at a 2nd stage in such cases.
Placing a stent also helps to open up the distal bile duct somewhat so that
accessories can be passed across more easily. Can the authors explain / comment
on this point? 
7. In my opinion, the pathophysiology of the current adverse event is as follows -
as mentioned earlier, the stone was impacted at the cystic duct - CBD junction
with a distal CBD narrowing. When the authors passed the thin (sharp) tipped
catheter across, it is possible that the tip entered the cystic duct rather than CBD.
On balloon inflation, the stone was entrapped between the bile duct wall and
balloon with possible tear / injury to the balloon. Due to the torn balloon, the
outer sheath became entangled with the stone and could not be retrieved. It
would be prudent if the authors can provide a better image for Fig 2B - although
the balloon catheter can be seen, please provide image that demonstrates the
cholangiogram, stone and the inflated balloon so that the exact location can be
ascertained. 
8. Despite the queries and concerns raised above, the authors must be
congratulated for their presence of mind, hand dexterity and innovative thought
process to deal with such an unusual adverse event, successfully retrieve the
balloon fragments and avoid emergency surgery in this patient. 
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