Recently, a new technique for performing underwater endoscopic submucosal dissection
(ESD) in a saline solution has been reported [1]
[2]. Although using a tapered hood is considered beneficial for underwater ESD in saline
immersion, the bubbles generated during ESD can hinder smooth dissection [3]. We describe a gas-free saline-immersion technique for ESD, in which a tapered hood
is filled with saline by pressing an air/water valve button, thus moving the bubbles
to outside the hood.
First, the hole for carbon dioxide (CO2) in the bottle cap is closed using a neoprene rubber plug (ARAM, Osaka, Japan) ([Fig. 1]). Subsequently, when the air/water valve button is pressed, the saline solution,
but not the CO2, is infused. Filling the hood with the saline solution pushes out the bubbles generated
during ESD, thus maintaining an optimal endoscopic view.
Fig. 1 Solution infusion without carbon dioxide (CO2) insufflation. a Firmly pressing the air/water valve button enables water infusion. b Before the air/water valve button is pressed firmly, the CO2 present in the endoscope is pushed out, which obstructs the endoscopic field of vision.
c Plug used to prevent CO2 gas insufflation. d The plug is inserted into the bottle’s CO2 outlet (yellow arrowheads). e The bottle is filled with saline instead of water. f Pressing the button firmly enables saline infusion without CO2 insufflation.
The patient in the case presented here had a 30-mm sessile serrated lesion overlying
a diverticulum in the sigmoid colon ([Fig. 2]). We performed ESD with en bloc resection of the SSL using a calibrated, small-caliber-tip,
transparent hood to access the submucosa within the diverticulum [4] ([Video 1]). Although the submucosa remains visible during saline immersion, bubbles are generated
when the submucosa is dissected, which obstruct the endoscopic view. Therefore, a
gas-free saline-immersion technique was used to dissect the submucosa while pressing
the air/water valve button with the index finger. By pressing and holding the button,
the saline is infused into the space inside the hood, which removes the bubbles produced
by ESD. This continuous saline infusion facilitates smooth dissection by preventing
the obstruction of the endoscopic field of vision by gas. Furthermore, the saline
immersion technique softens the mucosa and muscles, enabling easy closure of the defect
using the reopenable clip-over-line method [5].
Fig. 2 Gas-free saline-immersion technique for endoscopic submucosal dissection (ESD). a A 30-mm sessile serrated lesion (SSL) completely overlying a diverticulum in the
sigmoid colon. b Mucosal incision. c Poor endoscopic visibility due to the bubbles passing into the hood during ESD under
saline immersion. d When the air/water valve button is pressed and the submucosal layer is dissected
while the saline is being pumped, the pressure of the saline prevents bubbles from
entering the hood. e When bleeding occurs, the pressure of the saline makes it difficult for blood to
enter the tapered hood. f, g Dissection of the submucosa within the diverticulum. h Mucosal and muscle layer defects within the diverticulum following ESD. i The mucosal defect has been completely closed using the reopenable clip-over-line
method (ROLM).
Video 1 A gas-free saline-immersion technique, using a plug that allows saline infusion without
carbon dioxide (CO2) gas insufflation, was used to perform endoscopic submucosal dissection (ESD) of
a sessile serrated lesion (SSL) in the sigmoid colon.
The gas-free saline-immersion technique for ESD is a feasible method with no CO2 gas emission during saline immersion.
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