In our practice of gastrointestinal endoscopy we have noticed that the use of internal
landmarks to determine the anatomical position of the endoscope tip can be inaccurate.
This was especially the case during colonoscopy [1]; sometimes it has been required to spray water through the endoscope channel and
watch how it fell because this was the only way to confirm the gravitational vertical
direction, which does not necessarily match the upper and lower orientation of the
video endoscopy monitor.
On this basis, we designed our new device. This is a transparent capsule of the same
kind as used in endoscopic mucosal resection [2] but with a double-layered wall. The space between the two walls is almost filled
with a transparent liquid, leaving a small air bubble inside. The capsule is attached
to the tip of the endoscope (Figure [1]), Following the laws of density and gravity, when the tip of the endoscope is rotated
in its transverse plane the air bubble will continue to float in its upper position,
indicating the vertically upward direction with respect to gravity. When the tip is
rotated in its sagittal plane, if the tip is bent downwards, the air bubble will slide
up in the opposite direction; if the tip is bent upwards, the air bubble will also
slide up in the same direction.
Figure 1 View from above of the double-walled capsule attached to the endoscope tip, showing
the air bubble inside the capsule.
For example when we see on the monitor during colonoscopy that the air bubble is at
the right far end of the capsule (Figure [2]), this means that the right side of the image is actually the upward vertical direction
with respect to gravity in the transverse plane and the tip is bent upwards in the
sagittal plane. Comparing these directions with the position of the patient we are
able to determine the position of the endoscope tip.
Figure 2 Endoscopic image showing the air bubble at the right far end of the capsule. This
indicates that the right side of the image is actually the vertically upwards direction
with respect to gravity, in the transverse plane, and the tip is bent upwards in the
sagittal plane.
In addition, using the 12 o’clock locating method with this device will help us to
determine the exact location of investigated lesions, for later examination or treatment.
Finally, based on the same idea, we could use air instead of liquid to fill the space
between the two walls of the capsule with a metal or plastic ball instead of the air
bubble.
