Fig. 2 Near-infrared fluorescence showed changes after the release the clamped SRA（transanal view）.

a. The blood vessels under clamping SRA cannot be observed on a white background.
b. At approximately 30 seconds after the release of the clamp, the vessels still cannot be detected.
c. At approximately 60 seconds after the release of the clamp, a thick white blood vessel is observed on the white background.
d. The blood vessels gradually became clearer and could be clearly observed at 90 seconds.