Boston bowel preparation score, from Gastrointest Endosc 2009;69:620-5.
4-point scoring system (0-4) applied to each of the 3 colon segments:
Right colon : cecum and ascending colon
Transverse colon: transverse colon, hepatic and splenic flexures
Left colon: descending colon, sigmoid colon, and rectum

0: unprepared colon segment with mucosa not seen because of solid stool that cannot be cleared.
1: portion of mucosa of the colon segment seen, but other areas of the colon segment are not well seen because
of staining, residual stool, and/or opaque liquid.
2: minor amount of residual staining, small fragments of stool, and/or opaque liquid, but mucosa of colon segment is seen well.
3: entire mucosa of colon segment seen well, with no residual staining, small fragments of stool, or opaque liquid.

Ottawa scale, from Rostom A, et al. Gastrointest Endosc 2004;59:482-6.
The cleanliness and fluid volume is assessed separately.
Part I. Cleanliness is assessed by a 4-point scoring system (0-4) for each colon segment, together with a summary score indicating overall cleanliness.
Right colon: cecum, ascending colon
Mid colon: transverse, descending
Rectosigmoid colon
Part II. Fluid quantity is assessed by a 2-point scoring system (0-2).
The scale has a range from 0 (perfect) to 14 (solid stool in each colon segment and lots of fluid, i.e., a completely unprepared colon).

Aronchick scale, from Aronchick CA, et al. Gastrointest Endosc 2000;52:346-52.
Scoring performed before any attempt of washing or suctioning
1 (excellent): small volume of clear liquid or >95% of the surface seen
2 (good): large volume of clear liquid covering 5–25% of the surface but >90% seen
3 (fair): some semi-solid stool that could be suctioned or washed away but >90% of surface seen
4 (poor): semi-solid stool that could not be suctioned or washed away and <90% of surface seen
5 (inadequate): repeat preparation and colonoscopy needed