A medical aid designed to classify the form of human feces into seven categories.
It suggests the form of the stool is a useful surrogate measure of colon transit time.
That conclusion has since been challenged.
The Bristol stool scale is part of the diagnostic triad for irritable bowel syndrome: pain/discomfort, bowel habit, and bloating (in women).
The seven types of stool are:
Type 1: Separate hard lumps, like nuts (hard to pass)
Type 2: Sausage-shaped, but lumpy
Type 3: Like a sausage but with cracks on its surface
Type 4: Like a sausage or snake, smooth and soft
Type 5: Soft blobs with clear cut edges (passed easily)
Type 6: Fluffy pieces with ragged edges, a mushy stool
Type 7: Watery, no solid pieces, entirely liquid
Types 1 and 2 indicate constipation, with 3 and 4 being the ideal stools as they are easy to defecate while not containing excess liquid, and 5, 6 and 7 tending towards diarrhea.