The Bristol Stool Scale or Bristol Stool Chart is a medical aid designed to classify the fæces form into seven groups. It was developed by Heaton and Lewis at the University of Bristol and was first published in the Scandinavian Journal of Gastroenterology in 1997. Lewis drew inspiration from the eye charts found in eye examination offices. The form of the stool depends on the time it spends in the colon.
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 (easily passed)
- Type 6: Fluffy blobs with ragged edges, a mushy stool
- Type 7: Watery, no solid pieces (entirely liquid)
Types 1 and 2 indicate constipation; 3 and (especially) 4 are the preferred types of stools as they are the easiest to pass Types 5-6 are more symptomatic of diarrhoea, while type 7 may be a sign of Cholera.
 - Wikipedia, original article
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