The Bristol Stool Scale or Bristol Stool Chart is a medical aid designed to classify the form of human feces into seven categories. It was developed by Heaton and Lewis at the University of Bristol and was first published in the Scandinavian Journal of Gastroenterology in 1997.^[1] The form of the stool depends on the time it spends in the colon.^[2]

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: Entirely liquid

Types 1 and 2 indicate constipation, with 3 and 4 being the "ideal stools" especially the latter, as they are the easiest to pass, and 5-7 being further tending towards diarrhea or urgency .^[2]

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