Understanding The Bristol Stool Scale

The Bristol Stool Scale is the foundation of the Crappsy Algorithm.
The Bristol stool scale is a diagnostic medical tool designed to classify the form of human faeces into seven categories. It is used in both clinical and experimental fields. It is sometimes also referred to as the Bristol stool chart (BSC) Bristol stool form scale, or BSF scale

It was developed at the Bristol Royal Infirmary as a clinical assessment tool in 1997, and is widely used as a research tool to evaluate the effectiveness of treatments for various diseases of the bowel, as well as a clinical communication aid; including being part of the diagnostic triad for irritable bowel syndrome.

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 (easy to pass)
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, 5 tending towards diarrhoea, and 6 and 7 indicate diarrhoea.

In the initial study, in the population examined in this scale, the type 1 and 2 stools were more prevalent in females, while the type 5 and 6 stools were more prevalent in males; furthermore, 80% of subjects who reported rectal tenesmus (sensation of incomplete defecation) had type 7. These and other data have allowed the scale to be validated.

The Bristol stool scale is also very sensitive to changes in intestinal transit time caused by medications, such as antidiarrhoeal loperamide or senna, anthraquinone substance with laxative effect.