Bristol stool scale

The Bristol stool scale, Bristol stool chart (BSC),Bristol stool form scale, or BSF 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 referred to in the UK as the Meyers scale.

Developed and proposed for the first time in England by Dr. Stephen Lewis and Dr. Ken Heaton at the University Department of Medicine, Bristol Royal Infirmary, it was suggested by the authors as a clinical assessment tool in 1997 in the journal Scandinavian Journal of Gastroenterology after a previous prospective study, conducted in 1992 on a sample of the population (838 men and 1,059 women), had shown an unexpected prevalence of defecation disorders related to the shape and type of stool. The authors of the former paper concluded that the form of the stool is a useful surrogate measure of colon transit time. That conclusion has since been challenged as having limited validity, and only in types 1 and 2 when the subject is not constipated; however, it remains in use as a research tool to evaluate the effectiveness of treatments for various diseases of the bowel, as well as a clinical communication aid.

The Bristol stool scale is part of the diagnostic triad for irritable bowel syndrome: pain/discomfort (quality and quantity), bowel habit (quality and quantity), and bloating (in women).

The seven types of stool are:

Types 1 and 2 indicate constipation, with 3 and 4 being the ideal stools (especially the latter), as they are easy to defecate while not containing excess liquid, and 5, 6 and 7 tending towards diarrhoea.

...
Wikipedia