Bristol Stool Scale (Types 1-7)

The Bristol Stool Form Scale (Heaton KW et al., Scand J Gastroenterol 1997) is a standardized visual-descriptive scale developed at the University of Bristol to assess stool form and consistency. It is used in gastroenterology, infectious disease medicine, and general practice to objectify patient-reported symptoms.

The scale comprises 7 types: type 1 - separate hard lumps ("nuts", severe constipation); type 2 - sausage-shaped but lumpy (constipation); type 3 - sausage-shaped with cracks on the surface (normal); type 4 - smooth, soft, like a sausage or snake (normal, optimal); type 5 - soft blobs with clear-cut edges (tendency toward diarrhea); type 6 - fluffy pieces with ragged edges (diarrhea); type 7 - watery, no solid pieces (severe diarrhea).

Used in the diagnosis of IBS (classification into IBS-C/IBS-D/IBS-M per Bristol), assessment of laxative and antidiarrheal efficacy, severity assessment of infectious diarrhea, and monitoring of patients with diverticulosis, CKD, or in palliative care. The Bristol scale is included in the Rome IV criteria for IBS as a standard tool for documenting stool form.

• Complaints of altered bowel habits — objectification for the medical record.
• Diagnosis and classification of irritable bowel syndrome (IBS-C/IBS-D/IBS-M).
• Monitoring treatment efficacy (laxatives, antidiarrheals, probiotics).
• Documenting stool character in infectious diarrhea, after GI surgery, and in patients receiving enteral nutrition.

Stool type

Stool type is determined visually or from patient report using an illustrated chart of the scale. Documented as "Bristol type 3", etc.

• Subjective — patients may inaccurately identify stool type, particularly with chronic perception disturbances.
• Does not account for bowel movement frequency — parallel recording is needed.
• Does not distinguish underlying causes (IBS vs IBD vs celiac disease — other methods are required).
• Assessment is difficult with mixed stool types (e.g., part type 2, part type 5).