Select a stool type to visualize clinical interpretation and standard diagnostic pathways.
Guidelines & Evidence
Clinical Details
Section 1
When to Use
When to Use
Standardized classification of stool consistency and form
To differentiate between constipation, normal bowel habits, and diarrhea
Initial screening and subtyping of Irritable Bowel Syndrome (IBS-C, IBS-D, IBS-M)
Monitoring response to fiber therapy, laxatives, or anti-diarrheal medications
Surrogate marker for colon transit time in clinical practice
Clinical Context
Stool form is a better indicator of transit time than stool frequency. This scale allows patients to communicate their bowel habits visually, reducing subjective descriptors like "loose" or "hard."
Section 2
Formula & Logic
The 7 Stool Types
01
Type 1: Separate hard lumps, like nuts (hard to pass).
02
Type 2: Sausage-shaped but lumpy.
03
Type 3: Like a sausage but with cracks on its surface.
04
Type 4: Like a sausage or snake, smooth and soft.
05
Type 5: Soft blobs with clear-cut edges (passed easily).
06
Type 6: Fluffy pieces with ragged edges, a mushy stool.
Subtyping is based on bowel habits on days with at least one abnormal bowel movement. Note: This requires the scale to be used over a representative period (e.g., 2 weeks).
IBS Definitions
IBS-C (Constipation): > 25% of stools are Type 1-2; < 25% are Type 6-7.
IBS-D (Diarrhea): > 25% of stools are Type 6-7; < 25% are Type 1-2.
IBS-M (Mixed): > 25% of stools are Type 1-2 AND > 25% are Type 6-7.
Clinical Pearls
Type 4 is often considered the "ideal" stool consistency
Stool consistency is highly dependent on water absorption in the colon; Type 1 reflects excessive water absorption due to slow transit
Bile acid malabsorption typically presents with persistent Type 6-7 stools
Section 4
Next Steps
Therapeutic Adjustments
01
Type 1–2: Increase soluble fiber and fluid intake; consider osmotic laxatives (PEG).
02
Type 6–7: Screen for malabsorption, infection, or IBD; consider anti-motility agents (Loperamide) if non-inflammatory.
Complementary Tools
Rome IV Criteria (IBS)
Wexner Constipation Score
IBS Symptom Severity Score (IBS-SSS)
Section 5
Evidence Appraisal
The Original Scale
Stool form scale as a guide to intestinal transit time.
Lewis SJ et al. • Scandinavian Journal of Gastroenterology. 1997;32(9):920-4. The foundational study at the Bristol Royal Infirmary.
Developed by Ken Heaton and S.J. Lewis in 1997 at the University of Bristol. It was initially designed to help standardise the description of faeces in clinical research, but has since become the ubiquitous standard in both clinical practice and public health education.
