Bristol stool form scale
The Bristol stool form scale sorts the shape of stool into seven steps. What follows is only what could be confirmed in the original paper and in a paper on its reliability.
In this app the step is always chosen by the person using it. The photo rules go as far as offering candidates.
- Type 1Separate hard lumps, rather like nuts.
- Type 2Sausage shaped but lumpy.
- Type 3Like a sausage with cracks on the surface.
- Type 4Like a sausage or a snake, smooth and soft.
- Type 5Soft blobs with clear cut edges, passed easily.
- Type 6Fluffy pieces with ragged edges, a mushy stool.
- Type 7Watery, with almost no solid pieces.
The Bristol stool form scale was published in 1997, and the original paper measured how stool form relates to gut transit time. It was not built as a table that names diseases.
When 34 clinicians scored 35 stool photographs as types 1 to 7, the intraclass correlation was 0.88 between raters and 0.89 within raters. When the same photographs were converted into clinical categories of normal, constipation and diarrhoea, those values fell to 0.75 and 0.65.
In a study that scored stool photographs inside diapers by machine, agreement with the researchers was 77.0 percent once consistency was grouped into four classes, and 60.3 percent when the original seven steps were kept.
This app is for an adult logging their own
Do not use this app for a baby, because the scale itself is different. A modified scale exists for children who are not yet toilet trained, and a separate baby stool log lets a carer keep entries on that scale.
For children who are not yet toilet trained, a modified Bristol scale has been validated separately. When parents, grandparents and childcare workers scored it, the intraclass correlation ran from 0.72 to 0.93.
What this app does not do
It states no probability, makes no diagnosis, gives no risk score and names no disease. It records and counts, and that is all. If you are worried about your body, take this log to a clinician.
The NHS advises seeking medical help when stool is black or dark red, and when there is bloody diarrhoea.
The NIDDK likewise lists black or tarry stool and dark or bright red blood mixed with stool as symptoms, and says to seek help right away.
Sources
- Lewis SJ, Heaton KW. Stool form scale as a useful guide to intestinal transit time. Scand J Gastroenterol. 1997;32(9):920-924. https://pubmed.ncbi.nlm.nih.gov/9299672/
- Chumpitazi BP, Self MM, Czyzewski DI, Cejka S, Swank PR, Shulman RJ. Bristol Stool Form Scale reliability and agreement decreases when determining Rome III stool form designations. Neurogastroenterol Motil. 2016;28(3):443-448. https://pubmed.ncbi.nlm.nih.gov/26690980/
- Ludwig T, Oukid I, Wong J, Ting S, Huysentruyt K, Roy P, Foussat AC, Vandenplas Y. Machine Learning Supports Automated Digital Image Scoring of Stool Consistency in Diapers. J Pediatr Gastroenterol Nutr. 2021;72(2):255-261. https://pubmed.ncbi.nlm.nih.gov/33275399/
- Wegh CAM, Hermes GDA, Schoterman MHC, Vaughan EE, Smidt H, Belzer C, Benninga MA. The Modified Bristol Stool Form Scale: A Reliable and Valid Tool to Score Stool Consistency in Dutch (Non)Toilet-trained Toddlers. J Pediatr Gastroenterol Nutr. 2021;73(2):210-216. https://doi.org/10.1097/MPG.0000000000003186
- NHS. Bleeding from the bottom (rectal bleeding). https://www.nhs.uk/symptoms/bleeding-from-the-bottom-rectal-bleeding/
- NIDDK (National Institute of Diabetes and Digestive and Kidney Diseases). Symptoms & Causes of GI Bleeding. https://www.niddk.nih.gov/health-information/digestive-diseases/gastrointestinal-bleeding/symptoms-causes