What is the Bristol Stool Scale (BSS)?
A 4-year-old female came to clinic with intermittent abdominal pain for 2-3 weeks. The pain was random and would last for several minutes. She would complain and her mother would have her lie down and then she would go on with her activities within a couple of minutes. The pain did not occur at night. Her bowel movements were reported as normal, but her mother said that usually they occurred at preschool or that she used the restroom by herself and her mother had not seen the stools. She was urinating, eating, and acting normally otherwise.
The past medical history showed at least 2 previous episodes of constipation that were successfully treated with water and increased fiber. Medications had not been used. The review of systems was negative.
The pertinent physical exam showed a healthy female with normal vital signs and growth parameters. The patient indicated that the abdominal pain was periumbilical without radiation, and the abdominal, back, and genitourinary exams were normal. The rest of her examination was normal.
The diagnosis of probable constipation was made after more extensive questioning of the patient and mother. The patient didn’t know how frequently she stooled but thought it “was a long time” between stools. When asked if the stools were like water she said no and answered similarly if they were toothpaste or yogurt-like. When asked if they were more like a stick or a rock she said yes and indicated on a Bristol Stool Scale chart that her stools that were Bristol 1-3 in consistency. She was sure they were not a Bristol 5, 6, or 7. The patient was started on a regiment of Miralax® and the parent was instructed to increase fiber, fluids and monitor her stools.
Discussion
The Bristol Stool Scale (BSS) is a tool to assist patients, family members and health care providers to share common language about stool consistency. The actual language and what that language means has implications both for clinical treatment but also research results. The BSS was originally developed at the Royal Infirmary in Bristol, UK and published in 1997. The study was performed with 66 volunteers aged 15-62 years old where they looked at “normal” stools and transit time and after using senna and loperamide medications.
The original Bristol Stool Form Scale description with notations in brackets:
- Type 1 Separate hard lumps, like nuts [constipation/encopresis, difficult to pass]
- Type 2 Sausage-shaped but lumpy
- Type 3 Like a sausage or snake but with cracks on its surface
- Type 4 Like a sausage or snake, smooth and soft [average stool]
- Type 5 Soft blobs with clear-cut edges
- Type 6 Fluffy pieces with ragged edges, a mushy stool
- Type 7 Watery, no solid pieces. [diarrhea, easy to pass and may involuntarily be passed]
Learning Point
The BSS has been used as a standard and also modified for other populations including toilet-trained children and for those in diapers. “Especially the form of soft stools is altered when it is pressed together between the buttocks and is spread out in the diaper. Also the duration that the stools have been in the diaper will change the appearance.”
Use of drawings or pictures does help with clarification and grading of the stools (see To Learn More below for images). However some of the finer grading may not be clear to patients or family members. For example, a Bristol 1 is relatively easy to identify as the hard lumps of stool are pellet-like and separated apart from each other. Bristol 2 and 3 are similar though in that the stool is formed but the difference is in the segmentation. For Bristol 2, the appearance of segmentation occurs as lumps of stool that are adhered together, but with Bristol 3 the segmentation appears because of cracks on the outside of the stool. The parent and/or patient may only see that the stool is formed and there is segmentation. They may not be able to note the difference between the grades. The same is true for the opposite end of the BSS. Parents and patients may not be able to indicate the difference between “soft blobs” of Bristol 5 and “fluffy pieces” of Bristol 6 as both look very soft and mushy to them.
These differences can be very important for outcomes of research studies. They can also be important for monitoring of clinical outcomes of treatment in gastroenterological diseases. In these instances, it would be important to spend time with the patient and family member to help them to be able to accurately indicate the differences between the different levels. In a general pediatrics or similar setting, usually it is close enough to be able to distinguish between probably constipation (hard stools, Bristol 1-2) from normal variations (Bristol 3-5) and probably diarrhea (watery stools, Bristol 6-7). Patients and family members should also be asked about the range of stool consistency they usually encounter and not just the last stool that was produced. Stool consistency is only one factor in assessing clinical or research outcomes, including where the stool was produced (i.e. toilet, diaper), stool frequency, abdominal pain, eating patterns, infectious disease exposure, etc. all can help with patient management. Sometimes parents will also note “watery” stools that occur along with “hard” stools. This pattern may be because of overflow of liquid stool around hard stool that may occur in a constipation or encopresis setting.
Questions for Further Discussion
1. What other questions do you use to help patients provide more accurate grading of their stool consistency?
2. What questions do you use to help patients provide accurate grading for other clinical scales such as pain scales?
3. What causes acute abdominal pain? A review can be found here.
3. What causes recurrent abdominal pain? A review can be found here.
Related Cases
- Disease: Constipation | Abdominal Pain
- Symptom/Presentation: Abdominal Pain
- Specialty: Gastroenterology | General Pediatrics
- Age: Preschooler
To Learn More
To view pediatric review articles on this topic from the past year check PubMed.
Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews.
Information prescriptions for patients can be found at MedlinePlus for these topics: Bowel Movements and Abdominal Pain.
To view current news articles on this topic check Google News.
To view images related to this topic check Google Images.
To view videos related to this topic check YouTube Videos.
Lewis SJ, Heaton KW. Stool form scale as a useful guide to intestinal transit time. Scand J Gastroenterol. 1997;32(9):920-924. doi:10.3109/00365529709011203
Vriesman MH, Velasco-Benitez CA, Ramirez CR, Benninga MA, Di Lorenzo C, Saps M. Assessing Children’s Report of Stool Consistency: Agreement Between the Pediatric Rome III Questionnaire and the Bristol Stool Scale. J Pediatr. 2017;190:69-73. doi:10.1016/j.jpeds.2017.07.002
Huysentruyt K, Koppen I, Benninga M, et al. The Brussels Infant and Toddler Stool Scale: A Study on Interobserver Reliability. J Pediatr Gastroenterol Nutr. 2019;68(2):207-213. doi:10.1097/MPG.0000000000002153
Wegh CAM, Hermes GDA, Schoterman MHC, et al. 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. doi:10.1097/MPG.0000000000003186
Author
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa
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