An Overview of the Bristol Stool Chart

A diagnostic scale that categorizes feces by shape, color, and consistency.

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The Bristol Stool Chart (also called the Bristol Stool Scale or the Bristol Stool Form Scale) is a diagnostic tool to evaluate samples of human feces based on the shape and consistency of the stool. Samples are then assigned a number 1–7 that corresponds to descriptions on the scale.

The scale was created in 1997 by a team of doctors at the British Royal Infirmary in Bristol, England. It has since become a useful diagnostic tool for clinicians working with patients who have gastrointestinal disorders including irritable bowel syndrome (IBS).

bristol stool chart
Illustration by Jessica Olah, Verywell

Classifications

The Bristol Stool Chart classifies stool samples according to shape and consistency and assigns a sample a number from 1-7 depending on its characteristics. Your doctor may ask you to look at the chart and identify which number most closely resembles your bowel movements.

  • Type 1: Separate hard lumps (hard to pass)
  • Type 2: Lumpy, sausage-shaped
  • Type 3: Sausage-shaped with cracks on the surface
  • Type 4: Sausage-shaped or snake-like; smooth and soft
  • Type 5: Soft blobs with clear-cut edges (easy to pass)
  • Type 6: Fluffy pieces with ragged edges; mushy
  • Type 7: Entirely liquid, watery, no solid pieces

Stools that are well-formed and easy to pass (Types 3 and 4) are considered "ideal." Stool that is hard and difficult to pass (Types 1 and 2) indicates constipation. Patients often report feelings of incomplete bowel movements, bloating, and abdominal pain. Constipation can lead to straining and the development of hemorrhoids.

Stool that contains excess liquid or is entirely liquid indicates diarrhea (Types 5, 6, and 7). Patients often report feelings of urgency or continence issues with their stool at this point on the scale. Prolonged diarrhea may lead to dehydration and malnourishment.

Other stool characteristics such as volume, frequency, color, and the presence of mucous or blood will also be evaluated. The results of a stool culture and assessments such as the Rome Criteria can be used together with the Bristol Stool Chart to provide clues about a possible diagnosis or cause for gastrointestinal symptoms.

What Do the Different Poop Colors and Shapes Mean?

Uses

Your doctor may use the Bristol Stool Chart if you have symptoms related to your bowels or notice a change in stool appearance or your bowel habits, including:

  • Diarrhea
  • Constipation
  • Diarrhea alternating with constipation
  • Abdominal cramps
  • Bloating and gas
  • Nausea or fullness
  • "Greasy" floating stool (steatorrhea)
  • Other symptoms suggestive of malabsorption

Your doctor may ask you to provide a stool sample for visual inspection as well as other tests. You may also be asked to observe your stool and compare it to the Bristol Stool Chart, or your doctor may simply ask you about your bowel habits when you are being seen in the office.

In addition to using the Bristol Stool Chart, your doctor may also ask you how often you typically have a bowel movement and if you have been having them more or less often than usual. They may also ask you about how much stool you pass, the smell and color, and whether or not it is easily removed from the toilet bowl when you flush.

Remember, what is considered a "normal" bowel movement varies from one person to another and there are many factors that influence bowel habits. In general, a person's bowel habits are considered to be regular if they have a bowel movement anywhere from one to three times a day to three times a week, typically within a half hour of eating.

A person's bowel habits are influenced by many factors and can change day to day. A few common reasons you may experience a change in bowel habits include:

  • Diet
  • Stress
  • Travel
  • Dehydration
  • Medications
  • Age-related changes
  • Activity levels and exercise
  • Illness (such as gastroenteritis or "food poisoning")
  • Hormone-related changes such as during menstruation or pregnancy
  • More serious conditions such as inflammatory bowel disease or colon cancer

Outside of the doctor's office, the Bristol Stool Chart is also used by researchers as a way to measure colon transit time and investigate functional bowel disorders. Clinical researchers have also used the chart to assess the effect of certain medications on patients' bowel function as well as to assess the ability of certain medications to treat bowel disorders.

A modified version of the chart was introduced in 2011 for use in pediatric patients. The modified version of the chart includes drawings that children can use to self-assess their stools when being evaluated for constipation, soiling, and other bowel disorders.

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