IBS Symptom History
To aid in diagnosing irritable bowel syndrome (IBS), physicians will ask a patient for a history of their gastrointestinal symptoms. The frequency and duration of the IBS symptoms, as outlined in the Rome III criteria, will also be considered. IBS can be categorized as IBS with Constipation (IBS-C), IBS with Diarrhea (IBS-D), or IBS with mixed patterns of constipation and diarrhea (IBS-M).1
Some common IBS symptoms present in a patient symptom history include:
The Bristol Stool Form Scale for IBS
Physicians also use the Bristol Stool Form Scale (BSFS), created in the Bristol Royal Infirmary in England, to categorize the consistency of stools. The BSFS describes 7 types of stool:2
- Type 1: Separate hard lumps, like nuts (hard to pass).
- Type 2: Sausage-shaped, but lumpy.
- Type 3: Like a sausage, but with cracks on its surface.
- Type 4: Like a sausage or snake, smooth and soft.
- Type 5: Soft blobs with clear-cut edges (passed easily).
- Type 6: Fluffy pieces with ragged edges, a mushy stool.
- Type 7: Watery, no solid pieces, entirely liquid
Figure 1. The Bristol stool form scale
Stool types 1 and 2 are characterized by hard stools and indicate constipation. These stools are difficult to pass and may require straining. Stool types 3 and 4 are considered normal. Type 5 may indicate diarrhea, and types 6 and 7 indicate diarrhea, with those types having less shape and more urgency to pass.2
In IBS-C patients, more than 25 percent of bowel movements are types 1 or 2. In patients with IBS-D, more than 25 percent are types 6 or 7. In patients with the mixed subtype of alternating constipation and diarrhea, more than 25 percent of bowel movements are types 1 or 2, and more than 25 percent are types 6 or 7.2
When the Bristol Stool Form Scale was first published, the authors postulated that it could be used as a marker for colon transit time, but that concept has since been challenged. Even so, the Bristol scale provides a convenient way for patients to describe their bowel habits, and it is routinely used in clinical trials and in diagnosing IBS.
Symptom Frequency in IBS
In addition to the presence of IBS symptoms, patients are also asked to share the frequency of these symptoms in an IBS symptom history. Patients will be asked how often they experience bowel movements and other digestive symptoms, as well as the length of time these symptoms have been experienced. Diagnostic criteria for IBS includes:
- Recurrent abdominal pain or discomfort at least 3 days/month in the previous 3 months
- Less than 2 bowel movements per week (indicating IBS with constipation)
- More than 3 bowel movements per day (indicating IBS with diarrhea)3