Objective: Defining normal stool habit is important when evaluating diarrhoea or constipation, but common confounders such as irritable bowel syndrome (IBS) or the intake of medications with gastrointestinal side effects have not been considered in earlier population based studies defining what is normal. We hypothesized that the exclusion of subjects with common confounders would help to better understand what are "normal bowel habits". We aimed to prospectively study bowel habits in a carefully studied random sample of the general population.
Material and methods: Two hundred and sixty-eight randomly selected subjects between 18 and 70 years completed symptom diaries for one week and were clinically evaluated by a gastroenterologist. They also had a colonoscopy and laboratory investigations to exclude organic disease.
Results: One hundred and twenty-four subjects had no organic gastrointestinal abnormality, IBS, or relevant medication; 98% of them had between three stools per day and three per week. Seventy-seven percent of all stools were normal, 12% hard, and 10% loose in consistency. Urgency was reported by 36%; straining by 47% and incomplete defecation by 46%. After the exclusion of subjects with organic abnormalities, women had significantly more symptoms than men in terms of abdominal pain, bloating, constipation, urgency, and feeling of incomplete evacuation but these gender differences disappeared after excluding subjects with IBS.
Conclusions: This study confirms that normal stool frequency is between three per week and three per day. We could not demonstrate any gender or age differences in terms of stool frequency, defecatory symptoms or abdominal bloating. Some degree of urgency, straining, and incomplete evacuation should be considered normal.