Constipation is difficult to define since it is a subjective experience. However, defecation less than three times per week would suggest its likelihood. Alternatively, The Rome III Criteria for functional constipation may be applied which propose that, amongst other symptoms, at least two of the following should be present for at least 3 months:

• Straining
  
• Lumpy or hard stools
  
• Sensation of incomplete evacuation
  
• Sensation of anorectal obstruction/blockage
  
• Less than three defecations per week

Loose stools rarely present without the use of laxatives. Another way to consider this is where straining occurs in at least 25% of time.

Hard stools are present at least 25% of time (Drossman et al., 1982).