Constipation is a common GI motility disorder that affects 2% to 27% of North Americans, with most estimates at 12% to 19%.1 Constipation afflicts more than twice as many women as men.1 Although most people experience occasional bouts of constipation, for many it is a chronic condition.
The activities and relationships of those with chronic constipation (CC) are generally affected. Health-related quality of life is more negatively impacted in people with CC and other GI motility disorders than in the general healthy population—and even than in people with other chronic conditions, such as asthma.2 Relatively few people with symptoms of CC seek medical treatment, and those who do are often not effectively treated.3,4 CC imposes a substantial economic burden through direct (physician and hospital visits and medications) and indirect (absence from or reduced productivity at work) costs.5-7
Defining chronic constipation
One challenging issue facing the patient and the clinician is determining what constipation actually is. There is no formal clinical definition, and clinicians, patients, and diagnostic criteria define constipation differentl 8-10 (see Table 1). Another challenge is deciding when to consider the condition chronic, which is often arbitrarily defined by most criteria—including the Rome II criteria—as lasting at least 3 months.9 Rome II states that the symptoms should be present for at least 1 year.
New definition Because the Rome II criteria can be restrictive in clinical practice, the American College of Gastroenterology (ACG) recently recommended an expanded definition of constipation: “Unsatisfactory defecation characterized by infrequent stools, difficult stool passage, or both. Difficult stool passage includes straining, a sense of difficulty passing stool, incomplete evacuation, hard/lumpy stools, prolonged time to stool, or need for manual maneuvers to pass stool.”11 The ACG Chronic Constipation Task Force also clarified what is meant by chronic, stating that “Chronic constipation is defined as the presence of these symptoms for at least 3 months.”11 Additionally, the Task Force recognized that this disorder can have a significant impact on quality of life. Realizing the restrictive nature of the Rome II criteria for constipation, the Rome III Criteria were recently released. The differences between Rome II and Rome III are outlined in Table 1.12
Types of constipation Defining CC is essential for accurate diagnosis and satisfactory treatment. Understanding its causes is crucial for proper diagnosis. Constipation can be classified into two broad categories: primary and secondary (see the tables on the Web13-17). Secondary causes of constipation should be considered before proceeding with diagnostic testing or therapy.
Evaluation and diagnosis
A thorough evaluation is needed to assess the patient's condition, rule out systemic disease, and determine the 
best course of treatment. “Diagnostic workup for constipation” (on the Web) offers a helpful algorithm.17,18
Diagnostic tools Given the sensitive nature of the subject, a useful tool for evaluating stool consistency is the Bristol Stool Form Scale, which helps the patient describe bowel movements in an objective and minimally embarrassing manner.19 Another helpful tool is a daily diary for recording bowel movement frequency (date and time), daily symptoms of constipation (straining, bloating, feelings of incomplete evacuation), and frequency and dosage of any medications taken for symptom relief.
These tools are useful for comparing the patient's definition of constipation with the clinician's and determining whether any misconceptions exist regarding what constitutes “normal” bowel habits. Unfortunately, there is no standard definition of a “normal” number of bowel movements, but the literature suggests a range from three per day to three per week.20,21