Part 2: Symptoms
2a: What are the symptoms of IBS?
The most common symptoms that IBS patients complain of are: frequent diarrhea, abdominal pain (usually in the lower abdomen area), gas, bloating, diarrhea alternating with constipation, mucus in the stool, bowel urgency or incontinence, and a feeling of incomplete evacuation after a bowel movement. Since IBS is considered mainly to be a disorder of the lower gastrointestinal tract, the symptoms tend to remain located below the navel. However, several symptoms of the upper gastrointestinal tract have also been shown to be common in those with IBS, including: difficultly swallowing, a sensation of a lump in the throat or a closing of the throat, heartburn or acid indigestion, nausea (with or without vomiting), and chest pain.
A number of expert investigators during a meeting in Rome, Italy, developed a consensus definition and criteria for IBS, known as the "Rome" criteria.
At least 3 months of continuous or recurrent symptoms of:
1. Abdominal pain or discomfort, e.g.:
a. Relieved with defecation and/or
b. Associated with a change in frequency of stool; and/or
c. Associated with a change in consistency of stool; and
2. Two or more of the following, at least on one-fourth of occasions or days:
a. Altered stool frequency
b. Altered stool form (e.g. watery/loose stools or hard stools)
c. Altered stool passage (e.g. sensations of incomplete evacuation after bowel movements, straining, or urgency)
d. Passage of mucus and/or
e. Bloating or feeling of abdominal distention.
In addition, a number of other non-colonic symptoms may be present in patients with IBS. These include: nausea, feeling full after eating only a small meal, sensation of urinary urgency, incomplete emptying after urinating, fatigue, and pain during sexual intercourse.
2b: How severe are these symptoms?
As with just about everything associated with IBS, the severity of symptoms vary greatly from person to person, ranging from barely noticeable to completely debilitating, and can vary for the same person over periods of time.
2c: Does everybody get the same symptoms?
No. Although the symptoms listed in 2a are the most common, each person's experience and presentation will be slightly different. The severity and frequency of abdominal pain or discomfort will also vary from an intermittent abdominal discomfort during stress life events to severe continuous abdominal pain. Likewise, bowel habits can vary. Diarrhea, constipation, or alternating between the two may be the predominant bowel pattern.
Part 3: Medical Facts
3a: What causes IBS?
Recent physiological and psychosocial data have emerged to improve our understanding of IBS. A biopsychosocial model of IBS involving physiological, emotional, cognitive, and behavioral factors is now felt to be involved in symptom generation. Physiological factors implicated in the etiology of IBS symptoms include: visceral hypersensitivity to spontaneous contractions and to balloon distention of the bowel, autonomic dysfunction including exaggerated colonic motility response to stress and alterations in fluid and electrolyte handling by the bowel, and an alteration in the gastrocolonic response. However, alterations in these physiological parameters are generally found in only a subset of patients and frequently do not correlate with bowel symptoms. Behavioral factors such as stressful life events are reported by up to 60% of IBS patients to be associated with the first onset of the disease or with its exacerbation. Laboratory stressors have also been shown to affect gastrointestinal motility and visceral perception. Cognitive factors such as inappropriate coping styles and illness behavior are common in IBS patients and influence healthcare utilization and clinical outcomes. Emotional and psychiatric factors, such as anxiety and depression, are present in 40 to 60% of IBS patients seeking healthcare with increased prevalence in those patients presenting to tertiary referral centers. IBS patients who have sought medical care are more likely to have abnormal psychological profiles, abnormal illness behaviors, and psychiatric diagnoses than patients with other medical illnesses.
3b: What is the role of psychological and/or social factors in IBS?
Psychiatric diagnoses are present in 42-62% of IBS patients who have sought medical consultation. In comparison, psychiatric diagnoses are present in around 20% of patients with other gastrointestinal diagnoses. The majority of these psychiatric diagnoses are cases of anxiety and depression. Other common diagnoses include somatization disorder and hypochondriasis.
Stress can affect the functioning of the gastrointestinal tract of all people, and particularly those with IBS. Several studies have shown that IBS patients are more likely to report that stress changes their stool pattern and leads to abdominal pain than people without bowel problems. In one study 65% of IBS patients reported a severe stressful life event prior to developing IBS. The kinds of psychological stressors often reported by patients with IBS vary considerably, but include: loss of a parent or spouse through death, divorce, or separation, and sometimes is accompanied by feelings of unresolved grief, and also significant life changes which demand many social and personal adjustments such as moving to a new job or a new city.