Irritable Bowel Syndrome
Incidence of Irritable Bowel Syndrome (IBS).
Irritable bowel syndrome is estimated to affect between 10 and 20% of the population, with 1-2% of the population diagnosed yearly. Most patients develop symptoms before the age of 40, but development of symptoms after the age of 40 does not exclude irritable bowel syndrome.
Diagnosis of IBS.
Irritable bowel syndrome is a gastrointestinal disorder which results in abdominal pain and changes in bowel habits, without specific pathology. This means it is a diagnosis of exclusion, which must be made after other causes are ruled out.
It is thought to be a syndrome caused by alterations of motility of the gastrointestinal tract, increased sensitivity to pain, and psychological pathology. This association is not clear, but it appears that people who seek treatment for irritable bowel syndrome have a higher incidence of psychiatric disturbances than the general population, including panic disorders, anxiety disorders, depression, and hypochondria. Doctors seeing patients with irritable bowel syndrome often question the patients about symptoms related to these disorders.
Symptoms of IBS.
Symptoms of irritable bowel syndrome are alterations in bowel habits, distention of the abdomen, and abdominal pain. The alteration of bowel habits includes constipation or diarrhea, and usually patients have primarily one or the other, but may have a combination of both. Hard stools, painful bowel movements, which may be infrequent, and lack of response to laxatives characterize constipation. Patients with diarrhea have small volumes of loose stools, and often feel urgency before bowel movements. They may also experience frequent bowel movements.
Abdominal pain with IBS.
The abdominal pain in patients with irritable bowel syndrome is often diffuse, and commonly includes the lower abdomen. Some patients have a constant dull ache with episodes of sharp pain occurring frequently. Sometimes the pain occurs as a result of a meal, and may be somewhat relieved by a bowel movement. Other symptoms may include mucous in the bowel movement, or passage of clear or white mucous, heartburn, nausea or vomiting, and sexual dysfunction, including pain with sexual intercourse.
The symptoms of irritable bowel syndrome worsen in many patients in the period around menstruation. The symptoms are often related to stress.
If patients have onset in middle age, or symptoms that are only acute, progression of symptoms, and symptoms at night, weight loss or anorexia, fever, rectal bleeding, fatty stools, or intolerance to lactose or gluten, the physician will look for other causes of these symptoms, which are not consistent with irritable bowel syndrome.
Recently, studies have found microscopic inflammation in some patients with irritable bowel syndrome. This finding may lead to new treatment strategies.
The criteria for diagnosis of irritable bowel symptoms require that a patient have recurrent abdominal pain at least 3 days per month during the previous 3 months. Those episodes must be associated with at least two of the following symptoms: pain is relieved by bowel movement, onset of pain is associated with a change in stool frequency or appearance or form of stools, abdominal pain, difficulty or urgency with bowel movements, passage of mucous, and abdominal pain and the feeling of bloating or distention.