Patients with irritable bowel syndrome usually present with the following symptoms:

Colicky abdominal pain: Patients with irritable bowel syndrome suffer from acute episodes of sharp, colicky pain in the lower abdomen. This pain is often relieved by defecation.

Altered Bowel Habits: Both constipation and diarrhea can occur in the patients suffering from irritable bowel syndrome, however, one of them may predominate in a single patient. Those with constipation pass hard, infrequent stools. In contrast, those with diarrhea have low volume stools but with frequent defecation.

Abdominal distension: Bloating and gas causes abdominal distention in these patients. Abdominal distention typically worsens during the day.

Other symptoms: Patients of irritable bowel syndrome may have sexual dysfunction, urinary frequency, urgency and dysuria may be present. Other non-specific symptoms include nausea, vomiting and heart burn.

The diagnosis of irritable bowel syndrome is difficult. It was once considered a diagnosis of exclusion; however, this belief is no longer valid. The diagnosis is based on history, general physical examination, laboratory investigations and radiographic studies [6].

The findings in history and general physical examination often indicate iron deficiency anemia. Weight loss is also a common feature. A family history of certain gastrointestinal disorders including celiac disease, inflammatory bowel disease and colorectal carcinoma is often present.

The following investigations are necessary to establish the diagnosis with certainty.

Blood studies

Blood studies include:

• Complete blood count: This is used to rule out anemia, inflammation and infection.

• Electrolyte levels: They can demonstrate electrolyte imbalance and dehydration in metabolic disorders.

Stool examination

Stool examination is performed to exclude infection or infestation as the cause of diarrhea.

History-specific examinations

History-specific examinations in irritable bowel syndrome include:

• Hydrogen breath test
  This test excludes bacterial overgrowth in patients presenting with diarrhea and the complaints of lactose and fructose intolerance.
• Tissue transglutaminase antibody test
• Thyroid function test
• Erythrocyte sedimentation rate
• C-reactive protein

History specific imaging studies

These studies include:

• Barium studies of the upper gastrointestinal tract are performed to detect any obstruction or inflammatory condition (such as Crohn’s disease)
• Abdominal CT scan is also required to look for tumors, obstruction and pancreatic diseases.

History specific procedures
History specific procedures include:

• Anal manometry (to detect rectal distention)
• Flexible sigmoidoscopy (to evaluate the presence of distal obstruction)
• Colonoscopy (to look for polyps or carcinoma in the colon) [7]

The management of irritable bowel syndrome includes dietary measures and psychological support.

Dietary measurements

The dietary measures that are recommended in the patients suffering from irritable bowel syndrome are listed below.

• Fiber supplementation is essential to improve symptoms of constipation and diarrhea
• Polycarbophil compounds (Fibercon) are highly recommended
• Adequate water intake is necessary
• Caffeine avoidance is recommended to limit anxiety
• Legumes should be avoided to limit bloating
• Lactose and/or fructose intake should be restricted
• Gluten free diet is also beneficial [8]

Drugs

A number of other drugs have a beneficial role in the management of irritable bowel syndrome. These drugs are:

• Alosetron (a nerve receptor antagonist specifically used for irritable bowel syndrome) [9][10]
• Anti-cholinergics (such as dicyclomine and hyoscyamine)
  Anti-diarrheals (such as loperamide)
• Tricyclic anti-depressants (such as imipramine and amitriptyline)
• Anti-biotics (such as rifaximin)

The life expectancy in the patients suffering from this disease is the same as that in healthy population. Female patients may have an increased risk of ectopic pregnancies and miscarriages; however, there is no association with stillbirth.

The quality of life is also affected. Work absenteeism is more common in such patients due to severe abdominal pain and altered bowel habits.

There is no specific cause for the development of irritable bowel syndrome.

Enteric infection may lead to the development of irritable bowel syndrome in the majority of the cases. A study demonstrated the prevalence of irritable bowel syndrome in patients suffering from enteritis caused by Giardia lamblia to be as high as 46.1% as opposed to only 14% in the controls [1]. 

Since irritable bowel syndrome is more common in families, genetic factors may also play a predisposing role. Other predisposing factors include inflammatory processes like food intolerance, lack of dietary fibers in the diet and alterations in the gut microbiota [2] [3]. Anxiety, excessive worry and sexual or physical abuse are also contributing factors.

Irritable bowel syndrome affects both men and women and occurs most commonly in individuals between 30 and 50 years of age. In Western countries, female-to-male ratio is 2:1. According to the epidemiological data from the United States, around 5 to 9% of men and 14 to 24% of women are affected.

The global incidence of irritable bowel syndrome is estimated to be 1-2% annually while the prevalence is around 10 to 15%. Prevalence is similar in white and black population but lower in Hispanics.

The pathogenesis of irritable bowel syndrome includes several components which are further explained below:

Altered gastrointestinal motility: The electrical activity of the bowel is disturbed which causes altered gastrointestinal motility of both the small and large gut.

Visceral hyperalgesia: There is hypersensitivity of the small and large gut is increased, particularly with rapid distention. This is more common in women and in the patients in whom this disease is predominantly characterized by diarrhea.

Psychopathology: There is no well-known association between psychopathic disturbances and the pathogenesis of irritable bowel syndrome. Yet, patients under medical care are highly prone to the development of depression, panic and anxiety. These patients usually present with history of suicidal attempts [4].

Microscopic inflammation: Inflammation of both the colon and the small bowel have been demonstrated in the patients suffering from irritable bowel syndrome [5]. The number of lymphocytes and enteroendocrine cells in the bowel is also increased. The latter secrete serotonin, the action of which causes diarrhea.

Irritable bowel syndrome can be prevented by ensuring proper hygiene. The use of high fiber diet is also helpful.

Irritable bowel syndrome (IBS) is a chronic gastrointestinal disorder that is characterized by abdominal pain, altered bowel habits (diarrhea, constipation or both) without any underlying obvious pathologic change in the small and large gut. The disease is not life threatening condition but it can disrupt the quality of life.

Irritable bowel syndrome is a disorder in which the motility of the large gut and small gut are disturbed. The patients usually develop abdominal discomfort and altered bowel habits. The disease runs in families usually affecting the younger age group.

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