Irritable Bowel Syndrome

Clinical criteria and spectrum of symptoms

The diagnosis is based on the presence of the so-called clinical triad. The patient must present with at least two persistent signs from the following:

1. Pain syndrome or pronounced abdominal discomfort, the intensity of which invariably decreases after the act of defecation.
2. A noticeable change in the usual frequency of stool.
3. A change in the shape and consistency of feces.

In addition, the spectrum of functional disorders often includes pathological impurities in the feces (primarily mucus secretion) and pronounced flatulence. Abdominal bloating in this pathology becomes a consequence of developing dysbiosis, which enhances putrefactive and fermentative processes in the intestinal lumen. The disease proceeds cyclically: periods of exacerbation lasting from several weeks to months are replaced by remissions of indefinite duration.

Patterns of pain syndrome and stool disorders

Depending on which symptoms come to the fore, three main clinical patterns of the disease are distinguished:

• Spastic type. Characterized by persistent constipation accompanied by pronounced abdominal pain.
• Diarrheal type. Manifests as frequent watery diarrhea, which may periodically be replaced by normal stool. A distinctive feature is a painless course.
• Mixed type. Proceeds with a classic alternation of diarrhea and constipation episodes.

The «morning attack syndrome» is highly characteristic of the diarrheal variant. With it, episodes of watery diarrhea mixed with mucus occur predominantly in the morning hours (as a rule, immediately after breakfast) with a frequency of 3–4 times. After morning bowel emptying, the patient's condition completely normalizes, and stool disorders do not bother them for the rest of the day.

Physical examination findings

During the objective examination, the clinician faces a discrepancy between active complaints and meager physical findings indicating the absence of organic signs.

Upon visual inspection, abdominal distension can be noted, but visible intestinal peristalsis is not detected. Upon palpation, the abdomen remains soft, but diffuse tenderness is revealed along the course of all parts of the colon. Particular attention is paid to the palpation of individual segments: the sigmoid colon is palpated as a dense cord due to spasm, while the cecum is most often bloated, and gurgling is clearly defined upon palpation.

Diagnostic algorithm

Since IBS is a diagnosis of exclusion, the clinician is obliged to rule out tumor processes and inflammatory bowel disease (IBD). The diagnostic search includes several stages:

1. Laboratory methods. General and biochemical blood tests lack any signs of systemic inflammation or other pathological shifts. Stool analysis reveals only signs of dysbiosis.
2. Radiological methods. Barium enema (irrigoscopy) allows visualization of functional dyskinesia. The images show uneven filling and emptying of the lumen, fluid hypersecretion, and a typical alternation of dilated and spastic sections of the bowel.
3. Endoscopy. Performing a colonoscopy with mandatory biopsy is a strictly necessary step. Only morphological verification allows for reliable differential diagnosis with colitis (for example, ulcerative colitis, where mucosal changes are pronounced).

Basic treatment principles

Therapeutic tactics vary depending on the leading syndrome. When constipation predominates, the patient management algorithm includes the following components:

• Diet therapy: based on a significant increase in the plant fiber quota in the daily diet.
• Medication support: non-absorbable laxatives are used to facilitate defecation, and anticholinergic drugs (antspasmodics) are used to relieve pain syndrome. In addition, sedatives are prescribed to correct the psycho-emotional background.
• Psychotherapeutic aspect: the most important part of the doctor's work is to convince the patient of the benign nature of their disease and the absolutely favorable prognosis for life, which in itself reduces the level of anxiety.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Differential diagnosis between irritable bowel syndrome and ulcerative colitis (UC).
• Radiological signs of colonic dyskinesia during irrigoscopy.
• The role of dysbiosis and fermentation processes in the development of flatulence.
• Mechanisms of action of anticholinergic agents in relieving spastic pain.

Other topics in the "Digestive System" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.