Irritable Bowel Syndrome - Diagnosis

Irritable Bowel Disease Workup Plan

The diagnosis of irritable bowel syndrome is a diagnosis of exclusion. A preliminary diagnosis is made based on the Rome II criteria (1999).

Abdominal pain and/or discomfort for 12 weeks, not necessarily consecutive, in the last 12 months:

• their severity decreases after defecation; and/or are associated with changes in the frequency of defecation;
• and/or associated with changes in stool consistency, as well as

Two or more of the following:

• altered frequency of bowel movements (more than 3 times a day or less than 3 times a week);
• changes in stool consistency (lumpy, hard stools or watery stools);
• changes in stool passage (straining during defecation, urgent urge to defecate, feeling of incomplete evacuation);
• passage of mucus and/or flatulence or a feeling of bloating.

The final diagnosis is made by excluding organic pathology. To apply Rome II criteria, the absence of so-called "alarm symptoms" is necessary. In this case, the sensitivity of the criteria is 65%, specificity - 95%.

"Alarm Symptoms" That Rule Out Irritable Bowel Syndrome

History	Weight loss Onset of symptoms after the age of 50 Night-time symptoms that force the patient to get up to go to the toilet A burdened family history of cancer and inflammatory bowel disease Constant severe abdominal pain as the only and leading symptom of gastrointestinal damage Recent use of antibiotics
Examination data	Fever Hepatomegaly, splenomegaly
Laboratory and instrumental data	Presence occult blood in feces Decreased hemoglobin concentration Leukocytosis Increased ESR Biochemical changes in blood

If there are “alarm symptoms”, a thorough laboratory and instrumental examination of the patient is necessary.

Laboratory research

Mandatory laboratory tests

It is carried out to exclude “symptoms of anxiety” and diseases that have a similar clinical picture.

• General blood test. Conducted to exclude inflammatory or paraneoplastic genesis of abdominal pain syndrome.
• Analysis of feces for the intestinal group of pathogenic bacteria (shigella, salmonella, yersinia), helminth eggs and parasites. The study is carried out three times.
• Coprogram.
• General urine analysis.
• Serum albumin concentration.
• The content of potassium, sodium, calcium in the blood.
• Proteinogram.
• Study of blood immunoglobulins.
• Concentration of thyroid hormones in the blood.

Irritable bowel syndrome is characterized by the absence of changes in laboratory tests.

Additional laboratory tests

Conducted to identify concomitant diseases of the hepatobiliary system.

• Serum aminotransferases, GGT, ALP.
• Total bilirubin concentration.
• Research on hepatitis virus markers: HBAg, Anti-HCV.

Instrumental research

Mandatory instrumental studies

• Irrigoscopy: typical signs of dyskinesia are uneven filling and emptying, alternating spasmodically contracted and dilated areas and/or excessive secretion of fluid into the intestinal lumen.
• Colonoscopy with biopsy is a mandatory method of examination, as it allows to exclude organic pathology. In addition, only morphological examination of intestinal mucosa biopsies makes it possible to ultimately distinguish irritable bowel syndrome from inflammatory bowel diseases. The study often provokes symptoms of the disease due to visceral hypersensitivity characteristic of irritable bowel syndrome. FEGDS with biopsy of the small intestinal mucosa: is performed to exclude celiac disease.
• Ultrasound of abdominal organs: allows to exclude gallstone disease, cysts and calcifications in the pancreas, and volumetric formations in the abdominal cavity.
• Lactose challenge test or lactose-free diet for 2-3 weeks: to diagnose latent lactase deficiency.

Additional instrumental studies

They are carried out with the aim of detailing the changes detected during the implementation of mandatory research methods.

• RKT.
• Doppler examination of abdominal vessels.

Differential diagnosis of irritable bowel syndrome

Irritable bowel syndrome must be differentiated from the following diseases and conditions:

• colon neoplasms; inflammatory bowel disease; diverticular disease; pelvic floor muscle dysfunction;
• neurological diseases (Parkinson's disease, autonomic dysfunction, multiple sclerosis);
• side effects of drugs (opiates, calcium channel blockers, diuretics, anesthetics, muscle relaxants, anticholinergics); hypothyroidism and hyperparathyroidism.

Symptoms similar to the clinical picture of irritable bowel syndrome are observed in:

• physiological conditions in women (pregnancy, menopause);
• consumption of certain products (alcohol, coffee, gas-forming foods, fatty foods) - can cause both diarrhea and constipation;
• changes in the usual way of life (for example, a business trip);
• the presence of ovarian cysts and uterine fibroids.

In patients with constipation predominating in the clinical picture, it is necessary to exclude obstruction of the colon, primarily of a tumor nature. This is especially relevant in patients over 45 years of age, as well as in young patients with:

1. onset of the disease;
2. severe or treatment-refractory symptoms;
3. family history of colon cancer.

If diarrhea syndrome predominates in the symptoms, irritable bowel syndrome must be differentiated from the following diseases.

• Inflammatory bowel diseases: Crohn's disease, ulcerative colitis.
• Infectious diseases caused by Lamblia intestinalis, Entamoeba histolytica, Salmonella, Campylobacter, Yersinia, Clostridium difficile, parasitic infestations.
• Side effects of medications (antibiotics, potassium supplements, bile acids, misoprostol, abuse of laxatives).
• Malabsorption syndrome: sprue, lactase and disaccharidase deficiency.
• Hyperthyroidism, carcinoid syndrome, medullary thyroid cancer, Zollinger-Ellison syndrome.
• Other causes: postgastrectomy syndrome, HIV-associated enteropathy, eosinophilic gastroenteritis, food allergy.

If the clinical picture is dominated by pain syndrome, irritable bowel syndrome must be differentiated from the following conditions:

• partial obstruction of the small intestine;
• Crohn's disease; ischemic colitis;
• chronic pancreatitis;
• gastrointestinal lymphomas;
• endometriosis (symptoms usually occur during menstruation);
• diseases of the biliary tract.

Colonoscopy with biopsy is of great importance for differential diagnosis.

Indications for consultation with other specialists

• Infectious disease specialist - if there is a suspicion of an infectious nature of diarrhea.
• Psychiatrist (psychotherapist) - to correct psychosomatic disorders.
• Gynecologist - to exclude causes of pain syndrome associated with gynecological diseases.
• Oncologist - in case of detection of malignant neoplasms during instrumental examinations.

[1], [2], [3], [4], [5], [6], [7], [8], [9], [10]