When dealing with symptoms like persistent bloating, abdominal pain, or changes in bowel habits, healthcare providers use a “diagnostic ladder.”
This starts with non-invasive tests and moves toward more detailed investigations to identify the root cause of gastrointestinal (GI) distress.
Blood work is typically the first step to rule out systemic issues like infection, anemia, or autoimmune responses.
Inflammatory Markers (CRP & ESR): High levels suggest active inflammation, helping doctors differentiate between Inflammatory Bowel Disease (IBD) and Irritable Bowel Syndrome (IBS).
Full Blood Count (FBC): Used to detect anemia (suggesting internal bleeding) or elevated white cells (indicating infection).
Coeliac Disease Screen: Checks for specific antibodies (tTG-IgA) to see if gluten is causing intestinal damage.
Nutrient & Vitamin Panel: Tests for deficiencies in B12, Iron, Folate, and Vitamin D, which are common in malabsorption disorders like Crohn’s disease.
Organ Function: Liver Function Tests (LFTs) and Pancreatic enzymes (Amylase/Lipase) to rule out accessory organ involvement.
Stool samples provide a direct window into bowel health and are often more accurate for GI-specific issues than blood tests.
Faecal Calprotectin: A critical biomarker for intestinal inflammation; essential for diagnosing IBD.
FIT (Fecal Immunochemical Test): Detects “hidden” (occult) blood that isn’t visible to the naked eye—a key screen for colorectal cancer.
Microscopy & Culture: Identifies bacterial pathogens (C. diff, Salmonella) or parasites.
H. Pylori Antigen: Used to detect the bacteria that causes stomach ulcers.
These tests are non-invasive and highly effective for diagnosing functional and metabolic digestive issues.
Urea Breath Test: The gold-standard non-invasive test for H. pylori.
Hydrogen/Methane Breath Test: Used to diagnose SIBO (Small Intestinal Bacterial Overgrowth) or sugar intolerances (Lactose/Fructose).
Gastric Emptying Study: Measures how quickly food leaves the stomach; used for diagnosing Gastroparesis.
Imaging helps doctors see the “map” of your GI tract to identify blockages, tumors, or gallstones.
| Test | Primary Purpose |
| Abdominal Ultrasound | Best for viewing the gallbladder, liver, and pancreas. |
| CT Abdomen | High-detail view used for obstructions, tumors, or acute appendicitis. |
| MRI / MRCP | Specialized imaging for the bile ducts and tracking Crohn’s disease. |
| Barium Studies | A “real-time” X-ray to see how liquids move through the esophagus and stomach. Now rarely done. |
Endoscopies are the “gold standard” because they allow doctors to see the lining of the gut and take biopsies (tissue samples).
Gastroscopy (OGD): A camera passed through the mouth to inspect the stomach for ulcers, gastritis, or GORD.
Colonoscopy: A thorough examination of the large bowel. It is the primary tool for finding polyps and diagnosing bowel cancer.
Capsule Endoscopy: A swallowed “pill camera” that captures images of the small intestine, which traditional scopes cannot reach.
For complex or chronic symptoms, specialized physiological tests may be required:
Anorectal Manometry: Evaluates pelvic floor function for chronic constipation.
pH Monitoring: Measures acid levels in the esophagus over 24 hours.
SeHCAT Scan: The definitive test for Bile Acid Malabsorption (BAM).
If you experience “Red Flag” symptoms, you should seek a referral to a Gastroenterologist urgently:
Rectal Bleeding: Visible blood in your stool.
Unexplained Weight Loss: Losing weight without diet or exercise changes.
Persistent Vomiting: Inability to keep down food or fluids.
Iron-Deficiency Anemia: Found on routine blood tests.
Family History: A strong history of bowel or stomach cancer.
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