Tests & investigations
Tests and investigations explained
Clear guides to common blood tests, urine tests, scans and NHS screening programmes — what they involve, why they are done, and how to understand results in plain English.
- Allergy blood test (specific IgE)
An allergy blood test measures specific IgE antibodies to foods and environmental allergens, confirming sensitisation alongside your symptom history.
- Blood tests overview
Blood tests check your health, diagnose conditions and monitor medicines; most are quick vein samples that need no preparation, though some require fasting.
- Bowel cancer screening
Bowel cancer screening uses a home FIT kit to detect hidden blood in poo; it is offered every 2 years in England and a positive result leads to colonoscopy.
- Cervical screening (smear test)
Cervical screening checks for high-risk HPV and abnormal cells to prevent cervical cancer; those aged 25 to 64 with a cervix are invited every 3 to 5 years.
- Cholesterol blood test
A cholesterol blood test measures total cholesterol, LDL, HDL and triglycerides to help assess your risk of heart disease and stroke on the NHS.
- Colonoscopy
A colonoscopy is a test that uses a flexible camera to examine the whole colon, used after a positive FIT, for symptoms or surveillance, and to remove polyps.
- CT scan
A CT scan uses X-rays and a computer to build detailed cross-section images, helping doctors detect cancers, strokes, injuries and blood clots.
- ECG (electrocardiogram)
An ECG is a painless test that records your heart's rhythm and electrical activity using sticky pads, helping detect arrhythmias and heart attacks.
- Endoscopy (gastroscopy)
An endoscopy, or gastroscopy, uses a flexible camera to examine the oesophagus, stomach and duodenum, detecting ulcers, coeliac disease and cancer.
- Full blood count (FBC)
A full blood count (FBC) checks red cells, white cells and platelets, helping GPs detect anaemia, infection and other blood disorders early.
- HbA1c blood test
An HbA1c blood test measures your average blood sugar over 2-3 months, and GPs use it to diagnose and monitor diabetes without any fasting needed.
- Iron blood tests (ferritin)
Iron blood tests measure ferritin, serum iron and transferrin saturation to diagnose iron deficiency anaemia and guide GP treatment decisions.
- Kidney function tests
Kidney function tests measure creatinine and eGFR levels in a blood sample, detecting chronic kidney disease early and tracking kidney health.
- Liver function tests (LFTs)
Liver function tests measure enzymes and proteins in the blood to detect liver inflammation, fatty liver disease and other liver conditions.
- Mammogram
A mammogram is a breast X-ray used in NHS screening to detect breast cancer early, offered to women aged 50 to 71 every three years in England.
- MRI scan
An MRI scan uses magnets and radio waves, not radiation, to produce detailed images of the brain, spine, joints and soft tissues inside the body.
- Pregnancy test
A pregnancy test detects the hormone hCG in urine or blood, and most home pregnancy tests are accurate from the first day of a missed period.
- PSA test
A PSA test is a blood test that can indicate prostate problems including cancer, though levels can also be raised for benign, non-cancerous reasons.
- Thyroid function test
A thyroid function test is a blood test measuring TSH and sometimes T4, used to diagnose an underactive or overactive thyroid gland problem.
- Ultrasound scan
An ultrasound scan uses sound waves, with no radiation, to create images of the body and is commonly used in pregnancy and abdominal checks.
- Urine test (urinalysis)
A urine test, or urinalysis, checks a urine sample for infection, blood, protein and glucose using a dipstick test or laboratory culture method.
- X-ray
An X-ray uses low-dose radiation to image bones and some tissues, quickly detecting fractures, chest infections and joint disease in most cases.