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.

Waiting for a result or looking for it in the NHS App? Find out who to contact and how to arrange follow-up.

• 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)

  England invites people with a cervix aged 25 to 64 for HPV primary screening. It is not a cancer test. The vaccine does not replace it. Bleeding between screens still needs a GP.

• Cholesterol blood test

  A cholesterol (lipid) blood test measures LDL, HDL and triglycerides to assess heart and stroke risk — what the results mean and when statins are considered.

• 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.

• Fasting before a blood test

  Which blood tests may require fasting, whether water and medicines are allowed, and why the test provider's instructions take priority.

• 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 checks TSH and often free T4 to diagnose underactive or overactive thyroid — what results mean and how treatment is monitored.

• 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.

• Understanding blood test results

  What reference ranges and flagged results mean, why one abnormal result may not diagnose illness, and who to contact for interpretation.

• 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.