Appendicitis Tests
Reviewed
Appendicitis tests include blood tests, urine tests, and imaging studies (CT, ultrasound, MRI) used to help diagnose appendicitis. Blood and urine tests look for signs of infection or other conditions but cannot confirm appendicitis. Imaging tests, especially CT scan, can confirm the diagnosis. Prompt diagnosis is important because a burst appendix can cause a life-threatening infection.
Preparation and collection
Blood and urine tests require no special preparation. For imaging tests, you may need to stop eating and drinking for several hours before the test. Your provider will give specific instructions.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- Blood tests cannot diagnose appendicitis; they only indicate infection or inflammation. A normal white blood cell count does not rule out appendicitis.
- Urine tests cannot diagnose appendicitis; they help rule out urinary tract infections or kidney stones. Contamination may cause false results.
- CT scans use radiation which slightly increases lifetime cancer risk; children and unborn babies are more sensitive. Contrast dye may cause allergic reactions.
- Ultrasound is less accurate than CT for diagnosing appendicitis and depends on operator skill and patient body habitus.
- If you have certain metals or implanted medical devices, MRI may not be safe.
What to do next
Your provider will consider all test results together with your symptoms and physical exam. If appendicitis is confirmed, surgery (appendectomy) is usually needed as soon as possible to prevent the appendix from bursting. If your appendix has already burst, you must have surgery right away to remove the appendix and clean the infection from your abdomen.