Appendicitis Tests

What are appendicitis tests?

Appendicitis tests are used to diagnose appendicitis, an inflammation (swelling) or infection of your appendix. Your appendix is a small finger-sized pouch attached to your large intestine in the lower right side of your abdomen (belly).

The cause of appendicitis isn't always clear. Your appendix may become inflamed or infected if something blocks the opening where it attaches to your intestine. If appendicitis isn't treated promptly, your appendix can burst and spread bacteria in your abdomen. This can lead to a life-threatening bacterial infection called peritonitis. A burst appendix can also cause a pus-filled infection in your appendix called an abscess.

Appendicitis can happen at any age, but it's more common in people in their teens and twenties. The main treatment for appendicitis is an appendectomy, which is surgery to remove the appendix. Your appendix has no known function, and you don't need it to be healthy.

What are they used for?

Appendicitis tests are used to confirm or rule out a problem with the appendix in people who have appendicitis symptoms.

If you have appendicitis, you'll likely feel pain on the right side of your abdomen. However, some people may have different symptoms because their appendix isn't in the usual place. This can make appendicitis hard to diagnose.

Because appendicitis can be difficult to diagnose, your health care provider may use a range of tests, including:

• Physical exams, to check for pain in the lower right side of your abdomen.
• Blood tests, which look for signs of infection and inflammation. But blood tests can't show whether appendicitis is the cause.
• A urine (pee) test, which your provider can use to rule out conditions that cause symptoms similar to appendicitis. These include urinary tract infections or kidney stones.
• Imaging tests, which take pictures of your appendix. If your symptoms and other tests suggest that you have appendicitis, imaging tests can confirm the diagnosis.

The most common kinds of imaging tests are:

• CT (computed tomography) scans. This is a type of medical imaging test that uses special x-ray equipment to make detailed pictures of the inside of your body.
• Ultrasounds. This is an imaging test that uses sound waves to make pictures of organs, tissues, and other structures inside your body.
• MRI (magnetic resonance imaging) scans. This is a type of imaging test that is usually painless and uses magnets, radio waves, and a computer to create detailed pictures of the inside of your body. MRI scans show organs and soft tissues clearly and can help tell healthy from unhealthy tissue in many cases.

Why do I need appendicitis testing?

You may need testing if you have abdominal (belly) pain that usually:

• Starts near your belly button and moves lower and to your right
• Hurts more when you move, take deep breaths, cough, or sneeze
• Gets worse within hours or comes on suddenly

If you have any severe abdominal pain, it's important to get medical help as soon as possible. This is because severe abdominal pain can be a sign that your appendix may burst.

Along with pain, other appendicitis symptoms include:

• Nausea and vomiting
• Fever
• Loss of appetite
• Swelling in your abdomen
• Diarrhea or constipation
• Problems passing gas

What happens during appendicitis testing?

Before ordering appendicitis tests, your provider will ask questions about your symptoms and medical history. They will then likely start with a physical exam.

During a physical exam, your provider will press on the right side of your abdomen to see if you feel any pain. If you do feel pain, it may be a sign that you have appendicitis.

If your provider thinks you could have appendicitis, they may order one or more tests to help confirm or rule out the diagnosis. These include blood tests, urine tests, and imaging tests.

To collect a blood sample, a health care professional will insert a small needle into a vein in your arm to collect a small amount of blood into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

To collect a urine sample, a health care professional may give you a cleansing wipe, a small container, and instructions for how to use the "clean catch" method. It's important to follow these instructions so that germs from your skin don't get into the sample.

To perform a CT scan, a health care professional may first use a contrast dye so that your tissues and organs show up better in the pictures. They may give you this dye as:

• A drink that you swallow.
• An injection into a vein using an intravenous (IV) line.
• An enema, which is a tube that injects the contrast medium into your intestines through your anus.

You will then lie still on a table that passes slowly through the center of a large donut-shaped x-ray machine. For some scans, the x-ray machine moves around you to take pictures. You may hear whirring sounds from the machine.

For an ultrasound, a health care professional will put a special gel on your abdomen after you lie on an exam table. The healthcare professional will then move a handheld wand-like device across your abdomen. Images of your organs will show up on a monitor.

To perform an MRI scan, a health care professional may first give you a dye using an intravenous (IV) line. You'll then lie very still on a table that slides into an MRI scanner, which is a tunnel-shaped machine. If you have trouble being in closed-in spaces, talk with your provider about options that may make you more comfortable. A health care professional may also give you earplugs or headphones to help block loud sounds from the scanner.

If there's a chance you could be pregnant, you will likely have a pregnancy test to rule out an ectopic pregnancy, which can cause pain similar to appendicitis. It's also important to know whether you're pregnant before having a CT scan. That's because the x-rays could harm a fetus. A pregnancy test may be done with a blood or a urine test.

Will I need to do anything to prepare for the tests?

• Blood and urine tests don't require any special preparations.
• For imaging tests, you may have to stop eating and drinking for several hours before the test. Your provider will tell you how to prepare.

Are there any risks to the tests?

• A blood test has very little risk. You may have slight pain or bruising at the spot where the needle was put in, but it usually goes away quickly.
• A urine test has no risk.
• Imaging tests are safe. If your test includes contrast dye, there's a small chance you could have an allergic reaction to it. Reactions can often be managed with medicine. If you get the dye through an IV, it may cause a slight burning feeling.
• CT scans are generally safe. They do use x-rays which are a form of radiation. The small amount of radiation in a CT scan is not considered harmful to most adults. But exposure to radiation can slightly increase the risk of developing cancer later in life. Radiation can especially affect children and fetuses because their bodies are still growing.
  
  If you're concerned about radiation exposure for yourself, your fetus, or your child, ask about other imaging tests to diagnose appendicitis. If your child needs a CT scan, ask if the machine will be adjusted to use the lowest amount of radiation possible.
• An ultrasound has no risk.
• MRI scans are generally very safe. But if you have certain metals and/or implanted medical devices in your body, ask your provider if an MRI is safe for you.

What do the results mean?

To confirm or rule out appendicitis, your provider will consider your symptoms, medical history, and the results of your exam and appendicitis tests.

Blood test results:

• A high white blood cell count means you probably have an infection. But the test results don't show what's causing the infection. It's also possible to have appendicitis with a normal white blood cell count.
• A high level of c-reactive protein (CRP) in your blood means that you have inflammation in your body that could be from appendicitis. But this test alone can't diagnose appendicitis.

Urine test results:

• A high level of white blood cells or bacteria in your urine may mean that a urinary tract infection is causing your symptoms.
• Blood, crystals or high levels of certain minerals in your urine may mean that kidney stones are causing your symptoms.

Imaging test results:

• An appendix that is blocked, larger than normal, burst, or has an abscess means that you probably have appendicitis.
• If your appendix looks normal, imaging tests may help find other problems that could be causing abdominal pain.

If your provider diagnoses appendicitis, you'll usually have surgery to remove your appendix as soon as possible before it can burst. If your appendix has already burst, you must have surgery right away. The surgeon will remove your appendix and clean the infection from your abdomen.

Learn more about laboratory tests, reference ranges, and understanding results.