Tests for Appendicitis

Appendicitis occurs in about 250,000 people in the United States every year. Most commonly, the condition affects people in their 20s, but it can affect anyone at any age, even children.

Between 7% and 9% of people will be diagnosed with appendicitis in their lifetime. Appendicitis is diagnosed by evaluating symptoms, a physical exam, blood tests, urine tests, and imaging tests.

This article explains the symptoms of appendicitis and which tests healthcare providers use to diagnose the condition.

Early Signs and Symptoms of Appendicitis

To receive prompt diagnosis and treatment, it's essential to identify early signs of appendicitis. These may include:

• Pain in your abdomen that migrates to the lower right
• Loss of appetite
• Nausea
• Vomiting
• Fever
• Abdominal swelling
• Trouble passing gas
• Constipation
• Diarrhea

Appendicitis pain is distinct from other kinds of abdominal pain in its location, persistence, and severity. Appendicitis is often first felt near your belly button, then moves to the lower right quadrant of the abdomen. The pain can start suddenly and may wake you from sleep. Moving, coughing, and sneezing often make the pain worse.

Symptoms in Kids

Symptoms of appendicitis in kids are the same as in adults. However, sometimes it can be more challenging to ascertain in small children because they may not be able to describe what they are experiencing accurately. Researchers found that the most common symptom in children under age 5 was abdominal pain followed by vomiting, fever, refusal to eat, and diarrhea.

How Is Appendicitis Diagnosed?

To diagnose appendicitis, a healthcare provider will likely do the following:

• Take your medical history
• Perform a physical exam
• Run some lab tests
• Order imaging tests

Types of Appendicitis Tests

There is not just one test to diagnose appendicitis definitively. Instead, healthcare providers use a combination of assessments to determine if your symptoms and imaging are consistent with an appendicitis diagnosis.

Physical Exam

During a physical exam, a healthcare provider will ask when your symptoms started, where the pain is located, the intensity of your pain, and if you take any medications. They will examine your abdomen by pressing on it to evaluate the sensitivity level and assess if there is any swelling. They may also perform a digital rectal exam or a pelvic exam.

Blood Testing

Lab tests may include blood work. Healthcare providers will look for signs of infection in your blood, like a high white blood cell count. Blood tests can also help determine if you are dehydrated, if your electrolytes are out of balance, or if there is inflammation.

Urine Testing

A urinalysis (urine test) is done to rule out other conditions, like pregnancy or a urinary tract infection (UTI). To collect a urine sample, you will pee in a cup. A lab technician will evaluate the results.

Imaging Scans

Imaging tests look inside your body to see your appendix. Using imaging, healthcare providers may get a better idea if your pain is caused by infection, inflammation, blockage, or something else. Imaging can also determine if something not related to your appendix is causing your pain.

Imaging tests for appendicitis may include:

• Abdominal ultrasound: It uses high-frequency sound waves to view the inside of the body. Ultrasound has a 71% to 92% sensitivity for identifying appendicitis.
• Magnetic resonance imaging (MRI): As a first-line imaging test for diagnosing appendicitis, it has a 97% sensitivity for identifying the condition. It produces images using magnetic fields and radio waves.
• Computed tomography (CT scan): CT scans use X-rays to take a three-dimensional (3D) image. Since they use X-ray technology, they are not a radiation-free option. CT scans have a 98% sensitivity for identifying appendicitis.

Can Tests Misdiagnose Appendicitis?

It is possible to misdiagnose appendicitis, leading to unnecessary intervention. It is also possible to miss correctly diagnosing appendicitis, leading to the risk that the appendix will burst without treatment.

Researchers have found that appendicitis was potentially missed in 6% of adults and 4% of children. The study noted that people more likely to have an appendicitis diagnosis missed in the emergency room had only abdominal X-rays.

A false-positive appendicitis diagnosis (a test that indicates you have the condition when you do not) could lead to an unnecessary appendectomy (negative appendectomy). These unnecessary surgeries occur at rates of up to 40%.

Researchers conclude that the high rate of negative appendectomies is due to diagnosing appendicitis based on clinical examinations alone. However, when a physical exam is combined with a CT scan, a correct diagnosis is obtained at a rate of 98%.

Checking for Appendicitis at Home

There is no at-home test for appendicitis. However, knowing the early signs of appendicitis can help you receive medical care and an accurate diagnosis on time.

How to Prepare for Testing

Most of the time, you don't need special preparation for testing. At the hospital, you may be asked to change into a gown, allowing technicians to see your abdomen for imaging and lab workers to collect blood from a vein.

Understanding Your Results

An emergency room healthcare provider will review your results with you. If your urine tests are positive, they may indicate that your pain is due to an infection rather than appendicitis. A high white blood cell count may also denote infection and prompt a healthcare provider to order further imaging tests to confirm appendicitis.

If a radiologist (a medical specialist who reads imaging results) suspects appendicitis based on images, they likely detected an enlarged appendix or could observe a partial or complete rupture in the images.

Summary

Healthcare providers use several tests to diagnose appendicitis. These tests include a physical exam, blood work, urinalysis, ultrasound, MRI, and CT scans. Most people do not receive all of these tests. Usually, you will have an exam, labs, and then one of the imaging tests if indicated. Imaging tests are highly accurate for diagnosing appendicitis.