Getting an Appendicitis Diagnosis: Tests and Other Ways

Appendicitis is inflammation of the appendix, a small finger-shaped pouch of tissue attached to your large intestine in the lower right part of the abdomen. Your appendix can become inflamed when something like swollen tissue from an infection or hardened stool is causing a blockage.

Although the appendix serves no known function in the body, the consequences can be serious when it becomes inflamed. That’s why proper diagnosis of appendicitis is key—timely diagnosis means timely treatment. If appendicitis isn’t treated, the organ can burst, leading to dangerous infections within the abdomen.

Because the initial symptoms of appendicitis, such as abdominal pain and swelling, nausea, vomiting, fever, diarrhea, constipation, and difficulty passing gas, are similar to many other conditions, appendicitis may not be able to be diagnosed on symptoms alone. Healthcare providers will likely take other diagnostic steps as well.

To identify appendicitis, healthcare providers rely on medical history assessments, physical exams, blood tests, urine tests, and imaging. Primary care providers, emergency room physicians, or radiologists perform this work.  

Healthcare providers rely on specific criteria to evaluate the severity of the case to assist in diagnosing appendicitis. The modified Alvarado scoring system is the most commonly used diagnostic criteria in clinical practice. Dr. Alfred Alvarado originally developed the system in 1986 for use among pregnant people. It soon gained traction for all suspected appendicitis cases and remains among the standard approaches.

The modified Alvarado scoring system relies on assessments of current symptoms and results from clinical tests. Healthcare providers calculate a score from 0-9, with scores of seven or higher indicating a higher chance of having appendicitis.

In this system, two points each are awarded for elevated white blood cell count (from blood tests) and pain or tenderness in the lower right abdomen. In addition, providers add one point each for the following:

• Migrating abdominal pain (pain that moves)
• Recurring tenderness in the abdomen
• Fever
• Nausea or vomiting
• Lack of appetite

The first step in the diagnosis of appendicitis involves an assessment of your symptoms and overall medical status. The healthcare provider will likely ask about medications or supplements you’re taking and dietary issues you may have as well as your history of diseases, treatments, and alcohol or drug use. They may also ask about any family history of digestive diseases.

In addition, they’ll ask about your symptoms. Specifically, they’ll need to know when your pain started, how severe it is, and where in your abdomen it’s located. They may inquire about any other signs or issues you have.

Healthcare providers will also want to assess your abdomen. This may involve:

• Gently pressing on or jiggling the affected area and the surrounding area of your abdomen
• Pressing on the right knee while you lift your leg
• Asking you to lie down on your left side and moving and rotating your leg to assess for pain
• Using a stethoscope to listen to the inside of the abdomen

Depending on what other conditions they suspect, your provider may also do a visual and physical exam of the pelvis in people assigned female at birth. They may also perform a digital rectal exam, in which they physically assess a male’s prostate or female’s rectum with a gloved hand. 

Blood and urine tests can help healthcare providers rule out other potential causes of symptoms and can indicate signs of appendicitis. These clinical tests may include:

• White blood cell count, with high levels indicating infection
• C-reactive protein (CRP) tests, with elevated levels of this liver protein indicating infection
• Urinalysis, in which a sample of urine is tested for signs of kidney stones or bladder infection
• Pregnancy test, as being pregnant can cause abdominal symptoms

While a physical exam and clinical tests are often enough to diagnose appendicitis, imaging of the appendix and inside the abdomen helps healthcare providers assess the scope of inflammation and infection. It also allows them to locate blockages and screen for complications, such as abscesses (pockets of pus) or a burst appendix (when your appendix ruptures, which can spread infection).

Computerized tomography (CT) scans, ultrasound, and magnetic resonance imaging (MRI) are the most commonly used imaging methods.

Computerized Tomography (CT)

CT scans rely on multiple X-rays to develop three-dimensional images of the appendix. This is performed while you’re lying down. Depending on the case, you may have to swallow, be injected with, or use an enema (administered through your rectum) of contrast dye. This substance helps radiologists better visualize inflammation or infection in the region when looking at the images.

While CT scans are highly accurate, they’re not appropriate for everyone. Because of the risk of exposing a fetus to radiation, people who can get pregnant should have a pregnancy test before a CT scan. Meanwhile, other options should be used for children first to limit their radiation exposure. 

Magnetic Resonance Imaging (MRI)

Abdominal MRI is another form of imaging that relies on X-ray to produce images of the appendix and abdomen. This type produces highly accurate and reliable images, though it may not be as widely available and requires trained specialists.

MRI does not emit radiation, so radiologists may consider this MRI if you’re pregnant.

Abdominal Ultrasound

With ultrasound, the images are made using directed sound waves within the abdomen. The procedure is performed while you’re lying down. The provider will use a hand-held device that transmits the image to a screen. Because ultrasound doesn’t rely on radiation, it’s safer for children and pregnant people.

A wide range of conditions can cause symptoms that resemble those of appendicitis. As such, a big part of diagnosis involves ruling out other conditions that share symptoms. This is primarily done by evaluating imaging results.

Additionally, because certain bacterial or viral infections can cause symptoms similar to appendicitis, blood tests may be necessary to rule out these other underlying causes.

Conditions that cause symptoms similar to appendicitis include:

• Abdominal adhesions: Bands of scar-like tissue between organs in the abdomen
• Inflammatory bowel disease (IBD): A set of chronic intestinal diseases, including Crohn’s disease and ulcerative colitis
• Intestinal obstruction: A partial or complete blockage of the intestinal tract
• Pelvic inflammatory disease (PID): An infection and scarring of the uterus, ovaries, or other female reproductive organs
• Kidney stones: The development of solid, calcium deposits in the kidneys
• Ectopic pregnancy: When a fetus implants outside the uterus
• Ovarian torsion: When blood supply to the ovaries is cut off
• Testicular torsion: When the spermatic cord which supplies blood to the testicles is twisted, cutting off the blood supply

Appendicitis is an inflammation of the appendix that causes symptoms like pain and fever. Because the inflammation can lead to serious complications, appendicitis is considered a medical emergency that requires surgery. As such, an accurate and timely diagnosis of appendicitis is crucial.

To diagnose appendicitis, healthcare providers—often primary care providers or emergency physicians—mainly rely on physical examination, assessment of medical history, and clinical testing. They may also perform imaging methods, such as CT scans, MRI, or ultrasound. In doing so, they can rule out other potential causes of appendicitis-like symptoms, including scarring in the abdomen, inflammatory bowel diseases, and kidney stones.