Appendicitis is a disease caused by a blockage or inflammation in the appendix organ.If left untreated, the appendix can rupture inside of a person's body and be life-threatening.Severe pain in the lower right abdomen is one of the defining symptoms of appendicitis.Nausea, vomiting, and low-grade fever can also be present in appendicitis, but not always.Appendicitis is a potentially dangerous medical condition marked by the inflammation of the appendixthe tiny, tube-shaped organ in your digestive system.Generally, appendicitis is most common in people between ages 10 and 30, but a person could suddenly develop it at any point during their life. According to the National Institute of Health, acute appendicitis is the leading cause of emergency abdominal surgery in the US.Typically, appendicitis comes on without much warning, and doctors aren't completely certain about why some people get it and others don't. Even worse, if appendicitis is left untreated, the appendix can rupture, causing a serious widespread infection, and even death.Despite the severity of the condition, however, doctors can easily treat appendicitis by surgically removing the appendix by what's called an appendectomy.INSIDER spoke with Dr. Jennifer Anders, assistant professor of pediatrics at John Hopkins University School of Medicine about how to identify the most definitive signs of acute appendicitis.If you are experiencing the following symptoms or any extreme pain, you should seek immediate medical care. You have unexplained pain in your abdomenDr. Anders told INSIDER that pain in the abdomen is the most classic symptom of appendicitis."That tube [the appendix] is normally communicating with the big tube [the small intestine] off of the flow of digestive juices, and helping to turn food into stool in the large intestine. Fluid can move in and move out [from it]," Dr. Anders added.When a person develops appendicitis, they feel pain because their appendix has become inflamed due to an infection or blockage. Dr. Anders said this can happen due to pieces of undigested food getting stuck, or swelling at the neck of the appendix tube.According to The National Center for Biotechnology Information, as the appendix swells, certain nerve fibers become stimulated and travel to the spinal cord. In turn, the body sends pain signals throughout the abdominal area.Your pain isn't subsiding with timeUnlike other conditions that cause uncomfortable sensations in the abdomen, like gastroenteritis, the pain doesn't usually come and go in waves. According to Dr. Anders, appendicitis pain starts as a constant, achy feeling in the abdomen, rather than an intermittent cramping sensation. And it doesn't go away. In fact, it gets worse with time.She told INSIDER, "It sort of starts as a vague, constant sense of pain that becomes more intense throughout the day."Your pain moved to a specific point in the lower-right part of your abdomen"Over the course of the day, [appendicitis] pain will migrate or organize itself in the lower-right part of the abdomen," said Dr. Anders. She explained this happens because as the inflamed appendix becomes even tighter, it begins to press up against the peritoneum, or inner lining of the abdomen. She told INSIDER, "As the tube [the appendix] starts to swell up and become thick and larger in size, it can grow to the size of the thumb. At that point, it's tight and firm, so it's [producing] an aching kind of pain. And then that infected sack of material starts to touch that peritoneum, or the lining of the inside of the abdomen, which causes pain in that area"You have a low-grade feverWhile an elevated temperature doesn't automatically mean appendicitis, it can be a sign of the condition if you're experiencing another symptom, according to Dr. Anders.Like with many other conditions, a fever greater than 99 degrees Fahrenheit can indicate the body's immune system is trying to fight off some form of infection. Since bacteria can collect in the appendix if it is blocked, the appendix can become a breeding ground for infection to happen.Some studies, however, have shown a fever may not always be present if you have appendicitis, so it's importantnot to rule it out.You don't feel like eating anythingSince the appendix is part of the digestive system, experiencing appendicitis symptoms can make you feel sick to your stomach."People with appendicitis generally have no appetitethe thought of eating makes them feel worse," said Dr. Anders.In other words, if you feel like you can't even stomach saltine crackers, you may want to consult your doctor.On top of that, you're throwing upOn that note, Dr. Anders said that vomiting can be another sign of acute appendicitis. This goes hand and hand with the nausea sensation the disease causes.The National Institute of Health, however, noted that projectile vomiting usually occurs when the appendix is already ruptured, which means you need to get to a hospital as soon as possible.You get a blood test and your white blood cell count is highWhen you develop acute appendicitis, your body naturally reacts by attempting to fight off the infection. When this happens, your body produces a greater number of white blood cells.Although there is no blood test to specifically identify appendicitis, you might want to consider asking your doctor to perform a blood test and inform you if you have an elevated number of white blood cells, pointing to a possible infection in your appendix.You feel rebound tenderness when someone presses near your belly buttonPhysicians usually check for appendicitis by seeing if a patient responds with rebound tenderness when they gently press on the lower-right part of the abdomen. Dr. Anders said, "If there's pain when we push down, we call that tenderness."Rebound tenderness is a bit different, however. This means the patient feels pain in the area even after the doctor releases the pressure.Dr. Anders told INSIDER, "When a patient has appendicitis, it [will] hurt when I push down [on the area]. But if I hold still, [sometimes] that pain subsides Then when I let go, and everything shakes and bounces around from that process, that's going to be very painful for somebody with appendicitis. We call it the 'rebound'it's all the stuff in the abdomen shaking and moving as it springs back into place. It's very painful."You can barely move because of how badly it hurtsAs appendicitis pain progresses, it generally becomes so severe that a person can barely move. Dr. Anders told INSIDER, "Any kind of movement that jostles that tight, swollen sack around, is going to cause excruciating pain. [This includes] walking around or jumping ... If a person says that they are able to jump, it's probably not appendicitis. But if they want to stay still that's a pretty convincing sign."Your pain doesn't respond to ordinary painkillersSometimes people may mistake appendicitis pain for a less serious condition, like indigestion. This is especially the case if you're experiencing the early stage of the disease when the pain is merely a dull ache.But if you've been treating yourself with anti-inflammatory drugs or antacids and see no relief, or feel the pain getting worse, there's a chance it could be appendicitis. "If the pain can't be managed by over-the-counter medicine, like acetaminophen, it's time to go to see a doctor and get checked," Dr. Anders told INSIDER.Your symptoms came on quickly and with little warningContrary to other conditions that may persist for weeks, like irritable bowel syndrome or gas, appendicitis is fast moving.According to Dr. Anders, appendicitis symptoms often present over the course of a 24-hour period. Most people don't endure the disease for more than a few days because the pain causes them to head to the emergency room. Studies show that approximately 75% of appendicitis patients typically present a full range of symptoms within that first 12- to 24-hour period.According to Dr. Anders, if you're experiencing a sudden unexplained pain that gets worse or any other rapid onset of symptoms, you should seek prompt medical attention.Join the conversation about this storyNOW WATCH: Meet the three women who married Donald Trump Click here to read full news..