RELATED STORIES • Appendix stones

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Your appendix is a finger-shaped pouch that projects out from your colon on the lower right side of your abdomen. The small structure has no known purpose, but that doesn't mean it can't cause problems. Appendicitis is a condition in which the appendix becomes inflamed and filled with pus.

The main symptom of appendicitis is pain that typically begins around the navel and then shifts to the lower right abdomen. The pain of appendicitis usually increases over a period of six to 12 hours, and eventually may become very severe.

Anyone can develop appendicitis, but it most often strikes people between the ages of 10 and 30. Appendicitis is one of the most common reasons for emergency abdominal surgery in children.

The standard treatment for appendicitis is surgical removal of the appendix. In many cases the surgery is straightforward, and you recover quickly. But if your appendix has ruptured, the surgery may be more complicated and you'll take longer to heal. A ruptured appendix that's not promptly treated can lead to serious complications such as infection. In rare instances appendicitis that results in a ruptured appendix can be fatal.

Appendicitis can cause a variety of symptoms that may change over time. The most common early symptom is an aching pain around your navel that often shifts later to your lower right abdomen. As the inflammation in your appendix spreads to nearby tissues, especially the inner lining (peritoneum) of your abdomen, the pain may become sharper and more severe.

Eventually, the pain tends to settle in your lower right abdomen ¾ near your appendix at what's known as McBurney point. This point is about halfway between your navel and the top of your right pelvic bone. But the location of your pain may vary, depending on your age and the position of your appendix. Young children, especially, may have appendicitis pain in different places.

If you apply gentle pressure to the area that hurts, it will feel tender. As you release the pressure, especially if you do it suddenly, appendicitis pain often will feel worse (rebound tenderness). It will also tend to get worse if you cough, walk or make other jarring movements. This is particularly true if the inflamed appendix is touching the peritoneum — the silk-like membrane that lines the inner abdominal wall and enfolds the intestines. The pain may lessen somewhat if you lie on your side and pull your knees up toward your chest.

In addition to pain, you may have one or more of the following signs and symptoms:

• Nausea and sometimes vomiting
• Loss of appetite
• A low-grade fever that starts after other signs and symptoms appear
• Constipation
• An inability to pass gas
• Diarrhea
• Abdominal swelling

It's not always clear why appendicitis occurs. Sometimes it's the result of an obstruction when food waste or a hard piece of stool (fecal stone) becomes trapped in an orifice of the cavity that runs the length of your appendix.

Appendicitis may also follow an infection, such as a gastrointestinal viral infection, or it may result from other types of inflammation. In both cases, bacteria may subsequently invade rapidly, causing the appendix to become inflamed and filled with pus. If not treated promptly, your appendix eventually may rupture.

The pain from appendicitis may change over time, so establishing a diagnosis can sometimes be difficult. In addition, abdominal pain can arise from a number of health problems other than appendicitis. Other conditions with abdominal pain that may resemble that of appendicitis include:

• Ectopic pregnancy. Pain may occur from this type of pregnancy, which is one that occurs outside the lining of the uterus.
• Certain ovarian cysts. A right-sided ovarian cyst may produce pain in the same general area as appendicitis.
• Kidney stone. Occasionally, a stone from the right kidney will pass into the ureter, which runs from the kidney to the bladder, and get stuck there. This causes considerable pain that may mimic appendicitis, especially in adults.
• Crohn's disease. This condition, which causes chronic inflammation of the digestive tract, also can mimic appendicitis.

To help diagnose appendicitis, your doctor will likely examine your abdomen. When gentle pressure on the painful area is suddenly released, appendicitis pain will often feel worse if the adjacent peritoneum is inflamed. Other signs your doctor may watch for include abdominal rigidity and a tendency to stiffen your abdominal muscles in response to pressure over the inflamed appendix (guarding).

In addition, doctors may recommend the following procedures:

• Blood test. This allows your doctor to check for a high white blood cell count, which may indicate an infection.
• Urine test. Your doctor may also want you to have a urinalysis to make sure that a urinary tract infection or a kidney stone isn't causing your pain. If it is a kidney stone, red blood cells are usually seen during microscopic examination of the urine.
• Imaging tests. Your doctor may also recommend an abdominal X-ray or ultrasound scan to help confirm appendicitis or find other causes for your pain. An ultrasound scan uses high-frequency sound waves and computer technology to provide images of your internal organs. More commonly, a computerized tomography (CT) scan is used for confirming a diagnosis. A CT scan is an imaging test that uses a series of computer-generated X-rays to provide a more comprehensive view of your internal organs than conventional X-rays do. It can also help reveal other potential diagnoses if your appendix is not the source of your pain. Because a CT scan produces radiation, it's essential for women of childbearing age to have a pregnancy test before proceeding with the scan.

The most serious complication of appendicitis is an infection of the lining of your abdominal cavity (peritonitis). This may occur if your appendix ruptures (perforates) and the contents of your intestines and infectious organisms invade the peritoneal cavity. When this happens, you may suddenly feel better. But soon after, your entire abdomen may become distended with gas and fluid and will likely feel tight, hard and tender to the touch. You'll also have pain throughout your abdomen, but may not have the severe, localized pain of appendicitis. In addition, you may not be able to pass gas or have a bowel movement because of the inflammation. Other signs and symptoms may include a fever, thirst and a low urine output.

Peritonitis is a medical emergency. If you or a family member develops signs of this abdominal infection, go to an emergency room immediately. Even with prompt treatment, peritonitis can be extremely serious.

Children are more likely to have a ruptured appendix than adults are. Children don't always have typical symptoms of appendicitis, and parents may delay getting treatment. For that reason, it's best not to take abdominal pain lightly. Even if you suspect a "stomachache" isn't serious, call your doctor just to make sure.

Sometimes, infection and the seepage of intestinal contents may form an abscess, a walled-off area of infection (appendiceal abscess). The abscess may be as small as a walnut or as large as a grapefruit. Regardless of its size, it requires surgery before the abscess itself perforates, causing peritonitis.

If you have acute appendicitis, you'll need to have your appendix surgically removed (appendectomy). Your surgeon may perform traditional open surgery, using a single long abdominal incision, or choose laparoscopic surgery, which requires only a few small abdominal incisions.

In a laparoscopic procedure, your surgeon inserts a laparoscope — a pencil-thin tube with its own lighting system and miniature video camera — into your abdomen through a hollow instrument (cannula). Only a small incision is needed. The video camera then produces a magnified view of the inside of your abdomen on an outside video monitor. This allows your surgeon to see the surgery in detail. To remove your appendix, your surgeon uses tiny instruments inserted through one or two other small abdominal incisions.

In general, laparoscopic surgery allows you to recover faster and heal with less scarring. But if your appendix has ruptured and infection has spread beyond the appendix, or if an abscess is present, you'll need a larger incision so that your surgeon can clean the abdominal cavity. You'll receive intravenous antibiotics and will need to stay in the hospital during your recovery.