Appendicitis is inflammation of the appendix. The appendix is a small pouch attached to your large intestine.

Appendicitis is one of the most common causes of emergency abdominal surgery in the United States. Appendicitis usually occurs when the appendix becomes blocked by feces, a foreign object, or rarely, a tumor.

The symptoms of appendicitis vary. It can be hard to diagnosis appendicitis in young children, the elderly, and women of childbearing age.

Typically, the first symptom is pain around your navel. (See: abdominal pain.) The pain initially may be vague, but becomes increasingly sharp and severe. You may have reduced appetite, nausea, vomiting, and a low-grade fever.

As the inflammation in the appendix increases, the pain tends to move into your right lower abdomen and focuses directly above the appendix at a place called McBurney's point.

If the appendix ruptures, the pain may lessen briefly and you may feel better. However, once peritonitis sets in, the pain worsens and you become sicker.

Abdominal pain may be worse when walking or coughing. You may prefer to lie still because sudden movement causes pain.

Later symptoms include:

• Fever
• Loss of appetite
• Nausea
• Vomiting
• Constipation
• Diarrhea
• Chills and shaking

With appendicitis, pain increases when the abdomen is gently pressed and then the pressure is suddenly released. If peritonitis is present, touching the abdomen may cause a spasm of the abdominal muscles. A rectal examination may identify abdominal or pelvic pain on the right side of your body.

Doctors can usually diagnose appendicitis by your description of the symptoms, the physical exam, and laboratory tests alone. In some cases, additional tests may be needed. These may include:

• Abdominal ultrasound
• Abdominal CT scan
• Diagnostic laparoscopy

Note: In December 2005, the US Food and Drug Administration recalled a drug used during some imaging tests after reports of life-threatening side effects and two deaths. The drug, called NeutroSpec, is used to help diagnose appendicitis in patients ages 5 and older who may have the condition but do not show the usual signs and symptoms.