Most people who have had sudden stomachaches have always ended up in the operating room. The main reason is because their appendix had to be removed. This small pouch which no one knows why it is in our bodies in the first place can be the source of excruciating pain when it swells.

Appendicitis typically starts with a pain in the middle of your tummy (abdomen) that may come and go.
Within hours, the pain travels to the lower right-hand side, where the appendix usually lies, and becomes constant and severe.
Pressing on this area, coughing, or walking may all make the pain worse. You may lose your appetite, feel sick, and occasionally experience diarrhoea.

Appendicitis typically starts with a pain in the middle of your tummy (abdomen) that may come and go.
Within hours, the pain travels to your lower right-hand side, where the appendix is usually located, and becomes constant and severe.
Pressing on this area, coughing, or walking may all make the pain worse.
If you have appendicitis, you may also have other symptoms, including:
feeling sick (nausea)
being sick
loss of appetite
diarrhoea
a high temperature (fever) and a flushed face

Sourced from: http://www.nhs.uk/Conditions/Appendicitis/Pages/Symptoms.aspx

The only treatment for a swollen appendix is surgery whereby it is removed. Is there a way of diagnosing appendicitis? Well a thorough medical checkup will do. The doctor will check if your white blood cell count is alright. Urine tests will also be done just to ensure that you have a clean bill of health.

Is there a test to diagnose appendicitis?

The diagnosis of appendicitis begins with a thorough history and physical examination. Patients often have an elevated temperature, and there usually will be moderate to severe tenderness in the right lower abdomen when the doctor pushes there. If inflammation has spread to the peritoneum, there is frequently rebound tenderness. Rebound tenderness is pain that is worse when the doctor quickly releases his or her hand after gently pressing on the abdomen over the area of tenderness.

White blood cell count

The white blood cell count usually becomes elevated with infection. In early appendicitis, before infection sets in, it can be normal, but most often there is at least a mild elevation even early in the process. Unfortunately, appendicitis is not the only condition that causes elevated white blood cell counts. Almost any infection or inflammation can cause the count to be abnormally high. Therefore, an elevated white blood cell count alone cannot be used to confirm a diagnosis of appendicitis.

Urinalysis

Urinalysis is a microscopic examination of the urine that detects red blood cells, white blood cells and bacteria in the urine. Urinalysis usually is abnormal when there is inflammation or stones in the kidneys or bladder. The urinalysis also may be abnormal with appendicitis because the appendix lies near the ureter and bladder. If the inflammation of appendicitis is great enough, it can spread to the ureter and bladder leading to an abnormal urinalysis. Most patients with appendicitis, however, have a normal urinalysis. Therefore, a normal urinalysis suggests appendicitis more than a urinary tract problem.

Sourced from: http://www.medicinenet.com/appendicitis/page3.htm