How is appendicitis diagnosed? 

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 hand after gently pressing on  the abdomen over the area of tenderness. 

White Blood Cell Count 

The white  blood cell count in  the blood 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. Unfortunately, appendicitis is not the only condition that causes elevated white blood cell counts. Almost any infection  or inflammation  can cause this count to be abnormally high. Therefore, an elevated white blood cell count alone cannot be used  as a sign  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. 

Abdominal X-Ray 

An abdominal x-ray may detect the fecalith (the hardened and calcified, pea-sized piece of stool that blocks the appendiceal opening) that may be the cause of appendicitis. This is especially true in children. 

Ultrasound

An ultrasound is a painless procedure that uses sound waves  to identify organs within the body. Ultrasound can identify an enlarged appendix or an abscess. Nevertheless, during appendicitis, the appendix can be seen in only 50%  of patients. Therefore, not seeing the appendix during an ultrasound does not exclude appendicitis. Ultrasound  also is helpful in  women because it can exclude the presence  of conditions involving the ovaries, fallopian tubes and uterus that can mimic appendicitis. 

Barium Enema 

A barium enema is an x-ray test where liquid barium is inserted into the colon from the anus to fill the colon. This test can, at times, show an impression on the colon in the area of the appendix where the inflammation from the adjacent inflammation impinges on the colon. Barium enema also can exclude other intestinal problems that mimic appendicitis, for example Crohn's disease. 

Computerized tomography (CT) Scan 

In patients who are not pregnant, a CT Scan  of the area  of the appendix  is useful  in diagnosing appendicitis and peri-appendiceal abscesses as well as in excluding other diseases inside  the abdomen  and pelvis that  can mimic appendicitis. 

Laparoscopy  

Laparoscopy  is a surgical procedure in which a small fiberoptic tube with a camera is inserted into  the abdomen through  a small puncture made on the abdominal wall. Laparoscopy allows a direct view  of the appendix as well as other abdominal and pelvic organs. If appendicitis  is found, the inflamed appendix can be removed with the laparascope. The disadvantage  of laparoscopy compared to ultrasound and CT is that it requires  a general anesthetic. 

There is no one  test that will diagnose appendicitis with certainty. Therefore, the approach to suspected appendicitis may include a period of observation, tests as previously discussed, or surgery. 

Why can it be difficult to diagnose appendicitis? 

It can be difficult to diagnose appendicitis. The position of the appendix  in the abdomen may vary. Most  of the time  the appendix is in the right lower abdomen,  but the appendix, like other parts of the intestine, has a mesentery. This mesentery  is a sheet-like membrane  that attaches the appendix to other structures within the abdomen. If the mesentery  is large, it allows  the appendix to move around. In addition, the appendix may be longer than normal. The combination of  a large mesentery and a long appendix allows the appendix  to dip down into  the pelvis (among the pelvic organs in women). It also may allow the appendix to move behind the colon (called a retro-colic appendix). In either case, inflammation of the appendix may act more like the inflammation of other organs, for example, a woman's pelvic  organs.

The diagnosis of appendicitis also  can be difficult because other inflammatory problems may mimic appendicitis. Therefore, it is common to observe patients with suspected appendicitis for a period of time to see  if the problem will resolve on its own or develop characteristics that more strongly suggest appendicitis or, perhaps, another condition.