Appendicitis: Encyclopedia II - Appendicitis - Diagnosis

Appendicitis - Diagnosis

Diagnosis is based on history and physical examination backed by blood tests and imaging.

The classical physical finding in appendicitis is diffuse pain in the umbilical region which can become localised at McBurney's point if the inflammed appendix comes into contact with the parietal peritoneum. This point is located on the right-hand side of the abdomen one-third of the distance between the anterior superior iliac spine and the navel.

Other physical findings include right sided tenderness on a digital rectal exam. Since the appendix normally lies on the right, if a finger is inserted into the rectum and there is tenderness when pressure is applied toward the right it increases the liklihood that the patient has appendicitis.

Other signs used in the diagnosis of appendicitis are the psoas sign (useful in retrocecal appendicitis), the obturator (internus) sign, Blumberg's sign, and Rovsing's sign.

Ultrasonography and Doppler sonography also provide useful means to detect appendicitis, especially in children. In some cases (15% approximately), however, ultrasonography of the iliac fossa does not reveal any abnormalities despite the presence of appendicitis. This is especially true of early appendicitis before the appendix has become significantly distended and in adults where larger amounts of fat and bowel gas make actually seeing the appendix technically difficult. Despite these limitations, in experienced hands sonographic imaging can often distinguish between appendicitis and other diseases with very similar symptoms such as inflammation of lymph nodes near the appendix or pain originating from other pelvic organs such as the ovaries or fallopian tubes.

In places where it is readily available, CT scan has become the diagnostic test of choice, especially in adults. A properly performed CT scan with modern equipment has a detection rate (sensitivity) of over 95% and a similar specificity. Signs of appendicitis on CT scan include lack of contrast (oral dye) in the appendix and direct visualization of appendiceal enlargement (greater than 6 mm in diameter on cross section). The inflammation caused by appendicitis in the surrounding peritoneal fat (so called "fat stranding") can also be observed on CT, providing a mechanism to detect early appendicitis and a clue that appendicitis may be present even when the appendix is not well seen. Thus, diagnosis of appendicitis by CT is made more difficult in very thin patients and in children, both of whom tend to lack fat within the abdomen.

Adapted from the Wikipedia article "Diagnosis", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki