Ultrasonography and CT Scan For Diagnosis of Appendicitis

Ultrasonography for diagnosis of appendicitis:

Ultrasonography is a commonly used diagnostic tool for diagnosis if appendicitis, along with Doppler sonography as they are very useful. Ultrasonography can show collection of free fluid in right iliac fossa along with a visible appendix and without blood flow in color Doppler, especially in children and helpful in diagnosing appendicitis. But in approximately 15% of cases Ultrasonography may not show any abnormality (in the right lower quadrant of abdomen known as iliac fossa) despite presence of appendicitis in those patients. Normal right iliac fossa in Ultrasonography (despite presence of appendicitis) may be due to larger amounts of fat and bowel gas in adults, which make actually visualizing the appendix technically difficult and in case of early appendicitis, before the appendix has become significantly distended. Despite these shortcomings, Ultrasonography can be very useful in detecting appendicitis and differentiating it from other diseases with similar symptoms such as inflammation of lymph nodes, pain originating from other pelvic organs such as the ovaries or fallopian tubes etc., especially in an experienced hand.

Computed tomography (CT) in diagnosis of appendicitis:

CT scan is frequently used for diagnosis of appendicitis, these days, where it is available, especially in atypical cases and in case Ultrasonography has missed the diagnosis. But CT scan should not be used in case of pregnant women and in children due to risk of radiation. If properly done CT can detect appendicitis in more than 95% and with accuracy (95% specificity). In case of appendicitis, there is absence of oral dye in appendix and in IV dye/contrast there is enhancement of wall of appendix. The enlargement of appendix can be easily detected and measured by CT.

In one study report in Massachusetts General Hospital the chance of finding a normal appendix at surgery was 20% before CT scan became available and came down to 3% after introduction of CT for diagnosis of appendicitis.

Comparison of Ultrasonography and CT scan in diagnosis of appendicitis:

CT scan is better than Ultrasonography for diagnosis of appendicitis, especially for adults and adolescents, as CT scan is more accurate in diagnosis. CT scan has sensitivity of 94% and specificity of 95%, whereas Ultrasonography has sensitivity of 86% and specificity of 81%.

 



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