Introduction: Acute appendicitis is one of the most common surgical emergencies. The RIPAS score has been
developed to aid clinical diagnosis of acute appendicitis as high sensitive and specific score system. The aim 
of our study is to reduce use of CT abdomen in cases of acute appendicitis by using effective score system, 
thus reducing the risk of lifetime radiation induced fatal cancer.
Patients and Methods: Clinical data from 61 patients admitted to surgery department in Abdulrahman AlMishari Hospital (Riyadh- Kingdoms Saudi Arabia) who had undergone an emergency appendectomy was 
retrospectively collected following 15 RIPAS score system. The probability was calculated and a score of 0.5, 
1.0 or 2.0 was allocated to each parameter. The receiver operating curve (ROC), sensitivity, specificity, 
positive predictive value (PPV) and negative predictive value (NPV) of the new scoring system were derived 
using the stats direct statistical software.
Results: The standard RIPAS score system for acute appendicitis had a sensitivity of 88% and a specificity of 
67% with accuracy of 81%. In the modified RIPAS scoring system, CT finding were substituted for RIPAS 
scores in the ranges of 7 to 8, 7 to 9, 7 to 10, 7 to11 and 7 to 12. The modification resulted in the greatest 
accuracy 95% in diagnosis appendicitis in patients with score in the range of 7 to 12. This modification 
theoretically would have decreased the use of CT by about 30% in this group of retrospectively studied 
patients. Furthermore, in patients with RIPAS score of 2to 6, another diagnosis should be considered; in 
patients with score of 7 to 12, CT should be performed; and in patients with score 13 to 16, appendectomy 
should be performed promptly without further studies.
Conclusion: The modified RIPAS score is useful as an aid in diagnosis acute appendicitis in the adult 
populations. This scoring system eliminates unnecessary use of CT and the attendant potential cancerinducing radiation