HomePhilippine Scientific Journalvol. 44 no. 1 (2011)

Accuracy of the Modified Alvarado Scale in Predicting Acute Appendicitis at MCU-FDTMF

Khem G. Perez | Henry G. Falcotelo



The Modified Alvarado Scale (MAS) was designed to improve the diagnosis of appendicitis and to predict the occurrence of appendiceal perforation which is not determined by the original Alvarado Scale. At the MCU-FDTMF, the high appendiceal perforation rate of 32.37% in the year 2004 to 2006 was alarming and needs further investigation.


One hundred eight of the 377 patients who underwent appendectomy at the MCU-FDTMF Department of Surgery from January 2007 to December 2009 were scored preoperatively using the Modified Alvarado Scale. Eighty-two percent had a MAS score of 8 to 12 and with no score less than 4. Intraoperative findings were then related to the preoperative MAS score. The accuracy rate of diagnosing complicated appendicitis preoperatively using the Modified Alvarado score was 87%. It showed a positive predictive value of 81.6% when the MAS score was ≥ 11. The accuracy rate of diagnosing acute appendicitis preoperative using MAS score is 41.7%. However, the positive predictive value was 100% when the MAS score was ≥ 11, and 97% when the MAS score was ≥ 7. Furthermore, the MAS score of ≥ 7 was found to be highly predictive of acute appendicitis comparable to the results of the abdominal CT scan which was > 95%.


In conclusion, the MAS score was found to be a good diagnostic tool to predict acute appendicitis preoperatively at the MCU- FDTMF. It also predicted the stage of acute appendicitis as to complicated or uncomplicated based on preoperative MAS score.