Introduction: Appendicitis is considered as one of the major causes leading to acute abdomen and as one of the most prevalent cases in urgent need of surgery. Although diagnosis of acute appendicitis is based on the accounts, clinical examinations and laboratory results, but making any certain diagnosis often seems to be quite difficult, even for experienced surgeons. This problem is more appreciable/ discernible concerning some groups like pregnant women, children/infants, and aged people. So, there has been always a constant effort to achieve inexpensive and feasible/available methods for improving the process of diagnosis.

Materials & methods: All the patients who were suspected of having acute appendix, operated in the emergency of Be'sat Hospital in Hamadan during six months ago, have been checked. 5 cc peripheral blood has been obtained from each of those hospitalized patients whom were suspected of having acute appendicitis and supposed to have surgery afterwards. Serum D-Lactae level measured using Spectrophotometric method. Serum level of above 0.25 mg in deciliter has been considered for patients whom their test-result was positive.

Findings: In acute appendicitis diagnosis, the sensitivity of D-Lactae measurement was (79%) and specificity (58%) for all patients, positive predictive value (87%) and negative predictive value (43%) as the result of the test have been calculated. The accuracy of the test was 74%.

Discussion & Conclusions: Serum lactate test could be an influential aid in diagnosis of acute appendicitis. This test is quite inexpensive and widely available. Besides, the method of measurement is simple. Test sensitivity, in all age groups, is high; positive predictive value of the test, in comparison with other laboratory tests, is high. Accuracy of the test is also high and is comparable to other laboratory tests.