Positive Predictive Value of Serum Amylase in Predicting Acute Appendicitis taking Histopathology as Gold Standard

Background: Worldwide acute appendicitis is one of the most commonly encountered abdominal emergencies. Despite recent advances in imaging and laboratory parameters, the diagnosis still remains clinical. This study was carried out to determine positive predictive value of serum amylase in diagnosing acute appendicitis taking into account histopathology as gold standard. Methods: Total 103 patients of both genders aged between 15-40 years presenting with pain and tenderness in right iliac fossa and vomiting having raised serum amylase > 85U/L were included. These patients underwent appendectomy followed by histopathology of excised tissue. Diagnosis of appendicitis was confirmed on histopathology postoperatively and results of increased serum amylase levels were interpreted accordingly as true positive/ false positive. Informed consent was taken from all enrolled patients. Results: Mean age of the enrolled patients was 27.8 +/- 7.5 years. There were 59 (57.3%) male and 44 (42.7%) female patients, with a male to female ratio of 1.3:1. The BMI of enrolled patients ranged from 22.0 Kg/m2 to 34.4 Kg/m2 with a mean of 26.9 +/- 3.4 Kg/m2. Diagnosis of appendicitis was confirmed in 93 (90.3%) patients on histopathology. Thus there were 93 true positive and 10 false positive cases. It yielded a positive predictive value of 90.3% for serum amylase in predicting acute appendicitis taking histopathology as gold standard. Similar positive predictive value was noted across various subgroups based on age, gender and BMI. Conclusion: In the present study, the positive predictive value of raised serum amylase was found to be 90.3% in predicting acute appendicitis which along with simplicity and routine availability of the test and low cost advocate the preferred use of this novel biomarker in the diagnostic workup of such patients in future surgical practice.