Grey zone appendicitis (intermediate risk alvarado score 5-6): Role of blood test biomarkers to detect early appendicitis and to decrease the incidence of negative appendectomy. Cost and effectiveness. Randomized controlled trial

Introduction: many investigations emerged in the last decades and contribute towards a diagnosis of unsure appendicitis; they are valuable to the emergency general surgeons. This study aims to assess the role of laboratory markers (bilirubin and phospholipase A2) individually or combined with Computed Tomography (CT) for the diagnosis of grey zone appendicitis (Alvarado Score 5-6). Methods: This prospective Randomized controlled trial included all 310 patients admitted with right iliac fossa (RIF) pain who had Alvarado Score 5-6 (intermediate risk of appendicitis). All underwent full laboratory investigations including serum total bilirubin and phospholipase A2. All are underwent CT scan and classified into group A with normal CT but with persistent right iliac fossa pain and group B with proved acute appendicitis by CT. All cases underwent a laparoscopic or open appendectomy. Other causes of hyperbilirubine¬mia are excluded among the patients. Results: Among the 310 patients, a laparoscopic appendectomy was performed in 300 cases (97%), and an open ap¬pendectomy was performed in 10 cases (3%). Bilirubin had equal specificity and sensitivity with phospholipase A2(26.47% &40.94% respectively),but when combined together, the sensitivity and specificity rise(38.40 %&32.35%).the accuracy of diagnosis of early appendicitis with serum bilirubin and phospholipase A2 assessment is 39.35%.both serum bilirubin and phospholipase A2 has a strong positive predictive value for early appendicitis. Conclusion: high bilirubin and phospholipase A2 are a statistically significant diagnostic markers for early acute appendicitis and should be combined with CT in diagnosis of unsure cases of acute appendicitis.