Background <p>Appendicoliths are recognized risk factors for complicated appendicitis and adverse surgical outcomes. However, current preoperative assessments lack a standardized method to evaluate appendicoliths beyond simply documenting their presence. This study aimed to develop and validate a CT-based appendicolith scoring system incorporating both location and morphological characteristics to predict postoperative outcomes in patients with acute appendicitis.</p> Methods <p>We retrospectively analyzed 241 adult patients with acute appendicitis and radiologically confirmed to have appendicoliths who underwent appendectomy between August 2021 and December 2023. Two researchers, blinded to clinical outcomes, independently scored appendicoliths based on location (root = 3, mid-section = 2, tip = 1) and morphology (granular = 3, rod-shaped = 2, sediment-like = 1). Total scores (range 2–6) were calculated as the sum of the location score and the morphology score (Location + Morphology=Total), and inter-observer agreement was assessed. Patients were stratified into three groups: low-risk (2–3 points), intermediate-risk (4 points), and high-risk (5–6 points). Clinical characteristics, operative outcomes, and postoperative complications were compared across groups. Univariate regression and receiver operating characteristic (ROC) curve analyses were performed to evaluate the scoring system’s predictive performance.</p> Results <p>The cohort comprised 130 males and 111 females (median age 35 years). Inter-observer agreement for the total score was excellent (<i>κ</i> = 0.937). High-risk patients (<i>n</i> = 129) demonstrated significantly larger appendiceal diameters compared with low-risk (<i>n</i> = 41) and intermediate-risk (<i>n</i> = 71) groups (<i>P</i> &lt; 0.001), with a positive correlation between score and diameter (<i>γ</i> = 0.298, <i>P</i> = 0.003). High-risk patients also exhibited significantly longer hospital stays (median 7.0 vs. 6.0 days, <i>P</i> = 0.003), higher rates of prolonged flatus (&gt; 48&#xa0;h, 58.9% vs. 40.9–43.9%, <i>P</i> = 0.030), and increased postoperative complications (14.7% vs. 4.2–4.9%, <i>P</i> = 0.043). Univariate analysis showed that the appendicolith severity grade was significantly associated with postoperative complications (Crude <i>OR</i> = 2.164, 95% <i>CI</i>: 1.014–4.617, <i>P</i> = 0.046). ROC analysis demonstrated moderate predictive utility for postoperative complications (<i>AUC</i> = 0.641, 95% <i>CI</i>: 0.533–0.748) and prolonged hospitalization (<i>AUC</i> = 0.636, 95% <i>CI</i>: 0.558–0.714), with an optimal cutoff of ≥ 4.5 points.</p> Conclusion <p>This CT-based appendicolith scoring system provides a simple, reproducible, and clinically useful tool for preoperative risk stratification in acute appendicitis. Higher scores correlate with increased inflammatory severity, prolonged recovery, and an increased risk of postoperative complications, potentially guiding perioperative management decisions.</p> Graphical abstract <p></p>