Background/Objectives: Acute appendicitis (AA) is among the most common surgical emergencies. Differentiating between complicated (CAA) and uncomplicated (UAA) forms is essential for selecting the appropriate management—operative or non-operative—and for optimizing patient prioritization and outcomes. This study aimed to evaluate the diagnostic performance of emerging inflammatory indices in distinguishing these forms of AA. Methods: A total of 514 adult patients with surgically confirmed AA were retrospectively analyzed. Six immune-inflammatory indices—neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), monocyte-to-lymphocyte ratio (MLR), systemic immune-inflammation index (SII), systemic inflammation response index (SIRI), and pan-immune-inflammation value (PIV)—were calculated and compared with intraoperative and histopathological findings. Postoperative outcomes, including length of hospital stay (LOS) and hospitalization costs, were also evaluated. Results: All six indices were significantly higher in intraoperatively identified complicated cases (p < 0.0001). In histopathological analysis, five indices (NLR, MLR, SII, SIRI, and PIV) remained significantly elevated in patients with wall necrosis or perforation (p = 0.000–0.019), while PLR did not reach statistical significance. The indices showed fair diagnostic accuracy (AUC = 0.664–0.719, p < 0.0001). NLR and MLR were independent risk factors for CAA (p = 0.006 and p = 0.016), and MLR was also independently associated with complicated histopathological findings (p = 0.036). PIV independently predicted both increased LOS and higher hospitalization costs (p = 0.001 for each). Conclusions: These easily calculable inflammatory markers can serve as useful adjuncts for preoperative stratification of AA, supporting timely decision-making and contributing to more cost-effective emergency surgical care.

Background: Major morbidity and mortality remain important concerns after colorectal cancer (CRC) surgery. Cancer-related sarcopenia and heightened systemic inflammation may increase the risk of early postoperative major complications. Methods: In this retrospective single-center study, we analyzed 190 patients undergoing major CRC surgery. Skeletal muscle gauge (SMG) and the pan-immune-inflammation value (PIV) were assessed as preoperative risk markers, and 30-day major complications were evaluated. Results: Low SMG was strongly associated with major complications (OR 6.50, 95% CI 3.24–13.05; p < 0.001), and high PIV was also associated with increased risk (OR 3.51, 95% CI 1.77–6.99; p < 0.001). In multivariable analysis adjusting for age, surgical urgency, and procedure type, low SMG and emergency surgery remained independent predictors of 30-day major complications. The highest-risk phenotype (high PIV/low SMG; n = 23) had a major complication rate of 78.3% (18/23) (p < 0.001). A clinical model including age, urgency, and procedure type yielded an AUC of 0.739 (95% CI 0.661–0.816). Adding low SMG improved discrimination (AUC 0.784, 95% CI 0.711–0.857), with only a small additional increase after adding high PIV (AUC 0.791, 95% CI 0.717–0.864). Conclusions: Preoperative low SMG was independently associated with 30-day major complications after CRC surgery, while PIV provided complementary risk-stratification value. The combined high-PIV/low-SMG phenotype identified patients with particularly high postoperative risk.