Prevalence and Preoperative Characteristics Associated with Complicated Appendicitis Among Children Undergoing Appendectomy in Southwestern Saudi Arabia: A Hospital-Based Cross-Sectional Study.

Background/Objectives: Complicated appendicitis carries greater morbidity than uncomplicated disease, yet its prevalence and determinants in southwestern Saudi Arabia are largely undocumented. This study estimated the prevalence of complicated appendicitis among children undergoing appendectomy and identified the preoperative characteristics independently associated with it. Methods: A hospital-based cross-sectional study included 275 children aged 14 years or younger who underwent appendectomy at King Fahd Central Hospital, Jazan, between January 2020 and December 2024. Complicated appendicitis was defined by appendiceal perforation, purulent intra-abdominal collection, or generalized peritonitis documented in the structured intraoperative record. Prevalence is reported with Wilson 95% confidence intervals. Adjusted prevalence ratios (aPR) with 95% confidence intervals were estimated by modified Poisson regression with robust variance, using preoperative variables selected for clinical plausibility. Two sensitivity analyses used broader outcome definitions. Results: Complicated appendicitis was present in 57 of 275 children, a prevalence of 20.7% (16.4-25.9). Prevalence did not differ by age group, sex, referral status, or symptom duration, but was higher among urban than rural residents (26.3% vs. 15.2%, p = 0.035). Two preoperative characteristics were independently associated with complicated disease: generalized abdominal tenderness (aPR 3.01, 1.75-5.20) and reported fever (aPR 1.87, 1.11-3.17). Symptom duration, clinical dehydration, leukocyte count, and admission haemoglobin were not independently associated with severity. Among children with imaging, appendiceal diameter contributed independently in an exploratory model (aPR 1.06 per mm, 1.02-1.11). Under broader outcome definitions, symptom duration and dehydration became significant while generalized abdominal tenderness remained associated throughout, indicating that several associations depend on how severity is defined. Conclusions: One in five children came to the operation with complicated appendicitis. Tenderness extending beyond the right iliac fossa, together with reported fever, was the most consistent bedside signal of advanced disease, whereas associations with delayed presentation, dehydration, and haemoglobin were sensitive to the outcome definition and require prospective confirmation.