Background: Surgical site infection (SSI) remains one of the most common postoperative complications following appendectomy. Body mass index (BMI) has traditionally been used to estimate surgical risk; however, it does not reflect local adiposity at the incision site. Subcutaneous tissue thickness (SCT), measured preoperatively by ultrasonography, may represent a more accurate predictor of SSI.

Methods: This prospective observational study included 192 patients aged 12 years and above undergoing emergency open appendectomy for uncomplicated acute appendicitis at a tertiary care centre. Preoperative ultrasonographic measurement of SCT was performed at the point of maximal tenderness. Patients were followed on postoperative days 1, 3, 7, and 30. SSI was assessed using the Southampton Wound Assessment Scale. Receiver operating characteristic (ROC) curve analysis was used to determine the predictive value of SCT for SSI.

Results: The mean SCT was 14.68 ± 5.89 mm. SSI occurred in 113 patients (58.9%, Southampton Grade 1 – 4). Patients who developed SSI had significantly greater SCT than those without SSI (17.22 ± 6.12 mm vs. 11.05 ± 2.92 mm, p<0.001). ROC analysis demonstrated good discriminatory ability (AUC=0.833, 95% CI 0.775–0.890, p<0.001). An SCT cutoff value greater than 15 mm yielded a sensitivity of 62.8%, specificity of 93.7%, positive predictive value of 93.4%, and diagnostic accuracy of 75.5%.