Objective: The objective of this study was to identify potential robust acoustic biomarkers for functional post-thyroidectomy voice disorder (PTVD) that may support early diagnosis and personalized treatment strategies, using acoustic analysis and explainable machine learning methods. Methods: Spectral and cepstral features were extracted from /a/ and /i/ voice recordings collected preoperatively and 4–6 weeks postoperatively from a total of 126 patients. Various Support Vector Machine (SVM) and Boosting models were trained. SHapley Additive exPlanations (SHAP) analysis was applied to enhance interpretability. SHAP values from training and test sets were compared via scatter plots to identify stable candidate biomarkers with high consistency. Results: GentleBoost (AUC = 0.85) and LogitBoost (AUC = 0.81) demonstrated the highest classification performance. Performance metrics across all models were evaluated for statistical significance. DeLong’s test was conducted to assess differences between ROC curves. The features iCPP, aCPP, and aHNR were identified as stable candidate biomarkers, exhibiting consistent SHAP distributions in both training and test sets in terms of direction and magnitude. These features showed statistically significant correlations with PTVD (p < 0.05) and demonstrated strong effect sizes (Cohen’s d = −2.95, −1.13, −0.60). Their diagnostic relevance was further supported by post hoc power analyses (iCPP: 1.00; aCPP: 0.998). Conclusions: SHAP-supported machine learning models offer an objective and clinically meaningful approach for evaluating PTVD. The identified features may serve as potential biomarkers to guide individualized voice therapy decisions during the early postoperative period.

Background Gallstone ileus due to a cholecystoduodenal fistula is a rare complication of chronic cholelithiasis, often leading to small bowel obstruction. While ileal obstruction is common, duodenal impaction and its consequences, including afferent loop syndrome, remain underreported. A clinically important but underrecognized complication in such anatomically complex cases is delayed duodenal perforation following relief of obstruction. Method We present a 77-year-old female who developed afferent loop syndrome secondary to a gallstone migrating through a cholecystoduodenal fistula 40 years after distal gastrectomy with Billroth II reconstruction. The gallstone lodged in the third portion of the duodenum, causing afferent loop obstruction, bile stasis, and acute pancreatitis. Result Emergency laparotomy and gallstone removal were performed to restore afferent loop flow. On postoperative day 2, the patient developed a duodenal perforation at the previous site of impaction, requiring reoperation and surgical repair. The postoperative course thereafter was uneventful, and the patient was discharged in good clinical condition. Conclusion This case underscores the need for close postoperative monitoring in gallstone-induced duodenal obstructions due to the risk of delayed perforation and highlights the importance of recognizing cholecystoduodenal fistula as an underlying cause of afferent loop syndrome. Novel aspect This case emphasizes a rare place of intestinal obstruction due to gallstone and the possibility of delayed perforation after a gallstone-induced afferent loop syndrome, recommending intense postoperative care for these patients.