Exploring Symptom Domains of Postoperative Bowel Dysfunction by Integrating LARS and Wexner Scores: A Longitudinal Factor‐Analytic Study

ABSTRACT Background Postoperative bowel dysfunction after sphincter‐preserving surgery for rectal cancer is heterogeneous and may not be fully captured by composite scores such as the low anterior resection syndrome (LARS) and Wexner scores. This study aimed to identify clinically relevant symptom domains and examine their associated clinical factors. Methods We analyzed 320 patients who underwent low anterior resection with longitudinal bowel function assessment. Correlations among individual LARS and Wexner components were evaluated using Spearman's correlation and hierarchical clustering. Exploratory factor analysis using pooled postoperative observations was performed to identify latent symptom domains, and multivariable mixed‐effects models were used to examine associated clinical factors. Results Correlation analysis demonstrated heterogeneous inter‐item relationships, and factor analysis identified three domains: incontinence, urgency/clustering, and gas control. In multivariable analysis, greater incontinence severity was associated with age 50–70 years, BMI ≥ 23, neoadjuvant chemotherapy, radiotherapy, very low anterior resection, and a transanal approach. Greater urgency/clustering severity was associated with radiotherapy, whereas age ≥ 70 years was associated with lower severity. Gas‐related symptoms may also represent a partially distinct domain. Postoperative time was a significant determinant of all three domains, with symptom severity remaining higher at 6, 12, and 24 months than preoperatively. Conclusions Postoperative bowel dysfunction, as captured by the LARS and Wexner scores, appears to consist of multiple symptom domains with different clinical determinants. Patients with similar composite scores may have different symptom profiles requiring different management strategies. A domain‐based approach may support individualized functional assessment and treatment after rectal surgery.