Anorectal Pathophysiology in Solitary Rectal Ulcer Syndrome: Insights From a Cross-Sectional Study.

Background and objectives Solitary rectal ulcer syndrome (SRUS) is a rare, benign rectal disorder characterized by symptoms such as rectal bleeding, constipation, mucus discharge, and incomplete evacuation, often leading to diagnostic delays due to overlap with other colorectal conditions. Functional anorectal abnormalities are thought to contribute significantly to its pathogenesis, yet systematic evaluation remains limited. This study aimed to assess anorectal manometry (ARM) and balloon expulsion test (BET) findings in adult SRUS patients and to analyze their association with specific clinical symptoms. Methods This cross-sectional observational study included 24 adult patients with histologically confirmed SRUS from February 2023 to March 2024. Demographic and clinical data were recorded. All patients underwent ARM and BET. Findings were classified using London classification and normative Indian ARM parameters. Multiple correspondence analysis (MCA) and hierarchical clustering on principal components (HCPC) were used to identify symptom-pathophysiology patterns among SRUS patients. Univariable Firth's logistic regression explored associations between demographic variables, clinical features and ARM findings, while multivariable analysis was avoided due to small sample size. Results A total of 24 adult patients were included in the study: 12 (50%) males and 12 (50%) females. The median age was 26 years (range: 18-70). The most common symptoms were rectal bleeding (20; 83%), constipation (17; 71%), and mucus in stool (15; 63%). On ARM, the most frequent abnormalities were rectal hypersensitivity (10; 41.7%) and disorder of rectoanal coordination (9; 37.5%). Balloon expulsion was abnormal in nine (37.5%) patients. Multiple correspondence analysis identified two dimensions explaining 50.1% variance, distinguishing dysfunction severity (Dimension 1) and sensory-pressure phenotypes (Dimension 2). Hierarchical clustering revealed five distinct patient phenotypes: poor propulsion and dyssynergia phenotype (n=6, 25%), dyssynergia-dominant phenotype (n=4, 16.7%), hypersensitivity phenotype (n=7, 29.2%), normal phenotype (n=6, 25%), and isolated hypotension phenotype (n=1, 4.2%). Firth's logistic regression identified significant associations: constipation inversely predicted normal findings (OR=0.01, 95% CI: 0.00-0.10, p<0.001) and predicted rectal hypersensitivity (OR=21.00, 95% CI: 2.02-2885.43, p=0.007); digital rectal evacuation predicted abnormal expulsion with poor propulsion and dyssynergia (OR=25.00, 95% CI: 2.34-3457.52, p=0.005); disease duration predicted abnormal expulsion with dyssynergia (OR=1.08, 95% CI: 1.02-1.37, p=0.005). Conclusion SRUS patients show marked pathophysiological heterogeneity with distinct motor and sensory phenotypes. Constipation and digital evacuation strongly predict anorectal dysfunction. Objective ARM assessment is essential to identify these phenotypes and enable targeted therapies to optimize outcomes.