Phenotyping Increased Urge to Defecate in Irritable Bowel Syndrome: Analysis of Symptom, Sensory, and Psychological Profiles.

INTRODUCTION: Visceral hypersensitivity (VHS) is considered a hallmark of irritable bowel syndrome (IBS) characterized by altered thresholds for rectal pain and discomfort during rectal distention. Rectal distention can also elicit the urge to defecate, a normal physical sensation that is, reported more often in IBS and may involve mechanisms distinct from pain and discomfort. This study investigates clinical, psychological, and physiological correlates of increased urge to defecate in IBS compared with healthy controls (HC), including sex-based differences. METHODS: Patients with IBS (Rome III criteria) and HC underwent rectal balloon-distension and completed questionnaires on demographics, lifestyle, gastrointestinal (GI) and psychological symptoms, and health-related quality of life (HrQoL). Latent clusters were identified using finite-mixture modeling, and associated determinants were evaluated using multivariable logistic regression analyses. RESULTS: Among 322 participants (220 IBS, 102 HC), the occurrence of the urge to defecate was more frequent in IBS than in HC (80.9% vs. 51.9%; p < 0.001) and often co-occurred with rectal pain and discomfort, particularly in patients with VHS. Latent class analysis identified three clusters, primarily distinguished by rectal symptom-distribution, with the most symptomatic cluster showing greater GI-symptom severity, higher psychological burden, and lower HrQoL (all p < 0.001). Regression analyses confirmed associations of urge with GI symptom severity, depressive symptom scores, and co-occurrence of pain/discomfort, but no association was found based on IBS subtype or sex. CONCLUSION: Increased urge to defecate is highly prevalent in IBS, strongly associated with rectal pain, rectal discomfort, psychological burden, and reduced HrQoL, but not in the IBS subtype, suggesting shared or overlapping mechanisms, particularly in the context of VHS. These findings underscore its clinical and pathophysiological relevance, supporting its value for patient-phenotyping and tailored management. TRIAL REGISTRATION: The Maastricht Irritable Bowel Syndrome (MIBS) cohort study was registered under the registration number NCT00775060.