Causes of Solitary Rectal Ulcer Syndrome (SRUS)
Primary Etiology
The etiology of SRUS remains obscure, but the condition is most frequently associated with pelvic floor disorders and defecation dysfunction, particularly rectal prolapse and excessive straining during defecation. 1
Pathophysiological Mechanisms
The underlying causes of SRUS involve mechanical trauma and ischemic injury to the rectal mucosa through several mechanisms:
Mechanical Trauma
- Excessive straining during defecation is a primary causative factor, leading to direct mucosal injury from prolonged increased intra-abdominal pressure 1, 2
- Rectal prolapse (internal or external) causes repetitive trauma to the rectal mucosa through mucosal shearing and compression 1
- Digital evacuation or self-digitation to facilitate bowel movements contributes to direct mechanical injury 1
Ischemic Injury
- Pelvic floor dyssynergia leads to paradoxical contraction of the puborectalis muscle during defecation, causing chronic obstruction and localized ischemia 1, 3
- Increased intrarectal pressure from straining compromises mucosal blood flow, resulting in ischemic ulceration 1
Associated Pelvic Floor Disorders
- Defecation disorders including dyssynergic defecation and anismus are strongly associated with SRUS development 3
- Constipation requiring prolonged straining creates the mechanical conditions for mucosal injury 1, 2
- Incomplete rectal evacuation leads to repetitive straining attempts 2
Clinical Context
SRUS affects men and women equally with slight female predominance, and occurs across all age groups including children and the elderly 1. The syndrome presents with rectal bleeding, copious mucus discharge, prolonged excessive straining, perineal and abdominal pain, feeling of incomplete defecation, and constipation 1, 2.
Important Clinical Pitfall
Despite its name, only 40% of patients have actual ulcers, and only 20% have a solitary lesion—the remaining cases show varied morphology from hyperemic mucosa to broad-based polypoid lesions 1. This morphological heterogeneity can lead to diagnostic confusion with other rectal pathologies including malignancy, making histopathological confirmation essential 1, 2.