Hypothesis / aims of study
We hypothesized that anorectal dysfunction in colorectal cancer represents a multisystem disorder involving bowel motility, pelvic floor biomechanics, and lower urinary tract interaction.
The aim was to evaluate whether multimodal ultrasound (US), including standardized assessment of bladder neck mobility (BNM), enables integrated functional phenotyping and correlates with symptom dynamics and treatment response.
Study design, materials and methods
Prospective observational case series (n=6) with colorectal tumors (rectal, rectosigmoid, sigmoid, hepatic flexure).
Multimodal US protocol included:
- Intestinal assessment: wall thickness, tumor morphology, luminal patency, intraluminal fluid dynamics, peristalsis
- Identification of functional obstruction (constipation–ileus spectrum), bowel dilation, and gastrostasis;
- Pelvic US with dynamic BNM measurement during straining, performed according to a standardized method previously described in ICS studies [1-3]
- Evaluation of tumor compression, pelvic organ invasion (bladder, prostate, cervix, ureters), and complications
Serial US was used for monitoring during chemotherapy and supportive interventions, including dietary and microbiome-oriented strategies.
Results
All patients demonstrated a combined anorectal and pelvic floor dysfunction phenotype:
BNM was markedly increased (70–100 mm) in all cases and strongly correlated with symptom severity (incontinence, urgency, instability).
Periods of clinical improvement corresponded to reduced BNM (40–60 mm).
A functional obstruction spectrum was observed, including constipation and ileus-like states with loop dilation (up to 30 mm), impaired peristalsis, and gastrostasis.
In selected cases, preserved luminal patency with bidirectional fluid movement within tumor segments indicated partial functional continuity.
Tumor compression and invasion of adjacent pelvic organs contributed to combined anorectal and urinary dysfunction.
Chemotherapy-related effects included motility alterations (diarrhea vs hypomotility) and features of neuromuscular/autonomic impairment.
Dietary modulation and microbiome-oriented approaches (including probiotics) were associated with stabilization of bowel transit and reduction of ileus-like episodes in selected cases.
Interpretation of results
These findings support a multilevel model of anorectal dysfunction integrating:
1. Mechanical factors (tumor mass, compression, invasion)
2. Motility disturbances (constipation–ileus–diarrhea spectrum, gastrostasis)
3. Neuromuscular impairment (pelvic floor weakness, increased BNM)
4. Systemic/autonomic influences (chemotherapy, neuropathy, inflammation, microbiome alterations)
Bladder neck mobility, measured using a standardized ultrasound approach, represents a reproducible dynamic biomarker of pelvic floor instability and treatment response.
Multimodal US enables real-time assessment of these interacting mechanisms, bridging bowel and lower urinary tract dysfunction.
Concluding message
Anorectal dysfunction in colorectal cancer should be considered a multisystem functional syndrome rather than isolated sphincter pathology.
Multimodal ultrasound, integrating bowel function and pelvic floor dynamics, provides a novel tool for real-time functional phenotyping.
Incorporation of dynamic biomarkers such as standardized BNM assessment and bowel motility parameters may improve personalized management, monitoring, and interdisciplinary care, including dietary and microbiome-targeted interventions.