What is trabeculation of the bladder?

Bladder Trabeculation: Definition and Clinical Significance

Bladder trabeculation refers to irregular thickening and ridging of the bladder wall that appears as a coarse, mesh-like pattern on imaging studies, resulting from hypertrophy of the detrusor muscle bundles in response to chronic bladder outlet obstruction or detrusor overactivity. 1

Anatomic and Pathophysiologic Features

Trabeculation represents a secondary adaptive change in the bladder wall structure that develops when the detrusor muscle must generate higher pressures to overcome resistance during voiding. 2, 3 The condition manifests as:

• Irregular muscle bundles that create a ridged appearance on the internal bladder surface 1
• Increased bladder wall thickness visible on imaging modalities 1
• Variable depth and extent of trabecular ridges, ranging from superficial to deep (>10 mm) 2

The trabeculations are most numerous toward the bladder apex and can be distinguished from normal anatomic structures during imaging interpretation. 1

Grading Systems

Two validated grading systems exist for quantifying trabeculation severity:

Standard 4-Grade System 2:

• Grade 0 (None): No visible trabeculation
• Grade 1 (Mild): Depth <5 mm affecting <50% of bladder surface
• Grade 2 (Moderate): Depth 5-10 mm affecting ≥50% of bladder surface
• Grade 3 (Severe): Depth >10 mm affecting ≥50% of bladder surface

This grading system demonstrated almost perfect interobserver reliability (intraclass correlation coefficient 0.985) and test-retest reliability (Cohen's kappa 0.870-0.955). 2

Clinical Associations and Diagnostic Implications

Trabeculation serves as an important marker for underlying pathology:

In Neurogenic Bladder: Trabeculation occurs in 57% of spinal cord injury patients overall and 31% within the first year post-injury, strongly associated with upper motor neuron lesions, vesicoureteral reflux, and bladder diverticula. 4 Severe trabeculation in neurogenic bladder patients indicates significant intrinsic outlet resistance and may obviate the need for additional bladder outlet procedures during augmentation cystoplasty. 3

In Pelvic Organ Prolapse: Trabeculation affects 54.9% of women with severe (stage 3-4) prolapse and correlates with detrusor overactivity (the only independent predictor on multivariate analysis), urge incontinence, voiding difficulty, and postvoid residual >100 mL. 5

In Benign Prostatic Hyperplasia: Bladder wall trabeculation represents a morphologic consequence of chronic outlet obstruction that can be assessed via imaging to guide treatment decisions. 1

Imaging Detection

Trabeculation is most reliably identified on:

• Fluoroscopic voiding cystourethrography (VCUG): Direct visualization during contrast filling and voiding phases 1
• Ultrasound: Assessment of bladder wall thickness and surface irregularity, particularly useful in neurogenic bladder surveillance 1
• CT urography: Can demonstrate trabeculation as irregular bladder wall contour, though may produce false-positives from benign prostatic hypertrophy or post-treatment changes 1

Clinical Pitfalls

Common misinterpretations include confusing trabeculation with:

• Blood clots in the bladder 1
• Benign prostatic hypertrophy mimicking bladder lesions 1
• Post-treatment changes from prior interventions 1

The presence of trabeculation should prompt evaluation for underlying causes including bladder outlet obstruction, detrusor instability, or neurogenic dysfunction, as it indicates a hostile bladder environment requiring more aggressive management. 6, 3