Chapter 35: Disorders of the Bladder and Lower Urinary Tract

The bladder architecture features the trigone, a smooth triangular region bounded by ureteral and urethral orifices that maintains unidirectional urine flow through pressure-dependent valve mechanisms. Normal micturition requires coordinated activity across three hierarchical neural levels: the sacral spinal cord centers that generate reflex contractions, the pontine micturition center in the brainstem that coordinates detrusor contraction with external sphincter relaxation, and higher cortical structures that mediate conscious inhibition and voluntary control. Disruption of pontine coordination, commonly occurring after spinal cord injury, results in detrusor-sphincter dyssynergia, a condition where involuntary bladder contractions occur simultaneously with sphincter tightening rather than relaxation, trapping urine within the bladder. Childhood continence develops through maturation of these central control mechanisms and the learned ability to voluntarily contract the external sphincter. Chronic lower urinary tract obstruction initiates compensatory changes including detrusor hypertrophy, trigonal remodeling, and progressive dilation of the ureters known as hydroureters, which may ultimately compromise renal function. Obstruction presents clinically through straining during voiding, increased urinary frequency, hesitancy, and overflow incontinence from retained urine exceeding sphincter capacity. Stress urinary incontinence, characterized by involuntary urine leakage during activities that increase abdominal pressure such as coughing or heavy lifting, frequently results from pelvic floor muscle weakness related to childbirth trauma or age-related atrophy. This weakness can obliterate the posterior urethrovesical angle, eliminating the anatomical configuration necessary for continence maintenance. Clinical assessment integrates physical examination findings, urinalysis and laboratory markers, and advanced urodynamic testing to establish accurate diagnoses and guide therapeutic interventions.