Chapter 44: Urinary Tract Disorders

Urinary incontinence, defined as involuntary urine loss, encompasses multiple mechanistic categories including stress incontinence resulting from increased abdominal pressure and pelvic floor weakness, urge incontinence triggered by detrusor muscle overactivity or neurological lesions, overflow incontinence from bladder outlet obstruction or atonic detrusor dysfunction, and functional incontinence arising from external factors unrelated to urinary system integrity. Micturition control involves integrated signaling between the central nervous system, bladder smooth muscle, and urethral sphincter mechanisms, with disruption at any level producing distinct clinical presentations. Treatment varies by underlying etiology and ranges from conservative pelvic floor reeducation and behavioral modification to pharmacological interventions targeting specific pathophysiological mechanisms and surgical correction when anatomical obstruction exists. Lower urinary tract infections, predominantly caused by uropathogenic Escherichia coli, present with dysuria, frequency, and urgency, with diagnosis confirmed by urinalysis demonstrating nitrites and leukocyte esterase alongside bacterial culture exceeding diagnostic thresholds. Uncomplicated lower UTIs respond to short-course nitrofurantoin or single-dose fosfomycin, while interstitial cystitis represents a chronic non-infectious bladder inflammation requiring exclusion of infectious causes before diagnosis. Pyelonephritis, indicating upper urinary tract infection with ascending bacterial colonization, presents with the classic triad of fever, costovertebral angle tenderness, and constitutional symptoms, with white blood cell casts on urinalysis confirming renal parenchymal involvement and necessitating aggressive antibiotic therapy to prevent permanent renal scarring. Nephrolithiasis encompasses calcium-based stones comprising the majority of cases alongside struvite, uric acid, and cystine compositions, each with distinct metabolic antecedents and risk factor profiles. Acute stone passage produces characteristic renal colic with flank pain radiating toward the groin, with non-contrast helical computed tomography providing definitive diagnosis and assessment of obstruction severity. Management involves pain control, hydration to promote spontaneous passage, and intervention via extracorporeal shock-wave lithotripsy or endoscopic laser lithotripsy for stones unlikely to pass naturally, supplemented by long-term dietary and pharmacological prevention strategies targeting specific stone composition mechanisms.