Urinary Tract Obstructions and Incontinence

• Upper and lower urinary tract obstructions can be compared and contrasted based on various features.

Location of Obstruction

• Upper urinary tract obstructions occur in the ureters and kidneys, specifically the renal pelvis, calyces, and collecting ducts.
• Lower urinary tract obstructions occur in the bladder and urethra.

Common Causes

• Upper obstructions are commonly caused by nephrolithiasis (kidney stones), tumors, strictures, and congenital anomalies.
• Lower obstructions are commonly caused by prostate enlargement (BPH), urethral stricture, pelvic organ prolapse, or neurogenic bladder.

Pathophysiology

• Upper obstructions lead to urine backup, increasing hydrostatic pressure in Bowman's capsule, decreasing GFR, and raising the risk of infection, hydronephrosis, ischemia, and fibrosis.
• Lower obstructions involve interference with bladder storage or emptying, often resulting from neurological injury or anatomical obstructions.

Key Mechanisms

• Upper obstructions result from supersaturation and crystallization of salts, which form stones and increase pressure, reducing renal filtration and leading to dilation and damage.
• Lower obstructions disrupt bladder contraction and sphincter coordination (often neurogenic), increasing bladder pressure due to outlet resistance and impairing emptying.

Clinical Manifestations

• Upper obstructions typically manifest as renal colic (intermittent flank pain), hematuria, nausea/vomiting, urgency, and frequency.
• Lower obstructions manifest as hesitancy, poor stream, intermittency (feeling of incomplete emptying), daytime voiding, nocturia, and urgency.

Compensation and Outcomes

• Unilateral upper obstruction may be compensated for by the other kidney.
• Prolonged obstruction in the upper tract can lead to renal atrophy and failure.
• Compensation in the lower tract depends on outlet behavior.

Visual Table: Urinary Tract Obstructions (Upper vs. Lower)

• Upper tract obstructions are in the kidney and ureter, while lower tract obstructions occur in the bladder and urethra.
• Common causes: kidney stones, tumors, and strictures for upper tract; prostate enlargement, pelvic organ prolapse, and neurogenic bladder for lower tract.
• Pathophysiology: back pressure leading to hydronephrosis and decreased GFR in upper tract; nerve damage or outlet obstruction disrupting flow in lower tract.
• Mechanism details: salt supersaturation leading to stone formation in upper tract; bladder detrusor/sphincter miscoordination or blockage in lower tract.
• Clinical signs: renal colic, urgency, and hematuria in upper tract; hesitancy, dribbling, nocturia, and weak/intermittent stream in lower tract.
• Complications: infection, renal scarring, and decreased function in upper tract; incomplete voiding, infections, and bladder damage in lower tract.
• Compensation: the other kidney may compensate if unilateral in upper tract; no compensation as function depends on outlet behavior in lower tract.

Visual Table: Types of Urinary Incontinence

• Stress incontinence cause: weak pelvic floor, post-surgery; key features: increased intra-abdominal pressure and decreased sphincter control; how it appears: leaks when laughing, coughing, or sneezing.
• Urge incontinence cause: overactive bladder, neuro issues; key features: sudden urge and loss of control from brain; how it appears: "Gotta go NOW" scenario.
• Overflow incontinence cause: BPH, bladder not emptying properly; key features: blocked outlet, full bladder leaks when overfilled; how it appears: constant dribbling, weak stream.
• Functional incontinence cause: mobility/cognition limitations; key features: normal bladder, but delayed access or awareness; how it appears: inability to reach bathroom in time.

Types and Clinical Manifestations of Urinary Incontinence

• Stress incontinence: caused by pelvic floor weakness or sphincter dysfunction, resulting in leakage with coughing, laughing, or sneezing.
• Urge incontinence: is caused by overactive detrusor muscle or neurologic loss of inhibition, causing strong urges to void with frequent urination and small volumes.
• Overflow incontinence: is caused by bladder outlet obstruction or underactive bladder, resulting in dribbling, weak stream, nocturia, and incomplete emptying.
• Functional incontinence: is caused by immobility or cognitive impairment, leading to involuntary leakage due to an inability to reach the toilet in time.

Mixed Incontinence

• A combination of stress and urge symptoms.

Neurogenic Bladder

• Spinal cord injuries lead to either overflow or urge symptoms, depending on the site of injury.