Chap 35 (patho)

Disorders of the Bladder and Lower Urinary Tract

Structure of the Bladder

The bladder is a hollow organ responsible for storing urine before excretion. Its anatomical structure and layers are essential for its function.

• Fundus and Neck: The fundus is the main body of the bladder, while the neck connects to the posterior urethra.

• Ureters: Tubes that transport urine from the kidneys to the bladder, entering bilaterally near the base and close to the urethra.

• Trigone: A triangular area defined by the entry points of the ureters and the urethra.

Layers of the Bladder

• Outer Serosal Layer: Covers the upper surface and is continuous with the peritoneum.

• Detrusor Muscle: A network of smooth muscle fibers responsible for bladder contraction.

• Mucosal Layer: Composed of loose connective tissue.

• Inner Mucosal Lining: Made of transitional epithelium, allowing for expansion and contraction.

Neurologic Control of Bladder Function

Bladder function is regulated by complex neural pathways involving reflex centers and conscious control.

• Spinal Cord Reflex Centers: Located in the sacral (S1-S4) and thoracolumbar (T11-L2) regions.

• Nerves:

  • Pelvic nerve: Controls the detrusor muscle.

  • Pudendal nerve: Controls the external sphincter.

  • Hypogastric nerve: Influences both bladder and sphincter.

• Micturition Center (Pons): Coordinates reflex control of urination.

• Brain (Cortical & Subcortical Centers): Provides conscious control over urination (voluntary decision to void).

Storage and Emptying of Urine

Urine storage and release are governed by both autonomic and somatic nervous systems.

• Involuntary Control (Autonomic Nervous System):

  • Parasympathetic: Promotes bladder emptying.

  • Sympathetic: Promotes bladder filling.

• Voluntary Control (Somatic Nervous System):

  • External sphincter and pelvic floor muscles regulate urine release.

• Urine is stored at low pressure until voluntary voiding occurs.

Autonomic Nervous System (ANS) Drugs and Diagnostic Studies

Pharmacological agents and diagnostic tests are used to assess and manage bladder function.

• Nicotinic Receptors: Enhance sympathetic neuron activity, increasing bladder storage.

• Muscarinic Receptors: Block sympathetic neurons, allowing bladder emptying.

Diagnostic Tests and Studies

• Laboratory & Radiographic Studies: Urine tests and x-rays.

• Urodynamic Studies:

  • Uroflowmetry: Measures speed of urine flow.

  • Cystometry: Assesses bladder pressure and capacity.

  • Urethral Pressure Profile: Evaluates urethral strength.

  • Sphincter Electromyography: Measures muscle activity of the sphincter.

  • Ultrasound Bladder Scan: Determines residual urine volume in the bladder.

Alterations in Bladder Function

Bladder dysfunction can result from obstruction, incontinence, or structural and neurological changes.

• Urinary Obstruction: Retention or stasis of urine due to blockage.

• Urinary Incontinence: Involuntary loss of urine.

Causes

• Structural changes in the bladder, urethra, or surrounding organs.

• Impairment of neurologic control of bladder function.

Signs of Outflow Obstruction and Urine Retention

• Bladder distention

• Hesitancy

• Straining to initiate urination

• Small and weak urine stream

• Increased frequency

• Sensation of incomplete bladder emptying

• Overflow incontinence

Neurogenic Bladder Disorders

Neurogenic bladder disorders arise from nerve damage affecting bladder control.

Common Causes

• Stroke and advanced age

• Parkinson disease

• Spinal cord injury

• Injury to the sacral cord or spinal roots

• Medical pelvic surgery

• Diabetic neuropathies

• Multiple sclerosis

Types of Neurogenic Bladder Disorders

• Spastic Bladder:

  • Inability to store urine (urine leaks out).

  • Caused by nerve damage above the sacral cord.

  • Bladder contracts automatically without brain control.

• Flaccid Bladder:

  • Inability to empty urine properly.

  • Caused by nerve damage in the sacral cord or peripheral nerves.

  • Weak or absent bladder contractions, leading to urine retention.

Principles of Treatment for Neurogenic Bladder Disorders

• Prevent bladder overfilling

• Prevent urinary tract infections (UTIs)

• Protect kidneys from damage

• Reduce social and emotional stress

Treatment Options

• Catheter use (to empty bladder)

• Bladder retraining (timed voiding)

• Medications (to relax or contract bladder)

• Surgery (if other methods are ineffective)

Types of Incontinence

Urinary incontinence is classified based on symptoms and underlying mechanisms.

• Stress Incontinence: Leakage due to pressure on the bladder (e.g., coughing, sneezing).

• Urge Incontinence: Sudden, strong urge to urinate followed by involuntary leakage.

• Overflow Incontinence: Bladder overfills and urine leaks out due to inability to empty.

• Mixed Incontinence: Combination of stress and urge symptoms.

Treatment Options for Incontinence

• Depends on type, age, and health condition

• Behavioral and medication treatments

• Pelvic floor (Kegel) exercises (first-line treatment)

• Surgery (if needed)

• Devices to block or collect urine

• Catheters (indwelling or self-catheterization)

Elderly Incontinence

Incontinence in the elderly is multifactorial and often related to age-associated changes.

• Overall bladder capacity is reduced

• Urethral closing pressure is reduced

• Weak pelvic muscles and declining detrusor muscle function

• Increased post-void residual (PVR) volumes

• Restricted mobility

• Increased medication use

• Comorbid illnesses

• Infection

• Fecal impaction

Bladder Cancer

Bladder cancer presents with various urinary symptoms and is diagnosed through multiple modalities.

• Frequent urination

• Increased urgency

• Painful urination (dysuria)

• Hematuria (blood in urine)

Diagnostic Measures and Treatment Methods

• Cytologic studies

• Excretory urography

• Cystoscopy and biopsy

• Ultrasonography and CT scans

• Treatment depends on cytologic grade and degree of invasiveness

• Methods include surgical removal, radiation therapy, and chemotherapy

Additional info: The notes also briefly mention cirrhosis, which is a liver disorder and not directly related to the bladder or urinary tract. For completeness:

Cirrhosis (Additional info)

• Long-term liver damage leads to scar tissue replacing healthy liver cells.

• Common causes: Alcohol, hepatitis, fatty liver disease, toxins, drugs.

• Effects: Poor blood flow, portal hypertension, impaired protein synthesis, increased bleeding risk.

• Symptoms: Weakness, jaundice, bruising/bleeding, ascites, hepatic encephalopathy.

• Lab findings: Elevated ALT/AST, increased clotting time, low albumin, low platelets, high ammonia.

• High ammonia can cause confusion and progress to hepatic encephalopathy.