urine elimination

Concept of Elimination

• Elimination: removal of physiologic waste products from the body via excretion and secretion; two main pathways discussed here are urinary elimination (kidneys and intestines) and bowel elimination (fecal).
• Urinary elimination (kidneys and associated structures) handles:
  • Solute waste from blood
  • Excess liquid not needed for homeostasis
• Bowel elimination involves the processing and expulsion of unused portions of ingested solid material.

Urinary Elimination: Overview

• Primary roles:
  • Controls blood concentration and composition
  • Rids body of excess fluid and electrolytes
• Normal urinary elimination supports:
  • Maintenance of ion concentration necessary for neuronal and muscle function
  • Bone strength
  • Cellular regeneration
  • Blood pressure homeostasis to ensure adequate circulation of oxygen and nutrients
• Physiology depends on proper function of both upper and lower urinary tracts.

Anatomy of the Urinary Tract

• Upper urinary tract: kidneys and ureters
• Lower urinary tract: urinary bladder, urethra, pelvic floor

Physiology of Urination (Micturition)

• Definition: the process of emptying the bladder
• Steps:
  • Urine collects in the bladder
  • Pressure stretches receptors in the bladder wall
  • Stretch receptors transmit impulses to the voiding reflex center in the spinal cord
  • If the environment is appropriate (time/place): the conscious brain relaxes the external urethral sphincter, and urination occurs
• If environment is not appropriate:
  • The conscious mind delays urination
  • The micturition reflex subsides until the bladder fills again
  • Voluntary control requires intact nerves supplying the bladder, urethra, spinal cord and brain, and motor areas of the cerebrum

Patterns of Voiding

• voiding patterns vary by individual
• General expectations:
  • Everyone should void at least every $6$ hours
  • Most people void $6 ext{–}7$ times per day
  • A common reference range is $4 ext{ to }10$ times per day

Factors Affecting Urinary Elimination

• Fluid and food intake
• Muscle tone
• Psychosocial factors
• Pathologic conditions
• Surgical and diagnostic procedures
• Medications

Alterations in Urination

• Alterations are common and can be age- or disease-related
• Understanding alterations helps in providing appropriate nursing interventions and high-quality, patient-centered care

Alterations in Urination: Common Terminology

• Polyuria (diuresis): production of abnormally large amounts of urine
  • Can cause excessive fluid loss, intense thirst, dehydration, weight loss
• Polydipsia: extreme thirst (often associated with polyuria)
• Anuria: absence of urine or < $100 ext{ mL/day}$
• Oliguria: reduced urine production
  • Defined as < $400 ext{ mL/day}$ or < $30 ext{ mL/hour}$
  • May signal impending renal failure
• Urinary frequency
• Nocturia: voiding at night
• Urgency: sudden, strong desire to void
• Dysuria: painful or difficult voiding
• Urinary hesitancy
• Neurogenic bladder: does not perceive bladder fullness and/or cannot control urinary sphincters

Prevalence and Related Factors

• About half of all women will experience a urinary tract infection (UTI) at least once in life
• Women experience urinary incontinence more than men
• About 44 ext{ ext%} of adults aged $65+ ext{ years}$ experience urinary leakage
• Urinary retention is reported more by men and is related to treatment for enlarged prostate
• Lower urinary tract symptoms may be related to: constipation, irritable bowel syndrome, sexual activity, delayed/premature voiding

Genetic Considerations and Nonmodifiable Risk Factors

• Disabilities (physical, cognitive, developmental)
• Family history of incontinence
• Genetic considerations: spina bifida, myelomeningocele
• Aging-associated factors: neurodegenerative diseases (Parkinson's, Alzheimer’s), general age-related changes in function
• Male-specific: enlarged prostate; Female-specific: weakened bladder/urethral sphincter support muscles
• Both: decreased bladder capacity

Nursing Assessment

• Key components: observation and patient interview
• Focus areas:
  • Voiding pattern
  • Description of urine and any changes
  • Urinary elimination problems
  • Factors influencing urinary elimination

Nursing Assessment: Physical Examination

• Abdominal assessment
• Examination of soft tissues of genitalia and perianal areas
• Urethral meatus examination
• Assess feces and urine
• Assess fluid volume status

Nursing Assessment: Diagnostic Tests (Urine-related)

• Urine tests:
  • Urinalysis
  • Urine culture
  • Post-void residual urine
• Ultrasonic bladder scan
• Prostate-specific antigen (PSA)
• Urinary stress tests
• Radiologic exams:
  • Intravenous pyelography (IVP)
  • Retrograde pyelography
  • Renal arteriography or angiography

Nursing Assessment: Diagnostic Tests (Imaging and Others)

• Kidney, ureter, bladder (KUB) radiography
• Cystoscopy
• Noninvasive tests:
  • Ultrasound
  • Computed tomography (CT)
  • Magnetic resonance imaging (MRI)
  • Renal scan
• Kidney biopsy
• Blood levels of urea and creatinine

Independent Interventions

• Interventions depend on the underlying cause and severity
• Examples:
  • Increase fluid intake as appropriate
  • Monitor intake and output (I&O)
  • Catheter care
  • Patient teaching
  • Incontinence care
  • Aseptic technique is essential

Collaborative Therapies

• Referrals before or after discharge as needed:
  • Wound and ostomy nurse
  • Occupational therapist
  • Home health nurse
  • Medical supply company
• Include family members and caregivers
• Collaboration is particularly important for patients in long-term care or assisted living

Collaborative Therapies: Pharmacologic Therapy

• Anticholinergic medications: reduce urinary frequency, treat incontinence
• Cholinergic medications: promote urination
• Antibiotics: treat urinary infections
• Urinary analgesics: treat pain
• Urinary antispasmodics: treat spasms
• Diuretics:
  • Loop diuretics
  • Thiazide diuretics
  • Potassium-sparing diuretics
  • Carbonic anhydrase inhibitors and osmotic diuretics

Collaborative Therapies: Dialysis

• Indications: for patients with severely reduced or absent renal function
• Hemodialysis: blood flows through an external machine and returns to the body
• Peritoneal dialysis: dialysis solution is instilled into the abdominal cavity
• Dialysis must be performed at frequent intervals

Lifespan Considerations

Newborns

• Glomerular filtration rate (GFR) is lower than in adults
• Limitations in concentrating and diluting urine; monitor dehydration or overhydration
• Healthy newborns typically void within the first 24 hours
• By delivery, ensure void occurs within $48$ hours
• Patterns of voiding: more frequent
• Urine may be cloudy in newborns; straw-colored in early infancy

Toddlers and Preschoolers

• Most develop urinary control between ages $2 ext{ and }5$ years
• Daytime control usually precedes nighttime control
• Reminders for hygiene: flushing, handwashing
• Instruction in wiping

School-age Children

• Kidneys double in size between ages $5$ and $10$
• Child typically voids $6 ext{ to }8$ times per day
• Enuresis is common; diurnal enuresis (daytime) may be pathologic

Pregnant Women

• Enlarging uterus increases urinary frequency
  • symptom often decreases during the second trimester and reappears in the third
• GFR rises by as much as 50 ext{%} beginning in the second trimester; remains high until birth
• Renal tubular reabsorption increases to compensate
• Glycosuria may occur due to kidneys’ inability to reabsorb all filtered glucose; may be normal or indicate gestational diabetes
• Postpartum: risk for overdistention, incomplete bladder emptying, residual urine
• UTIs risk increases postpartum

Older Adults

• Renal function begins to decline with age
• Blood flow to kidneys decreases due to atrophy of supplying vessels
• Urine tends to be more dilute
• Nighttime diuresis occurs; more fluid, electrolytes excreted at night, potentially interrupting sleep
• Impaired excretion increases risk of drug overdose and adverse effects
• Decreased ability to concentrate urine increases dehydration risk
• Bladder becomes more fibrous with decreased capacity and increased residual urine
• Autonomic regulation of the bladder declines; pelvic floor muscles weaken
• Increased risk of hyponatremia
• Use of prescription diuretics for hypertension or cardiac conditions can worsen urine concentration and electrolyte regulation