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