Factors affecting urinary elimination:
· Fluid intake
· Loss of body fluids
· Body positions
· Psychological factors
· Obstruction of urine flow: renal calculi, prostatic enlargement, tumors, structural abnormalities
· Neurologic injury: spinal cord injury, cerebral vascular accident (stroke), brain tumor
· Decreased muscle tone
· Surgery: anesthesia, edema, immobility
· Urinary diversions
· Developmental Factors
1. Fluid intake:
The amount of fluid that a person ingests is the most influential factor in determining urine output. If a person increases his or her volume of fluid intake, an associated increase will occur in the volume of urine output.
Antidiuretic hormone (ADH) plays a significant role in the reabsorption of water in the tubules of the nephrons. When ADH is present, the distal tubule of nephrons becomes permeable to water. Release of ADH causes the kidney to reabsorb more water, thus producing a more concentrated urine.
When fluid intake increases, ADH release is suppressed. In the absence of ADH, the renal tubules become relatively impermeable to water, and little water is reabsorbed, producing an increased volume of dilute urine.
If fluid intake is greatly increased, frequency of voiding increases because the bladder fills more quickly and vice versa.
2. Loss of Body Fluid:
When a person loses a great deal of body fluid, the kidneys increase reabsorption of water from the glomerular filtrate to maintain the proper osmolality of the ECF.
Increased loss of body fluids can occur with vomiting, diarrhea, excessive diaphoresis secondary to fever or exercise, excessive wound drainage, extensive burns, or blood loss from trauma or surgery.
Diet may affect urinary elimination. If the diet contain a high percentage of foods with a high water content (e.g. soup, fruits, vegetables), urine volume will be greater than if intake of such foods is limited.
If a person ingests large quantities of salty foods without increasing water intake, urine output will decrease and the urine will be more concentrated.
Alcohol and caffeine containing fluids or foods such as coffee, tea, cola or chocolate, irritate the bladder and contain a diuretic that an increase urine output.
4. Body Position:
Body position plays an important role in the ability to empty the bladder completely with each voiding.
The typical body position for urinary elimination in men is standing upright. The normal position for voiding in women is sitting. Some men find it difficult to empty their bladders fully into a urinal while lying flat in bed.
If women use a bedpan while flat in bed, she also may be unable to empty her bladder completely
Cognitive impairment interferes with a person’s ability to maintain urinary continence. Neurologic condition such as Alzeheimer disease, brain tumor, or cerbrovascular accident (stroke), delirium can reduce the person’s ability to perceive bladder fullness or to delay voiding until he or she reaches the toilet.
6. Psychological Factors:
Stress and anxiety can affect urinary elimination.
In stressful situations, a person can experience a strong urge to urinate. Stress can also cause the reverse problem of urinary retention: the persons muscles may be become so tense that he or she cannot relax the perineal muscles and voiding is inhibited.
Privacy for voiding is important psychologically. Many people relax their perineal muscles without adequate privacy.
7. Obstruction of Urine Flow:
Obstruction of the normal flow of urine can lead to problems with urinary elimination and when severe can cause kidney damage.
Structural abnormalities within the urinary tract, urinary tumors or Other tumors that press against the urinary tract, renal stones and prostatic enlargement are possible causes of urinary obstruction.
8. Infections of the Urinary Tract:
UTI’s are usually caused by microorganisms normally found in the gastrointestinal tract. Most found organisms are Escherichia coli, Klebsiella and Proteus.
The person with a UTI often experiences urgency, a subjective feeling of being unable to delay the urge to void voluntarily. Urine becomes abnormal, containing pus (pyuria) and blood (hematuria).
Adequate blood perfusion to the kidneys is necessary to ensure urine formation. When arterial blood pressure drops too low, the renal arteries do not have enough pressure to cause glomerular filtration which results in less urine output
10. Neurologic Injury:
Neurologic injury after a stroke or spinal cord injury can disrupt normal patterns of urinary elimination. Injury by trauma, hemorrhage or tumor to the frontal lobes of the brain, which control the voluntary nature of voiding, can lead to incontinence.
11. Decreased Muscle Tone:
Weakened abdominal and perineal muscles can impair bladder contraction and control of the external urinary sphincter.
Abdominal and perineal muscles can weaken because of obesity, multiple pregnancies, stretching during childbirth, menopausal atrophy due to decreased estrogen and chronic constipation.
Continuous bladder drainage with catheter can also decrease bladder tone.
During pregnancy, the increasing size and weight of the growing uterus can exert pressure on the bladder, a common cause of urinary frequency in pregnant women.
Compression of the bladder by the uterus may also lead to the obstruction of urinary flow and incomplete emptying of the bladder.
Many post – operative clients are volume depleted because of limited fluid intake and loss of blood and fluid during surgery. Surgery involving the urinary system, intestines or reproductive organs predisposes a client to urinary retention.
Anesthesia can also affect urinary elimination. Anesthetic agents slow the glomerular filtration rate, reducing urinary output.
Medications classified as diuretics are administered to increase urine output. They affect reabsorption of sodium and water in the tubules of the nephron.
Commonly used diuretics include hydrochlorothiazide, furosemide, and spironolactone. Tricyclic antidepressants and antihistamines can cause urinary retention.
15. Urinary Diversion:
A urinary diversion is a surgical procedure in which the normal pathway of urine elimination is altered. The ureters are re – routed from a diseased or damaged urinary system to a new outlet, called a stoma.
Urinary diversions alter normal urinary elimination because the person no longer has control over voiding.
16. Developmental Factors:
Infants — urine output varies according to fluid intake but gradually increases to 250 — 300 ml. Infant may urinate as often as 20 times a day
Preschoolers — independent toileting
School age — urinates six to eight times a day. Enuresis- involuntary passing of urine when control should be established (about 6 years of age) can be a problem for some school — age children. Nocturnal Enuresis, or bed wetting is the involuntary passing of urine during sleep. It should not be considered a problem until after the age of 6.
Elders — The ability to concentrate urine declines. Bladder muscle tone diminishes, causing increased frequency of urination and nocturia (awakening to urinate at night). Diminished bladder muscle tone and contractibility may lead to residual urine in the bladder after voiding, increasing the risk of bacterial growth and infection. Urinary incontinence may occur due to mobility problems or neurologic impairments.
Alteration in urinary elimination:
Most patients with urinary problems are unable to store urine or fully empty the bladder. These disturbances result from impaired bladder function, obstruction to urine flow, or inability to voluntary control micturition.
Dysuria: Dysuria means painful voiding. Pain is often associated with UTI’s and is felt as a burning sensation during urination. Any bladder inflammation or trauma or inflammation of the urethra can cause dysuria.
Polyuria: Polyuria is the formation and excretion of excessive amount of urine in the absence of a concurrent increase in fluid intake. Urine output of more than 2500 to 3000 ml in 24 hours is considered polyuria.
Untreated diabetes insipidus and hyperglycemia can greatly increase urine output. Ingestion of diuretics, caffeine and alcohol also results in polyuria.
Oliguria: Oliguria is the formation and excretion of decreased amounts of urine, or urinary output less than 500 ml in 24 hours or 30 ml/hr in an adult
A severe decrease in fluid intake or any disease state or injury that leads to an excessive loss of body fluids can cause oliguria. E.g. excessive vomiting, diarrhea, diaphoresis, burns or bleeding can decrease urine output.
Anuria: Anuria is the formation and excretion of less than 100ml of urine in 24 hours or refers to a lack of urine production. In kidney failure patients, anuria is present.
Urgency: Most adults can postpone emptying the bladder until it contains 250 to 400ml of urine. Urgency is the subjective feeling of being unable to delay voiding voluntarily.
Urgency implies a strong micturition reflex caused by inflammation or infection of the urethra or bladder incompetent urethral sphincter, weak perineal muscle control or psychological stress.
Frequency: Voiding at frequent intervals is known as frequency. Frequency occurs when a person voids more than normal, without a significant increase in fluid intake. Each voiding usually contains less than 250ml of urine. It can be due to UTI or pressure on the bladder from pregnancy.
Frequency and urgency often occur together; the term overactive bladder is sometimes used in this situation
Nocturia: Voiding two or more tomes at night. Ingestion of large amounts of fluids before bed, especially those containing alcohol or caffeine, may promote nocturia.
People with medical conditions such as CHF may also experience nocturia.
Hematuria: Hematuria is blood in the urine; it can be gross (visible on visual examination) or occult (not visible on visual examination. As the number of the red blood cells increases, the urine may become bright and red. Pathologic causes of hematuria include UTIs, urinary tract tumors, renal calculi, poisoning and trauma to the urinary mucosa.
Pyuria: Pyuria means that the urine contains pus, which is the accumulation of the end products of an inflammatory response. Pus containing microorganisms and white blood cells give urine a cloudy color and often a strong unpleasant odor. Pyuria occurs in the presence of a UTI.
Enuresis/ Bedwetting: Enuresis is involuntary voiding, with no underlying pathophysiologic origin, after the age at which bladder control is usually achieved.
Bladder control is achieved in 3 to 4 years. Factors associated with nocturnal enuresis include small bladder capacity, sound sleeping, stress and anxiety at home or school
Residual Urine: Volume of urine remaining after voiding (> 100 ml)
Urinary retention: Accumulation of urine in bladder, with inability to bladder to empty full
Urinary Incontinence: Involuntary loss of urine