Elimination-Urine

ELIMINATION

URINARY SYSTEM

  • Primary Functions:

    • Eliminate metabolic waste products and excess fluid from the body in the form of urine to maintain homeostasis.

    • Regulate levels of electrolytes (e.g., sodium, potassium, calcium) and acid-base balance.

    • Produce hormones important for blood pressure regulation (e.g., Renin), red blood cell production (e.g., Erythropoietin), and calcium metabolism (e.g., Vitamin D activation).

    • Assist in keeping bones strong through Vitamin D activation.

    • Participate in glucose metabolism during prolonged fasting.

  • Components of the Urinary Tract:

    • Kidneys: Filter blood and produce urine.

    • Ureters: Transport urine from kidneys to bladder.

    • Bladder: Stores urine.

    • Urethra: Expels urine from the body.

KIDNEYS

  • Description:

    • Two bean-shaped organs, roughly the size of a fist, located bilaterally below the ribcage, adjacent to the spine (specifically, T12 to L3 vertebrae). They are retroperitoneal.

  • Functioning:

    • Each kidney contains approximately 1 million nephrons, the functional units responsible for blood filtration.

    • On average, kidneys filter 120 to 150 quarts (or approximately 180 L) of blood daily, a process involving glomerular filtration, tubular reabsorption, and tubular secretion, to produce about 1 to 2 quarts (approximately 1000 - 2000 mL) of urine.

    • Urine is transported from the renal pelvis in the kidneys down to the bladder by the ureters, which are thin, muscular tubes (one ureter from each kidney) that use peristaltic waves to propel urine.

    • As urine fills the bladder, its muscular walls (detrusor muscle) stretch, accommodating increasing volume without significant pressure changes until a certain threshold.

  • Bladder Capacity:

    • The average functional capacity of the adult bladder is typically between 300-600 mL, but can hold up to 2 cups (approximately 470 mL) of urine before the urge to void becomes strong.

    • An initial urge to empty the bladder typically occurs with about 150-200 ml of urine, becoming stronger around 400-600 ml.

    • Micturition (urination) is a complex reflex involving the autonomic and somatic nervous systems. When bladder volume increases, stretch receptors send signals to the spinal cord and then to the brain. The central nervous system then signals the internal urethral sphincter (involuntary) to relax and the detrusor muscle to contract, while voluntary control allows the external urethral sphincter to be released.

FACTORS INFLUENCING URINATION

  • Categories:

    • Psychological: Stress, anxiety, and privacy can affect the urge and ability to urinate.

    • Sociocultural: Cultural norms and personal privacy preferences influence voiding patterns and frequency.

    • Health conditions: Neurological disorders, diabetes, prostate enlargement, UTIs, and kidney diseases directly impact urinary function.

    • Personal habits: Ignoring the urge to void, timing of fluid intake, and voiding schedules.

    • Fluid intake: Increased fluid intake leads to increased urine production; decreased intake leads to concentrated urine and reduced output.

    • Surgical procedures: Anesthesia can temporarily suppress bladder function, leading to urinary retention. Post-operative pain can also impede voiding.

    • Medications: Diuretics, anticholinergics, sedatives, and some pain medications can alter kidney function or bladder contractility.

    • Age: Decreased bladder capacity and weakening pelvic floor muscles are common with aging.

UNWANTED URINATION

  • Muscle Groups Involved in Prevention: The ability to control urination (continence) relies on the coordinated function of several muscle groups:

    1. Urethra: Contains both internal (involuntary) and external (voluntary) sphincters that regulate urine flow.

    2. Bladder neck: The junction where the bladder tapers into the urethra, primarily controlled by the internal urethral sphincter, which is formed by the detrusor muscle and remains contracted to prevent leakage.

    3. Pelvic floor muscles: A group of muscles that support the bladder, uterus, and bowel, and provide voluntary control over the external urethral sphincter, allowing for the conscious inhibition or initiation of voiding.

ANTI-DIURETICS AND DIURETICS

  • Antidiuretics:

    • Minimize fluid loss by increasing water reabsorption in the renal tubules, thereby reducing urine production in the kidneys (e.g., Antidiuretic Hormone (ADH) or Vasopressin, which acts on the collecting ducts; NSAIDs like Ibuprofen can indirectly affect renal blood flow and reduce urine output).

  • Diuretics:

    • Increase urination (diuresis) by promoting the excretion of water and electrolytes (sodium, chloride, potassium) from the kidneys, thereby increasing urine production.

    • Commonly prescribed for conditions like Hypertension (to reduce blood volume), Edema (to excrete excess fluid), and Heart Failure (to reduce fluid overload and cardiac workload). Examples include loop diuretics (e.g., Furosemide), thiazide diuretics (e.g., Hydrochlorothiazide), and potassium-sparing diuretics (e.g., Spironolactone).

TYPES OF URINARY INCONTINENCE

  • Stress Incontinence:

    • Involuntary leakage of urine due to increased intra-abdominal pressure (e.g., during coughing, sneezing, laughing, lifting, or exercising) when the bladder sphincter is weakened or pelvic floor muscles are insufficient.

  • Urge Incontinence:

    • Characterized by a sudden, strong, uncontrollable urge to urinate, leading to involuntary urine leakage, often associated with an overactive bladder (detrusor muscle instability).

  • Overflow Incontinence:

    • Occurs when the bladder does not empty completely and becomes overdistended, leading to constant dribbling of urine. Causes include urethral obstruction (e.g., enlarged prostate) or weak bladder muscle contraction.

  • Functional Incontinence:

    • The physical inability or mental impairment to reach the toilet in time or manage clothing due to factors like mobility issues, cognitive deficits, or environmental barriers, despite a normal functioning urinary tract.

  • Bedwetting (Nocturnal Enuresis):

    • Involuntary urination during sleep, more common in children but can affect adults, potentially caused by hormonal imbalances (low ADH), overactive bladder, or psychological factors.

URINARY RETENTION

  • Definition:

    • The inability of the bladder to completely empty, potentially leading to significant residual urine volume.

  • Symptoms:

    • Acute retention presents with severe suprapubic pain, urgency, and inability to void. Chronic retention symptoms include abdominal distention, urinary frequency (voiding small amounts), hesitancy, a weak/slow urine stream, incomplete emptying sensation, and paradoxical urinary leakage (overflow incontinence).

  • Causes:

    • Can result from infections (e.g., UTI causing urethral inflammation), obstruction (e.g., enlarged prostate in men, strictures, bladder stones, fecal impaction), neurological conditions (e.g., spinal cord injury, multiple sclerosis, stroke), or certain medications (e.g., anticholinergics, opioids).

  • Postvoid Residual (PVR):

    • The amount of urine remaining in the bladder immediately after voiding. A PVR of greater than 50-100 mL is often considered indicative of inadequate bladder emptying and may require intervention.

URINARY TRACT INFECTIONS (UTI)

  • Cause:

    • Primarily caused by bacteria (most commonly Escherichia coli) entering the urinary tract, typically ascending from the perineum through the urethra to the bladder (cystitis) and potentially further to the kidneys.

  • Demographics:

    • More common in women due to their shorter urethra (allowing bacteria easier access to the bladder) and its proximity to the anus. Women also lack the prostatic fluid's antibacterial properties.

  • Consequences:

    • If untreated, a lower UTI (cystitis) may ascend and lead to pyelonephritis (kidney infection), which is a more severe condition with symptoms like fever, flank pain, and potential for sepsis and kidney damage.

  • Risk Factors:

    • Sexual activity (trauma to urethra), menopause (estrogen deficiency alters vaginal flora and urethral tissue), urinary retention/obstruction (stagnant urine promotes bacterial growth), frequent catheter use (introduces bacteria), diabetes (compromised immune system, glucose in urine), use of diaphragms/spermicides, and poor hygiene.

  • Symptoms:

    • Dysuria (burning/painful urination), increased urgency and frequency to urinate with often little urine output, suprapubic tenderness, cloudy or foul-smelling urine, and sometimes hematuria. Fever and flank pain suggest upper UTI (pyelonephritis).

KIDNEY STONES

  • Definition:

    • Hard formations of minerals and salts (primarily calcium oxalate, uric acid, struvite, or cystine) that form in the kidneys and can travel down the urinary tract. Also known as renal calculi, nephrolithiasis, or urolithiasis. They can cause severe pain (renal colic), hematuria, and obstruction.

COMMON URINARY SYMPTOMS

  • Urgency:

    • A sudden, compelling need to urinate, which is difficult to postpone. Often associated with inflammation or irritation of the bladder (e.g., UTI, overactive bladder).

  • Dysuria:

    • Burning or stinging sensation during urination, a common symptom of UTIs, urethritis, or vaginitis.

  • Frequency:

    • Increased urination episodes within a 24-hour period, often involving small volumes. Can be due to increased fluid intake, UTI, bladder irritation, or decreased bladder capacity.

  • Hesitancy:

    • Difficulty initiating or maintaining a urine stream, often associated with prostatic enlargement, strictures, or neurological issues affecting bladder emptying.

  • Polyuria:

    • Excessive urine output, defined as generally greater than 2.5 - 3 liters over 24 hours. Common causes include diabetes mellitus, diabetes insipidus, diuretic use, or excessive fluid intake.

  • Oliguria:

    • Low urine output, defined as less than 400-500 ml in 24 hours for adults. Can indicate dehydration, kidney dysfunction, or urinary obstruction, and requires prompt assessment.

  • Nocturia:

    • Awakening at night one or more times to urinate, disrupting sleep. Common in older adults, heart failure, uncontrolled diabetes, or prostate issues.

  • Dribbling:

    • Involuntary leakage of urine immediately following the completion of urination, often due to weak pelvic floor muscles or prostate issues in men.

  • Hematuria:

    • Presence of blood in urine, which can be macroscopic (visible to the naked eye) or microscopic (detected by urinalysis). Causes range from UTIs, kidney stones, trauma, to more serious conditions like kidney disease or bladder/kidney cancer.

  • Retention:

    • Difficulty in bladder emptying completely, as described previously.

  • Odor:

    • Normal urine has a characteristic mild ammonia odor due to urea. A foul odor may suggest a UTI (due to bacterial activity); a sweet, fruity aroma could indicate uncontrolled diabetes mellitus (due to ketones); and certain foods (e.g., asparagus) or medications can alter urine odor.

COLLECTION OF URINE

  • Methods:

    • Urine specimen cup: For random or clean-catch samples.

    • Bedpan: For non-ambulatory patients.

    • Urinal: For male patients, especially non-ambulatory.

    • Hat: A collection device placed in the toilet for easy measurement and sampling.

    • Foley catheter: An indwelling catheter for continuous drainage and sterile sample collection.

    • In and out catheters (straight catheterization): For intermittent sterile collection or bladder decompression.

  • Assessment Methods:

    • Monitoring of Intake and Output (I&O): A crucial assessment for evaluating renal function, fluid and electrolyte balance, and bladder emptying capacity. All fluid intake (oral, IV, tube feedings) and all fluid output (urine, vomitus, diarrhea, wound drains) are meticulously measured and documented over a specified period (e.g., 8 hours, 24 hours) to determine fluid balance.

  • Intake Measures:

    • Include all oral liquids, semi-solids (e.g., gelatin, ice cream), enteral fluids (tube feedings, flushes), and parenteral fluids (intravenous fluids, blood products).

  • Output Measures:

    • Encompass urine, vomitus, drainage tube contents (e.g., nasogastric, chest tube), fluids from wound drains (e.g., Jackson-Pratt, Hemovac), and significant liquid stool via diarrhea.

  • Characteristics of Urine:

    • Color: Normal is pale straw to amber, influenced by urochrome (a pigment) and hydration status. Abnormal colors may include hematuria (red/pink), dark yellow/orange (dehydration, liver issues), blue/green (certain medications or rare genetic conditions).

    • Clarity: Normal urine is transparent when voided. Cloudy urine can indicate infection (pus, bacteria), presence of phosphates, blood cells, or protein.

LAB COLLECTION FOR URINE TESTING

  • Labeling:

    • All specimens must be labeled accurately with the patient’s full name, medical record number, date of birth, date of collection, time of collection, and type of collection (e.g.,