Understanding Urinary Elimination and Related Procedures
Sterility and sterile technique reminders
Sterile field awareness: keep your sterile field from being touched by non-sterile items (e.g., sweatshirt must not touch the sterile area).
When reaching over or around the sterile field, do not contaminate it; go around the field rather than over it.
Handling waste: discard items by going around the sterile field and into appropriate waste containers.
Donning and maintaining sterile gloves: avoid touching non-sterile surfaces with sterile gloves; even small adjustments (e.g., pushing up glasses) can contaminate the gloves.
Conscious habit: sterile technique requires constant, deliberate attention to small movements that might contaminate gloves or field.
Course logistics and student engagement
Catheter kit: bring your catheter kit; we will open the kit and lay out items step-by-step during class.
QR code questions: a QR code will appear during PowerPoint slides to answer questions; responses pull up class statistics.
Screenshot option: you can screenshot questions/answers for later review.
Canvas access: ensure you’ve accessed PowerPoint, Sheer Path lessons, and EAQs; EAQs can be taken once; some students take them earlier or closer to the test.
Urinary elimination and overall physiology (context)
Purpose: urinary elimination is the final step of kidney processing to remove excess water and waste as urine; essential for electrolyte and fluid balance.
Kidney-heart connection: kidneys influence blood pressure regulation; understanding their link to cardiac function helps in managing BP.
Renal anatomy and pathways (A&P recap embedded)
Kidneys: two, located on either side of the spinal column; retroperitoneal (behind the peritoneal cavity).
Ureters: two tubes carrying urine from the kidneys to the bladder.
Bladder: hollow, muscular sac that stores urine.
Urethra and urinary meatus: pathway for urine to exit the body.
Left kidney sits higher than the right due to liver placement.
Nephron and filtration (functional unit of the kidney)
Nephron: the functional unit where filtration and reabsorption occur; there are many nephrons per kidney.
Blood flow through nephron: arterial input through capillaries where diffusion/osmosis allow exchange; waste is filtered into filtrate.
Filtration products: filtered substances include ext{water}, ext{glucose}, ext{amino acids}, ext{urea}, ext{uric acid}, ext{creatinine}, ext{electrolytes}.
Urine formation: filtrate passes through nephron tubules where selective reabsorption concentrates urine.
Filtration and reabsorption percentages (key statistic)
Of all filtrate, only about 1egin{cases} ext{ ext{percent}}[-2pt] ext{(1 ext%)} ext{ leaves as urine; the remainder is reabsorbed.} \ ext{100 ext% filtrate}
ightarrow 1 ext{ ext% urine}, 99 ext{ ext% reabsorbed.} \
ext{This reabsorption occurs via osmosis and diffusion in the nephron walls.}
ext{Formula form: } 1est ext{ \% urine} = 1 ext{ percent of filtrate becomes urine; } 99 ext{ ext% reabsorbed.}
ext{(In words: most filtrate is reabsorbed back into the blood.)}
ewcommand{
ephron}{}
ephron
}
If proteins or blood appear in urine (proteinuria or hematuria), it indicates glomerular injury; large proteins and intact blood should not be filtered into urine.
Large proteins and hematuria in urine are signs of a glomerular problem or kidney injury.
Major kidney functions beyond filtration
Erythropoietin (EPO) production: kidneys signal bone marrow to make red blood cells when oxygen delivery is low.
Vitamin D activation: kidneys convert vitamin D to its active form to regulate calcium and phosphate metabolism.
Calcium/phosphate balance: kidney activity helps regulate these minerals in conjunction with vitamin D.
Blood pressure regulation: kidneys participate in the renin-angiotensin-aldosterone system (RAAS).
Major electrolytes (critical for homeostasis)
Key electrolytes filtered and regulated by the kidneys: ext{Na}^+, ext{K}^+, ext{Ca}^{2+}, ext{P}^{-3}, ext{Mg}^{2+}
Electrolyte balance is essential; even small imbalances can destabilize the whole body.
RAAS (Renin-Angiotensin-Aldosterone System): overview and steps
Trigger: renal ischemia or low blood pressure leads to renin release.
Step 1: Renin converts angiotensinogen to angiotensin I: ext{Renin} + ext{Angiotensinogen}
ightarrow ext{Angiotensin I}Step 2: Angiotensin I is converted to angiotensin II by ACE: ext{Angiotensin I}
ightarrow ext{Angiotensin II} \
via angiotensin-converting enzyme.Step 3: Angiotensin II causes vasoconstriction and stimulates aldosterone release.
Step 4: Aldosterone increases sodium and water reabsorption in kidneys, increasing blood volume and pressure.
Practical note: RAAS is a common drug target in hypertension (e.g., ACE inhibitors block the conversion of Angiotensin I to II).
Quick mnemonic: Renin → Angiotensinogen → Angiotensin I → Angiotensin II → Aldosterone.
ACE inhibitors (example, pharmacology context)
ACE stands for Angiotensin-Converting Enzyme; inhibitors block the conversion of Angiotensin I to II, lowering BP.
Examples: lisinopril, captopril, and other “-pril” drugs.
Vitamin D activation and calcium regulation (renal role)
Kidney converts vitamin D to its active form, enabling calcium absorption and utilization.
Calcium utilization is improved when vitamin D is active; many calcium supplements include vitamin D for this reason.
Ureters, bladder, and urethra: anatomy and function details
Ureters: carry urine from kidneys to bladder; each side has one.
Bladder: hollow, muscular organ; stores urine; contractions drive urination.
Detrusor muscle: the muscular wall of the bladder; major contractions occur here during voiding.
Trigone: triangular area within the bladder, near the ureteral openings and internal urethral sphincter.
Urethra role: conducts urine to the outside; external urethral sphincter provides voluntary control.
Female vs male differences:
Female bladder sits anterior to uterus and vagina; closer to abdominal wall; shorter urethra (approx. 1–1.5 inches ≈ 2.5–3.8 cm).
Male urethra is longer (about 7–8 inches) and passes through the prostate; longer catheterization duration risk is higher for males.
Urethral infection risk: females have higher risk of UTIs due to shorter and more exposed urethra and proximity to perineal area; proper cleaning and hygiene are critical.
Catheterization considerations: longer female urethras increase infection risk; catheter insertion requires sterile technique.
Urination (micturition) physiology and control
Urination is controlled by the bladder, urinary sphincter, and CNS.
Filling phase: bladder stretches; detrusor remains relaxed to allow storage; contractions are inhibited during filling.
Sensation to void typically occurs around 400-600 ext{ mL} in the bladder.
Post-void residual (PVR): volume of urine left after urination; can be measured by bladder scanner or catheterization.
CNS control: central nervous system pathways regulate when to relax the urinary sphincter and contract the detrusor.
Urine flow mechanics: bladder contractions (detrusor) and sphincter relaxation coordinate urination; if time/place is not appropriate, control can prevent leakage.
Normal urine output guidance: healthy adults typically produce about 30 ext{ mL/hour} when fluid intake is typical.
UTI, asymptomatic bacteriuria, and CAUTI (catheter-associated UTI)
Bacteriuria vs symptomatic UTI: presence of bacteria in urine without symptoms is bacteriuria and often not treated; symptomatic UTI requires antibiotics.
E. coli is the most common causative agent of UTI and often originates from the colon.
CAUTI: catheter-associated UTI; the most common healthcare-associated infection; CMS reimbursement considerations apply (standing orders and ICU/long-term care policies).
Signs/symptoms of lower UTI: dysuria, urgency, frequency, suprapubic tenderness, foul odor; fever and flank pain suggest upper UTI.
Bacteria in urine with no symptoms is called bacteriuria; asymptomatic cases are generally not treated with antibiotics.
Infection prevention: avoid unnecessary catheter use, maintain sterile technique, catheter care every shift, and remove catheters as soon as possible to reduce CAUTI risk.
Antibiotic stewardship: avoid treating asymptomatic bacteriuria; awareness of antibiotic resistance and “superbugs.”
Common urinary bacteria: Escherichia coli (E. coli) is a common cause of CAUTI.
If a patient has a catheter and develops signs of infection, urine cultures may be obtained; standing orders may guide testing in certain facilities.
Urinary diversions and alternatives to the bladder
Continent urinary reservoir: uses ileum/colon to create a reservoir; ureters drain into reservoir; a stoma connects to the abdominal wall; patient catheterizes the stoma to drain urine; one-way valve prevents continuous flow.
Orthotopic neobladder: a pouch created from ileum placed where the bladder would be; patient voids by natural urination with Valsalva maneuver; requires patient education and capacity to perform self-management.
Ureterostomy (ileal conduit): ureters connected to ileum and brought to abdominal wall as a stoma; urine collects in an external pouch; incontinent diversion (no sensation, requires a bag).
Nephrostomy tubes: tubes placed directly into the renal pelvis from the skin; urine drains into an external bag, bypassing the ureters and bladder; high infection risk due to external tract.
Key distinctions: continent diversions require self-catheterization and have valves; incontinent diversions require external drainage bags; nephrostomy bypasses the bladder entirely.
Types of urinary incontinence (major categories and causes)
Transient (temporary): reversible; caused by delirium, medications, infections, mobility impairment, acute illness, or temporary factors.
Functional: external or environmental barriers to toileting (e.g., mobility/dexterity issues, cognitive impairment, environmental barriers, caregiver response delays).
Stress incontinence: leakage with increased intra-abdominal pressure (sneeze, cough, laugh, rise from chair); often due to urethral hypermobility or weak/incompetent urinary sphincter; management includes pelvic floor exercises (Kegel), avoiding bladder irritants, and moisture barrier products.
Urge incontinence (overactive bladder): involuntary leakage with a strong urge; common triggers include bladder inflammation, neurological issues, or obstruction; avoid bladder irritants (e.g., caffeine, alcohol); pelvic floor exercises and addressing UTIs are key.
Reflex urinary incontinence: involuntary leakage at unpredictable intervals due to spinal cord injury (usually between C1–S2 levels); manage with toilet scheduling or intermittent catheterization; use containment products; monitor for autonomic dysreflexia.
Overflow incontinence (due to chronic retention): incomplete bladder emptying; may be mild or severe; signs include frequency, urgency, incontinence with retention; overflow can cause continuous leakage.
Nocturia: waking from sleep to void; can be due to fluids near bedtime or other medical factors.
Dribbling: leakage of small amounts of urine; may occur with stress or other incontinence types.
Key clinical concepts: pelvic floor muscle training (Kegels: pelvic floor exercises), bladder irritants (caffeine, artificial sweeteners, alcohol), and toileting programs.
Polyuria vs oliguria vs nocturia:
Polyuria: voiding excessive amounts of urine; often associated with hyperglycemia (diabetes) or diuretic therapy.
Oliguria: decreased urine output relative to intake.
Nocturia: urination during sleep.
Post-void residual (PVR): residual urine after voiding; measured by bladder scanner or catheterization.
Assessment tools and clinical tips
Bladder scanner: noninvasive measurement of bladder volume; patient in supine position; gender settings may vary (e.g., hysterectomy changes gender designations for scanning).
Palpation: assess suprapubic area for distension when retention is suspected.
Documentation: dysuria (painful urination) should be documented as such; UTIs require symptom-based assessment rather than solely bacteriuria.
Toileting programs: scheduled toileting every couple of hours to reduce incontinence episodes and improve continence.
Double voiding technique: after urinating, wait briefly and attempt a second void to ensure better emptying.
Intermittent catheterization vs indwelling catheter: intermittent catheterization is preferred when possible to avoid infection; indwelling catheters pose higher infection risk but may be necessary in some chronic retention cases.
Practical considerations: care, safety, and ethics
Catheter care: maintain sterility; avoid contamination; remove catheter as soon as clinically possible to minimize CAUTI risk.
Never events and CMS policies: CAUTI is a major hospital-associated infection; organizations aim to minimize it due to cost and patient safety risks.
Staffing and teamwork: staffing shortages can impede timely assistance; emphasize patient safety, communication, and teamwork.
Patient dignity and privacy: respect patient privacy and avoid embarrassing situations; provide supportive communication when dealing with incontinence.
Environmental and daily living aids: keep bathroom lights on, ensure mobility aids are within reach, provide grab bars/raised toilet seats, and keep pathways clear to help prevent incontinence-related falls or delays.
Hygiene and cleanliness: clean toilet areas to encourage use; maintain a clutter-free environment; promote good hand hygiene and infection prevention.
Quick recall quiz reference (class activity example)
Question: Which carrier transports urinary waste to the bladder? Answer (per in-class QR activity): the ureters.
Urination terms: urination, micturition, and voiding all describe the same process; communicate appropriately with patients (avoid slang like “pee”) depending on age and population.
Important normal values and units:
Bladder sensation threshold: around 400$-$600 ext{ mL} of urine.
Normal urine output: ext{about } 30 ext{ mL/hour}.
Female urethra length: 1 ext{ to }1.5 ext{ inches}
ightarrow ext{approximately } 2.5 ext{ to }3.8 ext{ cm}.Male urethra length: 7$–$8 ext{ inches}.
Summary connections to practice and ethics
Evidence-based practice informs catheter use; minimize use, remove promptly, and use proper catheter care to lower CAUTI risk.
Antibiotic stewardship matters: treat symptomatic infections; avoid treating asymptomatic bacteriuria.
Patient education: explain bladder health, pelvic floor exercises, and toileting schedules; address anxiety or cognitive barriers to toilet use.
Real-world relevance: UTIs, incontinence, and urinary diversions impact quality of life; healthcare teams must balance safety, dignity, and practical care needs.
References to course materials (context from transcript)
Course materials include PowerPoint slides, Canvas resources, EAQs, and the use of a QR-coded question tool to engage students.
The lecture emphasizes anatomy and physiology (A&P) fundamentals as essential groundwork for understanding urinary elimination and renal function.
The content also integrates clinical scenarios such as catheter management, CAUTI risk, and the practicalities of urinary diversions in patients with significant urologic changes.