Exam 3
Anatomy and Physiology of the Urinary System
Primary Function of Urinary Structures:
Kidneys:
Filter blood continuously to remove metabolic waste products, excess solutes, and water.
Regulate electrolyte concentration, acid-base balance, blood pressure, and red blood cell production.
Ureters:
Bilateral, fibromuscular tubes connecting the renal pelvis to the urinary bladder.
Actively propel urine from the kidneys toward the bladder through smooth muscle peristaltic contractions.
Bladder:
Hollow, distensible, muscular organ located in the pelvic cavity that serves as a temporary reservoir for urine.
Capable of significant expansion and recoil due to the arrangement of the detrusor muscle.
Urethra:
Conduit that conveys urine from the bladder neck to the external urethral meatus for elimination from the body.
Front View and Anatomical Organization of the Urinary Tract:
Kidneys positioned retroperitoneally.
Bilateral ureters descending toward the pelvic basin.
Bladder situated anteriorly in the pelvis.
Internal and external urethral sphincters maintaining continence.
Urethra terminating at the external orifice.
Mechanisms of Voiding (Micturition):
The terms urination, micturition, and voiding are synonymous and describe the process of emptying the urinary bladder.
Step-by-step physiological sequence:
Urine accumulates in the bladder, producing progressive bladder wall distension.
Distension activates specialized intramural mechanoreceptors (stretch receptors).
Stretch receptors generate sensory afferent impulses transmitted along pelvic nerves to the sacral spinal cord (voiding reflex center).
When micturition is initiated, parasympathetic efferent stimulation causes coordinated contraction of the detrusor muscle.
The involuntary internal urethral sphincter relaxes and opens.
Under conscious control, somatic efferent signals to the voluntary external urethral sphincter are inhibited, relaxing the sphincter.
Urine flows freely through the urethra and exits the body.
Clinical Terminology Related to Urinary Elimination
Anuria:
Complete absence of urine production or excretion by the kidneys, or urinary output falling below in a period.
Indicates acute renal failure, bilateral renal artery occlusion, or complete urinary tract obstruction.
Oliguria:
Clinically diminished urine volume production, typically defined as output less than per period (or less than in adults).
Commonly results from severe dehydration, hypovolemia, shock, acute kidney injury, or renal hypoperfusion.
Polyuria:
Production and excretion of an abnormally excessive volume of urine, typically exceeding in a period.
Associated with diabetes mellitus (osmotic diuresis), diabetes insipidus (deficiency of antidiuretic hormone), excessive fluid consumption, or diuretic medication therapy.
Nocturia:
Excessive, repeated urination during nighttime sleep hours requiring waking.
May result from excessive evening fluid intake, cardiac failure (dependent edema reabsorption in recumbency), prostatic hypertrophy, or poorly managed diabetes.
Dysuria:
Difficult, burning, or painful sensations experienced during urination.
Typical hallmark of lower urinary tract infection, cystitis, urethritis, trauma, or local irritation.
Hematuria:
The abnormal presence of red blood cells in the urine.
Can be visible to the naked eye (gross hematuria) or detectable only via chemical dipstick or microscopy (microscopic hematuria).
Crucial clinical caveat: The visible color of the urine does not accurately reflect the true degree of blood loss; a very small quantity of blood can impart a deep red or smoky amber hue to an entire volume of urine.
Nocturnal Enuresis:
Involuntary loss of urine (bedwetting) occurring specifically during sleep in individuals past the age of anticipated nighttime bladder control.
Urinary Incontinence
Definition and Overview:
Urinary incontinence is the involuntary, uncontrollable loss or leakage of urine.
Represents a disruptive condition compromising skin integrity, physical comfort, functional independence, and psychological well-being.
Classifications of Urinary Incontinence:
Stress Incontinence:
Leakage of urine occurring in response to sudden increases in intra-abdominal pressure.
Triggered by coughing, sneezing, laughing, jumping, or heavy lifting.
Primary etiology: Weakness or attenuation of the pelvic floor muscles and urethral sphincter insufficiency, frequently following childbirth, pelvic surgery, or age-related tissue atrophy.
Urge Incontinence:
Involuntary leakage accompanied by or immediately preceded by an intense, sudden, uncontrollable urge to void.
Primary etiology: Involuntary, premature contractions of the bladder detrusor muscle during the filling phase (detrusor instability or overactive bladder).
Overflow Incontinence:
Continuous or frequent involuntary dribbling and loss of urine resulting from incomplete bladder emptying and marked chronic overdistension.
Primary etiology: Mechanical outlet obstruction of the urethra (e.g., severe benign prostatic hyperplasia, urethral stricture) or detrusor muscle underactivity/hypotonia.
Neurogenic Incontinence:
Loss of normal bladder sensory perception and motor control caused by structural impairment or disruption of the central or peripheral nervous system.
Etiologies include spinal cord injuries, stroke (cerebrovascular accident), multiple sclerosis, diabetic neuropathy, and Parkinson's disease.
Management Strategies for Incontinence:
Dietary and Fluid Adjustments:
Eliminate or strictly moderate intake of bladder irritants, particularly caffeine and alcohol, both of which stimulate detrusor contractility and promote diuresis.
Maintain balanced fluid intake throughout the day while minimizing excessive evening fluids.
Pharmacological Review:
Identify and manage medication side effects that exacerbate urinary leakage (e.g., timing of loop or thiazide diuretics, evaluating sedatives or anticholinergics).
Pelvic Floor Muscle Training (PFMT / Kegel Exercises):
Structured physical training targeting the levator ani and pubococcygeus muscles to improve tone and voluntary urethral closure pressure.
Regimens include specific floor exercises:
Assisted heel drops.
Dead bug exercises.
Bridge exercises.
Bird dog exercises.
Perineal Skin Care:
Protect cutaneous tissue from moisture-associated skin damage (MASD) and incontinence-associated dermatitis (IAD).
Cleanse promptly after every incontinent episode using gentle, pH-balanced perineal cleansers; avoid harsh bar soaps.
Apply moisture-barrier ointments, zinc oxide formulations, or dimethicone-based protective skin barriers.
Use specialized, breathable incontinence garments or pads (e.g., Depend underwear) while avoiding prolonged skin contact with saturated products.
Urinary Retention
Definition and Overview:
Urinary retention is the inability to void or completely empty the urinary bladder of accumulated urine.
Can manifest as acute, sudden urinary retention or progressive, chronic incomplete voiding.
Etiology and Common Causes:
Prostatic Enlargement:
Benign prostatic hyperplasia (BPH) or prostatic carcinoma causing mechanical compression and elongation of the prostatic urethra.
Urinary Tract Infections (UTIs):
Severe urethral or bladder inflammation causing edema, mucosal swelling, and reactive sphincter spasm.
Medication Side Effects:
Pharmacological agents that inhibit parasympathetic pathways or stimulate alpha-adrenergic receptors, reducing detrusor tone or increasing sphincter tone.
Includes anticholinergics, antihistamines, tricyclic antidepressants, antispasmodics, alpha-adrenergic agonists, opioids, and anesthetics.
Assessment Findings (Signs and Symptoms):
Subjective reports of intense lower abdominal fullness, suprapubic pressure, severe pelvic pain, or progressive discomfort.
Voiding in frequent, small amounts () that fail to alleviate pressure (overflow retention with dribbling).
Hesitancy, straining, weak stream, or feeling of incomplete bladder evacuation.
Inspection and Palpation:
Direct physical inspection of the lower abdomen reveals a visible, smooth, dome-shaped suprapubic protrusion.
Palpation yields a firm, tense, rounded, tender bladder rising above the level of the symphysis pubis.
Percussion produces a distinct dull sound over the fluid-filled bladder instead of typical abdominal tympany.
Diagnostic Assessment:
Bladder Scan (Portable Ultrasound):
Utilizes non-invasive ultrasound technology (such as the BladderScan BVI 9400) to measure residual bladder volume rapidly and reliably.
Accurately calculates volume in milliliters (e.g., displaying or significantly higher residual volumes).
Prevents unnecessary invasive catheterizations when minimal volume is present and confirms retention when elevated volumes are detected.
Nursing Interventions to Alleviate Retention:
Non-Invasive Facilitation Techniques:
Turn on a nearby sink faucet so the patient hears running water, stimulating the parasympathetic micturition reflex.
Provide absolute privacy and adequate time to void.
Position the patient in a natural anatomical posture for elimination (standing upright for males; sitting upright on a commode or toilet with feet firmly supported for females).
Place the patient's hands in a basin of warm water or pour warm water gently over the perineum.
Invasive Decompression:
Catheterization (intermittent straight catheterization or indwelling catheter insertion) when non-invasive measures fail or when rapid decompression is required.
Urinary Catheterization
Definition:
Urinary catheterization is the introduction of a flexible, pliable tube through the urethra (or surgically through the abdominal wall) directly into the urinary bladder to provide continuous or intermittent drainage of urine.
Clinical Indications for Catheterization:
Relief of acute or chronic urinary retention unresponsive to conservative management.
Bladder decompression preoperatively or postoperatively to avoid intraoperative injury and prevent post-anesthesia retention.
Facilitation of specific surgical interventions (e.g., gynecologic, urologic, colorectal, or prolonged pelvic procedures).
Facilitation of wound healing in patients with incontinence-associated contamination of open Stage III or Stage IV pressure ulcers located in the sacral, coccygeal, or perineal regions.
Precise, continuous monitoring of hourly fluid intake and output () in critically ill or hemodynamically unstable patients.
Promotion of physical comfort and dignity during end-of-life care in terminally ill patients.
Contraindications to Catheterization:
Routine collection of urine specimens when clean-catch, midstream, or non-invasive options are feasible.
Convenience of the nursing staff, healthcare team, or patient's family.
Classifications and Types of Urinary Catheters:
Self-Catheterization / Intermittent Catheterization:
Straight Catheter:
Single-lumen, flexible tube inserted into the bladder for immediate emptying and removed immediately once drainage is complete.
Utilized for intermittent decompression, post-void residual assessment, or obtaining sterile specimens.
Indwelling Catheters (Retention Catheters):
Maintained inside the bladder over time via an anchoring retention balloon inflated with sterile water.
Foley Catheter:
Standard double-lumen catheter; one lumen drains urine, while the second lumen connects directly to the distal retention balloon.
Coudé Catheter:
Features a distinct, semi-rigid, curved, tapered tip.
Specially designed to negotiate past urethral obstructions, tight curves, or an enlarged prostate gland in male patients.
Triple-Lumen Catheter:
Incorporates three separate conduits: one for urinary drainage, one for balloon inflation, and a third dedicated to continuous bladder irrigation (CBI) with sterile saline.
Primarily used after transurethral prostatic surgery to irrigate blood and prevent intravesical blood clot formation.
Suprapubic Catheter:
Placed via surgical incision through the lower anterior abdominal wall directly into the bladder dome above the symphysis pubis.
Indicated in cases of severe urethral strictures, extensive urethral trauma, or long-term neurogenic bladder requiring permanent diversion.
Non-Invasive External Catheters:
External Condom Catheter for male patients.
PureWick Female External Catheter:
Utilizes soft, wicking material placed between the labia against the urethral meatus, connected to low-pressure continuous wall suction to draw away voided urine without invasive urethral placement.
Nursing Care of the Patient with an Indwelling Catheter:
Primary Nursing Care Goals:
Prevent catheter-associated infections (CAUTIs).
Maintain an uninterrupted, free flow of urine.
Maintain skin and mucosal membrane integrity.
Evidence-Based Interventions for CAUTI Prevention:
Perform meticulous hand hygiene before and after handling or manipulating any component of the catheter system.
Maintain a strictly closed, sterile drainage circuit; avoid disconnecting the catheter from the drainage tubing.
Position the urinary drainage collection bag continuously below the level of the patient's bladder to prevent gravitational backflow of colonized urine.
Keep tubing unkinked and free of dependent loops to prevent stagnation.
Secure the catheter properly to the patient's thigh or lower abdomen using dedicated securement devices (e.g., StatLock) to eliminate traction, friction, and urethral mucosal trauma.
Provide routine perineal hygiene using mild soap and water daily and immediately following bowel contamination; avoid aggressive antiseptic solutions or powders on the meatus.
Empty the drainage bag at regular intervals using an individualized, clean graduated container; avoid touching the drainage spout to the collection receptacle.
Maintain catheterization only as long as medically necessary; assess the clinical need for the catheter daily and advocate for immediate removal when criteria are no longer met.
Factors Affecting Urinary Elimination
Hydration Status:
High fluid intake increases renal blood flow and dilutes urine, leading to frequent elimination of pale, low-osmolarity urine.
Dehydration or fluid restriction causes compensatory water reabsorption, producing scant, highly concentrated, dark urine that irritates the bladder wall.
Medications:
Diuretics:
Increase renal excretion of water and electrolytes, dramatically expanding urine volume and increasing voiding frequency.
Medications Inducing Retention:
Anticholinergics, antihistamines, antispasmodics, tricyclic antidepressants, and opioid analgesics suppress bladder smooth muscle contractility, resulting in incomplete emptying or urinary retention.
Surgery and Anesthesia:
General anesthesia, epidural blocks, and spinal anesthesia depress spinal reflex centers, relax the detrusor muscle, and inhibit the micturition reflex.
Surgical manipulation of pelvic or abdominal viscera often causes localized tissue trauma, inflammation, and edema adjacent to the bladder neck and urethra.
Prostatic Enlargement:
Hyperplasia or neoplastic growth of the prostate gland mechanically constricts the prostatic urethra, leading to hesitancy, interrupted stream, nocturia, and urinary retention.
Psychosocial and Privacy Factors:
Inability to relax the pelvic floor and external urethral sphincter in unfamiliar environments, when using bedpans, or in the presence of healthcare personnel (paruresis or "shy bladder").
Pathological Conditions Affecting Elimination:
Urinary Tract Infections (UTIs).
Pyelonephritis (bacterial infection ascending into the renal pelvis and kidney parenchyma).
Glomerulonephritis (immune-mediated inflammation of renal glomeruli disrupting filtration).
Renal Calculi (nephrolithiasis and urolithiasis).
Chronic Kidney Disease (CKD) and End-Stage Renal Failure.
Pathological Conditions: UTIs, Renal Calculi, and Renal Failure
Urinary Tract Infection (UTI):
Pathophysiology:
Colonizing microorganisms (predominantly uropathogenic Escherichia coli) ascend through the urethral meatus into the sterile bladder environment, adhering to and invading the mucosal lining.
Signs and Symptoms:
Dysuria, frequent urination, urgency, suprapubic tenderness or cramping, cloudy or foul-smelling urine, and hematuria.
In older adults, atypical signs predominate: sudden confusion, altered mental status, lethargy, anorexia, and unexplained falls.
Treatment:
Prescribed oral or intravenous antimicrobial therapy based on culture and sensitivity.
Increased oral fluid intake to mechanically flush bacteria from the urinary tract.
Urinary analgesics (e.g., phenazopyridine) for symptomatic dysuria relief.
General UTI Prevention Principles:
Cleanse perineal and genital anatomy before and after sexual intercourse.
Urinate immediately following sexual intercourse to flush transient microorganisms from the urethra.
Cleanse the rectal area daily; wipe exclusively from front to back after elimination to prevent fecal contamination of the meatus.
Consume adequate volumes of water throughout the day to ensure frequent dilute voiding.
Avoid holding urine for extended intervals; empty the bladder regularly as soon as the urge is perceived.
Renal Calculi (Kidney Stones):
Definitions:
Nephrolithiasis: The formation or presence of calculi within the renal parenchyma, calyces, or pelvis.
Urolithiasis: The presence of calculi anywhere along the urinary tract, including the ureters, bladder, or urethra.
Signs and Symptoms:
Severe, sharp, spasmodic flank or back pain radiating downward toward the lower abdomen, groin, labia, or testicles (renal colic).
Gross or microscopic hematuria caused by mucosal abrasion from jagged crystalline structures.
Dysuria, urinary urgency, and frequency.
Systemic manifestations if obstruction or co-existing infection occurs: fever, chills, and diaphoresis.
Nausea and vomiting secondary to intense pain and shared celiac ganglion pathways.
Treatment Modalities:
Spontaneous Passage:
Managed conservatively for small calculi () via aggressive hydration, analgesia (NSAIDs, opioids), and alpha-blockers (e.g., tamsulosin) to relax ureteral smooth muscle.
All voided urine must be carefully strained using a fine mesh filter to capture calculi for laboratory analysis.
Extracorporeal Shock Wave Lithotripsy (ESWL):
Non-invasive therapeutic modality directing high-energy acoustic shock waves through the body wall to fragment stones into fine, passable gravel.
Renal Failure:
Definition:
Severe, progressive or sudden decline in renal function characterized by the inability to filter metabolic waste, balance electrolytes, regulate systemic fluid volume, and maintain acid-base homeostasis.
Leads to azotemia (accumulation of blood urea nitrogen and serum creatinine) and uremia.
Acute vs. Chronic Failure:
Acute Kidney Injury (AKI): Rapid, sudden onset of renal impairment, potentially reversible with prompt intervention.
Chronic Kidney Disease (CKD): Progressive, irreversible destruction of functional nephrons over months to years, culminating in End-Stage Renal Disease (ESRD).
Primary Causes:
Diabetes mellitus (diabetic nephropathy).
Hypertension (arteriosclerotic nephrosclerosis).
Chronic cardiovascular disease and heart failure (chronic hypoperfusion and cardiorenal syndrome).
Clinical Assessment Findings in Renal Failure:
Oliguria or frank anuria.
Fluid volume overload manifested by peripheral pitting edema, pulmonary crackles, jugular venous distension, and hypertension.
Elevated serum Blood Urea Nitrogen () and serum creatinine.
Electrolyte disturbances including hyperkalemia, hyperphosphatemia, hypocalcemia, and hypermagnesemia.
Chronic normocytic anemia resulting from diminished erythropoietin synthesis by peritubular capillary cells.
Uremic syndrome: pruritus, metallic taste, anorexia, nausea, lethargy, encephalopathy, and asterixis.
Urinary Diversions
Definition and Indications:
A urinary diversion is a surgical rerouting of the anatomical pathway of urine excretion.
Indicated when bladder function is permanently lost, when the lower urinary tract is obstructed, or following surgical cystectomy for invasive bladder cancer, severe trauma, or refractory neurogenic bladder dysfunction.
Ureteral Stent:
Thin, flexible, hollow polymeric tube placed internally within the lumen of the ureter.
Extends from the renal pelvis to the urinary bladder, maintaining bilateral or unilateral patency despite extrinsic compression, strictures, or edema.
Coiled ends ("double-J" or "pigtail" anchors) secure the proximal end in the kidney and the distal end in the bladder, preventing migration.
Urostomy (Ileal Conduit):
Incontinent cutaneous urinary diversion.
A short segment of the ileum (or colon) is surgically isolated and resected from the gastrointestinal tract while maintaining its mesenteric blood supply; bowel continuity is re-established via end-to-end anastomosis.
The distal end of the resected ileal segment is brought out through the anterior abdominal wall and everted to create a pink, vascular, protruding stoma.
The patient's ureters are surgically implanted into the proximal end of the conduit.
Urine flows continuously through the conduit into an external ostomy drainage pouch attached to the abdominal skin.
Key clinical note: Mucus strands are normally present in the urine because the conduit is constructed from bowel tissue that continually secretes mucus.
Nephrostomy:
Direct percutaneous insertion of a drainage tube through the posterolateral flank into the renal pelvis of the kidney.
Indicated for complete ureteral obstruction, stricture, or leakage where retrograde or anterograde internal drainage cannot be established.
Urine drains directly from the kidney into an external collection pouch secured to the patient's flank or leg.
Urinary Diagnostic Tests
Post-Void Residual (PVR):
Measures the exact volume of urine remaining in the bladder immediately following voluntary completion of voiding.
Assessed either non-invasively via ultrasound bladder scanner or invasively via straight catheterization.
Normal values are generally below ; volumes repeatedly exceeding indicate incomplete emptying and urinary retention.
Ultrasound of the Bladder and Kidneys:
Non-invasive diagnostic imaging utilizing sound waves to visualize the anatomical structure, dimensions, and contents of the renal parenchyma, calyces, and bladder lumen.
Identifies hydronephrosis, masses, calculi, cysts, structural anomalies, and retained urine volumes.
X-ray of the Kidneys, Ureters, and Bladder (KUB):
Plain anteroposterior abdominal radiograph performed to determine the size, shape, and relative position of the urinary organs.
Specifically screens for radio-opaque calcifications, renal stones, and foreign objects within the urinary tract.
Computed Tomography (CT Scan):
High-resolution, cross-sectional radiographic imaging of the urinary tract (with or without iodinated intravenous contrast).
Provides detailed visualization of soft-tissue masses, vascular perfusions, renal trauma, complex cysts, and radiolucent or tiny calculi.
Cystoscopy:
Invasive direct endoscopic visualization of the urethral mucosa, bladder neck, interior detrusor lining, and ureteral orifices using an illuminated, specialized instrument (cystoscope) inserted through the urethra.
Utilized for direct inspection of bladder tumors, biopsy of suspicious tissue, identification of calculi, and resection of lesions.
Ureteroscopy:
Transurethral insertion of a rigid or flexible endoscope past the bladder neck and directly up the ureter toward the renal pelvis.
Used for direct visualization, diagnosis, and removal or laser fragmentation of ureteral calculi.
Urinalysis Reference Values and Specimen Assessment
Urinalysis (UA) Standard Reference Ranges:
Color: Yellow (straw to amber).
Clarity: Clear (turbidity or cloudiness suggests presence of cells, bacteria, or crystals).
Specific Gravity:
Reflects renal concentrating ability.
Values indicate excessive hydration or dilute urine.
Values indicate marked dehydration, concentrated solutes, or presence of high-density substances (e.g., glucose, radiographic contrast).
: (average physiological value is approximately ).
Protein: Negative (presence indicates compromised glomerular filtration membrane barrier).
Bilirubin: Negative (presence suggests hepatobiliary obstruction or hepatic dysfunction).
Urobilinogen: Normal in small amounts.
Glucose: Negative (presence indicates serum glucose exceeding the renal absorptive threshold of approximately ).
Ketones: Negative (presence indicates incomplete fatty acid metabolism in diabetic ketoacidosis, starvation, or fasting).
Occult Blood: Negative.
Red Blood Cells (RBCs): No more than (males) to (females) per high-power field ().
White Blood Cells (WBCs): No more than per high-power field () (elevations indicate infection or inflammation).
Bacteria: Negative.
Leukocyte Esterase: Negative (enzyme produced by leukocytes; positive result strongly indicates active infection).
Casts: No more than hyaline casts per low-power field ().
Crystals: Few (excess indicates risk for stone formation or metabolic disorder).
Reagent Strips for Urinalysis (e.g., URS-10T / HENSOtest):
Dipsticks with dry chemical reagent pads dipped into fresh, uncentrifuged urine and compared against color reference charts.
Standard Testing and Incubation Reading Times:
Glucose: Read at exactly .
Bilirubin: Read at exactly .
Ketone: Read at exactly .
Specific Gravity: Read at exactly .
Blood: Read at exactly .
: Read at exactly .
Protein: Read at exactly .
Urobilinogen: Read at exactly .
Nitrite: Read at exactly .
Leukocytes: Read at exactly .
Methods of Urine Specimen Collection:
Clean-Catch (Midstream) Specimen:
Patient cleanses the periurethral area using antiseptic or sterile wipes from front to back.
Patient begins voiding a small volume into the commode to flush external urethral flora.
Without interrupting the urinary stream, the sterile collection container is positioned to collect a midstream sample.
The initial stream and terminal stream are not collected in the container.
Sterile Specimen from an Indwelling Catheter:
Must never be collected from the drainage collection bag, as that urine is stagnant, colonized, and non-sterile.
Clamp the drainage tubing below the sampling port for up to to allow fresh urine to collect.
Disinfect the specialized needleless Luer-Lok aspiration port using an approved antiseptic swab (e.g., alcohol or chlorhexidine) and allow it to air-dry.
Attach a sterile Luer-Lok syringe to the port and aspirate the desired volume of fresh urine directly into the syringe.
Transfer the sample to a sterile specimen container, unclamp the drainage tubing, and label the container at the bedside.
Fresh (Random) Specimen vs. Timed Urine Collection:
Fresh / Random Specimen:
Collected spontaneously during routine urination for standard urinalysis or drug screening.
Timed Collection:
Used for quantitative assessment of renal clearance, proteinuria, creatinine clearance, catecholamines, or hormones.
Procedure:
Initiate the test by having the patient void and discard the first morning urine specimen; record this exact clock time as the formal start of the window.
Collect all subsequent urine voided over the next and transfer it into the designated dark amber container containing preservatives.
Keep the collection container refrigerated or stored on wet ice throughout the duration of the test.
Exactly after the recorded start time, instruct the patient to empty the bladder completely and add this final voided specimen to the container.
Critical procedural rule: If any single void is accidentally discarded, spilled, or lost during the period, the entire test is invalidated and must be restarted from the beginning.