Case 1: Celia + Maria

Urinary Tract: Kidneys

Paired “bean” organs in posterior abdominal wall (under ribs)

Kidneys: Capsule

Fibrous outer layer

Kidneys: Layers

Inside capsule

1. Cortex: Outer

• Contain nephrons (filtration unit)

2. Medulla: Inner

• Outer and inner medulla

• Contain renal pyramids

• Papilla: Inner medulla

  • Project into renal pelvis

  • Connected to calyces (ureter extensions) at hilum

  • Minor calyces → Major calyces → Pelvis → Ureter

• Hilum: Contain blood vessels, nerves and ureter

Urinary Tract: Ureters

Connect kidneys to pelvis

Unitary smooth muscle wall

Ureters: Length

24-34 cm

Ureters: Divisions

Proximal (Abdominal): Renal pelvis to iliac bifurcation (iliac artery from aorta splitting)

• Upper portion

• Muscle layers

  • Circular and longitudinal

• Mucosal folds

Distal (Pelvic): Iliac bifurcation to bladder

• Lower portion

• Dense fibrovascular and neural tissue

• Muscle layer

  • Less organized

  • Thin

Intramural: At ureterovesical junction (UVJ)

• 2 cm

• In bladder wall

Ureters: Sites Constriction

Ureteropelvic Junction (UPJ): Connection with kidneys

• Posterior to renal vein and artery in hilum

UVJ: Connection with bladder

Ureters: Innervation

SNS: Lumbar splanchnic nerve

PNS: Pelvic splanchnic nerve and vagus nerve

Urinary Tract: Bladder

In anterior pelvis

Body: Smooth muscle (detrusor)

Neck (Posterior Urethra): Funnel-shaped detrusor muscle extension from body

• Connect to urethra

• Contain internal sphincter

Bladder: Females

Anterior to uterus and colon

Smaller

Bladder: Males

Superior to prostate

Anterior to colon

Larger

Urinary Tract: Urethra

Connect urinary bladder to exterior (exit body)

Contain external sphincter

• Skeletal muscle

Urethra: Males

Long (20 cm)

Pass through prostate gland, external urethral sphincter, and corpus spongiosum

Male Urethra: Regions

Pre-Prostatic: In bladder wall

Prostatic: Through prostate gland

Membranous: Through perineum and deep muscles

Spongy: Through penis in corpus spongiosum

Urethra: Females

Short (3-4 cm)

Urinary Tract Physiology: Kidneys

Filter plasma

• Reabsorb electrolytes, molecules, vitamins, and water

• Excrete metabolic waste and chemicals (drugs)

Regulate fluid volume, composition, and pH

Hormone secretion

• Regulate BP, erythropoiesis, and Ca2+ metabolism

Produce urine

• Empty into calyces (Stretch = Initiate peristaltic contractions)

• Push urine into ureters

Urinary Tract Physiology: Ureters

Transport urine from kidneys to bladder

• Peristaltic smooth muscle contraction

• Gap junctions between cells = Simultaneous action potential propagation = Synchronized contraction

Urinary Tract Physiology: Proximal Ureter

Muscle layers form functional sphincter

Regulate urine outflow from renal pelvis

Initiate peristaltic waves

Urinary Tract Physiology: Distal Ureter

Increased pain sensation

Peristaltic coordination

Urinary Tract Physiology: Intramural Ureter

Prevent vesicoureteral reflux (VUR)

• Urine backflow from bladder → Kidneys

Increase pressure on ureters = Dilation + Lengthening = Tortuous (twisted) appearance

Urinary Tract Physiology: Sites of Constriction

Increased risk of calculi (stones) lodging + obstructing urinary flow

Urinary Tract Physiology: Bladder

Body:

• Store urine

  • Normal tone of detrusor muscles compress ureters to prevent urine backflow

• Peristaltic contractions open ureters for urine entry

Neck:

• Internal sphincter

• Natural tone (constricted) = Prevent bladder emptying

Bladder: Micturition

Empty urine into urethra

1. Bladder filling = Increase wall tension > Threshold level = Activate mechanoreceptors

2. CNS sends somatic signals to bladder = Open internal sphincter

3. Activate micturition reflex (autonomic from spinal cord) = Detrusor muscle contraction = Empty into urethra

• Inhibited or facilitated by cerebral cortex or brain stem

Urinary Tract Physiology: Urethra

External sphincter

• Voluntary control

• Contraction = Prevent bladder emptying

Urinary Tract Infections (UTI): Description

Urinary system infection

Lower: Bladder (cystitis) or urethra infection

• Most common

Upper: Kidney (pyelonephritis) or ureter infection

Recurrent:

• ≥ 3 episodes in 1 year

• ≥ 2 episodes in 6 months

UTI: Epidemiology

Risk factors:

• Structural/functional urinary tract abnormalities

  • Ex: Benign prostatic hyperplasia, VUR

• Metabolic conditions

• Genetic predisposition

• Previous UTI

• Antibiotic use

• Female

  • Shorter urethra

  • Anal and genital regions in close proximity

UTI: Etiology

Usually bacterial infection ascending from urethra to bladder

• E. coli: Most common

By Population:

• Adults:

  • Female: Most common

  • Male: Low before 50, increase with age from benign prostatic hyperplasia obstructing urinary tract

• Children: Most common

  • Female: Increased incidence in girls >1 years

  • Male: More common than girls (esp uncircumcised)

• Transgender:

  • Incidence depend on current genitourinary anatomy + history of gender-affirming surgery

  • M → F: Increased risk from lack of commensal vaginal bacteria

UTI: Recurrent Etiology

Bacterial Characteristics:

• Virulence factors = Evade host response = Increase adaptation and colonization

Host Factors: 

• Genetic predisposition

Behavioural Factors:

• Disturb vaginal microbiome = Increase colonization

  • Frequent sexual intercourse

  • Spermicide use

• Hygiene

  • Wiping back to front

UTI: Pathogenesis

1. Bacteria from bowel or vagina colonize periurethral mucosa

• Ascending Infection: Migrate from urethra → Bladder → Kidneys (sometimes)

2. Bacteria adapt to urinary tract

• Virulence factors

• Biofilm formation

UTI: Clinical Presentation

Lower:

• Urethra:

  • Dysuria

  • Urethra pruritus (itching)

  • Abnormal urethral discharge

• Bladder:

  • Suprapubic or pelvic pain

    • Increased during filling

    • Relieved from voiding

  • Nocturia

Upper:

• Kidney:

  • Flank pain

  • Fever

  • Malaise

  • Hematuria

  • Impaired renal function

    • Edema

    • Hypertension

UTI: Investigation

Urinalysis

Cultures

Imaging

UTI: Urinalysis

Best initial test

Collection:

• Clean-catch midstream sample

• Bladder catheterization

Pyuria: WBC in urine

• Positive leukocyte esterase (emzyme from WBC)

Bacteriuria: Bacteria in urine

• Nitrites: Gram- bacteria converting nitrates to nitrites

Alkaline Urine: Urease-producing organisms

UTI: Cultures

For complicated or recurrent UTI

Bacteriurua: ≥ 10^5 CFU/mL

Organisms from suprapubic aspiration

• Needle through abdomen into bladder to collect sample

UTI: Imaging

For suspected urinary tract obstruction (No response to antibiotics)

CT

Ultrasound

UTI Imaging: CT

Abdominal and pelvic

UTI Imaging: Ultrasound

Kidney and bladder

UTI: Treatment/Management

Antibiotics

Increase hydration

UTI Treatment: Antibiotics

Empiric first-line

• Nitrofurantoin

• Trimethoprim/sulfamethoxazole (TMP/SMZ)

• Fosfomycin (1 dose)

Complicated Lower: Fluorouinolones (first-line)

Recurrent: TMP/SMZ prophylaxis

UTI: Complications

Pyelonephritis

Benign Prostatic Hyperplasia: Description

Smooth muscle and epithelial cell proliferation in prostate

Increase risk of lower UTIs

Benign Prostatic Hyperplasia: Management

Little to no symptoms: Nonpharmacological therapy (watchful waiting)

Symptomatic: Pharmacotherapy and surgery

Benign Prostatic Hyperplasia: Nonpharmacological Therapy

Drugs: Stop/decrease drugs contributing to symptoms

• Ex: Opioids, TCA antidepressants, antihistamines

Diet Changes: Decrease caffeine and alcohol

Bladder-emptying techniques

Benign Prostatic Hyperplasia: Pharmacotherapy

First-line

Alpha Blockers:

• Inhibit alpha 1-receptors in bladder neck and urethra = Relax smooth muscles = Decrease urinary outflow resistance

5-Alpha Reductase Inhibitors (5-ARIs):

• Inhibit 5-alpha reductase = Decrease testosterone → DHT = Decrease prostatic growth + Increase prostatic apoptosis

Benign Prostatic Hyperplasia: Surgery

Second-line

Transurethral resection of prostate (gold standard)

• Remove excess prostatic tissue around urethra

Nephrolithiasis: Description

Crystalline mineral deposit form in kidneys and ureters

• Uretal or kidney stones (renal calculi)

Nephrolithiasis: Epidemiology

Risk factors:

• Male

• Older age

• Low fluid intake/dehydration

• Prolonged immobilization

• Diet

  • High Na+

  • Low Ca2+

  • Supplements

• Family history

Nephrolithiasis: Etiology

Calcium Oxalate Stones: Most common

• Caused by hypercalciuria, hyperoxaluria, hypocitraturia

Uric Acid Stones:

• Caused by

  • Gout: Uric acid crystals precipitate in joints

  • Hyperuricemia: High serum uric acid concentration

  • Hyperuricosuria: High uric acid excretion in urine (ketogenic diet)

  • High cell turnover

*Struvite Stones:

• Caused by urease-producing bacteria

Cysteine Stones:

• Caused by cystinuria (hereditary)

Nephrolithiasis: Pathogenesis

For calcium oxalate stones

1. Dehydration and high Ca2+ diet = Low urine volume + High Ca2+ reabsorption

2. Increased urine Ca2+ saturation = Crystals deposit in kidney (papillae) and ureters

• Cellular injury, oxidative stress, and inflammation increase crystal retention and aggregation

Nephrolithiasis: Clinical Presentation

Depend on location and size

• Larger = More symptoms

Severe unilateral flank pain (renal colic)

• Radiating (loin to groin)

• Paroxysmal or progressive

• Tenderness around kidneys

Hematuria

Nausea/vomiting

Dysuria

• Increased frequency and urgency

Nephrolithiasis: Investigation

Urinalysis

Microscopy

Blood test

CT

Ultrasound

X-ray

Stone composition analysis

Nephrolithiasis: Urinalysis

First-line

Hematuria

Alkaline/acidic urine

Nephrolithiasis: Microscopy

Determine crystals = Stone composition

Nephrolithiasis: Blood Test

Metabolic panel to determine metabolite (Ca2+, uric acid) concentration in blood

High WBC

Nephrolithiasis: CT

Gold standard

Stones/calcifications in kidneys and ureters

Determine size, location, density, and degree of obstruction

Nephrolithiasis: Ultrasound

Minimize radiation exposure (pregnant, pediatric)

Hyperechoic stones + Shadowing

Nephrolithiasis: X-Ray

Intravenous pylogram (IVP)

• X-ray + contrast

Rare → Use CT instead

Nephrolithiasis: Stone Composition Analysis

In first stone

Nephrolithiasis: Treatment/Management

Manage symptoms

Non-interventional

Interventional

Nephrolithiasis Treatment: Manage Symptoms

Analgesia

• First-line: NSAIDs

• Second-line: Opioids

Antiemetics

IV fluids (dehydration)

Nephrolithiasis Treatment: Non-Interventional

Medical expulsive therapy (MET)

• First-Line: Tamsulosin (alpha blocker)

• Prevent ureter muscle spasms to promote stone passing

Antibiotics for UTIs

Diet modifications

• Low Na+ and oxalate

• Supplement vit C

Nephrolithiasis Treatment: Interventional

Extracorporeal shock wave lithotripsy (ESWL): Acoustic shockwaves breakdown stones

• Noninvasive

*Ureteroenoscopy: Endoscope insertion to remove stone

• Invasive

Percutaneous nephrolithotomy (PCNL): Puncture renal pelvis calyx + insert endoscope to remove stone

• Invasive

• For larger stones

*Ureterolithotomy: Ureteral incision to remove stone

• Invasive

Nephrolithiasis: Prognosis

Small Stones (≤ 5 mm): Pass spontaneously

Larger Stones (≥ 10 mm) : Unlikely to pass spontaneously

Recurring stones within 10 years = 50%

Cause or caused by UTIs