45.3 Nephrolithiasis & Acute Urinary Tract Obstruction

ABFM Family Medicine Certification Study Guide Exam

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22 Chapter 22: Acute Orthopedic & Musculoskeletal Emergencies

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23 Chapter 23: Severe Infections, Sepsis & Systemic Emergencies

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24 Chapter 24: Metabolic, Endocrine & Electrolyte Emergencies

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25 Chapter 25: Hematologic, Urologic & Dental Emergencies

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26 Chapter 26: Psychiatric, Behavioral & Obstetric/Gynecologic Emergencies

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28 Chapter 28: Acute Cranial Nerves, Hearing & Sensory Symptoms

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29 Chapter 29: Acute Upper Respiratory Tract Infections

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30 Chapter 30: Acute Lower Respiratory Infections & Cough

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31 Chapter 31: Allergic, Nasal & Non-Infectious Pulmonary Conditions

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33 Chapter 33: Acute Upper Gastrointestinal Conditions

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34 Chapter 34: Acute Lower Gastrointestinal Conditions

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35 Chapter 35: Inflammatory, Functional & Malabsorptive GI Disorders

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36 Chapter 36: Acute Abdominal, Hepatic & Biliary Disorders

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37 Chapter 37: Acute Abdominal Wall, Hernias & Dental Conditions

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38 Chapter 38: Acute Infectious Dermatoses

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39 Chapter 39: Inflammatory, Allergic & Autoimmune Dermatoses

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40 Chapter 40: Acute Shoulder, Elbow & Upper Extremity Injuries

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41 Chapter 41: Acute Knee, Ankle & Lower Extremity Injuries

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42 Chapter 42: Acute Ambulatory Fractures & Dislocations

42.1 Distal Radius, Scaphoid & Common Upper Extremity Fractures 42.2 Metatarsal, Clavicle & Common Lower Extremity Fractures 42.3 Joint Dislocation Management: Nursemaid's Elbow & Shoulder Subluxation

43 Chapter 43: Acute Axial Musculoskeletal Pain & Falls

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44 Chapter 44: Acute Inflammatory Arthropathies & Generalized Pain

44.1 Acute Inflammatory Arthritis & Spondyloarthropathies 44.2 Myalgias, Rhabdomyolysis & Post-Viral Pain Syndromes 44.3 Acute Non-Headache Pain Management Strategies

45 Chapter 45: Acute Renal, Urinary & Genitourinary Conditions

45.1 Uncomplicated UTI, Pyelonephritis & Acute Urethritis 45.2 Hematuria Workup & Glomerulonephritis 45.3 Nephrolithiasis & Acute Urinary Tract Obstruction

46 Chapter 46: Acute Male Genitourinary & Prostatic Conditions

46.1 Acute Prostatitis, Epididymitis & Orchitis 46.2 Acute Scrotal Pain: Torsion vs Appendage, BPH & Male Genital Emergencies 46.3 Acute Urinary Retention & Incontinence Evaluation

47 Chapter 47: Acute Women's Health & Early Pregnancy Care

47.1 Early Pregnancy Diagnosis, Dating & Initial Complications 47.2 Abnormal Uterine Bleeding & Acute Menstrual Disorders 47.3 Premenstrual Syndrome & Premenstrual Dysphoric Disorder

48 Chapter 48: Breast Disorders, STIs & Pediatric Elimination

48.1 Palpable Breast Mass, Mastitis & Nipple Discharge 48.2 Sexually Transmitted Infections: Diagnosis, Staging & CDC Guidelines 48.3 Pediatric Enuresis & Encopresis

49 Chapter 49: Systemic Signs, Metabolic Dysregulation & Miscellaneous Infections

49.1 Acute Fever, Sepsis Screening & FUO in Primary Care 49.2 Acute Hyperglycemia & Symptomatic Hypoglycemia 49.3 Electrolyte Abnormalities: Mild-to-Moderate Disturbances 49.4 Vector-Borne, Tick-Borne & Rickettsial Illnesses

50 Chapter 50: Chronic Cardiovascular Diseases: Hypertension & Ischemia

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51 Chapter 51: Chronic Vascular, Valvular & Dyslipidemic Diseases

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52 Chapter 52: Chronic Respiratory Diseases: Asthma & COPD

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53 Chapter 53: Chronic Metabolic Diseases: Diabetes Mellitus

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54 Chapter 54: Obesity, Nutrition & Metabolic Bone Diseases

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55 Chapter 55: Chronic Endocrine Disorders

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56 Chapter 56: Chronic Kidney Disease & Venous Disorders

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57 Chapter 57: Chronic Gastrointestinal & Hepatic Diseases

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58 Chapter 58: Colorectal Surveillance & Chronic Pancreaticobiliary Care

58.1 Post-Polypectomy Colorectal Polyp Surveillance Guidelines 58.2 Chronic Pancreatitis & Exocrine Pancreatic Insufficiency 58.3 Chronic Nausea, Gastroparesis & Functional GI Disorders

59 Chapter 59: Chronic Musculoskeletal & Rheumatologic Disorders

59.1 Osteoarthritis: Hip, Knee & Hand Management 59.2 Spinal Conditions: Spinal Stenosis, Spondylolisthesis & Compression Fractures 59.3 Chronic Myopathies & Fibromyalgia Syndrome

60 Chapter 60: Chronic Neurologic & Neurodegenerative Disorders

60.1 Dementia: Alzheimer's, Vascular & Lewy Body Disease 60.2 Parkinson's Disease & Essential Tremor 60.3 Epilepsy: Chronic Antiseizure Medications & Post-Stroke Care

61 Chapter 61: Chronic Peripheral Nerves, Pain & Sensory Disorders

61.1 Diabetic & Chronic Peripheral Neuropathies 61.2 Chronic Pain Syndromes & Chronic Daily Headaches 61.3 Chronic Tinnitus, Presbycusis & Persistent Dizziness

62 Chapter 62: Chronic Psychiatric Disorders

62.1 Major Depressive Disorder & Generalized Anxiety Disorder 62.2 Bipolar Disorder: Maintenance Pharmacotherapy & Lithium Monitoring 62.3 Adult & Pediatric Attention-Deficit/Hyperactivity Disorder

63 Chapter 63: Chronic Behavioral Health & Neurodevelopmental Conditions

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64 Chapter 64: Chronic Substance Use Disorders & Tobacco Cessation

64.1 Alcohol Use Disorder: Pharmacotherapy & Relapse Prevention 64.2 Opioid & Stimulant Use Disorders: MOUD & Harm Reduction 64.3 Longitudinal Tobacco Cessation Pharmacotherapy

65 Chapter 65: Chronic Dermatologic Conditions

65.1 Acne Vulgaris, Rosacea & Seborrheic Dermatitis 65.2 Chronic Plaque Psoriasis & Biologic Therapies 65.3 Chronic Eczema, Hidradenitis Suppurativa & Cutaneous Lupus

66 Chapter 66: Chronic Reproductive, Infectious & Geriatric Special Care

66.1 Chronic Menstrual Disorders, Infertility & Sexual Dysfunction 66.2 Menopause Management & Hormone Replacement Therapy 66.3 Chronic HIV Infection Management & Primary Care Integration 66.4 Gender-Affirming Primary Care & Hormone Therapy 66.5 Advance Care Planning, Palliative Care & End-of-Life Symptom Control

67 Chapter 67: Continuity Care: Sleep, Fatigue, Cancer, Pregnancy & the Adult Preventive Visit

67.1 Chronic Insomnia & Obstructive Sleep Apnea 67.2 Chronic Malaise, Fatigue & ME/CFS 67.3 Primary Care During Cancer Treatment & Survivorship 67.4 Routine Prenatal Care & Longitudinal Pregnancy Management 67.5 The Periodic Adult Health Examination & Medicare Annual Wellness Visit

45.3 Nephrolithiasis & Acute Urinary Tract Obstruction

Key Takeaways Explain This Topic AI

Calcium oxalate calculi account for 70% to 80% of all renal stones and appear radiopaque on imaging with envelope-shaped crystals; major metabolic drivers include idiopathic hypercalciuria, hypocitraturia, and enteric hyperoxaluria from malabsorptive states or bariatric surgery.

Uric acid stones (5% to 10%) are uniquely radiolucent on plain radiographs but readily detectable on non-contrast CT; they precipitate in persistently acidic urine (pH <5.5) and can be chemically dissolved without surgery via urinary alkalinization with oral potassium citrate (target urine pH 6.5 to 7.0).

Struvite (triple phosphate) staghorn calculi form exclusively in persistently alkaline urine (pH >7.2) infected by urease-producing bacteria such as Proteus mirabilis; antibiotics cannot sterilize the stone matrix, mandating complete surgical removal (percutaneous nephrolithotomy).

Low-dose non-contrast CT of the abdomen and pelvis is the diagnostic gold standard for suspected nephrolithiasis, whereas renal and bladder ultrasound is the first-line imaging modality of choice in pregnant individuals and pediatric patients.

An obstructing ureteral calculus accompanied by urinary tract infection (fever, pyuria, urosepsis) represents an emergent surgical crisis mandating immediate urgent decompression via retrograde ureteral stenting or percutaneous nephrostomy, rather than delayed stone fragmentation.

Last updated: September 2026

Epidemiology, Pathophysiology & Stone Compositions

Nephrolithiasis (urolithiasis) affects approximately 10% to 12% of men and 7% to 8% of women in the United States during their lifetime, with annual healthcare costs exceeding $5 billion. Following an initial stone episode, the 5-year recurrence rate approaches 50% in the absence of targeted metabolic evaluation and dietary modification.

Physicochemical Pathogenesis

Stone formation is driven by urinary supersaturation of insoluble mineral salts, exceeding the thermodynamic solubility product ( K s p K_{sp} K s p ​ ). This triggers crystal nucleation, crystal growth, and crystal aggregation.

Randall's Plaques : In the majority of calcium oxalate stone formers, stone formation originates as subepithelial deposits of calcium phosphate in the basement membrane of the thin loops of Henle. These deposits erode through the papillary urothelium into the renal calyx, serving as an exposed, mineralized nidus (Randall's plaque) upon which calcium oxalate rapidly precipitates.

Promoters vs. Inhibitors : Pathophysiologic stone risk represents an imbalance between urinary stone promoters (calcium, oxalate, uric acid) and endogenous inhibitors of crystallization (most notably urinary citrate , pyrophosphate, and magnesium). COMPREHENSIVE COMPARISON OF RENAL CALCULI

• Stone Type Prevalence Radiopacity Urine pH Crystal Shape Key Risk Factors & Etiologies
• ═══════════════════════════════════════════════════════════════════════════════════════════════════════════
• Calcium Oxalate 70% to 80% Radiopaque Variable Bipyramidal • Idiopathic hypercalciuria
• (Dense) (5.5 - 6.5) "Envelope" / • Enteric hyperoxaluria (Crohn,
• dumbbell bariatric surgery, malabsorption)
• Hypocitraturia (acidosis, diarrhea)

• Calcium Phosphate 10% to 15% Radiopaque Alkaline Wedge-shaped prisms • Distal Renal Tubular Acidosis (RTA 1)
• (Very dense) (>7.0) or rosettes • Primary hyperparathyroidism

• Uric Acid 5% to 10% RADIOLUCENT Acidic Pleomorphic • Persistent acidic urine (pH <5.5)
• on X-ray; (<5.5) rhomboids or • Gout, metabolic syndrome, diabetes
• Visible CT needles • Chronic diarrhea (bicarbonate loss)

• Struvite 5% to 10% Radiopaque Alkaline Rectangular • Urease-producing bacteria
• (Mg-NH4-PO4; (Variable) (>7.2) "Coffin-lid" (Proteus mirabilis, Klebsiella)
• "Staghorn") prisms • Massive staghorn calculi

• Cystine 1% Faintly Acidic Pathognomonic • Autosomal recessive cystinuria
• Radiopaque (<6.5) HEXAGONAL • Defective COLA transporter
• (Ground-glass) plates • Sodium cyanide-nitroprusside (+)
• ═══════════════════════════════════════════════════════════════════════════════════════════════════════════
• Detailed Stone Chemistry & Metabolic Drivers
• 1. Calcium Oxalate Calculi (70% to 80%)

Idiopathic Hypercalciuria : The most prevalent identifiable metabolic abnormality, present in >50% of calcium stone formers (defined as 24-hour urinary calcium >250 mg in women or >300 mg in men, or >4 mg/kg/day). Driven by increased intestinal calcium absorption, reduced renal tubular calcium reabsorption, or bone resorptive states.

Hyperoxaluria : Oxalate is an organic dicarboxylic acid derived from endogenous hepatic metabolism and dietary absorption (spinach, rhubarb, beets, nuts, chocolate, black tea).

Enteric Hyperoxaluria : Seen in Crohn disease, chronic pancreatitis, celiac sprue, and Roux-en-Y gastric bypass . In malabsorptive states, unabsorbed fatty acids bind luminal calcium to form insoluble soaps. This leaves dietary oxalate unbound, free, and hyper-absorbed in the colon, precipitating severe calcium oxalate stones.

Hypocitraturia : Urinary citrate is the primary endogenous defense against calcium nephrolithiasis. Citrate binds ionized calcium in the tubular lumen, forming a soluble calcium-citrate complex that lowers free calcium ion activity and prevents crystal aggregation. Hypocitraturia (<320 mg/day) is triggered by chronic intracellular metabolic acidosis (distal RTA, chronic diarrhea, excessive animal protein intake, hypokalemia, or carbonic anhydrase inhibitors like topiramate).

The Dietary Calcium Paradox : Patients mistakenly believe that restricting dietary calcium prevents calcium stones. In reality, low dietary calcium INCREASES stone recurrence . In the gut lumen, adequate dietary calcium binds dietary oxalate, forming insoluble calcium oxalate that is excreted in feces. If dietary calcium is restricted, free oxalate absorption skyrockets, driving hyperoxaluria. Patients must maintain normal dietary calcium intake (1,000 to 1,200 mg/day) taken with meals, while restricting dietary sodium (<2,000 mg/day; sodium excretion drives passive calcium excretion in the proximal tubule) and limiting excess animal protein.

2. Calcium Phosphate Calculi (10% to 15%)

Calcium phosphate precipitates exclusively in alkaline urine (pH >7.0) .

Strongly associated with two major conditions:

Distal Renal Tubular Acidosis (Type 1 RTA) : Impaired collecting duct hydrogen ion excretion produces a persistently elevated urine pH (>5.5 to 6.5) alongside systemic hypokalemic metabolic acidosis and hypocitraturia, creating the ideal milieu for nephrocalcinosis and brushite/apatite stones.

Primary Hyperparathyroidism : Excessive parathyroid hormone (PTH) drives hypercalcemia, hypercalciuria, and alkaline urine.

3. Uric Acid Calculi (5% to 10%)

The Critical Role of Urine pH : The pKa of uric acid is 5.35. At a urine pH <5.5, over 85% of uric acid exists in its un-ionized, highly insoluble form (solubility <100 mg/L). At a urine pH >6.5, uric acid dissociates into soluble urate salts (solubility >1,000 mg/L—a 10-fold increase!).

Etiology : Driven primarily by persistently low urine pH (<5.5) , commonly seen in metabolic syndrome and type 2 diabetes mellitus (impaired renal tubular ammoniagenesis), chronic diarrhea (gastrointestinal loss of bicarbonate leading to concentrated, acidic urine), and gout or myeloproliferative disorders.

Radiographic Feature : Uric acid stones have a density similar to soft tissue; they are COMPLETELY RADIOLUCENT on plain X-rays (KUB) , but appear clearly on non-contrast CT (Hounsfield units typically 300 to 500 HU).

Chemolysis (Medical Dissolution) : Uric acid stones are uniquely treatable and dissolvable without surgical intervention through urinary alkalinization . Oral potassium citrate (20 to 30 mEq two to three times daily) is titrated to maintain a urinary pH of 6.5 to 7.0 . Over-alkalinization (pH >7.5) must be avoided to prevent calcium phosphate precipitation on the stone surface. Allopurinol is added only if hyperuricemia or marked hyperuricosuria is present.

4. Struvite / Triple Phosphate Calculi (5% to 10%)

Pathogenesis : Composed of magnesium ammonium phosphate ( M g N H 4 P O 4 ⋅ 6 H 2 O MgNH_4PO_4 \cdot 6H_2O M g N H 4 ​ P O 4 ​ ⋅ 6 H 2 ​ O ) and carbonate apatite. They form exclusively in the presence of upper urinary tract infections with urea-splitting (urease-producing) bacteria :

• Proteus mirabilis (most common)
• Klebsiella pneumoniae , Pseudomonas aeruginosa , Providencia , Morganella

Note : Escherichia coli DOES NOT produce urease and cannot cause struvite calculi!

Biochemical Reaction : Bacterial urease hydrolyzes urea into ammonia and carbon dioxide: Urea + H 2 O → Urease 2 N H 3 + C O 2 \text{Urea} + H_2O \xrightarrow{\text{Urease}} 2NH_3 + CO_2 Urea + H 2 ​ O Urease ​ 2 N H 3 ​ + C O 2 ​ Ammonia buffers hydrogen ions to form ammonium ( N H 4 + NH_4^+ N H 4 + ​ ) and hydroxide ( O H − OH^- O H − ), driving urine pH to highly alkaline levels (>7.2 to 8.0) , which precipitates magnesium, ammonium, and phosphate.

Staghorn Calculi : Struvite stones rapidly enlarge to fill the renal pelvis and calyces, creating a branched "staghorn" calculus. They frequently grow insidiously without classic renal colic, presenting with recurrent UTIs, alkaline urine, persistent pyuria, or progressive renal failure.

Management : Struvite calculi CANNOT be sterilized with antibiotics alone because bacteria reside within the crystalline matrix. Definitive therapy requires complete surgical removal (typically Percutaneous Nephrolithotomy [PCNL]) , followed by targeted antimicrobial therapy.

5. Cystine Calculi (1%)

Etiology : Autosomal recessive genetic mutation in SLC3A1 or SLC7A9 , impairing the dibasic amino acid transporter in the proximal tubule. This causes massive urinary excretion of Cystine, Ornithine, Lysine, and Arginine (COLA) .

Diagnosis : Pathognomonic flat, hexagonal crystals on urinalysis; positive sodium cyanide-nitroprusside screening test (turns red-purple).

Management : Aggressive hydration (>3.5 to 4 L/day to maintain urine output >3 L/day, including waking at night to drink), urinary alkalinization with potassium citrate (target pH >7.0 to 7.5), and thiol-chelating agents ( tiopronin or D-penicillamine) for refractory stone formation.

Clinical Presentation of Acute Renal Colic

Acute renal colic is universally described by patients as one of the most agonizing, excruciating pain experiences in medicine.

Cardinal Clinical Manifestations

Sudden Onset of Severe Flank Pain : Abrupt, unrelenting pain localized to the costovertebral angle, waxing and waning in paroxysms as the ureter hyperperistalses against obstruction.

Classic Dermatomal Radiation : Pain radiates anteriorly and inferiorly along the anatomical course of the ureter into the ipsilateral lower abdominal quadrant, groin, scrotum/testicle in males, or labium majorum in females (T10-L1 dermatomes).

Motor Restlessness (The "Colic Writhing") : The pain is visceral. In stark contrast to patients with acute peritonitis (who lie rigidly motionless because movement exacerbates somatic peritoneal irritation), patients with acute renal colic are characteristically unable to find a comfortable position, pacing the examination room, writhing, or tossing and turning on the gurney .

Autonomic Signs : Severe nausea, projectile vomiting, diaphoresis, pallor, and reflex hypertension/tachycardia.

Irritative Bladder Symptoms (UVJ Impaction) : When a calculus is lodged at the ureterovesical junction (UVJ—the narrowest anatomical constriction), it causes intense trigonal irritation, producing severe urinary frequency, urgency, dysuria, and pelvic fullness that mimics lower urinary tract cystitis.

Urinalysis in Renal Colic

Microscopic or Gross Hematuria : Present in 85% to 90% of acute nephrolithiasis presentations.

CRITICAL EXAM PEARL : The absence of hematuria occurs in 10% to 15% of confirmed stone cases ! Complete, high-grade ureteral obstruction prevents blood from flowing past the calculus into the bladder, resulting in a normal urinalysis. The absence of hematuria does NOT rule out acute nephrolithiasis in a patient with classic flank colic.

Diagnostic Imaging Protocols: NCCT vs. Renal Ultrasound DIAGNOSTIC IMAGING MODALITIES IN NEPHROLITHIASIS

• Imaging Modality Diagnostic Performance Role, Indications & Clinical Pearls
• ═══════════════════════════════════════════════════════════════════════════════════════════
• Low-Dose • Sensitivity: 98% • DIAGNOSTIC GOLD STANDARD in non-pregnant adults
• Non-Contrast CT • Specificity: 97% • Accurately measures stone size (maximum axial
• Abdomen/Pelvis • Radiation: ~1.5 - 3 mSv dimension), exact location, and Hounsfield units
• (NCCT) • Detects secondary obstruction: hydronephrosis,
• hydroureter, and perinephric fat stranding

• Renal & Bladder • Sensitivity: 70% to 85% • FIRST-LINE IMAGING in PREGNANCY & PEDIATRICS
• Ultrasound • Specificity: 90% to 95% • Visualizes hydronephrosis (pelvicalyceal dilation)
• NO radiation exposure • Identifies acoustic shadowing of renal stones
• Assesses ureteral jets on Doppler (absence = obstruction)
• Poor sensitivity for mid-ureteral stones and <5 mm stones

• Plain Radiographs • Sensitivity: 50% to 60% • Useful only for following known radiopaque
• (KUB: Kidneys, • Specificity: 70% calcium stones previously visible on X-ray
• Ureters, Bladder) • Low cost & radiation • Misses radiolucent uric acid stones entirely
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• Urological Surgical Emergencies: Immediate Decompression Criteria

Primary care clinicians must immediately identify presentations that represent life-threatening urological crises requiring emergent decompression rather than conservative management. EMERGENT INDICATIONS FOR IMMEDIATE SURGICAL DECOMPRESSION

• 1. OBSTRUCTING CALCULUS WITH CONCURRENT URINARY TRACT INFECTION / SEPSIS
• Clinical Triad: Ureteral stone obstruction + Fever / Pyuria / Bacteremia + Sepsis
• Pathophysiology: An obstructed renal collecting system under pressure creates an enclosed

abscess, rapidly precipitating bacterial endotoxemia, septic shock, and renal destruction.

• ACTION: IMMEDIATE EMERGENT SURGICAL DECOMPRESSION via:

• a) Retrograde Ureteral Stenting (Double-J stent), OR
• b) Percutaneous Nephrostomy (PCN) tube placement

• Concurrent IV broad-spectrum antibiotics and fluid resuscitation.
• CONTRAINDICATION: DO NOT attempt definitive stone fragmentation (lithotripsy) during sepsis!

2. COMPLETE ANURIC OBSTRUCTION

• Bilateral ureteral obstruction, OR acute obstruction of a solitary or transplanted kidney.
• Rapidly induces anuric post-renal acute kidney injury, fatal hyperkalemia, and uremic coma.

3. INTRACTABLE PAIN OR EMESIS

• Severe, debilitating pain or persistent nausea/vomiting refractory to maximal IV analgesia.

4. PROGRESSIVE RENAL INSUFFICIENCY

• Persistent obstruction leading to progressive elevation in serum creatinine.

Conservative Medical Expulsive Therapy (MET) & Interventional Strategies

For uncomplicated ureteral calculi in hemodynamically stable patients without infection or severe renal compromise, management is dictated primarily by stone size and anatomical location . MANAGEMENT BY CALCULUS SIZE & PASSAGE PROBABILITY

• Stone Size Spontaneous Passage Rate Recommended Clinical Management Strategy
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• < 5 mm 80% to 90% within 4 weeks • Conservative outpatient trial of passage
• Oral hydration (2 to 3 L/day) + oral NSAIDs
• Urine straining with fine mesh filter
• Follow-up imaging in 2 to 4 weeks

5 mm to 10 mm ~50% within 4 to 6 weeks • MEDICAL EXPULSIVE THERAPY (MET):

• Tamsulosin 0.4 mg PO daily x 4 weeks
• Accelerates expulsion; reduces analgesic needs
• Elective intervention if not passed in 4-6 wk

• > 10 mm <10% to 20% • Unlikely to pass spontaneously
• Conservative trials NOT recommended
• Early elective urologic intervention (SWL or URS)
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• Medical Expulsive Therapy (MET) Protocol

Alpha-1 Receptor Antagonists (Tamsulosin 0.4 mg PO daily) : Alpha-1D and alpha-1A adrenergic receptors are densely distributed in the distal third of the human ureter. Tamsulosin inhibits basal ureteral smooth muscle tone and hyperperistaltic spasm while preserving antegrade propulsive flow. Clinical trials and meta-analyses demonstrate that tamsulosin:

Increases spontaneous expulsion rates by 20% to 30% for distal ureteral stones between 5 mm and 10 mm.

Reduces time to expulsion by 2 to 6 days.

Significantly decreases analgesic requirements and recurrent emergency department visits.

Analgesia : Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) (e.g., Ketorolac 15-30 mg IV in the acute setting, followed by oral Ibuprofen 600-800 mg TID or Naproxen 500 mg BID) represent the first-line analgesics of choice for acute renal colic . NSAIDs inhibit cyclooxygenase, suppressing renal prostaglandin synthesis. This diminishes renal blood flow, lowers glomerular filtration rate, reduces renal pelvic pressure, and directly relieves ureteral smooth muscle spasm. Multiple clinical trials demonstrate that NSAIDs provide faster, more sustained pain relief with fewer adverse effects (sedation, vomiting) compared to opioids.

Urine Straining & Metabolic Follow-Up : The patient must strain all urine through a fine mesh filter. Any recovered calculus must be sent for X-ray diffraction or infrared spectroscopy stone composition analysis. Follow-up imaging (ultrasound or low-dose KUB/CT) must be performed in 2 to 4 weeks to confirm passage and rule out "silent" asymptomatic obstruction, which can permanently destroy renal function without pain.

Definitive Urological Interventions

When stones fail conservative therapy, exceed 10 mm, or cause persistent obstruction:

Extracorporeal Shock Wave Lithotripsy (SWL) : External acoustic shock waves focused under fluoroscopy or ultrasound to fragment stones into small gravel. Best suited for proximal ureteral or renal pelvis stones <20 mm (<2 cm) . Contraindicated in pregnancy, untreated UTI, bleeding diathesis/anticoagulation, and hard stones (cystine, brushite).

Ureteroscopy (URS) with Laser Lithotripsy : Rigid or flexible ureteroscope advanced transurethrally into the ureter or renal pelvis, utilizing a Holmium:YAG or Thulium laser fiber to pulverize the calculus, followed by stone basket retrieval. The treatment of choice for distal ureteral stones, stones >10 mm, lower pole renal stones, and patients on anticoagulation or pregnant.

Percutaneous Nephrolithotomy (PCNL) : Direct needle puncture into the renal calyx with tract dilation to accommodate a large-bore rigid nephroscope, allowing ultrasonic, pneumatic, or laser fragmentation. The gold standard for large renal calculi (>20 mm / >2 cm) and complex staghorn calculi .

Loading diagram... Comprehensive Management Flowchart for Acute Suspected Nephrolithiasis