1. Urolithiasis: Etiology, Symptoms, and Management
Suzanne Biehn Stewart, MD
Division of Urology
Duke University Medical Center

2. Overview
Urinary stones have plagued humans since the beginning of recorded history Initial stones uncovered in mummified remains of Egyptians ~7,000 years ago Overtime, we have made drastic improvements in our understanding of stone formation and treatment strategies
Babayan RK et al. “Urinary Calculi and Endourology,” Handbook of Urology, 3rd ed. 2004

3. Learning Goals Risk factors for stone disease Economic implications
Various types of stones
Causes of stone development
Common symptomatology
Acute Evaluation tools
Differentiate patients that need immediate vs delayed intervention
Various options for treatment
Treatment complications
Recommended follow-up

4. Epidemiology—1
Overall 1-3% of adults are affected in industrialized nations
In the US, highest prevalence is in the Southeast (the Stone Belt)
Courtesy of Preminger GM.

5. Natural History and Risk Factors
Epidemiology—2
Natural History and Risk Factors
Peak incidence age: years
Race: x more common in whites than blacks
Family history: fold risk
Body size: risk with weight

6. Epidemiology—3 Changing Trends Historically…. Currently….
Stones were 3x more common in males than females
Currently….
Males are only 1.3x more likely to form stones than females (2002)
Secondary to changes in diet, lifestyle and increased obesity in females
Scales et al. 2005

7. Changing Trends in Hospital Discharges for Renal Calculus by Gender
Epidemiology—4
Changing Trends in Hospital Discharges for Renal Calculus by Gender
12.2%, p = .002
21.0%, p = 0.001
Scales et al. 2005

8. Epidemiology—5 Stones are Common… Annual incidence in males = 1%
Lifetime risk in white males = 20%
Life long disease
Risk of recurrence after first stone:
Year %
Year %
Year – 80%
Average of 9 yrs intervening between episodes
And Costly…
In US, stone disease accounts for > 400,000 hospitalizations annually

9. Economic Implications
Epidemiology—6
Economic Implications
In 1993, inpatient and outpatient costs estimated$2.39 Billion/year1
By 2050, its estimated that there will be million extra stone cases in the US secondary to global warming
Leading to an additional healthcare cost of 0.9—1.3 billion/year2
1Thompson et al. 1995; 2Pearle M. 2o08

10. Etiology—1 Stone development is complex and multifactorial
Causes are specific to the type of stone formed (ie stone composition)
> 90% of patients a metabolic etiology can be found
General pathophysiology principals:
Supersaturation: Urine becomes oversaturated with a type of solute, which then comes out of solution (crystallization)
Dehydration, urinary obstruction and stasis
Inhibitor deficiency: Urine normally has substances which block crystallization (ie citrate and magnesium)
Dietary deficiencies

11. Influential Factors in Stone Formation
Etiology—2
Influential Factors in Stone Formation
Dehydration
Major player in majority of stones
Geographic location: high temperatures
Anatomic obstruction and urinary stasis
Metabolic/Urine composition
Urinary pH
Increased stone forming substances (calcium, oxalate, uric acide)
Decreased stone inhibiting substances (citrate and magnesium)
Diet
Urinary tract infection
Urease producing organisms: Proteus, Klebsiella, Pseudomonas, Serratia

12. Influential Factors in Stone Formation
Etiology—2
Influential Factors in Stone Formation
Sedentary lifestyle/immobilization
Increased bone reabsorption increases urinary calcium
Disease states
Sarcoidosis
Hyperparathyrodism
Inflammatory bowel disease
Chronic diarrhea
s/p Gastric bypass
Cystinuria
Gout
Medications
HIV Protease inhibitors: Indinavir and Nelfinavir

13. Etiology—2 Types of Stones Calcium-based: ~80% all stones
Calcium oxalate
Most common stone formed in industralized nations
Most common type of bladder stone
Radio-opaque
Very difficult to dissolve
Dehydration = common influential factor
Dihydrate: envelpes
Monohydrate: dumbells
Calcium oxalate
Dihydrate crystals
Monohydrate crystals

14. Etiology—3 Types of Stones Calcium-based: Non-calcium-based
Calcium phosphate
~10% of calcium stones
Influential factors: Hyperparathyroidism, UTI, dehydration
Non-calcium-based
Uric Acid (8%)
In pure form radiolucent
Form in acidic urine (pH < 6.0)
Dissolves with alkalization of urine
Calcium phosphate crystals
amorphous

15. Etiology—4 Types of Stones Non-calcium-based Uric Acid (8%)
Dehydration = common influential factor
Patients usually have normal plasma and urine uric acid levels
rhomboids
Uric acid stone
Uric acid crystals

16. Etiology—5 Types of Stones Non-calcium-based Struvite (10%)
Often called “infectious stones”
Associated with UTI
Majority of staghorn calculi are struvite composition
Form in alkaline urine
Radio-opaque
Coffin lids
Struvite stone
Struvite crystal

17. Etiology—6 Types of Stones Non-calcium-based Cystine (1%)
Caused by cystinuria—homozygous recessive disorder
Forms in acidic urine
Dissolves with urinary alkalization
Radio-opaque
Resistant to Extracorporeal Shock Wave Lithotripsy (ESWL)
May form staghorns
Hexagonal
Cystine stone
Cystine crystal

18. Etiology—7 Anatomic Locations for Stone Formation Kidney Ureter
Can form and be found anywhere along the urinary tract
Kidney
Stone nidus typically starts to develop
Ureter
Stone nidus can form here secondary:
Obstruction—i.e. stricture
Foreign object—i.e. stent
Bladder
Dysfunctional bladder
Obstruction—i.e. BPH
Foreign object

19. Symptoms—1 Not all patients with stones have symptoms
Stones become symptomatic when:
Cause obstruction and irritation
Typical sites of obstruction:
Ureteral Pelvic Junction (UPJ)
Ureter crosses over Internal iliac vessels
Ureteral Vesical Junction (UVJ)
Associated with infection

20. Symptoms—2 Classic symptoms: If associated with infection Fever
Obstruction Acute, colicky pain
Can be severe
May have associated nausea and vomiting
Location of pain can suggest location of stone
Flank
Abdominal
Radiate to groin or testicle
Irritation urothelial lining Hematuria
Gross or microscopic
Irritation of bladder lining Lower urinary tract symptoms
Frequency
Urgency
Dysuria
If associated with infection Fever

21. Evaluation—1 Laboratory tests: Imaging:
CBC—elevated white blood cell count
BMP—elevated creatinine
UA—positive nitrites, leukocyte esterase
Order Urine culture
If febrile—Blood cultures
Imaging:
Non-contrasted CT
1st line diagnostic test
Locate stone
Determine stone size
Identify signs of obstruction
hydronephrosis and hydroureter
KUB, Intravenous pyelogram (IVP), US

22. Evaluation—2 Success of spontaneous stone passage is correlated with:
Location of stone:
Distal > Proximal
Stone size:
95% of stones < 5 mm will pass within 40 days
Stone width (mm)
Approx % stones passed1
Mean time to passage2 1
90%
8 days 2
85% 3
83%
11 days 4
77%
22 days 5
56% 6
41% 7
30% ? 8
21% 9 3%
1Urology 10(6); Am J Roentgenol 178:101; J Urol 162:688; 1999

23. Evaluation—3 Which patients should undergo….
Trial of Passage (Surveillance) vs. Surgical Intervention
Indications for Hospital Admission:
Fever
Signs of infection
Elevated WBC
Solitary kidney
Intractable pain
Unable to tolerate fluid secondary to nausea/vomitting
Renal deterioration
Elevated creatinine attributed to obstruction

24. Trial of Passage (Surveillance)
Treatment—1
Trial of Passage (Surveillance)
Patient candidates:
Afebrile, pain controlled, no overt signs of infection or renal compromise
Medical management:
Oral hydration
Analegesics: tylenol, narcotics
Alpha blockers: Tamulosin (Flomax)
Relaxes ureteral smooth muscle
Increases stone passage rates up to ~ 44%
Decreases time to stone passage by ~2-4 days
Decreases pain associated with stone passage
Re-evaluate with imaging ~4-6 weeks
If stone remains….INTERVENTION becomes necessary

25. Patients with Active Infection
Treatment—2
Patients with Active Infection
Initial treatment:
Antibiotics
Drainage of kidney
Ureteral stent
Percutaneous nephrostomy tube
Proceed with stone removal after infection has cleared
Double J ureteral stents
Nephrostomy tube

26. Stone Size and Location
Treatment—3
Treatment strategy based on….
Stone Size and Location
Options:
Kidney and ureteral stones:
Extracorporeal Shock Wave Lithotripsy (ESWL)
Percutaneous nephrolithotomy with lithotripsy (PCNL)
Ureteroscopy with lithotripsy/extraction
Open surgery (rare)
Bladder stones:
Cystolitholapaxy
Cystolithotomy (open surgery)

27. Most common 1st line treatment for renal calculi
ESWL
Most common 1st line treatment for renal calculi
Indications:
Non-obstructed renal or ureteral calculi < cm
Contraindications:
Pregnancy
Coagulopathy
AAA (> 4cm)
Cystine, infectious stones (relative contraindication)
Advantages:
Non-invasive
Sedation only required
Outpatient intervention
Disadvantages:
Patients MUST pass stone fragments
Complications:
Steinstrasse 4-9%—may require 2nd intervention
Hematoma—renal/retroperitoneal

28. Treatment—5 PCNL Indications: Contraindications: Advantages:
Renal pelvis calculi ~ > 2cm
Staghorn calculi
Proximal ureteral calculi ~ > 1cm
UPJ obstruction
Contraindications:
Coagulopathy
Advantages:
High stone free rate
Renal stones—95%
Ureteral stones—75%
Disadvantages:
Anesthesia
Overnight hospital stay
Ureteral stent and/or nephrostomy tube in perioperative period

29. Complications with PCNL
Treatment—6
Complications with PCNL
Bleeding
Risk of transfusion = 3%
Hemodynamically unstable
Return to the OR
Hemodynamically stable
Large diameter nephrostomy tube and clamp tube to tampanode bleeding
Nephrostomy tampanode balloon catheter
Angiography and embolization
Pneumothorax/Hydrothorax
Percutaneous access:
Above 12th rib—10% risk of fluid in pleura
Above 11th rib—10% risk of pneumothorax/hydrothorax
Signs/symptoms: Pleuritic chest/flank pain, loss of breath sounds, respiratory distress/desaturation

30. Complications with PCNL
Treatment—6
Complications with PCNL
Bowel Injury
~0.2% risk
Colonic injury more common
Left access
Morbidly obese
Intraoperative detection: contrast in colon with nephrostogram
Postoperative signs: Fecaluria, pneumaturia,peritoneal signs, fever, ileus, leukocystosis
Renal pelvis laceration/perforation
Can occur with dilation of percutaneous tract
Commonly detected intraoperatively
Postoperatively: common symptom—flank pain
Treatment: Placement of large bore nephrostomy tube until tract closes

31. Treatment—7 Ureteroscopy (URS) Indications: Tools (aka toys):
Ureteral and lower pole renal stones
Morbid obesity
Bleeding diathesis
Ectopic or horseshoe kidney
Tools (aka toys):
Semi-rigid vs. flexible ureteroscope
Lithotripsy: laser, pneumatic, electrohydralic, ultrasonic
Extraction: stone grasper, basket
Advantages:
Outpatient procedure
High success rate of removal ~95% with Laser lithotripsy of ureteral stones
Disadvantages:
Anesthesia
Possible need for ureteral stent placement
Bilateral URS, solitary kidney, ureteral performation, impacted stone, prolonged URS, URS of infected stone.

32. Treatment—8 Complications of URS Ureteral false passage 0.4-0.9%
Entrance into ureteral orifice
Passing guidewire around impacted stone
Tx: Stent
Ureteral perforation 1-15%
More common with semi-rigid URS
Avulsion ~0.3%
Basketing large stone in proximal or mid-ureter
Complete avulsion requires operative repair
Ureteral Strictures 0-4%
Late complication
Increased risk with impacted stone, perforations
Ureteral orifice
Extravasation of contrast indicating perforation

33. Follow Up Care—1 Abbreviated Metabolic evaluation
First episode, solitary stone, uncomplicated course
UA, Ucx, stone analysis, BMP, Ca2+, Phosphorus, uric acid
Radiographic imaging
Extensive Metabolic evaluation
Recurrent episodes, medical conditions alter metabolism, non-calcium based stones
Same as abbreviated evaluation plus
24 hr urine collection (~2x): urinary pH, volume, sodium, potassium, citrate, uric acid, magnesium, oxalate, chloride, protein, creatinine, cystine

34. Follow Up Care—2 General Dietary Recommendations Oral fluid intake
Keep urine volume 2-3L/day
Low sodium diet
Low animal protein diet
Low oxalate diet
Chocolate, tea, spinach, rhubarb, nuts, beets
Moderate calcium intake
mg/day
Specific recommendations based on metabolic evaluation

35. Clinical Scenario—1
64 yo female with no previous medical history presents to the ED with left lower quadrant abdominal pain and fever. On CT, she is found to have diverticulitis and incidentally a 5mm, nonobstructing renal pelvic stone. How do you manage the stone?
PCNL
ESWL
URS
No immediate intervention necessary

36. Clinical Scenario—2
32 yo male with no past medical history presents to clinic with left abdominal pain, hematuria, temperature of 38.5C, WBC 16. On CT he has a left 7mm mid-ureteral stone. What is the appropriate management?
Immediate URS
Trial of passage with flomax, narcotics
Schedule outpatient ESWL
Hospital admission, abx, stent

37. Clinical Scenario—3
44 yo female POD #1 left PCNL with no nephrostomy tube develops worsening left flank pain, shortness of breath and shows a declining trend her oxygen saturations. What is the next step?
Pain meds, nasal cannula, incentive spirometry
Notify MD, likely needs CXR—pnuemothorax/hydrothorax
Notify MD, likely needs CT scan—unidentified renal pelvic perforation
Notify MD, likely needs nephrostomy tube—obstructing stone