Urolithiasis: Etiology,
Symptoms, and Management
SUZANNE BIEHN STEWART, MD
DIVISION OF UROLOGY
DUKE UNIVERSITY MEDICAL CENTER
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
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
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
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.
Epidemiology—2
Natural History and Risk Factors
 Peak incidence age:
 Race:
30-60 years
4-5x more common in whites than blacks
 Family history:
 Body size:
3 fold
risk with
risk
weight
Epidemiology—3
Changing Trends
 Historically….

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
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
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 1 10 - 15%
 Year 5
50 - 60%
 Year 10 70 – 80%


Average of 9 yrs intervening between episodes
And Costly…
 In US, stone disease accounts for > 400,000
hospitalizations annually
Epidemiology—6
Economic Implications
 In 1993, inpatient and outpatient costs
estimated$2.39 Billion/year1
 By 2050, its estimated that there will be 1.6-2.2
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
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)
1.

Dehydration, urinary obstruction and stasis
Inhibitor deficiency: Urine normally has substances which
block crystallization (ie citrate and magnesium)
2.

Dietary deficiencies
Etiology—2
Influential Factors in Stone Formation
Dehydration
1.


Major player in majority of stones
Geographic location: high temperatures
Anatomic obstruction and urinary stasis
3. Metabolic/Urine composition
2.



Urinary pH
Increased stone forming substances (calcium, oxalate, uric acide)
Decreased stone inhibiting substances (citrate and magnesium)
Diet
5. Urinary tract infection
4.

Urease producing organisms: Proteus, Klebsiella, Pseudomonas,
Serratia
Etiology—2
Influential Factors in Stone Formation
6. Sedentary lifestyle/immobilization

Increased bone reabsorption
increases urinary calcium
Disease states
7.
1.
2.
3.
4.
5.
6.
7.
Sarcoidosis
Hyperparathyrodism
Inflammatory bowel disease
Chronic diarrhea
s/p Gastric bypass
Cystinuria
Gout
Medications
8.
1.
HIV Protease inhibitors: Indinavir and Nelfinavir
Etiology—2
Types of Stones
1. Calcium-based: ~80% all stones
Calcium oxalate
a.
1.
2.
3.
4.
5.
Most common stone formed in industralized nations
Most common type of bladder stone
Radio-opaque
Very difficult to dissolve
Dehydration = common influential factor
Calcium
Dihydrate crystals
Monohydrate crystals
Etiology—3
Types of Stones
Calcium-based:
1.
Calcium phosphate
b.
2.
Calcium
phosphate
crystals
1.
~10% of calcium stones
2.
Influential factors: Hyperparathyroidism, UTI, dehydration
Non-calcium-based
Uric Acid (8%)
a.
1.
2.
3.
In pure form
radiolucent
Form in acidic urine (pH < 6.0)
Dissolves with alkalization of urine
Etiology—4
Types of Stones
2.
Non-calcium-based
Uric Acid (8%)
a.
4.
5.
Dehydration = common influential factor
Patients usually have normal plasma and urine uric acid
levels
Uric acid stone
Uric acid crystals
Etiology—5
Types of Stones
2.
Non-calcium-based
Struvite (10%)
b.
1.
2.
3.
4.
5.
Often called “infectious stones”
Associated with UTI
Majority of staghorn calculi are struvite composition
Form in alkaline urine
Radio-opaque
Struvite stone
Struvite crystal
Etiology—6
Types of Stones
2.
Non-calcium-based
Cystine (1%)
c.
1.
2.
3.
4.
5.
6.
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
Cystine stone
Cystine crystal
Etiology—7
Anatomic Locations for Stone Formation
Can form and be found anywhere along the urinary tract
Kidney
1.
Stone nidus typically starts to develop
a)
Ureter
2.
Stone nidus can form here secondary:
a)
1.
2.
Obstruction—i.e. stricture
Foreign object—i.e. stent
Bladder
3.
Stone nidus can form here secondary:
a)
1.
2.
3.
Dysfunctional bladder
Obstruction—i.e. BPH
Foreign object
Symptoms—1
 Not all patients with stones have
symptoms
 Stones become symptomatic
when:
1.
Cause obstruction and irritation

2.
Typical sites of obstruction:

Ureteral Pelvic Junction (UPJ)

Ureter crosses over Internal iliac
vessels

Ureteral Vesical Junction (UVJ)
Associated with infection
Symptoms—2
Classic symptoms:

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
Evaluation—1
 Laboratory tests:



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
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
1Urology
Stone
width
(mm)
Approx %
stones
passed1
1
90%
2
85%
3
83%
4
77%
5
56%
6
41%
7
30%
8
21%
9
3%
Mean
time to
passage2
8 days
11 days
22 days
?
10(6); 1977. Am J Roentgenol 178:101;2002. 2J Urol 162:688; 1999
Evaluation—3
Which patients should undergo….
Trial of Passage (Surveillance) vs. Surgical Intervention
 Indications for Hospital Admission:
Fever
Signs of infection
1.
2.
a)
Elevated WBC
Solitary kidney
Intractable pain
Unable to tolerate fluid secondary to nausea/vomitting
Renal deterioration
3.
4.
5.
6.
a)
Elevated creatinine attributed to obstruction
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
Treatment—2
Patients with Active Infection
 Initial treatment:

Antibiotics

Drainage of kidney

Ureteral stent

Percutaneous nephrostomy tube
Double J ureteral stents
 Proceed with stone removal after
infection has cleared
Nephrostomy tube
Treatment—3
Treatment strategy based on….
Stone Size and Location
 Options:

1.
2.
3.
4.

1.
2.
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)
Treatment—4
ESWL
Most common 1st line treatment for renal calculi
 Indications:
 Non-obstructed renal or ureteral calculi < 1.5-2 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
Treatment—5
PCNL
 Indications:
 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
Treatment—6
Complications with PCNL
Bleeding
1.

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
2.
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
Treatment—6
Complications with PCNL
Bowel Injury
3.

~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
4.

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
Treatment—7
Ureteroscopy (URS)
 Indications:
 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
Treatment—8
Complications of URS
Ureteral false passage 0.4-0.9%
1.



Entrance into ureteral orifice
Passing guidewire around impacted stone
Tx: Stent
Ureteral orifice
Ureteral perforation 1-15%
2.


More common with semi-rigid URS
Tx: Stent
Avulsion ~0.3%
3.


Basketing large stone in proximal or mid-ureter
Complete avulsion requires operative repair
Ureteral Strictures 0-4%
4.


Late complication
Increased risk with impacted stone, perforations
Extravasation of contrast indicating perforation
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
Follow Up Care—2
General Dietary Recommendations
Oral fluid intake
1.

Keep urine volume 2-3L/day
Low sodium diet
3. Low animal protein diet
4. Low oxalate diet
2.

Chocolate, tea, spinach, rhubarb, nuts, beets
Moderate calcium intake
5.

800-1000 mg/day
Specific recommendations based on metabolic evaluation
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?
a) PCNL
b) ESWL
c) URS
d) No immediate intervention
necessary
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?
a) Immediate URS
b) Trial of passage with flomax, narcotics
c) Schedule outpatient ESWL
d) Hospital admission, abx, stent
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
b) Notify MD, likely needs CXR—
pnuemothorax/hydrothorax
c) Notify MD, likely needs CT scan—unidentified renal
pelvic perforation
d) Notify MD, likely needs nephrostomy tube—obstructing
stone
a)