Urologic Stone Disease
Tintinalli Chapters 96-97
Randall Adolph
Epidemiology
• 3:1 M:F (~7% men/ 3% women)
• 3rd-5th decade most common (70%)
• Hereditary predisposition (RTA type 1, Hyperparathyroidism, cysteinuria, milk-alkali
syndrome, sarcoidosis, Crohn's disease)
• Climate (mountainous, desert, or tropical)
• Time of year (warmest three months)
• Lifestyle (sedentary)
• Medications: protease inhibitors, carbonic
anhydrase inhibitors, laxatives, triamterene
Patient Characteristics
• <16 year old comprise 7% of cases
• 1:1 M:F
• Causes: metabolic abnormalities 50%,
urological abnormalities 20%, infection
15%, immobilization 5%
• 1/3 have recurrence within 1 year
• 50% within 5 years
Pathophysiology
•
Formation requires three key elements
1. Supersaturation of urine with solutes
2. Relative lack of the inhibitors citrate &
pyrophosphate
3. Stasis or lack of urine flow
•
Composition:
1. 75% calcium oxalate
2. 10% staghorn calculi (struvite): associated with
urease-splitting bacteria, poor Ab. penetration
and usually require surgery
3. Uric acid stones 10%
Composition Continued
• Calcium oxolate Hyperoxaluria occurs in
the presence of small bowel disease-Crohn's disease, ulcerative colitis, and
radiation enteritis.
• Uric Acid10% of all stones
– excessive excretion of uric acid in the urine
– increases with uricosuric agents
– Radiolucent!!!
Obstruction leads to:
• Rapid redistribution of renal blood flow, ↓
glomerular filtration rate  renal excretion shifts
to unaffected kidney
• Causes rapid decrease in ureteral peristaltic
activity
• Complete obstruction may lead to loss of renal
function
• Increased occurrence of irreversible damage
after 1 to 2 weeks of obstruction
• Partial obstruction lower likelihood of renal injury,
may still result in irreversible damage.
Critical size
• 5 mm~ 90% < 5 mm and located in the
lower ureter pass spontaneously
• 15% pass if between 5 and 8 mm
• 95% >8 mm become impacted generally
requiring lithotripsy or surgical removal
• 75% of stones are located in the distal
third of the ureter
Area of impaction
• Renal calyx
• UPJ, where ureter passes over pelvic brim
and iliac vessels
• UVJ: smallest diameter of the urinary tract
• In FM the posterior pelvis: ureter is
crossed anteriorly by the pelvic blood
vessels and broad ligament
Places for obstruction
Causes of pain
• Colicky, severe flank pain: hyperperistalsis
of smooth muscle of the calyces, pelvis,
and ureter
• Dull ache: attributed to acute obstruction
and renal capsular tension
Clinically
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Usually asymptomatic until obstructs
acute onset severe pain, typically at rest
little if any POP
Typically flank, abdomen with referral to
ipsilateral labia or testicle
• May be writhing in pain, reluctant to lie still
• Episodic as passes, pain free until
obstructs more distally
Urinary pH
• pH> 7.6 suspicious for urea-splitting
organisms because the kidney will not,
under normal conditions, produce urine in
this alkaline range.
• pH < 5 often associated with the formation
of uric acid calculi.
LABORATORY
• UA hematuria supports diagnosis,
absent in 15% ;crystals seen w/wo stones
• Dipstick detects heme, myoglobin and
porphyrins, need micro (see RBCs)
• Urine C&S,
• BUN & Creatinine especially if imaging
with RCM, higher rates of complications in
DM >1.5, CRF >2.5
Imaging
• performed with a first episode of renal
colic.
• Other indications:
– Diagnosis is unclear
– Those in whom a proximal UTI, in addition to
a calculus, is suspected.
• A KUB is the standard, initial radiograph
done before injecting contrast media
during IVP.
Imaging
• Helical CT preferred modality
• US if pregnant
• Others IV urography, Radionuclide renal
scan, plain abd. Film
• Shows stone, location, IDs complications
• Unilateral ureteral dilatation and
perinephritic stranding together: PPV 96%
• Both absent NPV 93-97%
Noncontrast CT
• Advantages: fast, avoids RCM,
• Disadvantages: specificity/sensitivity low
for other pathologies (AAA, appendicitis)
• Does not evaluate renal function or degree
of obstruction
• If negative may need RCM to look for
other cause of pain
IV Urography
• Indicators of obstructing stone:
– 1st and most reliable indicator of obstruction is
a delayed nephrogram in the 5-minute film
– Visualization of the entire ureter is suggestive
of obstruction
– Ureteral contrast column cutoff, prolonged
nephrogram, renal enlargement, dilatation of
the collecting system, contrast extravastation
Helical CT
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Advantages: provides info on function
Disadvantages: uses RCM (allergy,nephrotoxic)
Nephrotoxicity: 9% in pts. with RI or DM
BUN, Creatinine before RCM
Metformin & RCM  severe Lactic acidosis,
nephrotoxicity
• False negative if stone small, radiolucent,
partially obstructing, or passes into bladder
before contrast passed by kidneys
US
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During pregnancy, children
May misses stones < 5mm
Less sensitive in middle ureter
Overall low sensitivity/specificity for stones
98% sensitive for hydronephrosis,
however 22% of cases not associated with
obstruction
US
• Advantages:
– noninvasive, no dyes or radiation, no known
side effects
– Superior to IVU for UVJ stones
• Disadvantages:
– excretion function not evaluated operator and
equipment dependant
– obesity may hinder ability to perform
Plain Films
• 90% stones radiopaque (Ca > Struvite >
Cystine)
• Uric acid and stones associated with
medications radiolucent
• Overall poor Sensitivity & Specificity
• Greatest utility is excluding other
pathologies
Stone gone wild
• infection occasionally occurs in the
presence of an obstructive stone.
• A history of fever and chills strongly
suggests superimposed infection and is a
urologic emergency. It is imperative to do
an IVP or an ultrasound study in these
cases
• Sterile pyuria strongly suggests renal
tuberculosis; confirmation acid-fast bacilli
Differential Diagnosis
• Aortic dissection , AAA
• Appendicitis: usually don’t see rebound,
guarding, distention with stone
• Infectious: fever with CVA, consider
pyelonephritis
• Papillary necrosis: DM, SCD, NSAID abuse; see
Hematuria and pyuria
• Vascular:Renal vein thrombosis, Mesenteric
ischemia
• Gynecological
vascular etiology
• If suspected, a contrast CT or angiogram done.
• Relatively rare: m/c renal artery embolism, most
often of cardiac origin (atrial fibrillation, subacute
bacterial endocarditis, mural thrombus)
• IVP should demonstrate decreased or absent
excretion of contrast material. Immediate
angiogram indicated early diagnosis allows
possible salvage of the ischemic kidney
Predisposing factors for renal vein thrombosis
include the nephrotic syndrome, malignancies,
and pregnancy
TREATMENT
• Pain control: Opiods and nsaids
• NSAIDs: analgesic, decrease ureterospasm
and renal capsular pressure by diminishing
GFR in the obstructed kidney.
• Obstruction with Infection: Urology
emergency
• Consult if: RI, Severe underlying disease,
extravasation or complete obstruction,
Multiple ED visits, large stone, sloughed renal
papillae
Management
• Average time to pass stone varies (7-20 days)
• Long acting CCB (Nifedipine) and steroids may
enhance passage
• F/U Urology in 7 days
• Stone saved/submitted to urologist for analysis.
• Dispo: return immediately if intractable, severe
pain, persistent nausea and vomiting, fever and
chills
Indications for Admission
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Obstruction with infection
Persistent pain
Persistent nausea and vomiting
Urinary extravasation
Hypercalcemic crisis
Relative Indications for Admission
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High-grade obstruction
Solitary kidney
Intrinsic renal disease
Size of obstructing stone
Duration of symptoms
Social situation
Admit
• severely dehydrated
• unrelenting pain or vomiting
• underlying infection with hydronephrosis
Bladder stones
• different from renal stones
• almost exclusively elderly men
• most often complication of other urologic
disease (Proteus).
• The other common indwelling catheter
• May complain of sudden interruption of the
urinary stream. This strongly suggests a
vesical stone that intermittently obstructs
the bladder outlet
Hematuria and Hematospermia
• Tintinalli Chapter 97
Hematuria
• Definition:
– >5 RBCs/hpf warrants an attempt at definitive diagnosis
• Timing:
– Initial suggests urethral disease
– B/n voiding and only staining undergarments, with clear urine
distal urethral or meatus
– Total disease of kidneys, ureters, or bladder
– Terminal bladder neck or prostatic urethra
• Amount
– Gross hematuria lower tract cause while microscopic tends to
be kidney disease
• Color:
– Brown/Smokey colored with casts and proteinuria suggests
glomerular
– Red clotted blood indicates source below kidney
HEMATURIA
• a harbinger of serious urologic disease
• Gross hematuria  5X more likely to have lifethreatening conditions when compared to those with
microhematuria.
• Lower and middle urinary tract ~60%
• Urologic malignancies 2.2% to 12.5% with
microscopic hematuria, up to 20% if > 50 years with
gross hematuria.
• Gross hematuria (>3 red blood cells/hpf on two of
three urinalyses found a potentially life-threatening
lesion in 9.1% of these patients.
Hematuria
• Young Pts. most often urolithiasis or UTI
• Consider glomerulonephritis, goodpasture,
HSP, Wilms Tumor, SCD/trait
• PSGN 7-14 days following pharyngitis,
Abs do not prevent this
• IgA nephropathy following viral URI
• Elderly: infection, Nephroolithiasis,
bladder, prostate, renal CA
Other sources of bleeding
• infection of the bladder (hemorrhagic
cystitis)
• varices of the bladder
• Diverticula
• bladder stones
• postradiation changes
• Anticoagulation at currently recommended
levels does not predispose patients to
hematuria
Risk factors for Uroepithelial CA
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Age >40
Excessive analgesic use
Smoking
Exposure to dyes, benzenes, aromatic amines
Pelvic irradiation
Cyclophosphamide
Hematuria in patients on blood thinners, have
underlying disease 80% of the time
glomerular and nonglomerular
• glomerular origin: frequently associated
with dysmorphic erythrocytes, RBC casts,
and significant proteinuria (2+ to 3+)
• IgA nephropathy (Berger's disease) m/c,
cause
• nonglomerular hematuria: uniformly round
erythrocytes and absence of erythrocyte
casts and proteinuria.
glomerular disease
• Typically young males have hematuria, erythematous
skin rash, and fevers suggesting immunoglobulin
nephropathy, or Berger's disease
• Family history of deafness, renal disease, and hematuria
is linked to Alport nephritis.
• A rash, arthritis, and hematuria are seen with systemic
lupus erythematosus.
• Hematuria, hemoptysis, and microscopic anemia are
common presentations of Goodpasture's syndrome.
• A preceding upper respiratory infection, pharyngitis, skin
infection, or rash with associated hematuria suggests
poststreptococcal glomerulonephritis.
nonglomerular disease
• A family history of bleeding disorders or
renal cystic disease suggest hemophilia
and polycystic kidney disease,
respectively.
• Suspect papillary necrosis in diabetics,
sickle cell patients, and analgesic abusers
(Classic urolithiasis, sudden flank pain and
hematuria)
Diagnosing
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Clarify symptoms and source:
traumatic/atraumatic
Gross/micro
Initial/total/terminal
Associated symptoms: flank pain, menstruation, dysuria,
etc.
• Travel (schistosomiasis)
• Abnormal RBC morphology, casts, protein suggest
glomerular source
• Strenuous exercise frequently cause, but deserves
investigation even if spontaneously resolves
Exercise-Induced
• Exercise-induced hematuria that does not
resolve after 48 hours commonly results
from punctate hemorrhagic lesions
suggesting bladder cancer
• Diagnosed by cystoscopy
dipstick
• positive only if there has been lysis of
RBCs or with myoglobinuria.
• [Hemoglobin] greater than 0.003 mg/L
(10,000 red blood cells/mm3 or 1 to 2
RBCs/hpf)
• Current recommendations: urinalysis and
cytology for 3 consecutive years if
resolution of hematuria or persistent
asymptomatic microhematuria
• ross hematuria should be reevaluated in
all instances
Renal Imaging
• IVP clearly delineates most renal tumors,
obstruction, or stones and their precise location
– Disadvantage: RCM, does not assess aorta,
retroperitenium and pelvis
• Helical CT fast highly sensitive and specific for
stone, RCM used for other pathologies
• Renal US to screen for AAA, Hydro, obstruction.
Study of choice in Pregnant and children
– Disadvantages: rarely identifies small stones, no idea
of functioning,
Treatment
• Abs. for infection
• Pain meds. & hydration for nephrolithiasis
• D/C only if asymptomatic, tolerating PO, Abs. &
analgesics & no sig. comorbidities
• <40 to PCP for repeat UA 1-2 weeks, if persists
or >40 and risk for CA, Urology for cystoscope
• Asymptomatic microscopic hematuria associated
with a 2 fold increase of future RF
• Proteinuria: a sign of prognostically significant
glomerular disease & needs further workup
Complications
• Gross hematuria may lead to intravesical
clot and subsequent outflow obstruction
• New glomerulonephritis: at risk for
Pulmonary edema, volume overload,
azotemia or HTN emergency need
admission
• Pregnant: May be preeclampsia,
pyelonephritis, obstructing stone call OB
and possibly admit
Hematospermia
• Trauma, injury (tumor with erosion),
inflammation, infection of ejaculatory system
• M/C iatrogenic from instrumentation, radiation.
• >40 prostate CA, BPH considerations
• <40 prostatitis, seminal vesiculitis, urethritis,
STD, epididymo-orchitis, calculi, TB
• UA warranted
• Usually benign, but urology referral indicated
Questions?
Question 1
•
What season is associated with an
increased incidence of stones?
a)
b)
c)
d)
Winter
Spring
Summer
Fall
Answer C
Question 2
• True or false: Hematuria seen in a patient
on therapeutic levels of blood thinners is
usually microscopic and benign?
False: underlying pathology 80% of time
Question 3
•
In the ED what is a value fror defining
hematuria?
a)
b)
c)
d)
Answer: D
Any RBCs/hpf
2 RBCs/hpf
4 RBCs/hpf
5 RBCs/hpf
Question 4
•
The most common cause of stone
formation is?
a)
b)
c)
d)
a)
metabolic abnormalities
urological abnormalities
infection
Immobilization
Answer: A 50%
Question 5
•
What is the most common composition of renal
stones?
a)
b)
c)
d)
Uric acid stones
struvite
calcium oxalate
Magnesium
Answer: C