Urinary stones pdf - All Lectures

Tikrit Medical College, Urology, Fifth year

أ.د. حممد حمسن عبد العزيز

Urinary Stones

Kidney stones: epidemiology

~10% of Caucasian men will develop a kidney stone by the age of 70.

Within 1 year of a calcium oxalate stone, 10% of men will form another calcium
oxalate  stone,  and  50%  will  have  formed  another  stone  within  10  years.  The
prevalence  of  renal  tract  stone  disease  is  determined  by  factors  intrinsic  to
the  individual  and  by  extrinsic  (environmental)  factors.  A  combination  of
factors often contributes to risk of stone formation.
Intrinsic factors



Age. The peak incidence of stones occurs between the ages of 20-50
years.



Sex. Males are affected 3 times as frequently as females.



Genetic. ~25% of patients with kidney stones report a family history of
stone disease.

Extrinsic (environmental) factors



Geographical location, climate, and season.



Ureteric stones become more prevalent during the summer, the highest
incidence occurring a month or so after peak summertime temperatures,
presumably  because  of  higher  urinary  concentration  in  the  summer
(encourages  crystallization).  Concentrated  urine  has  a  lower  pH,
encouraging cystine  and  uric  acid  stone  formation.  Exposure  to  sunlight
may  also  increase  endogenous  vitamin  D  production,  leading  to
hypercalciuria.



Water intake. Low fluid intake (<1200ml/day) predisposes to stone
formation.



Diet.  High  animal  protein  intake  increases  risk  of  stone  disease  (high
urinary  oxalate,  low  pH,  low  urinary  citrate).  High  salt  intake  causes
hypercalciuria.  Contrary  to  conventional  teaching,  low  calcium  diets
predispose to calcium stone disease, and high calcium intake is protective.



Occupation. Sedentary occupations predispose to stones compared with
manual workers.

Kidney stones: types and predisposing factors
Stones may be classified according to composition, X-ray appearance, or size
and shape.

Stone composition

% of all renal calculi

Calcium oxalate

85%

Uric acid

5-10%

Calcium phosphate + calcium oxalate

10%

Struvite (infection stones)

2-20%

Cystine

Tikrit Medical College, Urology, Fifth year

أ.د. حممد حمسن عبد العزيز

Other rare stone types (all of which are radiolucent): indinavir

(a protease inhibitor used for treatment of HIV); triamterene (a relatively
insoluble potassium sparing diuretic, most of which is excreted in urine);
xanthine.
Radiodensity on X-ray
Radio-opaque

Opacity implies the presence of substantial amounts of calcium within the

stone. Calcium phosphate stones are the most radiodense stones, being almost
as dense as bone. Calcium oxalate stones are slightly less radiodense.
Relatively radiodense

Cystine stones are relatively radiodense because they contain sulphur.

Magnesium ammonium phosphate (struvite) stones are less radiodense than
calcium containing stones.
Completely radiolucent
Uric acid, triamterene, xanthine, (indinavir cannot be seen even on CTU).

Size and shape

Stones can be characterized by their size, in centimeters. Stones which

grow  to  occupy  the  renal  collecting  system  (the  pelvis  and  one  or  more  renal
calyx) are known as staghorn calculi, since they resemble the horns of a  stag.
They  are  most  commonly  composed  of  struvite  (magnesium  ammonium
phosphate)(being caused by infection and forming under the alkaline conditions
induced by urea-splitting bacteria), but may be composed of uric acid, cystine,
or calcium oxalate monohydrate.

Kidney stones: mechanisms of formation

Periods of intermittent supersaturation of urine with various substances

can occur as a consequence of dehydration and following meals. The earliest
phase of crystal formation is known as nucleation. Crystal nuclei usually form on
the surfaces of epithelial cells or on other crystals. Crystal nuclei form into
clumps: a process known as aggregation. Citrate and magnesium not only inhibit
crystallization but also inhibit aggregation.
Factors predisposing to specific stone types
Calcium oxalate (~85% of stones)



Hypercalciuria



Hypercalcaemia: Almost all patients with hypercalcaemia who form stones
have primary hyperparathyroidism.



Hyperoxaluria



Hypocitraturia: Low urinary citrate excretion. Citrate forms a soluble
complex with calcium, so preventing complexing of calcium with oxalate to
form calcium oxalate stones.



Hyperuricosuria: High urinary uric acid levels

Tikrit Medical College, Urology, Fifth year

أ.د. حممد حمسن عبد العزيز

Uric acid (~5-10% of stones)



Gout: 50% of patients with uric acid stones have gout.



Myeloproliferative disorders. Particularly following treatment with
cytotoxic drugs.



Idiopathic uric acid stones (no associated condition).

Calcium phosphate (calcium phosphate + calcium oxalate = 10% of stones)



Occur in patients with distal renal tubular acidosis (RTA)

Struvite (infection or triple phosphate stones) (2-20% of stones)

These stones are composed of magnesium, ammonium, and phosphate.

They form as a consequence of urease-producing bacteria which produce
ammonia from breakdown of urea. Under alkaline conditions, crystals of
magnesium, ammonium, and phosphate precipitate.

Cystine (1% of all stones)

Occur only in patients with cystinuria: an inherited (autosomal-recessive)

disorder

Evaluation of the stone former

Determination of stone type and a metabolic evaluation allows

identification of the factors that led to stone formation, so advice can be given
to  prevent  future  stone  formation.  Stone  type  is  analyzed  by  polarizing
microscopy,  X-ray  diffraction,  and  infrared  spectroscopy,  rather  than  by
chemical  analysis.  Where  no  stone  is  retrieved,  its  nature  must  be  inferred
from its radiological appearance (e.g. a completely radiolucent stone is likely to
be composed of uric acid) or from more detailed metabolic evaluation.

Risk factors for stone disease



Diet.  Enquire  about  volume  of  fluid  intake,  meat  consumption  (causes
hypercalciuria,  high  uric  acid  levels,  low  urine  pH,  low  urinary  citrate),
multivitamins  (vitamin  D  increases  intestinal  calcium  absorption),  high
doses of vitamin C (ascorbic acid causes hyperoxaluria).



Drugs. Corticosteroids (increase enteric absorption of calcium, leading to
hypercalciuria); chemotherapeutic agents (breakdown products of
malignant cells leads to hyperuricaemia).



Urinary tract infection. Urease-producing bacteria (Proteus, Klebsiella,
Serratia, Enterobacter) predispose to struvite stones.



Mobility. Low activity levels predispose to bone demineralization and
hypercalciuria.



Systemic disease. Gout, primary hyperparathyroidism, sarcoidosis.

Tikrit Medical College, Urology, Fifth year

أ.د. حممد حمسن عبد العزيز



Family history. Cystinuria, RTA.



Renal anatomy. PUJO, horseshoe kidney.



Previous bowel resection or inflammatory bowel disease. Causes intestinal
hyperoxaluria.

Urine pH

Urine pH in normal individuals shows variation, from pH 5-7. After a meal,

pH is initially acid. This is followed by an alkaline tide, pH rising to >6.5. Urine
pH can help establish what type of stone the patient may have (if a stone is not
available for analysis), and can help the urologist and patient in determining
whether preventative measures are likely to be effective or not.



pH <6 in a patient with radiolucent stones suggests the presence of uric
acid stones.



pH consistently >5.5 suggests type 1 (distal) RTA (~70% of such patients
will form calcium phosphate stones).

Kidney stones: presentation and diagnosis

Kidney stones may present with symptoms or be found incidentally during

investigation of other problems. Presenting symptoms include pain or haematuria
(microscopic  or  occasionally  macroscopic).  Struvite  staghorn  calculi  classically
present with recurrent UTIs. Malaise, weakness, and loss of appetite can also
occur.  Less  commonly,  struvite  stones  present  with  infective  complications
(pyonephrosis,  perinephric  abscess,  septicaemia,  xanthogranulomatous
pyelonephritis).

Diagnostic tests

Plain abdominal radiography: calculi that contain calcium are radiodense.
Sulphur-containing stones (cystine) are relatively radiodense on plain
radiography.

Radiodensity of stones in decreasing order: calcium phosphate > calcium
oxalate > struvite (magnesium ammonium phosphate) >> cystine.

Completely radiolucent stones (e.g. uric acid, triamterene, indinavir) are
usually suspected on the basis of the patient's history and/or urine pH ,
and the diagnosis may be confirmed by ultrasound, or CTU.

Renal ultrasound: its sensitivity for detecting renal calculi is ~95%.
A combination of plain abdominal radiography and renal ultrasonography is
a useful screening test for renal calculi.

IVU: increasingly being replaced by CTU. Useful for patients with
suspected indinavir stones (which are not visible on CT).

Tikrit Medical College, Urology, Fifth year

أ.د. حممد حمسن عبد العزيز

CTU: a very accurate method of diagnosing all but indinavir stones. Allows
accurate determination of stone size and location and good definition of
pelvicalyceal anatomy.

Kidney stone treatment options: watchful waiting

The traditional indications for intervention are pain, infection, and

obstruction. Haematuria caused by a stone is only very rarely severe or
frequent enough to be the only reason to warrant treatment.

Options for stone treatment are watchful waiting, ESWL, flexible

ureteroscopy, PCNL, open surgery, and medical dissolution therapy.
When to watch and wait and when not to?

It is not necessary to treat every kidney stone. Thus, one would be

inclined to do nothing about a 1cm symptomless stone in the kidney of
a 95-year-old patient. On the other hand, a 1cm stone in a symptomless
20-year-old runs the risk over the remaining (many) years of the patient's life
of causing problems. It could drop into the ureter causing ureteric colic, or it
could increase in size and affect kidney function or cause pain.

Asymptomatic stones which are followed over a 3-year period are more

likely to require intervention (surgery or ESWL) or to increase in size or cause
pain if they are >4mm in diameter and if they are located in a middle or lower
pole calyx.

Another factor determining the need for treatment is the patient's job.

Airline pilots are not allowed to fly if they have kidney stones, for fear that the
stones could drop into the ureter at 30,000ft, with disastrous consequences!

Some stones are definitely not suitable for watchful waiting. Untreated

struvite  (i.e.  infection  related)  staghorn  calculi  will  eventually  destroy  the
kidney  if  untreated  and  are  a  significant  risk  to  the  patient's  life.  Watchful
waiting  is  therefore  NOT  recommended  for  staghorn  calculi  unless  patient
comorbidity is such that surgery would be a higher risk than watchful waiting.
Historical series suggest that ~30% of patients with staghorn calculi who did
not  undergo  surgical  removal  died  of  renal  related  causes:  renal  failure,
urosepsis (septicaemia, pyonephrosis, perinephric abscess).
Stone fragmentation: extracorporeal shock wave lithotripsy (ESWL)

The technique of focusing externally generated shock waves at a target

(the stone). First used in humans in 1980. The first commercial lithotriptor, the
Dornier HM3, became available in 1983. ESWL revolutionized kidney and
ureteric stone treatment. X-ray, ultrasound, or a combination of both are used
to locate the stone on which the shock waves are focused. Newer lithotriptors
generate less powerful shock waves, allowing ESWL with oral or parenteral
analgesia in many cases, but they are less efficient at stone fragmentation.
Efficacy of ESWL

Likelihood of fragmention with ESWL depends on stone size and location,

anatomy of renal collecting system, degree of obesity, and stone composition.

Tikrit Medical College, Urology, Fifth year

أ.د. حممد حمسن عبد العزيز

Most effective for stones <2cm in diameter, in favourable anatomical locations.
Less effective for stones >2cm diameter, in lower pole stones in a calyceal
diverticulum (poor drainage), and those composed of cystine or calcium oxalate
monohydrate (very hard).
Side-effects of ESWL

ESWL causes a certain amount of structural and functional renal damage

(found  more  frequently  the  harder  you  look).  Haematuria  (microscopic,
macroscopic)  and  oedema  are  common,  perirenal  haematomas  less  so
(0.5%  detected  on  ultrasound  with  modern  machines,  Effective  renal  plasma
flow (measured  by  renography)  has  been  reported  to  fall  in  ~30%  of  treated
kidneys.  There  is  data  suggesting  that  ESWL  may  increase  the  likelihood  of
development of hypertension. Acute renal injury may be more likely to occur in
patients with pre-existing hypertension, prolonged coagulation time, coexisting
coronary heart disease, diabetes, and in those with solitary kidneys.
Contraindications to ESWL
Absolute  contraindications:  pregnancy,  uncorrected  blood  clotting  disorders
(including anticoagulation).

Intracorporeal  techniques  of  stone  fragmentation (fragmentation within the
body)

Electrohydraulic lithotripsy (EHL)

Pneumatic (ballistic) lithotripsy

Ultrasonic lithotripsy

Laser lithotripsy: The holmium: YAG laser.

Kidney stone treatment: flexible ureteroscopy and laser treatment

It can also allow access to areas of the kidney where ESWL is less

efficient or where PCNL cannot reach. It is most suited to stones <2cm in
diameter. Indications for flexible ureteroscopic kidney stone treatment

ESWL failure.

Lower pole stone

Cystine stones.

Obesity such that PCNL access is technically difficult or impossible
(nephroscopes may not be long enough to reach stone).

Obesity such that ESWL is technically difficult or impossible.

Musculoskeletal deformities such that stone access by PCNL or ESWL is
difficult or impossible (e.g. kyphoscoliosis).

Stone in a calyceal diverticulum.

Bleeding diathesis where reversal of this diathesis is potentially
dangerous or difficult.

Patient preference.

Tikrit Medical College, Urology, Fifth year

أ.د. حممد حمسن عبد العزيز

Kidney stone treatment: percutaneous nephrolithotomy (PCNL)

PCNL is the removal of a kidney stone via a track developed between the

surface  of  the  skin  and  the  collecting  system  of  the  kidney.  A  posterior
approach is most commonly used; below the 12th rib (to avoid the pleura and far
enough  away  from  the  rib  to  avoid  the  intercostals,  vessels,  and  nerve).  The
preferred  approach  is  through  a  posterior  calyx,  rather  than  into  the  renal
pelvis,  because  this  avoids  damage  to  posterior  branches  of  the  renal  artery
which are closely associated with the renal pelvis. General anaesthesia is usual,
though regional or even local anaesthesia (with sedation) can be used.
Indications for PCNL

PCNL is generally recommended for stones >3cm in diameter, those that

have failed ESWL and/or an attempt at flexible ureteroscopy and laser
treatment. It is the first-line option for staghorn calculi, with ESWL and/or
repeat PCNL being used for residual stone fragments.

For stones 2-3cm in diameter, options include ESWL (with a JJ stent in

situ), flexible ureteroscopy and laser treatment, and PCNL.

Kidney stones: open stone surgery
Indications

Complex stone burden (projection of stone into multiple calyces, such
that multiple PCNL tracks would be required to gain access to all the
stone)

Failure of endoscopic treatment

Anatomic abnormality that precludes endoscopic surgery (e.g. retrorenal
colon)

Body habitus that precludes endoscopic surgery (e.g. gross obesity,
kyphoscoliosis)

Patient request for a single procedure where multiple PCNLs might be
required for stone clearance

Non-functioning kidney

If the kidney is non-functioning, the simplest way of removing the stone

is to remove the kidney.
Functioning kidneys options for stone removal
Small- to medium-sized stones: Pyelolithotomy, Radial nephrolithotomy.

Staghorn calculi



Anatrophic (avascular) nephrolithotomy



Extended pyelolithotomy with radial nephrotomies (small incisions over
individual stones)

Tikrit Medical College, Urology, Fifth year

أ.د. حممد حمسن عبد العزيز

Specific complications of open stone surgery

Wound infection (the stones operated on are often infection stones);

flank  hernia;  wound  pain.  (With  PCNL  these  problems  do  not  occur,  blood
transfusion  rate  is  lower,  analgesic  requirement  is  less,  mobilization  is  more
rapid and discharge earlier; all of which account for PCNL having replaced open
surgery  as  the  mainstay  of  treatment  of  large  stones.)  There  is  a  significant
chance  of  stone  recurrence  after  open  stone  surgery  (as  for  any  other
treatment  modality)  and  the  scar  tissue  that  develops  around  the  kidney  will
make subsequent open stone surgery technically more difficult.

Kidney stones: medical therapy (dissolution therapy)

Uric acid and cystine stones are suitable for dissolution therapy. Calcium

within either stone type reduces the chances of successful dissolution.
Uric acid stones

Uric acid stones form in concentrated, acid urine. Dissolution therapy is

based  on  hydration,  urine  alkalinization,  allopurinol,  and  dietary  manipulation:
the aim being to reduce urinary uric acid saturation. Maintain a high fluid intake
(urine  output  2-3L/day),  alkalinize  the  urine  to  pH  6.5-7.  In  those  with
hyperuricaemia,  add  allopurinol  300mg/day.  Dissolution  of  large  stones
(even staghorn calculi) is possible with this regimen.
Cystine stones



Reduce cystine excretion (dietary restriction of the cystine precursor
amino acid methionine and also of sodium intake to <100mg/day).



Increase solubility of cystine by alkalinization of the urine to >pH 7.5,
maintenance of a high fluid intake, and use of drugs which convert cystine
to more soluble compounds.

Ureteric stones: presentation

Ureteric stones usually present with sudden onset of severe flank pain

which is colicky (waves of increasing severity are followed by a reduction in
severity, but it seldom goes away completely). It may radiate to the groin as the
stone passes into the lower ureter. Examination

Spend a few seconds looking at the patient. Ureteric stone pain is colicky

the patient moves around, trying to find a comfortable position. Patients  with
conditions  causing  peritonitis  (e.g.  appendicitis,  a  ruptured  ectopic  pregnancy)
lie very still: movement and abdominal palpation are very painful. Many patients
with ureteric stones have dipstick or microscopic haematuria (and, more rarely,
macroscopic haematuria. The most important aspect of examination in a patient
with a ureteric stone confirmed on imaging is to measure their temperature. If
the  patient  has  a  stone  and a  fever,  they may  have  infection proximal  to  the
stone. A fever in the presence of an obstructing stone is an indication for urine

Tikrit Medical College, Urology, Fifth year

أ.د. حممد حمسن عبد العزيز

and blood culture, intravenous fluids and antibiotics, and nephrostomy drainage
if the fever does not resolve within a matter of hours.

Ureteric stones: diagnostic radiological imaging
The intravenous urogram (IVU), for many years the mainstay of imaging in
patients with flank pain, has been replaced by CT urography (CTU). Compared
with IVU, CTU:

Has greater specificity (95%) and sensitivity (97%) for diagnosing
ureteric stones: it can identify other, non-stone causes of flank pain .

Requires no contrast administration so avoiding the chance of a contrast
reaction (risk of fatal anaphylaxis following the administration of low-
osmolality contrast media for IVU is in the order of 1 in 100,000).

Is faster, taking just a few minutes to image the kidneys and ureters. An
IVU, particularly where delayed films are required to identify a stone
causing high-grade obstruction, may take hours to identify the precise
location of the obstructing stone.

Is equivalent in cost to IVU, in hospitals where high volumes of CT scans
are done.

If you only have access to IVU, remember that it is contraindicated in

patients with a history of previous contrast reactions and should be avoided in
those with hay fever, a strong history of allergies, or asthma who have not been
pre-treated  with  high-dose  steroids  24h  before  the  IVU.  Patients  taking
metformin for diabetes should stop this for 48h prior to an IVU. Clearly, being
able to perform an alternative test, such as CTU in such patients, is very useful.
Plain  abdominal  X-ray  and  renal  ultrasound  are  not  sufficiently  sensitive  or
specific for their routine use for diagnosing ureteric stones.

Ureteric stones: acute management
While  appropriate  imaging  studies  are  being  organized,  pain  relief  should  be
given.



A non-steroidal anti-inflammatory (e.g. diclofenac) by intramuscular or
intravenous injection, by mouth or per rectum. Provides rapid and
effective pain control. Analgesic effect: partly anti-inflammatory, partly
by reducing ureteric peristalsis.



Where NSAIDS are inadequate, opiate analgesics such as pethidine or
morphine are added

There is no need to encourage the patient to drink copious amounts of

fluids nor to give them large volumes of fluids intravenously in the hope that
this will flush the stone out. Renal blood flow and urine output from the

Tikrit Medical College, Urology, Fifth year

أ.د. حممد حمسن عبد العزيز

affected kidney falls during an episode of acute, partial obstruction due to a
stone. Excess urine output will tend to cause a greater degree of
hydronephrosis in the affected kidney which will make ureteric peristalsis even
less efficient .
Watchful waiting

In many instances, small ureteric stones will pass spontaneously within

days  or  a  few  weeks,  with  analgesic  supplements  for  exacerbations  of  pain.
Chances of spontaneous stone passage depend principally on stone size. Between
90-98%  of  stones  measuring  <4mm  will  pass  spontaneously.  Average  time  for
spontaneous  stone  passage  for  stones  4-6mm  in  diameter  is  3  weeks.  Stones
that have not passed in 2 months are unlikely to do so.

Ureteric  stones:  indications  for  intervention  to  relieve  obstruction  and/or
remove the stone



Pain which fails to respond to analgesics or recurs and cannot be
controlled with additional pain relief.



Fever. Have a low threshold for draining the kidney (usually done by
percutaneous nephrostomy).



Impaired renal function (solitary kidney obstructed by a stone, bilateral
ureteric stones, or pre-existing renal impairment which gets worse as a
consequence of a ureteric stone). Threshold for intervention is lower.



Prolonged unrelieved obstruction. This can result in long-term loss of
renal function. How long it takes for this loss of renal function to occur is
uncertain, but generally speaking the period of watchful waiting for
spontaneous stone passage tends to be limited to 4-6 weeks.



Social  reasons.  Young,  active  patients  may  be  very  keen  to  opt  for
surgical  treatment  because  they  need  to  get  back  to  work  or  their
childcare duties,  whereas  some  patients  will be  happy  to  sit  things  out.
Airline  pilots  and  some  other  professions  are  unable  to  work  until  they
are stone free.

Emergency temporizing and definitive treatment of the stone

Where the pain of a ureteric stone fails to respond to analgesics or

where renal function is impaired because of the stone, then temporary relief of
the  obstruction  can  be  obtained  by  insertion  of  a  JJ  stent  or  percutaneous
nephrostomy tube. Stone may pass down and out of the ureter with a stent or
nephrostomy  in  situ,  but  in  many  instances  it  simply  sits  where  it  is  and
subsequent definitive  treatment  is  still  required.  While  JJ  stents  can  relieve
stone pain, they can cause bothersome irritative bladder symptoms (pain in the
bladder,  frequency,  and  urgency).  JJ  stents  do  make  subsequent  stone
treatment  in  the  form  of  ureteroscopy  technically  easier  by  causing  passive
dilatation of the ureter.

Tikrit Medical College, Urology, Fifth year

أ.د. حممد حمسن عبد العزيز

The patient may elect to proceed to definitive stone treatment by

immediate  ureteroscopy  (for  stones  at  any  location  in  the  ureter)  or  ESWL
(if the stone is in the upper and lower ureter: ESWL cannot be used for stones
in  the  mid  ureter  because  this  region  is  surrounded  by  bone,  which  prevents
penetration of the shock waves).

Ureteric stone treatment

Many ureteric stones are 4mm in diameter or smaller and most such

stones (90%) will pass spontaneously, given a few weeks of watchful waiting,
with analgesics for exacerbations of pain. Average time for spontaneous stone
passage for stones 4-6mm in diameter is 3 weeks. Stones that have not passed
in 2 months are much less likely to do so, though large stones do sometimes
drop out of the ureter at the last moment.
Treatment options for ureteric stones



ESWL: in situ; after push-back into the kidney (i.e. into the renal pelvis
or calyces); or after JJ stent insertion



Ureteroscopy



PCNL



Open ureterolithotomy



Laparoscopic ureterolithotomy

The stone clearance rates for ESWL are stone-size dependent. ESWL is

more efficient for stones <1cm in diameter compared with those >1cm in size.
Conversely, the outcome of ureteroscopy is somewhat less dependent on stone
size.
Recommendations
Proximal ureteric stones



<1cm diameter: ESWL (in situ, push-back)



>1cm diameter: ESWL, ureteroscopy, PCNL

Distal ureteric stones



Both ESWL and ureteroscopy are acceptable options.



Stone free rate <1cm: 80-90% for both ESWL and ureteroscopy; >1cm:
75% for both ESWL and ureteroscopy.

Failed initial ESWL is associated with a low success rate for subsequent

ESWL. Therefore, if ESWL has no effect after 1 or 2 treatments, change
tactics.

Open ureterolithotomy and laparoscopic ureterolithotomy are used where

ESWL or ureteroscopy have been tried and failed, or were not feasible.

Tikrit Medical College, Urology, Fifth year

أ.د. حممد حمسن عبد العزيز

Bladder stones

Composition
Struvite (i.e. they are infection stones) or uric acid (in non-infected urine).
Adults

Bladder calculi are predominantly a disease of men aged >50 and with

bladder outlet obstruction due to BPH. They also occur in the chronically
catheterized patient (e.g. spinal cord injury patients

Children

Bladder stones are still common in Thailand, Indonesia, North Africa, and

the Middle East. In these endemic areas they are usually composed of
a combination of ammonium urate and calcium oxalate. A low-phosphate diet in
these areas (a diet of breast milk and polished rice or millet) results in high
peaks of ammonia excretion in the urine.
Symptoms

May be symptomless (incidental finding on KUB X-ray or bladder

ultrasound or on cystoscopy. In the neurologically intact patient: suprapubic or
perineal pain, haematuria, urgency and/or urge incontinence, recurrent UTI,
LUTS (hesitancy, poor flow).
Diagnosis

If you suspect a bladder stone, they will be visible on KUB X-ray or renal

ultrasound .
Treatment

Most stones are small enough to be removed cystoscopically (endoscopic

cystolitholapaxy),  using  stone-fragmenting  forceps  for  stones  that  can  be
engaged by the jaws of the forceps and EHL or pneumatic lithotripsy for those
that  cannot.  Large  stones    can  be  removed  by  open  surgery  (open
cystolithotomy).

Prevention of calcium oxalate stone formation

Low fluid intake

Low fluid intake may be the single most important risk factor for

recurrent stone formation. High fluid intake is protective, by reducing urinary
saturation of calcium, oxalate, and urate. Time to recurrent stone formation is
prolonged from 2 to 3 years in previous stone formers randomized to high fluid
vs. low fluid intake.

Dietary calcium

Conventional teaching was that high calcium intake increases the risk of

calcium oxalate stone disease. The Harvard Medical School studies have shown
that low calcium intake is, paradoxically, associated with an increased risk of
forming kidney stones, in both men and women

Tikrit Medical College, Urology, Fifth year

أ.د. حممد حمسن عبد العزيز

Calcium supplements

It is possible that consuming calcium supplements with a meal or with

oxalate-containing foods could reduce this small risk of inducing kidney stones.
Animal proteins

High intake of animal proteins causes increased urinary excretion of

calcium, reduced pH, high urinary uric acid, and reduced urinary citrate, all of
which predispose to stone formation.
Vegetarian diet

Vegetable proteins contain less of the amino acids phenylalanin, tyrosine,

and tryptophan that increase the endogenous production of oxalate. A
vegetarian diet may protect against the risk of stone formation.
Dietary oxalate

A small increase in urinary oxalate concentration increases calcium

oxalate supersaturation much more than does an increase in urinary calcium
concentration. Mild hyperoxaluria is one of the main factors leading to calcium
stone formation.