Radiology Cases in Pediatric Emergency Medicine
Volume 7, Case 5
Daniel C.H. Kidani, Medical Student
Loren G. Yamamoto, MD, MPH
Kapiolani Medical Center For Women And Children
University of Hawaii John A. Burns School of Medicine
Three cases will be presented:
This is a 16 year old female who presents to the
emergency department with a one day history of severe
right flank pain with associated vomiting. She denies
any fever, urgency, or dysuria. Her past medical
history is unremarkable.
Exam: VS T 36.8 degrees C, P53, RR 24, BP
120/80. She is alert, cooperative, in moderately severe
discomfort. HEENT unremarkable. Heart regular.
Lungs clear. Abdomen Diffuse tenderness on the right.
Guarding and rebound are present on the right. She
has severe right CVA tenderness.
UA: >100 RBCs, 20-50 WBCs, positive nitrite.
UCG negative. WBC 10.1, Hgb 13. BUN 11, Creat
0.8. An abdominal flat plate is ordered.
View her abdominal radiograph.
This abdominal flat plate demonstrates a possible
renal stone on the patient's right at the level of L3 and
View the arrow to see where the stone is. It is not
easy to see.
An IVP is ordered.
View her IVP at 5 and 20 minutes.
IVP at 5 minutes (below)
IVP at 20 minutes (below)
The first IVP image is taken at 5 minutes following
IV contrast. This shows prompt excretion of contrast
from the left kidney. Contrast is seen excreted from the
right kidney, but the ureter is not well visualized
suggesting an obstruction in ureter. The calyces are
blunted indicating hydronephrosis. The second IVP
image is taken at 20 minutes following IV contrast. This
shows delayed retention of contrast on the right. The
calyceal blunting of the right kidney indicating
hydronephrosis is more evident. There is a narrowing
of the ureter on the right in the area of the suspected
View a close-up of this.
This view shows a close-up of the same 20 minute
IVP on the right in the area of the suspected stone.
The black arrow points at this area.
This is a 15 year old male who presents to the
emergency department with abdominal pain, vomiting
and spots on his legs. He vomited 15 times. He also
noted a red spot on his eye. His pain is intermittent
Exam: VS T 37.5 degrees C, P70, R20, BP 125/80.
He is alert and comfortable. He has a subconjunctival
hemorrhage. HEENT otherwise unremarkable. Heart
regular without murmurs. Lungs clear. Abdomen soft,
non-tender with normal bowel sounds. No CVA
tenderness. He has a moderate degree of purpuric
lesions mostly on his lower extremities.
His CBC and coagulation studies are normal. His
UA shows 5-10 RBCs. An abdominal series is ordered.
View his abdominal series.
Supine view (below)
Upright view (below)
View a close-up of the supine view.
His abdominal radiographs demonstrate an
incidental finding of a two calcifications superimposed
on the right kidney, which are suggestive of kidney
stones. These are best seen on the supine (flat) view.
The calcifications are present on the upright view, but
they are superimposed over his 12th rib, making it more
difficult to see.
A CT scan is done.
View his CT scan.
His CT scan is unremarkable except for the
incidental finding of stones in his right kidney. The
arrow points to a stone in his right kidney.
He is discharged with a diagnosis of probable
anaphylactoid purpura, subconjunctival hemorrhage
and nephrolithiasis. Lithotripsy is considered.
This is a 19 year old female who presents to the
emergency department with a chief complaint of
abdominal pain. She has a two-day history of
abdominal pain progressing to right CVA tenderness
with radiation to the groin region. She also has fever,
vomiting, nausea, chills, dysuria, urinary frequency,
diarrhea, and general malaise.
Exam: VS: T 37 degrees C, P 67, RR 20, BP
105/68. She is alert, oriented, not toxic and in no
apparent distress. Her oral mucous membranes are
pink and moist. Heart regular without murmurs or extra
heart sounds. Lungs clear to auscultation and
percussion bilaterally. She has mild CVA tenderness
on the right side. Abdomen is soft and nondistended
with normal bowel sounds. She has some RUQ
tenderness. No rebound tenderness or peritoneal
signs. No masses were palpated. Her pelvic exam is
significant for mild right adnexal tenderness. There is
no cervical motion tenderness. Extremities
Her lab studies show: WBC 17.0, Hgb 13, platelet
count 295,000. UA 1+ protein, 4+ blood, positive
leukocyte esterase, many bacteria, 20-50 WBCs and
5-10 RBCs per high power field. UCG negative. An
abdominal series is ordered.
View her abdominal series.
Supine view (below)
Upright view (below)
There is nothing obvious on the supine (flat) view.
The upright view is significant for a calcification
overlying the right kidney. Another abdominal flat
plate is ordered to see if the calcification has moved.
View later abdominal radiograph.
This follow-up radiograph shows persistence of the
calcification over the right kidney. A CT scan is
View the patient's CT scan.
The first CT image shows a contrast enhanced left
kidney with prompt excretion of contrast. The right
kidney is excessively contrast enhanced with no
excretion of contrast. The black arrow points at two
stones in the renal collecting system.
The second CT image shows a dilated ureter on the
right kidney (black arrow). The third CT image shows a
dilated ureter on the right without contrast flow
compared to the normal sized contrast filled ureter on
the left. The fourth CT image shows another stone in
the right ureter just as it enters the bladder.
The patient is diagnosed with pyelonephritis,
hydronephrosis and urolithiasis. She is hospitalized
and treated with IV antibiotics, fluids and ketorolac.
Her urine culture later grows proteus species which
is a urea splitting organism suggesting that these are
Urolithiasis affects 2-10% of industrialized
populations, with a lower incidence in
non-industrialized countries. Most, 80%-85%, of
stones pass spontaneously; however, 20% of patients
require hospitalization. Recurrence rates are 14%,
35%, and 52% at 1, 5, and 10 years respectively, after
the first stone is passed. The peak onset of
symptomatic kidney stones is in the 3rd and 4th
decades of life, with a male to female ratio of 3:1(1).
High humidity and elevated temperatures seem to be
contributing factors to the development of renal calculi.
Symptomatic stones also have their highest incidence
in the higher temperatures of the summer months (4).
Nephrolithiasis is rare in children; however, the
incidence of urinary calculi in the United States is
increasing. Approximately 5-10 cases of urolithiasis
between 10 months and 16 years of age are seen at a
typical US pediatric center annually (1). Although
urolithiasis is uncommon in children younger than 2
years of age, the incidence does not seem to favor any
age group or gender (2). Approximately 66% of urinary
calculi in North American children are found in the
kidneys at the time of diagnosis, the remaining 1/3 are
located in the ureters (2).
The etiology of kidney stones is derived from an
imbalance of a delicate equilibrium within the kidneys.
The kidneys must both conserve water and excrete
substances with a low solubility, two opposing factors.
This balance must be maintained with the adaptation to
diet, climate, and activity. When this balance is
disrupted, the urine may become supersaturated with
insoluble materials which may aggregate into a
There are four basic types of renal calculi: calcium,
struvite, uric acid, and cystine stones. Calcium stones,
which account for 75%-85% of all renal calculi, consist
of calcium oxalate, calcium phosphate, or calcium
urate. Since most renal calculi are composed of
calcium, most urinary stones are radioopaque (4).
They are more common in males, often arise in the 3rd
decade of life, have a recurrence rate between 2 and 3
years, and is frequently familial (3). They are
associated with idiopathic hypercalciuria,
hyperuricosuria and primary hyperparathyroidism which
accounts for 50%, 20% and, 5% of calcium stones,
respectively. Another 20% are idiopathic (3).
Struvite (magnesium ammonium phosphate) stones
are relatively common, making up 10%-15% of all renal
calculi (3). These stones are due to chronic urinary
tract infections with gram-negative urease-producing
bacteria and therefore are commonly found in women
and in those patients requiring chronic bladder
catherization (3). Common organisms are Proteus,
Pseudomonas, and Klebsiella species. Struvite is
visualized on radiograph when it complexes with
calcium carbonate or calcium phosphate. These
stones are capable of obtaining large sizes, large
enough to fill the renal pelvis and calyces to produce
staghorn calculi (3).
Uric acid stones make up 5%-8% of renal calculi (3).
They are radiolucent, are more common in males, and
are commonly familial. Since pure uric acid stones are
radiolucent, CT, ultrasound, or intravenous
ultrasonography may be implemented for detection;
however, uric acid frequently complexes with calcium
oxalate making these stones radioopaque via
radiograph (4). About 25% of patients with uric acid
stones have gout.
Cystine stones are rare and account for
approximately 1% of all renal calculi (3). Because of
their sulfur content, cystine stones are only slightly
radioopaque, so are poorly visualized on x-ray. They
are due to a hereditary metabolic defect resulting in
proximal tubular and jejunal transport of the dibasic
amino acids: cystine, lysine, arginine, and ornithine.
Thus, a large amount of these amino acids are lost in
the urine; however, because of its relative insolubility,
cystine is the only one of these amino acids to form
Stones initially form on the renal papillae or within
the collecting system. Stones need not be
symptomatic; however, pain and obstruction arise when
stones break loose and enter the ureter or
ureteropelvic junction (3). It is not uncommon for
struvite, cystine, or uric acid stones to grow too large to
enter the ureter; these stones gradually fill the renal
papillae and even the renal calyces, forming staghorn
As the stone traverses the ureter it commonly
produces severe colicky pain and bleeding, termed
renal colic (5). The pain develops gradually,
manifesting initially in the flank progressing downward
and anteriorly toward the lower back and genitalia.
Stones obstructing the ureteropelvic junction may
present with mild to severe flank pain without radiation
due to distention of the renal capsule. Pain which
migrates downward suggests that the stone has passed
to the lower third of the ureter. In the absence of
migrating pain, the position of the calculi cannot be
predicted. If the stone makes its way to the
ureterovesical junction, symptoms consistent with
urinary tract infection may manifest; frequency,
urgency, dysuria (3). When the stone passes into the
bladder, the pain subsides; however, unique symptoms
arise if the stone enters the urethra (5). There is no
correlation between stone size and severity of
symptoms (4). The symptoms surrounding urolithiasis
in the pediatric patient varies with age. The
excruciating flank pain associated with stone passage
in the adult patient is rarely seen in children; however,
50% of children experience abdominal, flank, or pelvic
pain. The pain from renal calculi may mimic colic in
infants. Pre-school aged children commonly
experience the symptoms of urinary tract infections
while adolescents more commonly experience pain
similar to adults (2).
The patient who presents with a renal stone may be
mistaken for a patient with an aortic dissection, acute
appendicitis, mechanical back pain, bowel obstruction,
cholecystitis and biliary colic, constipation, epididymitis,
gastritis or peptic ulcer disease, UTI and
pyelonephritis, PID, pneumonia, testicular torsion, or
urinary obstruction (1). Thus, these differential
diagnoses must be considered.
Upon physical examination, the patient with renal
colic is typically writhing in pain and is unable to keep
still; in contrast to patients suffering from peritoneal
irritation who remain motionless to minimize the pain
(4). Fever is absent in uncomplicated cases of
urolithiasis. Pyelonephritis, pyonephrosis, or
perinephric abscess should be suspected if fever is
present. An abdominal examination is typically
unremarkable; although hypoactive bowel sounds may
indicate an ileus, which is common in patients suffering
from severe, acute pain. In male patients, pain may
radiate to the testicles; however, the testicles should
appear normal and be only mildly tender. One should
be wary of the older patient (>60 years old) with a
suspected primary case of nephrolithiasis and should
take care to rule out an aortic aneurysm (1).
The evaluation of a patient with a suspected renal
calculi should consist of a metabolic evaluation, urine
and dipstick, as well as imaging. Recovered stones
should be examined for composition, as treatment
differs according to stone type. Controversy exists as
to which patients require a thorough metabolic work-up;
however, abnormalities of serum calcium, phosphate,
electrolytes, and uric acid should be screened for in
first time stone formers. In recurrent stone formers or
patients with a family history of stone disease, a more
extensive evaluation is required. An initial 24 hour
urine collection on a random diet should be analyzed
for volume, urinary pH, and calcium, uric acid, oxalate,
phosphate, and citrate excretion. If necessary, a
second 24 hour urine collection can be made on a
restricted calcium diet. PTH and calcium load tests can
be performed to further clarify metabolic abnormalities
Urinalysis may reveal microscopic or gross
hematuria. 85% of patients with ureterolithiasis have
hematuria on microscopic exam of the urine, while 95%
have hematuria when both microscopy and urine
dipstick are used (1). Although hematuria is commonly
associated with urinary calculi, the degree of hematuria
is not predictive of stone size or passage.
Infection must be excluded in cases of renal calculi.
If a urinary tract infection is present with
hydronephrosis, hospital admission is mandatory
unless follow-up is readily available within 24 hours (1).
Non-contrast helical CT is currently the gold
standard imaging study for the diagnosis of
ureterolithiasis in the emergency department.
Non-contrast helical CT has been shown to have a
sensitivity of 95%-100% and a specificity greater than
that of an intravenous pyelogram (IVP). Advantages of
non-contrast helical CT are that it can be done in less
than 5 minutes and avoids the use of IV contrast.
However, helical CT does not provide information on
kidney function, the degree of obstruction, and does not
visualize indinavir stones well (1).
Prior to helical CT, IVP was the gold standard
imaging technique. Since IVP is dependent on the flow
of IV contrast from the kidney to the ureters, both
kidney function and degree of obstruction can be
assessed. It is also the test of choice for diagnosing
indinavir stones. However, an IVP is not as rapid as a
helical CT and exposes patients to both radiation and
the risk of nephrotoxicity or anaphylactoid reactions
due to contrast agents. The cost of an IVP is
comparable to a helical CT (1).
Although less sensitive or accurate than either an
IVP or helical CT in diagnosing ureteral calculi,
ultrasound is useful in the pregnant or unstable patient.
It is also a useful imaging modality in the course of
ruling out an abdominal aortic aneurysm in patients
older than 60 who present with a first or atypical
nephrolithiasis. Ultrasound may also be able to
elucidate stones at the ureterovesical junction that may
have been missed by helical CT or IVP (1).
Treatment of nephrolithiasis is dependent on stone
type. However, IV access should be obtained to
administer pain and antiemetic medications. IV
hydration is controversial as some believe fluid loading
forces the stone through the urinary tract at a faster
rate; however, some feel as if this may increases renal
colic (1). However, it is generally accepted that
increased fluid intake is beneficial in diluting the urine
and impeding stone formation.
In some instances, purely medical treatment is not
sufficient and surgical intervention is indicated.
Ureterolithiasis coupled with a fever, suggesting a
urinary tract infection represents a true medical
emergency. IV antibiotics and immediate drainage of
the infected hydronephrosis are indicated, either
through percutaneous nephrostomy or ureteral stent
placement. Antibiotics alone, in this situation, may be
When stones fail to pass spontaneously and impede
urine flow, surgical measures are often indicated.
Typically, stones lodge at three main sites: the
ureteropelvic junction, the point at which the ureter
crosses the iliac vessels, and the ureterovesical
junction. Although stones less than 6mm in diameter
commonly pass spontaneously, it is difficult to
determine which stones will pass. Conservative
observation with the proper pain medications is
appropriate for the first 6 weeks; if the stone has not
passed by the 6th week, more aggressive intervention
is required. Indication for intervention before the 6th
week includes severe pain that does respond to
medication, fever, chronic nausea and vomiting that
requires IV hydration, and social factors (e.g. need to
return to work or travel) (4).
Distal ureteral stones are best extracted via
ureteroscope or in situ extracorporeal shock wave
lithotripsy (ESWL). Ureteroscopic extraction involves
passing an endoscope through the urethra into the
ureter. With the aid of direct visualization, the stone is
removed via basket extraction. In situ ESWL involves
the use of external energy that is focused at the point of
the stone, resulting in stone fragmentation and
eventually stone passage. This technique is not
advised for women of childbearing age with stones in
the lower ureter since the effects of such treatment on
the ovaries is unknown (4).
Proximal and midureteral stones (i.e. above the
inferior margin of the sacroiliac joint) can also be
treated with ureteroscopy or in situ ESWL. With
ESWL, the stone can be pushed back via a retrograde
ureteral catheter into the renal pelvis so as to provide a
larger area for stone fragmentation. Stents may be
placed in the ureter to facilitate passage and prevent
Renal stones that are asymptomatic do not need to
be treated. However, they should be monitored via
serial abdominal radiographs or renal ultrasound. If the
stone is growing and becomes symptomatic, the
appropriate procedures should be undertaken. Stones
less than 3cm in diameter should be treated with
ESWL; while larger stones, and stones that reside in
the inferior calyx are best treated with percutaneous
1. Craig S. Renal Calculi. Available online at
June 28, 2000.
2. Kroovand LR. Pediatric Urolithiasis. Urologic
Clinics of North America 1997;24(1):173-184.
3. Asplin JR, Coe FL, Favus MJ. Nephrolithiasis.
In: Braunwald E, Fauci AS, Hauser SL, Isselbacher KJ,
Kasper DL, Longo DL, Martin JB, Wilson JD (eds).
Harrison's Principles of Internal Medicine, 14th Edition
CD-ROM. McGraw-Hill, New York, 1998,
4. Presti JC, Stoller ML, Carroll PR. Urology:
Urinary Stone Disease. In: Tierney LM, McPhee SJ,
Papadakis MA (eds). Current Medical Diagnosis and
Treatment, 39th edition. Lange Medical Books, New
York, 2000, pp929-933.
5. Hruska K. Renal Calculi (Nephrolithiasis). In:
Goldman L, Bennett JC (eds). Cecil Textbook of
Medicine, 21st ed. W.B. Saunders Company,
Philadelphia, 2000, pp622-627.
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