Master the board step 3

Master the Boards: USMLE Step 3
Vesicoureteral Reflux (VUR)
A 2-year-old girl presents with a urinary tract infection. She has had multiple urinary
tract infections since birth but has never had any follow-up studies to evaluate
these infections. Physical examination is remarkable for an ill-appearing child
who has a temperature of 40°C (104°F) and is vomiting. Voiding cystourethrogram
reveals abnormal urinary backflow from the bladder. Which of the following is the
most important step to prevent permanent damage?
a. ACE inhibitors
b. Trimethoprim-sulfamethoxazole
c. NSAIDs
d. Regular creatinine measurement
e. Surgical reconstruction
Answer: B. Antibiotic prophylaxis (trimethoprim-sulfamethoxazole or nitrofurantoin) is
used for the 1st year following diagnosis for any grade of VUR, particularly in younger
infants, to prevent kidney scarring from recurrent infections.
VUR is abnormal movement of urine from the bladder into the ureters/kidneys. Urine
usually travels from the kidneys through the ureters, then into the bladder. In VUR,
urine flow is reversed.
VUR predisposes the child to pyelonephritis, which leads to scarring, which leads to
reflux nephropathy (hypertension, proteinuria, renal insufficiency to end-stage renal
disease [ESRD], impaired kidney growth).
Diagnostic Testing
Perform a voiding cystourethrogram (VCUG) and renal scan. If scarring is
present, follow creatinine periodically.
Treatment
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Antibiotic prophylaxis
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Surgery under the following conditions:
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Any breakthrough UTI
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New scars
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Failure to resolve
Obstructive Uropathy
The first presentation of obstructive uropathy is often infection or sepsis. The
most common causes of obstructive uropathy are the following:
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Boys: Posterior urethral valves are the most common cause of bladder
obstruction. Look for walnut-shaped mass (bladder) above pubic symphysis
and weak urinary stream.
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Newborns: Hydronephrosis and polycystic kidney disease are the most
common causes of a palpable abdominal mass.
The best initial diagnostic tests are VCUG and renal ultrasound.
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