A 6-month-old boy is brought to the office for follow-up after a urinary tract infection. The boy was initially brought in 2 weeks ago with fever for 4 days. A urine culture from a catheterized urine specimen at that first visit grew 100,000 colony-forming units of Escherichia coli. The fever resolved within 48 hours with antibiotic therapy, and a full course of antibiotics was completed. Renal ultrasound performed 2 days ago showed mild right hydronephrosis; voiding cystourethrogram revealed dilation of the right ureter with blunting of the right renal calyces. The patient has no prior medical conditions and is up to date with vaccinations. Temperature is 36.7 C (98 F). Physical examination shows a circumcised male with a normal abdominal examination. If untreated, which of the following is the most likely long-term complication of this patient's condition?

Question

A 6-month-old boy is brought to the office for follow-up after a urinary tract infection.  The boy was initially brought in 2 weeks ago with fever for 4 days.  A urine culture from a catheterized urine specimen at that first visit grew >100,000 colony-forming units of Escherichia coli.  The fever resolved within 48 hours with antibiotic therapy, and a full course of antibiotics was completed.  Renal ultrasound performed 2 days ago showed mild right hydronephrosis; voiding cystourethrogram revealed dilation of the right ureter with blunting of the right renal calyces.  The patient has no prior medical conditions and is up to date with vaccinations.  Temperature is 36.7 C (98 F).  Physical examination shows a circumcised male with a normal abdominal examination.  If untreated, which of the following is the most likely long-term complication of this patient's condition?

Quizplus · Accepted Answer

11ec25c8_d733_dd9b_bc81_8b2cfdcbce71_MD0003_00 This patient's voiding cystourethrogram results suggest vesicoureteral reflux (VUR), defined as the retrograde flow of urine from the bladder into the ureter ± renal pelvis. VUR is the most common pediatric urologic condition and is present in about one third of children with febrile urinary tract infections (UTIs). The backward flow of urine may be caused by a defective valve in the ureter (primary VUR) or high bladder pressure (secondary VUR). retrograde flow of urine VUR may be asymptomatic or present with febrile UTI, as seen in this patient. Patients with VUR are at risk of developing recurrent UTIs and pyelonephritis due to reflux of nonsterile urine. Due to poor urinary drainage, the reflux itself can cause dilation of the renal collecting system. Bacterial penetration of the renal parenchyma induces an inflammatory response that can lead to ischemia and subsequent renal scar formation. Scarring is focal and manifests as wedges of fibrotic tissue due to chronic interstitial inflammation. Over time, scar tissue can lead to chronic renal insufficiency and secondary hypertension (Choice D). renal scar formation The first step in evaluation of a febrile UTI in an infant is renal and bladder ultrasound. If the ultrasound is abnormal (eg, hydronephrosis, scarring), voiding cystourethrography (VCUG) should be performed, which visualizes urine refluxing into the ureter and is the gold standard for diagnosing and grading VUR. Depending on VUR severity, dilation and blunting of the collecting system may be seen. The mainstay of therapy is antibiotic prophylaxis. VUR severity (Choice A) Acquired renal cysts are uncommon in children and typically develop in those undergoing dialysis for end-stage renal disease. VUR is not associated with renal cyst development. (Choice C) Postinfectious glomerulonephritis (inflammation of the renal glomerulus) can occur after skin or throat infection with group A Streptococcus. VUR and recurrent UTIs are not associated with glomerular disease. (Choice E) Obstructive uric acid renal stones are uncommon in children and associated with overproduction of uric acid (eg, tumor lysis syndrome). In contrast, VUR can lead to calcium stones (due to urinary stasis) and struvite stones (due to protease-producing bacterial UTIs). Educational objective: Vesicoureteral reflux is a risk factor for recurrent urinary tract infections and, if untreated, can lead to renal scar formation, hypertension, and chronic renal insufficiency. Scarring is focal due to chronic interstitial inflammation and fibrosis. References: Risk factors for renal scarring in children with primary vesicoureteral reflux disease. (http://www.ncbi.nlm.nih.gov/pubmed/23354192) Renal scar formation after urinary tract infection in children. (http://www.ncbi.nlm.nih.gov/pubmed/23133482)

A 6-Month-Old Boy Is Brought to the Office for Follow-Up