14.3 UTI, Enuresis & Genitourinary Anomalies
Key Takeaways
Pediatric UTI diagnosis requires both a positive urinalysis and culture growth above the threshold for the collection method used; bag specimens are for screening only, not for confirming the diagnosis.
Current AAP guidance recommends a renal-bladder ultrasound after the first febrile UTI in infants 2-24 months, reserving VCUG for abnormal ultrasound findings, recurrent febrile UTIs, or atypical presentations.
Vesicoureteral reflux is graded I-V by severity; low grades often resolve spontaneously while high grades (IV-V) carry a greater risk of renal scarring.
Enuresis is diagnosed at or after age 5; secondary enuresis, recurrence after 6 months of established dryness, is more concerning than primary enuresis and warrants a search for an underlying cause.
Posterior urethral valves occur only in boys, hypospadias repair requires an intact foreskin for reconstruction, and undescended testes should be referred for orchiopexy if not descended by 6 months.
UTI, Enuresis & Genitourinary Anomalies
Urinary tract infection diagnosis, imaging decisions after febrile UTI, enuresis classification, and common congenital genitourinary anomalies appear regularly on the ABHS Part 1 exam as short clinical vignettes testing protocol knowledge rather than subspecialty nuance.
Diagnosing Pediatric Urinary Tract Infection
Escherichia coli causes roughly 80-90% of pediatric urinary tract infections (UTIs); other organisms include Klebsiella, Proteus (especially in uncircumcised boys and children with urinary stones), Enterococcus, and, in adolescent girls, Staphylococcus saprophyticus. A febrile infant without an obvious source, especially an uncircumcised boy or a girl under 24 months, should always prompt consideration of UTI.
Diagnosis requires both a urinalysis suggestive of infection (positive leukocyte esterase and/or nitrite, pyuria greater than 5 white blood cells per high-power field) and a culture from a properly collected specimen showing significant growth of a single uropathogen — urinalysis alone is not diagnostic.
| Collection method | Use | Significant colony count |
|---|---|---|
| Clean-catch (midstream) | Toilet-trained children | 100,000 CFU/mL or more of a single organism |
| Bag specimen | Screening only in non-toilet-trained infants | Not valid for diagnosis; high false-positive rate, so a positive bag specimen must be confirmed by catheter or suprapubic aspiration |
| Transurethral catheterization | Preferred method in infants and non-toilet-trained children | 50,000 CFU/mL or more of a single organism |
| Suprapubic aspiration (SPA) | Gold standard; technically difficult, reserved for select cases | Any growth of a single organism |
Empiric Treatment
Once UTI is confirmed, start empiric antibiotics directed at E. coli — common oral choices include cephalexin, amoxicillin-clavulanate, or trimethoprim-sulfamethoxazole when local resistance patterns permit. Febrile infants and young children are treated as having upper tract involvement (pyelonephritis) even without classic flank findings; typical duration is 7-14 days of oral therapy if the child is well enough to take antibiotics by mouth and has reliable follow-up. Toxic-appearing infants, neonates under 2-3 months, or children unable to tolerate oral intake need parenteral antibiotics (commonly ceftriaxone) with transition to oral therapy once clinically improved.
When Imaging Is Indicated
Per American Academy of Pediatrics (AAP) guidance, a renal and bladder ultrasound (RBUS) is recommended after the first febrile UTI in infants 2-24 months old, to look for hydronephrosis, obstruction, or abnormal kidney size or scarring. A voiding cystourethrogram (VCUG) is not performed routinely after a first febrile UTI; it is reserved for children whose RBUS shows hydronephrosis, scarring, or other findings suggestive of high-grade vesicoureteral reflux (VUR) or obstructive uropathy, or for recurrent febrile UTIs and atypical or complex presentations.
VUR grading (International Reflux Study Classification, grades I-V) is a recurring exam concept:
| Grade | Findings |
|---|---|
| I | Reflux into the ureter only; no dilation |
| II | Reflux reaches the pelvis and calyces; no dilation |
| III | Mild-to-moderate dilation of the ureter, pelvis, and calyces |
| IV | Moderate ureteral tortuosity and pelvicalyceal dilation |
| V | Gross dilation and tortuosity, with loss of papillary impressions |
Low-grade reflux (I-II) frequently resolves spontaneously as the child grows; high-grade reflux (IV-V) carries a higher risk of persistent reflux and renal scarring, and is more likely to require surgical correction such as ureteral reimplantation. Repeated febrile UTIs in a child with VUR can lead to reflux nephropathy, chronic renal scarring that predisposes to hypertension and chronic kidney disease later in life.
Enuresis
Enuresis is involuntary urination in a child who has reached the developmental age at which bladder control is expected — by convention, age 5 years or older.
- Primary enuresis: the child has never achieved a sustained, at least 6-month, period of dryness.
- Secondary enuresis: wetting recurs after at least 6 months of established dryness; this pattern is more concerning and warrants evaluation for an underlying trigger such as UTI, diabetes mellitus or insipidus, constipation, obstructive sleep apnea, or psychosocial stress.
- Nocturnal enuresis: wetting during sleep only; the most common pattern, often familial, with a high rate of spontaneous resolution over successive years.
- Diurnal enuresis: daytime wetting; more likely to reflect underlying bladder dysfunction (overactive bladder, dysfunctional voiding) or a structural anomaly such as an ectopic ureter, and warrants closer evaluation.
Because spontaneous resolution is common, active treatment is generally reserved for children whose enuresis persists beyond about age 6-7 years, or sooner if it is causing significant distress. Uncomplicated primary monosymptomatic nocturnal enuresis, meaning no daytime symptoms, a normal exam, and a normal urinalysis, typically needs no imaging or laboratory workup beyond a good history and urinalysis. First-line management is behavioral: scheduled voiding, limiting evening fluids, and a bedwetting alarm. Desmopressin (DDAVP) is a pharmacologic option for nocturnal enuresis, used with caution to avoid excess evening fluid intake because of the risk of hyponatremia and water intoxication.
Common Genitourinary Anomalies
| Anomaly | Key features | Management |
|---|---|---|
| Posterior urethral valves (PUV) | Most common cause of lower urinary tract obstruction in male infants (boys only); may present antenatally with oligohydramnios and bilateral hydronephrosis, or postnatally with a poor urinary stream, palpable bladder, UTI, or renal failure; VCUG shows a dilated posterior urethra, the "keyhole sign" | Emergent bladder catheterization, then valve ablation; risk of bladder dysfunction and renal dysplasia or chronic kidney disease |
| Hypospadias | Ventral, not tip-of-glans, location of the urethral meatus from incomplete fusion of the urethral folds; may include ventral curvature (chordee) and is associated with undescended testes and inguinal hernia | Surgical repair typically around 6-12 months of age; circumcision must be avoided beforehand because the foreskin is used for reconstruction |
| Cryptorchidism | Undescended testis; common in premature infants; most descend spontaneously by 6 months corrected age | If undescended by 6 months, refer for orchiopexy, ideally completed by 12-18 months, to reduce the risk of infertility, testicular malignancy, and torsion |
A 10-month-old uncircumcised boy has a bag urine specimen positive for leukocyte esterase and nitrites. What is the most appropriate next step before diagnosing a UTI?
Start empiric antibiotics based on the bag specimen alone
Repeat the bag specimen in one week
Confirm with a catheterized or suprapubic specimen
Obtain a VCUG immediately
Following a first febrile UTI in a 14-month-old girl, renal and bladder ultrasound is normal. What is the most appropriate next step regarding a VCUG?
VCUG is not indicated unless there is recurrence or atypical findings
Perform VCUG routinely to rule out VUR
Perform VCUG only if the child is a boy
Delay ultrasound and go straight to VCUG
A VCUG shows reflux with moderate ureteral dilation and tortuosity and moderate dilation of the pelvis and calyces, without loss of papillary impressions. This corresponds to which VUR grade?
Grade II
Grade III
Grade IV
Grade V
A 9-year-old boy who has never had a dry night, with no daytime symptoms and a normal urinalysis, is brought in by his parents. Which statement is correct?
This is secondary enuresis and requires an urgent renal ultrasound
A VCUG is required before any treatment can begin
Desmopressin is contraindicated in all children under 10
This is primary nocturnal enuresis, and behavioral measures are reasonable first-line therapy
A newborn boy is noted to have a ventrally displaced urethral meatus and ventral curvature of the penis. Which of the following is correct regarding management?
Circumcision should be performed promptly to reduce infection risk
The foreskin should be preserved because it is used in the surgical repair
This finding requires no follow-up if the testes are descended
This anomaly is more common in girls than boys
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