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?
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?
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?
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?
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?