Antenatal Hydronephrosis

Definition: AP diameter renal pelvis > 20 wk EGA AP diameter renal pelvis > 30 wk EGA Incidence: 5% of pregnancies

Antenatal Hydronephrosis Standard work-up: –Postnatal ultrasound Look for –AP diameter –Calyceal/ureteral dilation –Renal size –Corticomedullary differentiation –Thinned/hyperechoic cortex –Cortical cysts –Ureterocele –Ectopic ureteral insertion Best after first 24 hours of life/when not volume depleted

ANH: Work-up (cont.) –VCUG Vesicoureteral reflux Posterior urethral valves Ureterocele –Antibiotics (Amoxicillin 10mg/kg/day) until VCUG done (and normal)

Is a VCUG Necessary? Ismaili et al., Journal of Pediatrics, June 2004 –258 pts with ANH –81 w/u WNL –49 uncomplicated duplication or dilation resolved –83 with significant findings 27 UPJ 23 primary VUR 15 primary megaureter 10 complicated duplication (ureterocele/ectopic ureter) 3 MCDK 2 posterior urethral valves 2 horseshoe kidney 1 renal dysplasia

Ismaili Article Continued Normal postnatal US 3% abnormal VCUG AP diameter 7-10mm -- 64% had significant findings AP diameter >10mm % had significant findings Recommends no VCUG if US wnl This is in sharp contrast to several earlier studies

Phan, et al., Pediatric Nephrology, October /111 pts with ANH and AP diameter <10mm (including several wnl) 16 (24%) had VUR

Anderson, et al., Pediatric Nephrology, November 1997 Postnatal renal sonogram could not predict presence of VUR in pts with AP diameter >4mm antenatally 9% of pts with nl postnatal US had VUR

Farhat, et al., Journal of Urology, September % of pts with VUR (w/u prompted by ANH) had a normal postnatal RBUS

Herndon, et al., Journal of Urology, September 1999 Of pts later dx’d with VUR (as part of ANH w/u) 88% had AP diameter <10mm 25% had nl postnatal RBUS Only 26 ureters (of 112 refluxing units) dilated on RBUS

Radiology % of patients with ANH and nl postnatal RBUS had VUR on VCUG

Breakdown of postnatal dx 60%--normal 25%--UPJ (includes those that require no intervention) 15%--VUR 1-2% other (diagnoses may overlap)

When to get an IVP/Mag 3 More reliable results after 8-12 weeks of life Mag 3 nuclear renogram preferred Most algorithms now are based on delayed T ½ on nuclear renogram and changes in differential function

Mag 3 Nuclear Renogram with Lasix Washout AP diameter >10mm After 12 weeks of life Differential function Drainage (measured as time to drainage of ½ volume of renal pelvis from administration of Lasix [or peak of tracer]), but the actual image may be more revealing, depending on region of interest drawn

When to intervene Differential function < 40% Progressive decrease in differential function on sequential nuclear renograms

Onen, Jayanthi, and Koff. Journal of Urology. September 2002 Looks at bilateral Initial evaluation: US, nuclear renogram, serum creatinine 13/38 kidneys required pyeloplasty— criteria: worsening hydronephrosis, decrease in relative function >10% Mean time to maximal improvement by US post-op 14 months in operated group 10 months in nonoperative group

Other Reasons for Intervention Symptomatic –Failure to thrive –UTI

IVP Megaureter Persistence of AP diameter >10mm, but preserved function at one year

DMSA Multicystic Dysplastic Kidney Assure that there is no function before abandoning kidney 42% of kidneys dx’d as MCDK kidneys antenatally are actually hydronephrosis/UPJ obstruction

Conclusions Most diagnoses made based on a finding of prenatal hydronephrosis can be handled conservatively. However, until we have better ways to predict who will require intervention, a complete work-up, including RBUS and VCUG is warranted in all pts with an AP renal diameter >4mm prenatally.

Urinary Tract Infections in Children Incidence –Neonates: M > F –Thereafter: F > M

Organisms Enterobacteriaciae –Escherichia (80%) –Klebsiella –Enterobacter –Citrobacter –Proteus –Providencia –Morganella –Serratia –Salmonella

Other Organisms Pseudamonas Staphylococcus Enterobacter

Risk Factors Perineal colonization Family hx Presence of a prepuce –10x risk –Periurethral colonization—circ eliminates this –Adherence of P fimbriated E. coli to prepuce Urethral length Urine pH (6-7 favors growth) Urine concentration—dilute has less nutrients Dysfunctional elimination

Risk Factors— Dysfunctional Elimination Residual urine Increased intravesical pressure Bladder overdistension Constipation –24% day wetters –34% night wetters 90% of pts with UTI and no structural anomalies had dysfunctional elimination

Not Risk Factors Bubble baths Improper wiping

Risk Factors Upper Tract Infections Antigen P1 blood group receptors Vesicoureteral Reflux –25-50% of patients with pyelonephritis have VUR –Less virulent strains of E. coli can cause pyelo inpatients with VUR Obstruction Heredity

Presentation Nonverbal Patient –Irritability –Poor feeding –Failure to thrive –Vomiting –Diarrhea –Fever Verbal Patient –Urgency –Frequency –Enuresis –Dysuria –Fever

Diagnosis Urine Culture is ABSOLUTELY NECESSARY Symptoms are not enough History is not enough Of patients with dysuria, urgency, frequency, enuresis 18% had + UCX, 40% had URI (yes, respiratory infection!) Local symptoms could be the same with vulvitis, urethritis, dysfunctional voiding, dehydration

Urine Cultures Bagged specimens are only valuable when negative Voided, midstream catch Catheterized best, and necessary in the pre-potty training age, especially if there is a fever and the diagnosis of UTI is going to lead to further testing

Diagnosis UA –WBC 70% reliable –Bacteria on a centrifuged urine UTI if WBC>10/mL & UCx >50k cfu/mL Dipstick LE 52.9%, Nitrite 31.4% sensitive Nitrites require 4hrs of bacterial incubation to be + LE may give false positive after prolonged exposure to air

Level of Infection Cystitis –Symptoms Dysuria Frequency Urgency 2 o enuresis Usually no systemic symptoms

Level of Infection Pyelonephritis –Fever –Flank pain –Pyuria –UCx positive –Elevated serum WBC, ESR, CRP

Asymptomatic Bacteruria Positive urine culture No urinary symptoms Only 4% later progress to symptomatic infection The organism may be commensal and protective to prevent infection with a more virulent organism In the absence of VUR, no treatment necessary, but look for voiding dysfunction

Pyelonephritis (continued Diagnosis: UCx and pyuria, but DMSA to be absolutely certain (in the first several days of symptoms) Risks from episodes of pyelo –Focal ischemia –Inflammatory changes –Renal scarring –Hypertension –Renal insufficiency

Treatment Lower Tract (no fever) –Treat 3-5 days –Start with TMP-SMX, nitrofurantoin or cephalosporin –Amoxil may change gut flora and lead to future infections with resistant organisms –FQ ok if there is no other oral agent to use

Treatment Pyelonephritis –Treat days –Start with Bactrim of Cephalosporin until culture is back –Hospitalization in severe cases Abscess –UCx may be negative –Parenteral abx x 10 days then 14d oral therapy

Work-up after a UTI Who? –Fever or documented pyelonephritis –<5yo What –RBUS (prior to discharge & yes, kidneys & bladder) –VCUG once afebrile –DMSA Prophylactic antibiotics until work-up

Prophylaxis Vesicoureteral reflux No Reflux, but <1yo –30-75% recurrence in the first year Frequent symptomatic UTIs