Antenatal Hydronephrosis

1. Antenatal Hydronephrosis

2. Antenatal Hydronephrosis • Definition: AP diameter renal pelvis > 4mm @ 20 wk EGA AP diameter renal pelvis > 7mm @ 30 wk EGA • Incidence: 5% of pregnancies

3. 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

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

5. 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

6. Ismaili Article Continued • Normal postnatal US 3% abnormal VCUG • AP diameter 7-10mm -- 64% had significant findings • AP diameter >10mm -- 100% had significant findings • Recommends no VCUG if US wnl • This is in sharp contrast to several earlier studies

7. Phan, et al., Pediatric Nephrology, October 2003 • 68/111 pts with ANH and AP diameter <10mm (including several wnl) • 16 (24%) had VUR

8. 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

9. Farhat, et al., Journal of Urology, September 2000 • 27 % of pts with VUR (w/u prompted by ANH) had a normal postnatal RBUS

10. 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

11. Radiology 1993 • 25% of patients with ANH and nl postnatal RBUS had VUR on VCUG

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

13. 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

14. 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

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

16. 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

17. Other Reasons for Intervention • Symptomatic • Failure to thrive • UTI

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

19. 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

20. 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.

21. Urinary Tract Infections in Children Incidence • Neonates: M > F • Thereafter: F > M

22. Organisms • Enterobacteriaciae • Escherichia (80%) • Klebsiella • Enterobacter • Citrobacter • Proteus • Providencia • Morganella • Serratia • Salmonella

23. Other Organisms • Pseudamonas • Staphylococcus • Enterobacter

24. 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

25. 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

26. Not Risk Factors • Bubble baths • Improper wiping

27. Risk FactorsUpper 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

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

29. 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

30. 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

31. 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

32. Level of Infection • Cystitis • Symptoms • Dysuria • Frequency • Urgency • 2o enuresis • Usually no systemic symptoms

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

34. 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

35. 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

36. 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

37. Treatment • Pyelonephritis • Treat 10-14 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

38. 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

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