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Urinary Tract Infections in Children

Urinary Tract Infections in Children . Diagnostic Imaging based on Clinical Practice Guidelines. Emily D. Kucera, M.D. Assistant Professor, UMKC. Learning Objectives. State prevalence, associations, and consequences of febrile UTI’s in children

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Urinary Tract Infections in Children

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  1. Urinary Tract Infections in Children Diagnostic Imaging based on Clinical Practice Guidelines Emily D. Kucera, M.D. Assistant Professor, UMKC

  2. Learning Objectives • State prevalence, associations, and consequences of febrile UTI’s in children • Discuss imaging options and timing of procedures • Discuss classification systems used in radiologic reports • Review variations of Clinical Practice Guidelines from reputable institutions- will discuss CMH guidelines and include others in handout.

  3. Febrile UTI’s • Most common serious bacterial infection occurring in infancy and childhood • Affects at least 3.6% of boys, 11% of girls • 10-30% of children with febrile UTI’s will develop renal scarring

  4. Diagnosis of UTI • Combination of clinical features and presence of bacteria in urine > 10⁵ cfu/ml • Acute pyelonephritis = UTI + fever • > 38℃ (100.4℉) - most common in infants • Cystitis = symptoms of dysuria, frequency, suprapubic pain in toilet-trained child

  5. Urinary Tract Infections in Children • Prevalence of positive culture in children 0-21 years 8.8 - 14.8% • Males < 1 year (3%); males > 1 year (2%) • Females < 1 year (7%); females > 1 year (8%) • 50-91% of children with febrile UTI’s are found to have acute pyelonephritis • All infants < 8 weeks of age with fever should be suspected of having an upper tract infection/pyelonephritis

  6. Organisms Associated with UTI’s in Children • Escherichia coli- Most common organism; causative agent in > 80% of 1st UTI • Klebsiellaspecies - 2nd most common organism. Seen more in young infants • Proteusspecies - May be more common in males • Enterobacter species - cause < 2% of UTI’s • Pseudomonasspecies - cause < 2% or UTI’s • Enterococcispecies- Uncommon > 30 days of age • Coagulase-negative staphylococcus- Uncommon in childhood • Staphylococcus aureus - Uncommon > 30 days of age • Group B streptococci - Uncommon in childhood

  7. Risk Factors for UTI’s • Male • Uncircumcised < 1 yr (5-20 x higher risk than circumcised males) • All < 6 months • Female • < 1 yr • non-African American race • fever > 39℃ (102.2℉)

  8. Atypical UTI’s • Seriously ill • Poor urine flow • Abdominal or bladder mass • Raised creatinine • Septicemia • Failure to respond to treatment within 48 hrs • Infection with non- E. coli organisms

  9. “Seriously Ill”

  10. Recurrent UTI’s • 2 or more episodes of acute pyelonephritis / upper urinary tract infection • or • 1 episode of acute pyelonephritis + > 1 episode of cystitis • or • > 3 episodes of cystitis/lower urinary tract infection

  11. Recurrent UTI’s • Girls are more prone to recurrences with age • Children who present early in life with UTI are more prone to recurrences • ¾ of children presenting < 1 year will have recurrences • > 1 year of age ~ 40% of girls, 30% of boys • Overall incidence of UTI recurrences after pyelonephritis is 20.1%

  12. Asymptomatic Bacteriuria • Most common in boys in early infancy • 1.6% boys < 2 months • affects 0.2% in school age boys • Girls have lower rates until 8-14 months • 1.5 - 2% in school age girls; peak prevalence 7-11 years of age

  13. Dysfunctional Elimination Syndromes (DES) • Constipation- seen in 50 % of DES and VUR • May induce uninhibited bladder contractions • Rectal distention causes bladder distortion causing detrusor dyssynergism and ureteral valve incompetence • Bladder instability • Infrequent voiding (< 4 times/day) • Contributes to UTI’s and slower resolution of reflux

  14. Associations with UTI’s • Dysfunctional Elimination Syndromes (DES) • 67% of girls with DES develop UTI’s • 40% of girls with UTI’s have DES • 20% of girls with DES have reflux

  15. A 6 month old female has had 3 UTI’s. Which of the following is the best approach? • No imaging needed • US + VCUG • MRI • DMSA scan

  16. Imaging Procedures • Ultrasound - detect renal anomalies, dilatation, renal sizes, bladder abnormalities, ureteral dilatation • VCUG - Voiding Cystourethrogram- assess for vesicoureteral reflux, bladder volumes, bladder abnormalities, urethral anatomy • DMSA Scintigraphy- assess for pyelonephritis and renal scarring • Radionuclide Cystogram - assess for VUR; used infrequently at CMH

  17. Abnormal Ultrasound Findings • Dilatation of at least 1 calyx • Anteroposterior (AP) diameter of the renal pelvis > 7 mm; ureteral diameter > 5 mm • Focal scarring • Difference of > 10% of length between kidneys or renal length > 2 standard deviations above mean • Bladder abnormality

  18. Hydronephrotic MCDK Normal

  19. Society of Fetal Urology Classification of Prenatal and Postnatal Hydronephrosis

  20. 1 2 4 3

  21. Duplicated Collecting Systems • Duplication of renal pelvis and ureter is one of the most common anomalies of the urinary tract • Partial - range from bifid renal pelvis to 2 ureters joining anywhere proximal to uterovesical junction • Complete - 2 separate ureters with the upper pole ureter draining more caudal and medial than the lower pole ureter = ectopia (Weigert-Meyer rule) • Ureteral duplication is of no clinical significance unless it is complicated with ectopia, VUR, UTI, or obstruction

  22. Duplicated Collecting Systems Non-dilated Dilated

  23. Voiding Cystourethrogram • Requires bladder catheterization: • 8 Fr feeding tube (No balloon) • Lidocaine gel used on majority of patients • Local analgesia • Dilates meatal opening • Radiation: • Decreased dose with pulse and digital techniques • 1-3% risk of UTI

  24. Need for Sedation • Sedation not needed in the vast majority of the cases • CMH Guidelines for sedation follow the AAP and ASA (Anesthesia) Guidelines • If need for anxiolysis, please directly communicate with the Radiologist who will be performing the exam at the time of scheduling • Child Life personnel available at the Main and the South Campuses.

  25. Vesicoureteral Reflux • International Reflux Grading System of VUR

  26. Bilateral Grade 2 Grade 1 Grade 3

  27. Vesicoureteral Reflux • Incidence 20-40 % of children presenting with UTI • Girls 17-34% Boys 18-45% • Increased incidence if family history of VUR • Parent to Child: up to 66% • Siblings: up to 34% • Overall prevalence in general population 1-3%

  28. Prevalence of VUR by Age • Prevalence in 54 studies of UTI in Children

  29. Prevalence of VUR • Girls: 0 - 18 yrs • Grade I - 7% • Grade II - 22% • Grade III - 6 % • Grade IV - 1% • Grade V - < 1%

  30. DMSA Scintigraphy • Intravenous injection of a radiopharmaceutical labelled with TC-99m • DMSA is concentrated in the proximal renal tubules. Identifies functioning renal tissue • Images obtained between 2-6 hours after injection • Usually requires sedation in children < 3 years of age

  31. Timing of DMSA • Acute imaging: Within 5-7 days of acute infection • 90% sensitivity for pyelonephritis • Cannot differentiate pyelonephritis from renal scarring • Delayed imaging ~ 6-12 months after UTI • Assess for renal damage • Gold standard for detection of parenchymal defects

  32. DMSA Normal Renal Scarring

  33. Risk of Renal Parenchymal Defects • In the presence of VUR, more frequent in boys and children > 1 year of age • ~ 5% of children presenting with 1st febrile UTI will have parenchymal defects • Pyelonephritis and renal scarring occur as frequently in children without VUR as with VUR • In the general population: 0.5 - 0.13% girls versus 0.17 - 0.11% boys will develop reflux nephropathy

  34. Renal Parenchymal Defects • Boys more susceptible to developing dysplasia or parenchymal defects in utero • Girls tend to acquire their parenchymal defects at a later age • Infants have a higher risk of renal damage • Recurrent UTI’s a significant risk factor for girls, not boys • The only effective way to reduce renal scarring associated with UTI’s is early diagnosis and prompt, effective treatment

  35. Renal Damage • Of children with acute pyelonephritis diagnosed by DMSA, 38-57% will develop permanent renal scarring • Seen in 78% of infants with dilating reflux(grades III-V), obstruction, clinically relevant anomalies (renal aplasia, ectopic kidney, complete duplication) • Seen in 15% of infants without the above diagnoses

  36. Risk of Renal Scarring Risk of Renal Scarring versus # of UTI’s

  37. A 5 year old female has recurrent febrile UTI’s. What imaging study would be useful to detect renal scarring? • VCUG • US • CT abdomen • DMSA scan

  38. Recommendations and Guidelines • No universally accepted work-up for children with UTI’s • Lack of consensus among different guidelines • Complex approaches; Regional variations • Multiple tables dividing children into different age groups • Classifying UTI’s into different variants • Determine nature and timing of imaging studies

  39. Utility of Diagnostic Imaging Procedures • Identifying pathologic malformations and risk factors • Changing management approaches • Affecting follow-up monitoring

  40. Outside of Guidelines • Infants and children: • known pre-existent uropathy or underlying renal disease • hydronephrosis or obstruction • neurogenic bladder • with urinary catheters in situ • immunosuppressed

  41. Clinical Practice Guidelines • Children’s Mercy Hospitals (last edited 2007) • Included in Handout • American Academy of Pediatrics (last edited 1999) • Cincinnati Children’s (last edited 2006) • NICE (National Institute for Health & Clinical Excellence) (2007) • Royal College of Physicians (1991)

  42. CMH Guidelines Ultrasound ⇓ VCUG ⇓ If identification of pyelonephritis or renal scarring ⇓ DMSA • Boys- All • Girls < 36 months • Girls 3-7 years of age with fever > 38.5℃ ( 101.3 ℉)

  43. CMH Guidelines Observation without imaging ⇓ If subsequent UTI ⇓ Ultrasound ⇓ VCUG ⇓ If pyelonephritis or renal scarring ⇓ DMSA • Girls > 3 years withfever < 38.5℃ (101.3℉) • All Girls > 7 years

  44. Children’s Mercy Guidelines • Children who should have RUS + VCUG after 1st febrile UTI • Failure of good response after 48-72 hrs of effective antibiotics • Infection with an unusual organism • Lack of assurance of close follow up • Abnormal urine stream, abdominal mass • Recurrence of febrile UTI

  45. Timing of VCUG during Acute Illness • VCUG during first 10 days of treatment IF • The patient has good response to Tx; afebrile > 24 hours • The infecting bacteria is susceptible to antibiotic administered • Voiding pattern has normalized to pre-infection • Younger infant should have no dysuria and normal behavior

  46. An uncircumcized 2 month old male was admitted with a febrile UTI that has not responded to antibiotic therapy after 48 hours. When is the best time to perform a VCUG? • On the day of admission • After 24 hours • After 24 hours without a fever • No need to do VCUG

  47. Vesicoureteral Reflux • Classification per CMH Clinical Practice Guidelines • Mild: grade I and II, unilateral grade III in a child < 2 years old • Moderate-Severe: all other grade III’s, IV, V

  48. Referral to Pediatric Urologist or Nephrologist • Any child with evidence of urinary tract obstruction: Refer to Pediatric Urologist • VUR > Grade III or evidence of renal damage • VUR > Grade III with break through infection • Any child with Grade V VUR should be referred immediately. • The presence of Grade IV and lower grades of VUR + the presence of renal damage frequently reflects intrauterine VUR and damage rather than acquired damage.

  49. Recommendations for Follow-up VCUG’s • CMH Clinical Practice Guidelines: • In children maintained on prophylactic Antibiotics: • every 2 years with grades I and II, and for those < 2 years with unilateral grade III • every 3 years for all others with grade III and IV

  50. Conclusions • Better understanding of the impact of febrile UTI’s on children • Better understanding of some of the radiologic procedures and findings • Understanding of CMH Clinical Practice Guidelines and ability to compare with other Clinical Practice Guidelines from reputable institutions • Effects on diagnostic imaging and timing of imaging procedures

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