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 years %
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
Klebsiella species - 2nd most common organism. Seen more in young infants
Proteus species - May be more common in males
Enterobacter species - cause < 2% of UTI’s
Pseudomonas species - cause < 2% or UTI’s
Enterococci species- 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 Female
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
> 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
% in school age girls; peak prevalence 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
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 Grade 3

27. Vesicoureteral Reflux
Incidence % of children presenting with UTI
Girls 17-34% Boys %
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
Renal Scarring
Normal

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: % girls versus % 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 versus # of UTI’s

37. A 5 year old female has recurrent febrile UTI’s
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 ⇓ Boys- All VCUG Girls < 36 months
If identification of pyelonephritis or renal scarring
DMSA
Boys- All
Girls < 36 months
Girls 3-7 years of age with fever > 38.5℃ ( ℉)

43. CMH Guidelines Observation without imaging ⇓ If subsequent UTI
Ultrasound
VCUG
If pyelonephritis or renal scarring
DMSA
Girls > 3 years with fever < 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 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. After 24 hours without a fever No need to do VCUG
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

52. AAP Guidelines
Every febrile infant or young child, 2 months-2 years of age, should be imaged with ultrasound and a study to detect for VUR
Those who do not demonstrate the expected clinical response within 2 days of antibiotics, should have ultrasound promptly and reflux study at earliest convenience

53. Cincinnati Children’s Guidelines
Children with 1st UTI, need Ultrasound and Voiding Cystogram:
all boys
girls age < 36 months (dependent on ability to verbalize dysuria
girls 3-7 years with fever > 38.5 ℃ (101.3℉)

54. Observation without Imaging per Cincinnati Children’s
Girls > 3 years with fever (< 38.5℃)
All girls > 7 years
Follow up with dipstick of routine urinalysis if symptoms of UTI

55. NICE Guidelines
Not recommend antibiotic prophylaxis following 1st UTI, even in child with VUR
Not routinely evaluate for VUR with imaging
Infants < 6 months with 1st UTI that responds to treatment - US within 4-6 weeks of UTI
Infants > 6 months- US not recommended unless atypical UTI

56. NICE Guidelines Infants < 6 months Responds to Tx within 48 hours
Atypical UTI
Recurrent UTI
Ultrasound during acute infection No
Yes*
Yes
Ultrasound within 6 weeks
Yesª
DMSA within 4-6 months following infection
VCUG
*In a child with non-E. coli UTI, responding well to antibiotics and no other
features of atypical infection, ultrasound can be requested on a non-urgent basis
ª If Ultrasound abnormal, consider VCUG

57. NICE Guidelines Children 6 months - < 3 yrs
Responds well to Tx within 48 hours
Atypical UTI
Recurrent UTI
Ultrasound during infection No
Yes*
Ultrasound within 6 weeks
Yes
DMSA 4-6 months following acute infection
VCUG
Noª
*In a child with non-E. coli UTI, responding well to antibiotics and no other features of atypical infection, ultrasound can be requested on a non-urgent basis
ªConsider VCUG if dilatation on ultrasound, poor urine flow, non-E. coli infection,
family history of VUR

58. NICE Guidelines Children > 3 yrs
Responds well to Tx within 48 hours
Atypical UTI
Recurrent UTI
Ultrasound during acute infection No
Yes*
Ultrasound within 6 weeks
Yes
DMSA 4-6 months following acute infection
VCUG
*In a child with non-E. coli UTI, responding well to antibiotics and no other features of atypical infection, ultrasound can be requested on a non-urgent basis

59. Royal College of Physicians in 1991
Infants: Ultrasound, VCUG, and DMSA
Children 1-7 yrs: Ultrasound and DMSA
> 7 yrs: Ultrasound and potential additional exams dependent on ultrasound findings

60. Guidelines of the Royal College of Physicians
Ultrasound should be considered in all cases of children with 1st UTI.
Late DMSA scintigraphy in children up to 7 years
VCUG in children < 1 year