Nephrology and genitourinary 2 Flashcards
Incidence of UTI
3-7% of girls
1-2% of boys
Will have at least one symptomatic UTI by age 6yrs
Importance of UTI in childhood
up to 50% have a structural abnormality of their urinary tract
Pyelonephritis may damage the growinf kidney by forming a scar - if bilateral, it predisposes to HTN and chronic renal failure
Which organisms commonly cause UTI in childhood
Usually bowel flora that enters the urinary tract via the urethra (except newborn - haematogenous)
E.coli is commonest
Klebsiella
Proteus
Pseudomonas (may indicate presence of structural abnormality)
Strep. faecalis
Proteus is commonly in boys - predisposes to phosphate stones
Differentials of haematuria
UTI (bacterial, viral, schistosomiasis, TB)
Glomerular (post-infectious glomerulonephritis, HSP, IgA nephropathy, thin basement membrane or Alport syndrome)
Urinary tract stones (eg. hypercalciuria)
Trauma
Other renal tract pathology (renal tract tumour, polycystic kidney disease)
Vascular (renal vein thrombosis)
Haematological (coagulopathy/sickle cell disease)
Drugs (cyclophosphamide)
Exercise induced
Presenting features of UTI in infants (<3 months)
Non-specific
Commonest to least common:
Fever usually
Vomiting
Lethargy
Irritability
Poor feeding/failure to thrive
Jaundice
Septicaemia
Offensive urine
Haematuria
Presentation of a child with UTI
Dysuria and frequency Abdominal pain or loin tenderness Fever with or without rigors Lethargy Anorexia Vomiting and diarrhoea Haematuria Offensive/cloudy urine Febrile convulsion Recurrence of enuresis
How can urine be collected in a child with nappies?
“clean-catch” sample - into waiting clean pot when nappy is removed. Recommended
Adhesive plastic bag applied to the perineum after careful washing (BUT contamination from the skin)
Urethral catheter if there is urgency in obtaining the sample
Suprapubic aspiration (SPA): fine needle inserted just above the symphysis pubis under US guidance - in severely ill, requiring urgent diagnosis and treatment
Urine sample in an older child
Midstream sample with careful cleaning and collection (white cells and bacteria may contaminate from foreskin)
Relevance of urinary white cells
Not a reliable feature of UTI
May lyse (not present) may be present in febrile children, balanitis or vulvovaginitis
Interpret the results of a urine culture
> 105 colony-forming units of a single organism per milliltre gives 90% chance of infection
Growth of mixed organisms usually indicates contamination
Samples that are taken from catheter or suprapubic aspirate, that show a single organism growth are diagnostic of infection
Interpret dipstick test results
Nitrite stick testing:
positive result is very likely to be UTI
Negative may be false
Leucocyte esterase testing:
May be positive or negative with a UTI
Also positive in febrile illness, balanitis and vulvovaginitis
Action if leucocyte and nitrite both positive
regard as UTI
Action if leucocyte negative and nitrite positive
Start antibiotic treatment
Diagnosis then depends on urine culture
Action if leucocyte positive and nitrite negative
Only start antibiotic treatment if clinical evidence of UTI
Diagnosis depends on urine culture
Action if leucocyte and nitrite both negative
UTI unlikely
Repeat or send urine for culture if history suggests
What is atypical UTI (NICE)
Seriously ill Poor urine flow Abdominal or bladder mass Raised creatinine Septicaemia Failure to respond to suitable antibiotics within 48 hours
Infected with non-E.coli organism
Define recurrent UTI
2 or more episodes of UTI with acute pyelonephritis/UUTI
1 episode of UTI with acute pyelonephritis/upper urinary tract infection plus one or more episodes of UTI with cystitis/ lower urinary tract infection
3 or more episodes of UTI with cystitis/lower urinary tract infection
Investigations in <6 months old children for atypical UTI
Ultrasound during acute infection
4-6 months later:
DMSA (a radionucleotide scan to assess renal function)
MCUG (micturating cystourethrogram)
Investigations in <6 months old children for recurrent UTI
Ultrasound during acute infection
4-6 months later:
DMSA (a radionucleotide scan to assess renal function and scars)
MCUG (micturating cystourethrogram)
Investigations for atypical UTI in ages 6 months - 3 years
US during acute infection
DMSA 4-6 months later
Investigations for recurrent UTI in ages 6 months - 3 years
Ultrasound and DMSA within 6 weeks
Investigations in a 6months - 3 yrs old child who is repsonding to UTI treatment
NONE
Investigations for atypical and recurrent UTI in ages >3 years
Atypical: ultrasound during acute infection
Recurrent:
Ultrasound within 6 weeks and DMSA
What is vesicoureteric reflux
Developmental anomaly
Ureters displaced laterally and enter directly into the bladder at an angle
Why is vesicoureteric reflux with ureteric dilatation important
Encourages infection
Kidney infection
Bladder voiding pressure is transmitted to the renal papillae
Epidemiology of VUR
<1% in healthy neonates (might be an underestimate)
5-6 times more common in females
30-70% incidence in infants with febrile UTI
Diagnostic tests for VUR
Lab tests to rule out UTI
Serum creatinine and electrolytes for renal function
VCUG (voiding cystourethrogram) main test
Renal bladder US
DMSA (nuclear medicine) - estimates differential function and renal parenchymal defects/scars
What is micturating cystourethrogram (VUR)
Involves urinary catheterisation and the administration of radiocontrast medium into the bladder - reflux is detected on voiding
Advantage: can see the grade of reflux
Disadvantage: requires catheterisation and radiation dose
What is indirect cystogram
A radionucleotide method for VUR
(MAG-3 and DTPA scans)
Advantage - no catheterisation required and lower radiation dose
Disadvantage - false negative
Aim of treatment in VUR
prevent progressive renal scarring
Prophylactic antibiotics may be used to prevent this - image by indirect cystogram
What is pyelonephritis
A bacterial infection of the upper urinary tract causing inflammation of the kidney
What is cystitis
Inflammation of the bladder
