Kidney and Urinary Tract Disorders Flashcards
Why are UTI’s important in children?
Up to half of patients have a structural abnormality of their urinary tract.
Pyelonephritis may damage the growing kidney by forming a scar, predisposing to hypertension and to chronic renal failure if the scarring is bilateral
What are some GU anomalies detectable on antenatal US screening?
Absence of both kidneys (renal agenesis) Multicystic dysplastic kidney Pelvic kidney Bladder exstrophy Obstruction to urine flow
What would you see on US if there was absence of both kidneys?
As amniotic fluid is mainly derived from fetal urine, there is severe oligohydramnios resulting in Potter syndrome, which is fatal.
What is multicystic dysplastic kidney?
It results from the failure of union of the ureteric bud (which forms the ureter, pelvis, calyces and collecting ducts) with the nephrogenic mesenchyme. It is a non-functioning structure with large fluid-filled cysts with no renal tissue and no connection with the bladder.
What are some causes of large cystic kidneys?
Multicystic dysplastic kidney
Autosomal recessive polycystic kidney disease
Autosomal dominant polycystic kidney disease
Tuberous sclerosis
How would you assess renal function in children?
Plasma creatinine concentration (main test)
Estimated GFR
Inulin or EDTA GFR
What is Potter syndrome?
Bilateral renal agenesis or bilateral multicystic dysplastic kidney.
Reduced fetal urine excretion.
Oligohydramnios causing fetal compression
What are the clinical features of Potter syndrome?
Facially - low set ears, beaked nose, prominent epicanthic folds and downward slant to eyes.
Pulmonary hypoplasia causing respiratory failure
Limb deformities
What is autosomal recessive polycystic kidney disease?
There is diffuse bilateral enlargement of both kidneys
What is autosomal dominant polycystic kidney disease?
There are separate cysts of varying size between normal renal parenchyma. The kidneys are enlarged
What is pelvic kidney?
When the lower poles are fused in the midline. The abnormal position may predispose to infection or obstruction to urinary drainage
How do you postnatally manage children with antenatally diagnosed anomalies?
Start prophylactic antibiotics, most of them are stopped unless it is a male with bilateral hydronephrosis and/or dilated lower urinary tract after 48h of life, in which case they may require surgery
How come some UTI’s are accompanied by fever?
UTI may involve the kidneys (pyelonephritis) when it is usually associated with fever and systemic involvement, or may be due to cystitis, when there may be no fever
How does a UTI present in infants?
Fever Vomiting Lethargy or irritability Poor feeding/failure to thrive Jaundice Septicaemia Offensive urine Febrile convulsions >6 months old
How does a UTI present in children?
Dysuria and frequency Abdominal pain or loin tenderness Fever with or without rigors Lethargy and anorexia Vomiting, diarrhoea Haematuria Offensive/cloudy urine Febrile convulsion Recurrence of enuresis
What are the main causes of dysuria alone?
Usually due to cystitis, or vulvitis in girls or balanitis in uncircumcised boys.
How can urine be collected in children in nappies?
A clean-catch sample into a waiting clean pot when the nappy is removed.
An adhesive plastic bag applied to the perineum after careful washing, although there may be contamination from the skin
Is a nitrate stick urine test useful in children?
Yes, a positive result useful as very likely to indicate a true UTI
What are the methods of dipstick testing in children?
Nitrate stick testing
Leucocyte esterase stick testing (for WBCs)
What is the likely infected organism in children’s UTI and where does it come from?
It is usually the result of bowel flora entering the urinary tract via the urethra, except in the newborn when it is more likely to be haematogenous.
The commonest organism is E.coli followed by Klebsiella, Proteus an Pseudomonas and Strep. faecalis.
What does Proteus UTI infection predispose to?
To the formation of phosphate stones by splitting urea to ammonia and thus alkalinising the urine
What may Pseudomonas UTI indicate?
It may indicate the presence of some structural abnormality in the urinary tract affecting drainage
What are some contributing factors to incomplete bladder emptying in children?
Infrequent voiding, resulting in bladder enlargement
Vulvitis
Incomplete micturition with residual post-micturition bladder volumes
Obstruction by a loaded rectum from constipation
Neuropathic bladder
Vesicoureteric reflux
What is vesicoureteric reflux?
A developmental anomaly of the vesicoureteric junctions. The ureters are displaced laterally and enter directly into the bladder rather than at an angle, with a shortened or absent intramural course.
What are the causes of vesicoureteric reflux?
It is familial (30-50% of cases)
It may also occur in bladder pathology (neuropathic bladder or urethral obstruction or temporarily after a UTI)
Is vesicoureteric reflux severe?
Its severity varies from reflux into the lower end of an undilated ureter during micturition to the severest form with reflux during bladder filling and voiding, with a distended ureter, renal pelvis and clubbed calyces
Why is vesicoureteric reflux important?
Urine returning to the bladder after voiding results incomplete bladder emptying, which encourages infection.
The kidneys may become infected (pyelonephritis)
Bladder voiding pressure is transmitted to the renal papillae; this may contribute to renal damage
What are the features of an abnormal UTI?
Seriously ill/septicaemia Poor urine flow Abdominal or bladder mass Raised creatinine Failure to respond to suitable antibiotics within 48 hours Infection with non-E.coli organisms
What investigations should you perform in a first UTI?
US of kidneys and urinary tract
DMSA to check for renal scars 3 months after UTI
MAG3 or MCUG to detect obstruction and vesicoureteric reflux
How would you manage UTI in an infant <3 months old?
Refer to hospital immediately where they require IV antibiotics such a cefotaxime
How would you manage an infant >3 months and children with acute pyelonephritis/upper UTI?
Usually treated with oral antibiotics with low resistance patterns (co-amoxiclav for 7-10 days)
How would you manage children with cystitis/lower UTI?
Oral antibiotics for 3 days
What are some medical measures for prevention of UTIs?
High fluid intake to produce a high urine output Regular voiding Ensuring complete bladder emptying by encouraging the child to try a second time Prevention or treatment of constipation Good perineal hygiene Lactobacillus acidophilus (a probiotic)
How should you follow up children with recurrent UTIs, renal scarring or reflux?
Urine culture with any non-specific illness
Long term, low dose antibiotic prophylaxis can be used
Circumcision in boys may sometimes be considered.
Anti-reflux surgery may be indicated if there is progression of scarring with ongoing reflux.
Blood pressure should be checked annually
Regular assessment of renal growth and function
What is daytime enuresis?
Lack of bladder control during the day in a child old enough to be continent (3-5 years). Nocturnal enuresis is also usually present.
What may cause daytime enuresis?
Lack of attention to bladder sensation Detrusor instability (sudden, urgent order to void induced by sudden bladder contractions) Bladder neck weakness A neuropathic bladder UTI Constipation An ectopic ureter
What is a neuropathic bladder?
The bladder is enlarged and fails to empty properly, irregular thick wall and is associated with spina bifida and other neurological conditions
What is likely to be the cause of girls who are dry at night but wet on getting up?
Pooling of urine from an ectopic ureter opening into the vagina
What may you see on investigated daytime enuresis?
Urine sample: UTI
US: bladder pathology (imcompltete emptying or thickening of the bladder wall)
Spinal XR: vertebral anomaly
MRI: confirm or exclude a non-bony spinal defect such as tethering of the cord
How would you treat daytime enuresis?
Treat any causes. Other children may benefit from star charts, bladder training and pelvic floor exercises
What is secondary enuresis?
The loss of previously achieved urinary continence
What may cause secondary enuresis?
Emotional upset (common)
UTI
Polyuria from an osmotic diuresis in DM or a renal concentrating disorder (sickle cell or chronic renal failure)
When might transient proteinuria be physiological?
During febrile illnesses or after exercise
How should persistent proteinuria be quantified?
By measuring the urine protein/creatinine ratio in an early morning sample.
