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.