Paeds nephrology and urology Flashcards
Renal agenesis
Detected on antenatal ultrasound screening
Amniotic fluid is mainly derived from foetal urine, so the absence of both kidneys leads to oligohydramnios resulting in Potter sequence
This is fatal
Multicystic dysplastic kidney aetiology
Results from the failure of the union of the ureteric bud and the nephrogenic mesenchyme (NB: ureteric bud gives rise to the ureter, pelvis, calyces and collecting ducts)
The kidney becomes a non-functioning structure with large fluid-filled cysts and no renal tissue and no connection to the bladder
The dysplastic kidney does not produce any urine (so if this was bilateral, it would cause Potter sequence)
Detected on antenatal ultrasound screening
Other causes of large cystic kidneys
Autosomal dominant and recessive polycystic kidney disease
- Main symptom is hypertension
- Can cause renal failure in late adulthood
- Extra-renal features include liver and pancreatic cysts, cerebral aneurysms and mitral valve prolapse
Potter sequence facies
Low-set ears
Beaked nose
Prominent epicanthic folds and downward slant to eyes
May also get pulmonary hypoplasia causing respiratory failure
Limb deformities
Cause of horseshoe kidney
Results from abnormal caudal migration
The lower pole of the two kidneys will fuse in the midline
This may predispose to infection or obstruction of urinary drainage
Duplex system
Can be detected on the antenatal ultrasound screening
Results from premature division of the ureteric bud
This can vary from simply a bifid real pelvis to complete division with two ureters
There are usually some functional issues with these ureters
The ureter from the lower pole often refluxes
The ureter from the upper pole may drain ectopically into the urethra or vagina or may prolapse into the bladder (ureterocoele)
Urine flow may be obstructed
Bladder exstrophy
Can be detected antenatally on ultrasound
Results from failure of fusion of the infraumbilical midline structures
Leads to an exposed bladder mucosa
Absence or severe deficiency of the anterior abdominal wall muscles is frequently associated with a large bladder and dilated ureters (megacystitis-megaureter)
It is also associated with cryptorchidism (absence of one or both testes in the scrotum)
Places where there may be obstruction to urinary flow
Pelvi-ureteric junction
Vesicoureteric junction
Bladder neck
Posterior urethra (due to mucosal folds or a membrane known as posterior urethral valves)
Antenatal treatment of congenital abnormalities
Male foetuses with posterior urethral valves may develop severe urinary outflow obstruction resulting in progressive bilateral hydronephrosis, poor renal growth and declining liquor volume with the potential to lead to pulmonary hypoplasia
Intrauterine bladder drainage may be performed
Postnatal treatment of congenital abnormalities
Prophylactic antibiotics may be started at birth to try and prevent UTIs
As GFR is low in newborns, urine outflow is low and so mild outflow obstruction may not be obvious in the first few days of life. Therefore, the ultrasound scan should be delayed for a few weeks
If there is bilateral hydronephrosis in a male infant, investigations are required:
Ultrasound
Micturating cystourethrogram (MCUG)
This is to exclude posterior urethral valves (if this is diagnosed, intervention is required such as cystoscopic ablation)
Why is UTI an important presentation in childhood?
UP to 50% of patients have a structural abnormality of the urinary tract
Pyelonephritis may damage the growing kidney by forming a scar, predisposing to hypertension and progressive CKD if the scarring is bilateral
Clinical features of UTIs in infants
Fever Vomiting Lethargy or irritability Poor feeding/faltering growth Jaundice Septicaemia Offensive urine Febrile seizure (>6 months)
Clinical features of UTIs in children
Dysuria, frequency and urgency Abdominal pain or loin tenderness Fever with or without rigors Lethargy and anorexia Vomiting, diarrhoea Haematuria Offensive/cloudy urine Febrile seizure Recurrence of enuresis (bed wetting)
How to collect urine samples in children for investigations?
For children in nappies, urine can be collected by:
- A ‘clean-catch’ sample into a waiting clean pot when the nappy is removed (BEST METHOD)
- Adhesive plastic bag applied to the perineum after careful washing -Urethral catheter if there is urgency in obtaining a sample and no urine has been passed
- Suprapubic aspiration (may be used in severely ill infants)
In older children, urine can be collected using a midstream sample
Contamination with white cells and bacteria can occur from under the foreskin in boys and from reflux of urine into the vagina during voiding in girls
Microscopy is used to identify the organisms
A culture should also be performed
Urine dipsticks can be used as a screening tool - culture should still be performed unless BOTH leucocyte esterase and nitrite are negative or if the clinical symptoms and dipstick tests don’t correlate
The presence of a mixed growth of organisms suggests contamination
Diagnosis of UTI
A bacterial culture of >10^5 colony-forming unites (CFU) of a single organism per millilitre in a properly collected specimen gives a 90% probability of infection
Most common causative organisms for a UTI
E.coli
Klebsiella
Proteus (more common in boys than girls. Predisposes to formation of phosphate stones)
Pseudomonas (may indicate presence of structural abnormality)
Streptococcus faecalis
UTI usually results from bowel flora entering the urinary tract via the urethra
Factors that contribute to incomplete bladder emptying in children
Infrequent voiding –> bladder enlargement
Vulvitis
Incomplete micturition with residual postmicturition bladder volumes
Obstruction by a loaded rectum from constipation
Neuropathic bladder
Vesicoureteric reflux
Vesicoureteric reflux
This is a developmental abnormality of the vesicoureteric junctions
The ureters are displaced laterally and enter directly into the bladder (rather than at an angle)
There is a shortened or absent intramural course
Severe cases may be associated with renal dysplasia
It is familial (30-50% chance of occurrence in first-degree relatives)
It can occur with bladder pathology (e.g. neuropathic bladder, urethral obstruction, after a UTI)
Severity can vary from mild 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.
The more severe forms of vesicoureteric reflux are associated with intrarenal reflux, which is the backflow of urine from the renal pelvis into the papillary collecting ducts
This is associated with a risk of renal scarring if UTIs occur
NOTE: it is unknown whether renal scarring is present from birth in children with VUR or whether it occurs as a result of damage to normal kidneys by UTIs in children with VUR
VUR tends to resolve with age
Infection can destroy renal tissue resulting in a shrunken, poorly functioning kidney
Why is vesicoureteric reflux-associated ureteric dilatation important?
Urine returning to the bladder from the ureters after voiding result in incomplete bladder emptying which encourages infection
Kidneys may become infected (pyelonephritis)
Bladder voiding pressure is transmitted to the renal papillae which may contribute to renal damage
Atypical UTI includes:
Seriously ill or septicaemia
Poor urine flow
Abdominal or bladder mass
Raised creatinine
Failure to respond to suitable antibiotics within 48 hours
Infection with atypical (non-E.coli) organisms
Investigations for VUR/UTI
The extent of investigation is controversial because the investigations are often invasive and may not benefit the patient
Mild VUR usually resolves spontaneously
There has been a move away from extensive investigation of ALL children with UTIs to those who have had atypical or recurrent UTIs
An initial ultrasound will identify:
Serious structural abnormalities and urinary obstruction
Renal defects
If urethral obstruction is suspected, MCUG should be performed promptly
NB: functional scans should be deferred for 3 months after a UTI, unless the ultrasound is suggestive of obstruction, to avoid missing a new scare and because false-positive results may be produced due to transient inflammation
Test urine sample in any infant or child presenting with:
Unexplained fever >38 degrees
An alternative site of infection in those who remain unwell despite treatment
Symptoms and signs suggestive of UTI
NB: if it is not possible or practical to collect urine by non-invasive methods, catheter insertion or suprapubic aspiration may be considered
Urine should be sent fo rculture in:
Infants with suspected upper urinary tract infection
Infants and children with a high to intermediate risk of serious illness
Infants < 3 months
Infants and children with a positive result for either leucocyte esterase or nitrites
- Nitrites + leucocyte esterase –> start antibiotics
- Nitrites without leucocyte esterase –> do not start antibiotics without good clinical evidence of UTI
Infants and children with recurrent UTIs
Infants and children with an infection that does not respond to treatment within 24-48 hours
When clinical symptoms and urine dipstick do not correlate
Management of UTI
ALL infants <3 months of age with suspicion or a UTI or if seriously ill should be referred immediately to hospital
- IV antibiotics (e.g. co-amoxiclav) for at least 5-7 days
- This should be followed by oral prophylaxis
Infants aged > 3 months and children with acute pyelonephritis/upper UTI
- If the urine dipstick is positive for either leucocyte esterase or nitrites, send a urine sample for culture and start antibiotic therapy
- Features of pyelonephritis:
- Bacteriuria + fever > 38 degrees
- Bacteriuria + loin pain/tenderness
- Oral antibiotics (e.g. trimethoprim for 7 days): choice of antibiotic should be based on resistance patterns
- If oral cannot be used, five IV antibiotics (e.g. co-amoxiclav for 2-4 days, followed by oral antibiotics for 7-10 days): choice depends on sensitivities
Children with cystitis/lower UTI:
Features of cystitis/lower UTI: dysuria but no systemic symptoms
Oral antibiotics (e.g. trimethoprim or nitrofurantoin) for 3 days
ADVISE to seek medical attention if the child is still unwell after 24-48 hours of antibiotic treatment, and encourage adequate fluid intake
Infants and children with atypical UTI should have an ultrasound of the urinary tract to identify structural abnormalities
DMSA and MCUG may also be performed in children < 6 months presenting with atypical or recurrent UTI
Medical measures for the prevention of UTI
AIM: ensure washout of organisms that ascend into the bladder form the perineum and reduce the presence of aggressive oragnisms in the stool, perineum and under the foreskin High fluid intake to produce high urine output Regular voiding Ensure complete bladder emptying Treatment and/or prevention of constipation Good perineal hygiene Lactobacillus acidophilus - probiotic to encourage the colonisation of the gut by this organism and reduce the number of pathogenic organisms Antibiotic prophylaxis (controversial)
Follow-up of children with recurrent UTIs, renal scarring or reflux
Urine should be dipsticked with any non-specific illness in case it is caused by a UTI and urine should be sent for MC+S
Long-term low-dose antibiotic prophylaxis can be used
Circumcision in boys may be considered
Anti-VUR surgery may be considered if there is progression of scarring
Regular blood pressure checks if renal defects are present
Urinalysis to check for proteinuria (suggestive of progressive CKD)
Regular assessment of renal growth and function
Define daytime enuresis
Lack of bladder control during the day in a child that is old enough to be continent (over 3-5 years)
Causes of daytime enuresis
Lack of attention to bladder sensation (manifestation of developmental or psychogenic problem)
Detrusor instability (sudden, urgent urge to void induced by sudden bladder contractions)
Bladder neck weakness
Neuropathic bladder (bladder is enlarged and fails to empty properly, irregularly thick wall, associated with spina bifida and other neurological conditions)
UTI
Constipation
Ectopic ureter
Investigations for daytime enuresis
Urine should be sent for MC+S
Ultrasound may reveal abnormalities
Urodynamic studies may be required
MRI may be used to exclude a spinal defect
Management tips for daytime enuresis
Children in whom a neurological cause has been excluded, may benefit from:
- Star charts
- Bladder training
- Pelvic floor exercises
Anticholinergic drugs (e.g. oxybutynin), which reduces bladder contractions, may be useful
Causes of secondary onset enuresis
The loss of previously achieved urinary continence may be due to:
Emotional upset (most common)
UTI
Polyuria from an osmotic diuresis (e.g. diabetes mellitus, diabetes insipidus, CKD)
Investigations for secondary enuresis
Urine dipstick to check for infection, glycosuria and proteinuria
Assessment of urine concentrating ability by measuring osmolality of an early morning urine sample
Ultrasound of the renal tract
Management of enuresis
Children < 5 years
REassure the parents tha tmany children aged < 5 years wet the bed and this is usually resolved without intervention
Ensure easy access to the toilet at night (e.g. potty near the bed)
Encourage bladder emptying before bed
Consider a positive reward system
Children > 5 years
If bedwetting is infrequent (<2 per week) reassure the parents and offer watch-and-see approach
If long-term treatemnt is required offer:
1) enuresis alarm with positive reward system
2) desmopressin (NB: fluid should be restricted 1 hour before desmopressin until 8 hours after)
If rapid or short-term control is required (e.g. school trips), offer desmopressin
If bedwetting recurs following treatment, restart previously successful treatments and offer combination treatment with desmopressin and an enuresis alarm
TCAs and antimuscarinics may be considered in special cases
When should children with enuresis be referred to secondary care?
If bedwetting has not responded to two courses of treatment, refer to secondary care, enuresis clinic or community paediatrician
All children with primary bedwetting (with daytime symptoms) should be referred to secondary care or an enuresis clinic
If secondary enuresis is caused by UTI or constipation, it can be managed in primary care. However, the following underlying causes are likely to need specialist referral:
Diabetes
Recurrent UTI
Psychological problems
Family problems
Developmental, attention or learning difficulties
Known or suspected physical or neurological problems
Advice for enuresis
Explain that bedwetting is NOT the child or the parents’ fault
Occurs because the volume of urine produced at night exceeds the capacity of the bladder to hold it, and the sensation of a full bladder does NOT wake the child
Reassure that pretty much all children become dry with time as their bladder capacity increases and they learn to wake at the sensation of a full bladder
The child should go to the toilet to pass urine regularly throughout the day, especially before bed
Caffeine-based drinks should be AVOIDED before bed
A healthy diet should be encouraged
There should be easy access to the toilet
Waterproof mattress or bed pads could be used
Parents and carers should take a neutral attitude towards bedwetting so that they don’t embarrass the children
Older children may prefer to change their wet bedding themselves
Lifting or waking during the night does not promote long-term dryness
Positive reward systems can be used (e.g. rewards for going to the toilet before bed, drinking the recommended amount of fluid during the day)
SUPPORT: ERIC (Education and Resources for Improving Childhood Continence)
When does proteinuria not need investigating?
Transient proteinuria may occur during febrile illness, or after exercise - this does not require investigation
How should persistent proteinuria be investigated?
Measuring the urine protein-to-creatinine ratio in an early morning sample (normal < 20mg/mmol)
Causes of proteinuria
Orthostatic proteinuria: this is when proteinuria is only found when the child is upright during the day. The prognosis is excellent and further investigation is not necessary Glomerular abnormalities: - Minimal change disease - Glomerulonephritis - Abnormal glomerula basement membrane (familial nephritides) Increased GFR Reduced renal mass in CKD Hypertension Tubular proteinuria Nephrotic syndrome
What are the three features which characterise nephrotic syndrome?
Proteinuria
Hypoalbuminaemia
Oedema
Causes of nephrotic syndrome
Cause is unknown
There are a few secondary causes (e.g. HSP, SLE, infections (e.g. malaria) or allergens)
Clinical features of nephrotic syndrome
Periorbital oedema (particularly on waking) - usually the earliest sign
Scrotal or vulva, leg and ankle oedema
Ascites
Breathlessness due to pleural effusion and abdominal distension
Infection such as peritonitis, septic arthritis or sepsis due to loss of protective immunoglobulins in the urine
Investigations performed at the presentation of nephrotic syndrome
Urine protein FBC and ESR U+Es, electrolytes, creatinine, albumin C3+4 Antistreptolysin O or anti-DNAse B titres and throat swab Urine microscopy and culture Urinary sodium concentration Hepatitis B and C screen Malaria screen if travel abroad
Steroid-sensitive nephrotic syndrome
In 85-90% of cases, proteinuria will resolve with corticosteroid therapy
These children will not preogress to CKD
It is associated with atopy
The nephrotic syndrome is often precipitated by respiratory infections
Features of steroid-sensitive nephrotic syndrome: Age 1-10 years No macroscopic haematuria Normal BP Normal comple,ment levels Normal renal function
Management of steroid-sensitive nephrotic syndrome
Initially give oral steroids (60mg/m^2 per day of prednisolone)
After 4 weeks, the dose should be reduced or alternate days for 4 weeks
Then it should be weaned or stopped
Children who do not respond after 4-6 weeks of corticosteroid therapy or have atypical features may have a more complex diagnosis and need a renal biopsy
NB: renal histology of steroid-sensitive nephrotic syndrome is usually normal on light microscopy, but fusion of podocytes is seen on electron microscopy (minimal change disease)
Complications of steroid-sensitive nephrotic syndrome
Hypovolaemia:
As the oedema forms, the intravascular compartment may become depleted
The child may complain of abdominal pain and feel faint
The body will respond with peripheral vasoconstriction and urinary sodium retention
Low urine sodium (<10 mmol/L) and high haematocrit are suggestive of hypovolaemia
Treated with IV 0.9% saline
If severe, IV 20% albumin infusion with furosemide may be needed (NB: this can precipitate pulmonary oedema and hypertension from fluid overload, and the diuretics could worsen the hypovolaemia)
Thrombosis:
Hypercoagulable state, resulting from:
- Urinary losses of antithrombin III
- Thrombocytosis (may be worsened by steroid therapy)
- Increased synthesis of clotting factors
- Increased blood viscosity from raised haematocrit
Infection:
High risk of infection by capsulated bacteria (Especially Pneumococcus)
Pneumococcal and seasonal influenza vaccination is recommended
Chickenpox and shingles should be treated with aciclovir
Hypercholesterolaemia:
Correlates inversely with serum albumin, though the cause is unknown
Prognosis for steroid-sensitive nephrotic syndrome
Relapses can be identified by parents using urine testing
Steroid-sparing agents may be considered if relapses are frequent (e.g. cyclophosphamide, tacrolimus, ciclosporin A, mycophenolate mofetil)
Causes of steroid-resistant nephrotic syndrome
Focal segmental glomerulosclerosis
Mesangiocapillary glomerulonephritis (membranoproliferative glomerulonephritis)
Membranous nephropathy
Management of steroid-resistant nephrotic syndrome
Oedema is managed with diuretics, salt restriction and ACE inhibitors
Congenital nephrotic syndrome
Presents in the first 3 months of life
RARE
More common in consanguineous families
Associated with high mortality
How is haematuria confirmed?
Red urine or tests positive for haemoglobin should be examined under the microscope to confirm haematuria (>10 RBCs per high-power field)
Glomerular haematuria is suggested by:
Brown urine
Presence of deformed RBCs (occurs as it passes through the glomerular basement membrane)
Casts
Often accompanied by proteinuria
Lower urinary tract haematuria is suggested by:
Red
Occurs at the beginning or end of the urinary stream
NOT accompanied by proteinuria
Unusual in children
Causes of haematuria
Glomerular:
Acute glomerulnophreitis (Usually + proteinuria)
Chronic glomerulonephritis (usually + proteinuria)
IgA nephropathy
Familial nephritis (e.g. Alport syndrome)
Thin basement membrane disease
Non-glomerular: Infection (bacterial, viral, TB, schistosomiasis) Trauma to genitalia Stones Tumours Sickle cell disease Bleeding disorders Renal vein thrombosis Hypercalciuria
Investigations for haematuria
ALL patients:
Urine MC+S
Protein and calcium excretion
Kidney and urinary tract ultrasound
Plasma urea, electrolytes, creatinine, calcium, phosphate and albumin
FBC, platelets, coagulation screen, sickle cell screen
If suggestive of glomerular haematuria:
ESR, complement levels and anti-dsDNA antibodies
Throat swab and antistreptolysin O/anti-DNAse B titres
Hepatitis B and C screen
Renal biopsy
Test mother’s urine for blood (if Alport syndrome is suspected)
Hearing test (if Alport syndrome is suspected)
