Q. Describe the broad categories for the causes of urinary incontinence in children.
A.
Functional
Structural
Neurogenic
Q. What features would raise the possibility of neurogenic urinary incontinence?
A. Maternal diabetes during pregnancy, which is a risk factor for sacral agenesis
A history of neurological disease, e.g. spina bifida
Continuous urinary incontinence
Straining to void
Abnormal urinary stream
Faecal incontinence or severe constipation
Palpable bladder
Spine or buttock abnormality, the latter suggesting sacral agenesis
Neurological signs or limb abnormalities
Q. What features would raise concern about a structural cause for the urinary incontinence?
A. Antenatal history, e.g. of a duplex kidney
Straining or poor urinary stream suggesting bladder outflow obstruction, e.g. posterior urethral valve or meatal stenosis following circumcision
Palpable bladder
Labial adhesions
Intra-labial mass such as ureterocele
Bifid clitoris seen in female epispadias
Q. What are the causes of functional urinary incontinence?
A.
Overactive bladder
Dysfunctional voiding
Voiding deferment
Vaginal reflux
Constipation
Giggle incontinence
Q. What is dysfunctional voiding?
A. This describes a specific phenomenon where there is involuntary contraction of the pelvic floor during voiding. Surprisingly, storage symptoms predominate with frequency, urgency and incontinence. Diagnosis can be made with non-invasive bladder assessment (see later discussion). Treatment centres on teaching pelvic floor relaxation, often in the form of biofeedback.
Q. What is vaginal reflux?
A. Characteristically girls who experience this complain of leaking within 10 minutes of voiding and leaving the bathroom. The mechanism is of urine entering the vagina during voiding, and then subsequently dribbling out. It is effectively treated by getting the girl to abduct her legs widely during voiding to separate her labia.
Q. A 7-year-old girl is referred to you because she wets during the day and at night. What history would you ask about her wetting?
A. The history is the most important part of the evaluation of this girl and will set the basis of her management. It is important to establish the incidence, pattern and progression (if any) of the incontinence since birth and establish the type, e.g. urge/stress/continuous/giggle. There fore, the following points should be clarified:
Primary or secondary? Has she had these symptoms since birth (primary) or have they developed after being continent (secondary)?
There fore primary incontinence refers to the group in which there has never been a prolonged dry spell, whereas in secondary incontinence the child has previously been dry for at least 6 months. The former has a higher chance of a significant organic aetiology. The pattern of the incontinence. Is the incontinence associated with urgency? Is the incontinence continuous, which might be related to an ectopic ureter? In a girl, being wet shortly after voiding may indicate vaginal reflux. A specific entity is ‘giggle incontinence’ where the only provoking factor is laughing or giggling.
Severity of the symptoms. How often does the wetting occur? When it does occur, how severe is it: does it just make her underwear damp, or is it so bad that she needs to change her clothes? Does she need pads?
Q. What risk factors for incontinence would you inquire about in this child?
A.
Voiding frequency. How often does the child void? This is better evaluated with a frequency- volume chart. However, useful clues can be gleaned from what the child and her parents tell you. ‘She often holds on until the last minute’ is useful to know. Similarly the child will often give an idea of how often, if at all, she uses the school toilets during the school day. This gives information about urinary frequency or withholding behaviour (voiding postponement).
Voiding behaviour. ‘Curtseying’ or sitting with the heel of the foot pushed into the perineum to control sudden episodes of urge may indicate detrusor overactivity. Straining to void and poor stream would indicate bladder outlet obstruction. This is perhaps more important in a boy where it may be a sign of meatal stenosis or more rarely posterior urethral valves. Drinking habits. Drinks containing additives and caffeine may be associated with voiding problems.
Constipation. This requires asking about how frequently the child opens her bowels and whether she strains to pass hard stool. Again, correction of constipation will often improve urinary symptoms. Rarely the co-existence of poor bowel symptoms can be an indicator of a neuropathic aetiology.
Urinary tract infections. These may be a cause for wetting. Episodes of cystitis-like symptoms are worth asking about. Positive urine cultures may be significant, although this information should be interpreted in the context of the child’s symptoms at the time, and exactly how the urine was collected.
Age at potty training. A very young age at potty training seems to be associated with later wetting.
Antenatal history. Congenital urological pathology may have been detected but not followed up.
Q. What would you look for when you examine the child?
A.
Abdomen. A palpable bladder or palpable stool would be significant.
Genitals. A split or bifid clitoris may be the only finding in epispadias; a rare condition where the sphincter mechanism will be severely deficient. Perineal excoriation may give an indication of severe wetting or vaginal reflux. In boys who have been circumcised make sure there is no meatal stenosis.
Spine. Inspect and palpate the spine looking for clues of spinal dysraphism such as pigmented or hairy lesions over the midline. Sacral agenesis is characterised by flattening of the buttocks. Abnormal gait or muscle wasting may indicate a neurological problem.
General health. Has the child other medical conditions that may contribute to poor bladder control?
Check blood pressure and perform a urine dipstick at the end of the examination.
Q. The parents have very helpfully brought a frequency-volume chart with them. What instructions would you give to other parents so that they could fill out a frequency-volume chart?
A. Two convenient days are selected. On those days every time the child voids the urine is collected, and the volume and time of each void is recorded. Wetting episodes are also noted. Additional information that should be collected includes time, volume and type of fluid intake. A bladder diary is more exhaustive and would include information about fluid intake and even bowel movements.
Q. What are the things you look at when you interpret a frequency-volume chart?
A. This is most sensibly applied to children over the age of 5 years. According to the International Children’s Continence Society normal voiding frequency is four to seven times per day (inclusive). The expected bladder capacity is calculated by adding one to the child’s age and then multiplying by 30 to give an answer in millilitres; this formula is useful up to the age of 12 years. This is compared to the Maximum Voided Volume on the chart. The normal range is between 65% and 150% of the expected capacity. The 24-hour urine output can also be calculated in addition to total/type of fluid intake.
Q. Is there any value in a renal ultrasound scan?
A. This will give information about bladder capacity. A post-void residual of more than 20 mL on repeated measurement is significant. A thickened bladder with upper tract dilation may reflect a neuropathic bladder or bladder outflow obstruction. Renal abnormalities, such as a duplex kidney with an abnormal upper moiety may indicate the presence of an ectopic ureter.
Q. What are the general measures that can be taken to help a child with urinary incontinence?
A. This is sometimes called urotherapy. A large part of this is education of the child and parents. An explanation is given of normal bladder function and the cause of their child’s incontinence. They are given information about regular voiding habits, normal voiding posture and lifestyle advice about fluid intake and the prevention of constipation. Progress can be monitored with frequency- volume charts and ideally support and encouragement is provided from regular follow-up.
Q. Would you proceed to urodynamics if the child has not responded to urotherapy?
A. Urodynamics are invasive and inappropriate this stage. A non-invasive bladder assessment with a clinical nurse specialist would be more appropriate. This is based on observation of storage and voiding behaviour especially flow rate, flow pattern and residual volume.
An alarm can be used additionally to detect incontinence. Recently flow rates are being combined with electromyography (EMG) recordings from pelvic and abdominal floor muscles. This is done noninvasively using skin electrodes. This provides a rich source of information about abdominal wall and pelvic floor contraction during voiding.
Q. Are urodynamics ever performed in children?
A. Videocystometrogram (VCMG) is a test performed under very limited and specific circumstances; most of the required information will have been gathered by the evaluation described above. VCMG is most commonly performed if:
It has not been possible to achieve a diagnosis by other means
There has been no response to treatment
There is a suspicion of a neuropathic bladder
The bladder line may be urethral or suprapubic. Placement of bladder and rectal lines is a significant undertaking and is likely to require sedation or even general anaesthesia.
Nocturnal enuresis
Q. An 8-year-old boy attends the clinic with his mother. She is very concerned that he always wets the bed during the night. She thinks he is too old to be doing this. You have taken a careful history about continence similar to the one above. He has no daytime urinary symptoms. What is this condition called?
A. Primary (it has always been present), mono-symptomatic (there are no other urinary symptoms, e.g. urgency) enuresis (‘intermittent incontinence while sleeping’).
Q. What is the prevalence of this condition?
A. Approximately 5%-10% of all 7-year-olds will have this condition. It is more common in boys than in girls and 2%-3% are still wet in their late teens.
Q. If untreated what is the natural history?
A. Untreated, 15% will get better every year, although the prognosis may not be so good for children whose symptoms are as severe as this.
Q. Are there any explanations for the cause of mono-symptomatic nocturnal enuresis?
A. The normal circadian reduction in urine output during sleep is diminished in at least two- thirds of children with this condition.
Impaired bladder function has been described in children with the moniker of monosymptomatic nocturnal enuresis, with reduced functional bladder capacity, nocturnal and even daytime detrusor overactivity demonstrated in these children.
It is possible that these children have an abnormal arousal mechanism that prevents the sensation of a full bladder awakening them, as it would in other children. This fits with the observation of many parents of children with this problem who report that their children are very difficult to wake.
Q. What management strategies could be offered?
A.
Behavioural - Establish a regular drinking and voiding pattern during the day. Reduce fluid intake in the evening, and void before going to bed. ‘Lifting’ is where the child is woken and taken to the bathroom, typically at the time his parents are going to bed.
Alarm - An enuresis alarm in the bed is activated when the child wets. This method can often take up to a couple of months before an effect is seen. However, it is associated with the greatest long-term success, with benefit seen in up to two-thirds of children using it. Pharmacology - Desmopressin will produce results quickly, but these are not sustained once treatment is stopped. Anti-muscarinics may be added as an adjunct to desmopressin. Tricyclic antidepressants have been used to treat this condition but are more frequently associated with side effects.