Paediatric medicine - Daytime wetting in children

Mr Prasad Godbole explores the management options available to deal with this common problem.

Encourage water-based drinks and fizzy drinks should be avoided
Encourage water-based drinks and fizzy drinks should be avoided

Daytime wetting and bedwetting are fairly frequent problems in children. Normally, children gain continence by four to five years of age during the day.

Symptoms of daytime voiding problems are usually treated if they persist after five years of age or if they occur after a period of having been completely dry during the day.

This article will concentrate on daytime wetting, the different causes, and ways in which it can be managed.

The urinary tract
Before potty training, the bladder empties by a reflex spinal mechanism independent of higher control. Higher control develops during the potty training phase.

Subsequent to this, the micturition cycle involves the storage phase and emptying phase. In the storage phase, the bladder remains compliant and at low pressure as it stretches to capacity before the sensation for voiding is initiated.

Micturition itself relies on a coordinated contraction of the detrusor muscle and relaxation of the sphincter to allow complete emptying.

Adequate storage properties of the bladder - good compliance and low pressure-are dependent on adequate fluid intake and cycling of the bladder through the storage and emptying phase at regular intervals throughout the day.

The working of the bladder and sphincter is dependent on nerves to and from the bladder and sphincter to the spinal column and up to the brain.

Daytime wetting
Some children may experience daytime wetting, even when the bladder itself behaves normally. This may be due to a number of factors:

  • Delayed control due to immaturity of the nerve pathways.
  • 'Holders on' - children hold on for as long as possible and as a result have accidents.
  • Wetting can be caused as a result of urine infections.
  • Some children may develop giggle incontinence.

In other children, the bladder or sphincter may behave abnormally (functional incontinence).

Bladder muscle over/underactivity: sometimes, the muscle may be twitchy (unstable bladder or overactive) and makes the child feel the need to pass urine with urgency. Children may have marked frequency. The bladder may be underactive and the detrusor may be hypocontractile leading to retention of urine and accidents.

Lack of co-ordination between the bladder muscle and the sphincter: sometimes the sphincter remains closed or can open and close repeatedly during the detrusor contraction. This may give a stop-start or staccato nature to the urinary stream.

The bladder may not empty adequately and the child may get urine infections and wetting. This is known as dysfunctional voiding or detrusor sphincter dyssynergia.

The bladder may not empty adequately due to a bladder outlet obstruction. Other structural abnormalities may also lead children to be wet.

Primary care management
A careful history is essential to determine whether the aetiology points towards problems during the storage phase or the emptying phase.

A history of fluid intake (including the consumption of fizzy drinks), voiding and constipation should be taken. A frequency of voiding diary is very useful in gauging the fluid intake and voided volumes during the day.

In a child who is dry at night, the first morning void gives an estimate of the maximum bladder capacity. The formula age +3 gives an approximation of the bladder capacity in fluid ounces.

Urinalysis will aid a UTI diagnosis. In cases of intractable symptoms a renal tract ultrasound can be obtained to ascertain structural anatomy and pre- and post-void residual volumes.

Simple measures that can be carried out at home include requiring the child to pass urine at regular intervals during the day (timed voiding), avoiding fizzy drinks, encouraging plenty of water-based drinks and avoiding constipation.

Where it appears that the bladder is overactive or unstable (small voided volumes with frequency and urgency) a trial of anticholinergics such as oxy-butynin can be instituted.

Specialist management
Once referred, children are usually seen by a specialist continence nurse and undergo a non-invasive urodynamic assessment.

This incorporates a comprehensive history, completion of a frequency volume chart and uroflow studies.

Based on the outcome of these studies, children may require advice alone, medication such as anticholinergics (oxybutynin, tolterodine) or alpha-blockers (doxazosin) or may require invasive assessment including a cystoscopy and formal urodynamic studies with suprapubic catheters.

Other modalities of treatment for intractable symptoms where indicated include injection of botulinum A toxin to the detrusor and biofeedback therapy.

  • Mr Godbole is a consultant paediatric urologist and surgeon at the Sheffield Children's NHS Foundation Trust and the BMI Thornbury Hospital in Sheffield
  • The views and opinions expressed in this article are the sole responsibility of the author. The Sheffield Children's Foundation Trust does not accept any responsibility for the content of the above article or the accuracy thereof

Referral criteria
Referral may be based on any one criterion:

  • Symptoms not responding to simple measures described above within three months of instituting management.
  • Symptoms suggestive of a bladder outlet obstruction.
  • Children with recurrent UTIs.
  • Children with night-time wetting with daytime symptoms not responding to conservative management.

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