Natural Filling Cystometry in Small Boys With Posterior Urethral Valves: Unstable Valve Bladders Become Stable During Sleep

Best practice in the assessment of bladder function in infants

The purpose of this article is to review normal developmental bladder physiology in infants and bladder dysfunction in conditions such as neurogenic bladder, posterior urethral valves and high grade vesicoureteric reflux. We contrast the classical concept that bladder function in nontoilet-trained children is thought to be 'reflexive' or 'uninhibited', with the results of more recent research showing that infants most commonly have a stable detrusor. The infant bladder is physiologically distinct from the state seen in older children or adults. The voiding pattern of the infant is characterized by an interrupted voiding stream due to lack of proper urinary sphincter relaxation during voiding. This is called physiologic detrusor sphincter dyscoordination and is different from the pathologic 'detrusor sphincter dyssynergy' seen in patients with neurogenic bladder. Urodynamic abnormalities in neonates born with spina bifida are common and depend on the level and severity of the spinal cord malformation. Upper neuron lesions most commonly lead to an overactive bladder with or without detrusor sphincter dyssynergy while a lower neuron lesion is associated with an acontractile detrusor with possible denervation of the external urinary sphincter. In infants with neurogenic bladder, the role of 'early prophylactic treatment (clean intermittent catheterization and anticholinergics)' versus initial 'watchful waiting and treatment as needed' is still controversial and needs more research. Many urodynamic-based interventions have been suggested in patients with posterior urethral valves and are currently under scrutiny, but their impact on the long-term outcome of the upper and lower urinary tract is still unknown. Cumulative data suggest that there is no benefit to early intervention regarding bladder function in infants with high-grade vesicoureteric reflux.

Bladder function in preterm and full-term infants

The purpose with the present review was to characterise bladder function in healthy preterm and full-term infants from findings in studies using the four-hour voiding observation. Characteristics of the free voiding pattern were very similar in preterm and full-term infants. The frequency of voidings was once an hour, bladder volume inducing voiding varied, infants often woke up before voiding and the bladder was not completely emptied at every voiding. Furthermore, interrupted voidings interpreted as a detrusor-sphincter dyscoordination, were seen and were clearly an immature phenomenon since the frequency was high in the preterm infants and then decreased. Concluding these findings the voiding pattern seems to be immature early in life and there is distinct evidence for a connection to the CNS already in the preterm infant.

Does Treatment With Clean Intermittent Catheterization in Boys With Posterior Urethral Valves Affect Bladder and Renal Function?

PURPOSE

In boys with resected posterior urethral valves (PUV) deterioration of renal function is seen during childhood and adolescence, which may partly be caused by bladder dysfunction. We present data on renal and bladder function initially and at followup of boys with PUV in whom the bladder dysfunction has been treated since infancy.

MATERIALS AND METHODS

The study included 35 boys with PUV. Bladder regimen, including early toilet training from the age of 1.5 years and detrusor relaxant drugs for the treatment of incontinence from ages 4 to 6 years, was introduced to all patients. A total of 19 boys were started on clean intermittent catheterization (CIC) at a median age of 8 months due to pronounced bladder dysfunction with poor emptying, unsafe pressure levels, high grade reflux and renal impairment.

RESULTS

No serious complications of CIC have been seen during followup. Of the 19 boys 2 stopped performing CIC due to noncompliance of the parents at 1 and 3 years, respectively. Initial renal function, measured as median glomerular filtration rate (GFR) in percent of expected for age, was 60% in the CIC group and 90% in the nonCIC group. At followup at a median age of 8 years the CIC group (n = 14, 3 transplanted boys excluded) had an increase in median differential GFR (difference between followup and initial GFR) of 7% (p <0.01), which was similar increase to that of the nonCIC group. In the 2 boys who stopped performing CIC renal function deteriorated with a median differential GFR of -24%. In the CIC group detrusor instability decreased. Poor compliance was seen in 6 of the 19 boys initially and only one remained poorly compliant. In 1 of the boys who stopped performing catheterization a low compliant bladder developed. In all of the other cases bladder capacity increased more than expected for age.

CONCLUSIONS

The results suggest that treatment of bladder dysfunction in boys with PUV can counteract the deterioration in renal function seen during childhood but the number of patients in our study is limited.

Comparison between conventional cystometry and stimulated filling cystometry by diuretics in a neurogenic bladder after spinal cord injury

OBJECTIVE

To determine in the neurogenic bladder whether cystometry performed under near physiologic condition by filling stimulation using diuretics reveals different findings compared with conventional cystometry (CMG).

DESIGN

One group of subjects from a university teaching hospital was tested in two conditions. The maximum detrusor pressure (MPdet) and compliance of the bladder in CMG and furosemide-stimulated filling cystometry (FCMG) were compared in 27 patients with neurogenic bladder after spinal cord injury. The MPdet was estimated. Compliance was calculated. For CMG, the bladder was filled. FCMG was performed 3 hr after CMG. For FCMG, furosemide was injected after infusion of normal saline. Recording intravesical pressure started after emptying the bladder immediately after furosemide injection.

RESULTS

Significant differences were found between CMG and FCMG in hyperreflexic neurogenic bladders with respect to a decrease in MPdet and increase in compliance with FCMG. However, there were no significant differences in MPdet and compliance in hyporeflexic or areflexic neurogenic bladders between the two techniques.

CONCLUSION

We have found that FCMG is useful in evaluating both genuine MPdet and compliance in patients with hyperreflexic neurogenic bladder dysfunction. FCMG provides more reliable information on detrusor characteristics than CMG in hyperreflexic neurogenic bladder. We suggest that FCMG is an alternative, effective, and near physiologic diagnostic method, having short assessment time for improving evaluation of the detrusor characteristics of hyperreflexic neurogenic bladder.

Bladder function in healthy neonates and its development during infancy

PURPOSE

Bladder function in healthy neonates and its development during infancy are described.

MATERIALS AND METHODS

Results of free voiding studies of healthy neonates and infants using 4-hour voiding observation and urodynamics studies were reviewed.

RESULTS

According to these studies, voiding in the healthy neonate is characterized by small, frequent voids of varying volume in the individual case and interrupted voiding in 30% of the cases. Interrupted voiding is clearly an immature phenomenon since it is seen in 60% of preterm neonates and disappears completely before the age of toilet training. These voidings are considered to be due to a dyscoordination between the sphincter and detrusor, which has also been observed on urodynamic studies and which probably also explains incomplete emptying seen in this age group. Emptying remains incomplete to the age of toilet training when residual urine is median 0 ml. during 4 hours of observation. Voiding rarely occurs during quiet sleep even in the neonatal period, when signs of arousal are often noted before voiding. However, voiding during sleep in 60% occurs of preterm infants, indicating that it may be due to maturation of the central nervous system. Bladder instability is rarely seen in healthy neonates and infants according to urodynamic studies but hyperactivity is suggested in the neonatal bladder with premature voiding contractions after only a few milliliters of filling and with leakage of urine. This latter phenomenon probably explains the low cystometric bladder capacity in this age group. High voiding pressure levels also accompany this low bladder capacity.

CONCLUSIONS

Thus, it can be suggested that the neonatal bladder is regulated by neuronal pathways with connections to the cerebral cortex in the neonatal period, which is contrary to the earlier concept of voiding as an automatic event in response to a constant volume in the bladder. This theory does not mean that voiding is conscious or voluntary in this age group, but only that the voiding reflex disturbs the neonate. New characteristics include the concept of physiological dyscoordination, such as hyperactivity of the detrusor seen as low bladder capacity, and high voiding pressures in the neonatal period.