Medical management of pediatric stone disease

Childhood urolithiasis remains endemic in certain parts of the world, namely, Turkey and the Far East. The prevalence of nephrolithiasis in North American children varies widely among geographic regions and accounts for 1 per 1000 to 1 per 7600 pediatric hospital admissions. Stones occur in children of all ages. The clinical manifestations of stone disease are often more subtle in children when compared with the dramatic adult presentation. This article discusses the evaluation and medical management of pediatric stone disease.

Urodynamic findings before and after noninvasive management of bladder calculi

OBJECTIVES

To determine the most frequent urodynamic observations associated with bladder calculi, and to assess whether the presence of calculi alters these observations.

PATIENTS AND METHODS

Fifty patients with bladder stones were included in a prospective study in which two urodynamic tests were used, one at inclusion and another once the patient was stone- free after treatment by noninvasive methods (mainly extracorporeal shockwave lithotripsy).

RESULTS

The results from the urodynamic evaluation with the stone in the bladder were: bladder outlet obstruction in 51%, detrusor overactivity in 68%, detrusor under-activity in 10%, and a normal study in 18%. There were no significant differences between the urodynamic study before or after treatment in maximum flow rate and postvoid residual volume, detrusor overactivity and detrusor pressure at maximum flow.

CONCLUSIONS

Conversely to what has been accepted for years, bladder calculi are not always associated with bladder outlet obstruction and the urodynamic results are not influenced by the presence of bladder stones during the urodynamic testing.

Dielectric properties of certain biological materials at microwave frequencies

In the medical field, microwaves play a larger role for treatment than diagnosis. For the detection of diseases by microwave methods, it is essential to know the dielectric properties of biological materials. For the present study, a cavity perturbation technique was employed to determine the dielectric properties of these materials. Rectangular cavity resonators were used to measure the complex permittivity of human bile, bile stones, gastric juice and saliva. The measurements were carried out in the S and J bands. It is observed that normal and infected bile have different dielectric constant and loss tangent. Dielectric constant of infected bile and gastric juice varies from patient to patient. Detection and extraction of bile stone with possible method of treatment is also discussed.

Spontaneous expulsion of large vesicle calculi in a woman with paraparesis

INTRODUCTION

Urolithiasis is a common but preventable complication of Spinal Cord Disorders (SCD).

CASE REPORT

We report a 25-year-old woman with paraparesis who spontaneously passed two large calculi perurethra without pain and developed urethral scarring. Detrusor hyperreflexia, absence of sensations and lack of sphincter tone could have contributed to painless expulsion of the large calculi in this patient.

CONCLUSION

Dysuria, a prominent symptom of urolithiasis may not be present in subjects with SCD. Awareness about urolithiasis among health professionals involved in the care of SCD patients is necessary for prevention and early intervention.

Stones in enterocystoplasties

OBJECTIVES

To assess the aetiology of stones which occur in enterocystoplasties and continent diversions, generally attributed to the presence of foreign material, e.g. staples, or to recurrent urinary infection, in patients with augmented or substituted bladders.

PATIENTS AND METHODS

The study comprised 467 patients who had undergone reconstruction of the lower urinary tract and had been followed up for at least 3 years using videourodynamics and ultrasonography.

RESULTS

Stones were found in 42 patients (9%); 50% were found incidentally and the remaining patients presented with symptomatic infections (27%) or deterioration in urinary continence (23%). Stones occurred in 6% of patients with augmentation, in 7% of those with substitution cystoplasty and in 22% of patients with continent diversions. Most patients with stones (88%) used clean intermittent self-catheterization (CISC). Stones were 5-10 times commoner in patients using CISC than in patients voiding spontaneously.

CONCLUSION

Urinary stasis was a more important cause of stone formation than was bacteriuria in patients with cystoplasty. The presence of mucus and bacteriuria are presumed to be contributory. To reduce the risk of stone formation, orthotopic cystoplasty and spontaneous voiding are to be preferred to continent diversion and CISC. Periodic bladder washouts may be an alternative solution.

Long-term catheterization of the bladder: prevalence and morbidity

OBJECTIVE

To estimate the prevalence and morbidity of long-term catheterization (LTC) of the urinary bladder.

PATIENTS AND METHODS

A postal survey was conducted over two successive years from February 1989 to determine the incidence of LTC in three Bristol Health Districts with a total population of 827,595. During the first year the number of patients requiring emergency treatment for complications of LTC was also monitored over a 6-month period. In the second year, 54 patients were selected from the first survey and each was visited by one investigator every 2 weeks for 12 weeks to obtain information on catheter management, the incidence and type of complications, the attitudes of the patients or carers about the catheter and to assess the pH and microbiology of the patient's urine.

RESULTS

The initial surveys identified 457 and 467 patients with long-term catheters during the 2 years, respectively; there were similar numbers of men and women in both years. The survey of catheter complications recorded 506 emergency referrals during the 6 months and the detailed study of 54 patients showed that 48% experienced catheter blockage, 37% reported urine by-passing the catheter and 30% noted haematuria. Patients found the catheter uncomfortable and depended on nursing support. Catheter blockage was associated with bladder stones, a high urinary pH and the presence of Proteus spp in the urine.

CONCLUSION

The prevalence and high morbidity of LTC cause a considerable demand on the available District and Hospital nursing services; most patients with long-term catheters are elderly, disabled or debilitated and more nurses need to be trained in the technique of catheterization and the management of the catheterized patient. Further research is required to reduce the morbidity of LTC by investigating measures to reduce catheter blockage and encrustation at the urine/biomaterial interface.

Age-related physiologic and pathologic changes affecting lower urinary tract function

The physiologic changes and pathologic conditions that are frequently seen in the elderly population create a clinical challenge requiring knowledge of the "normal" voiding function, as well as commonly observed alterations. This article reviews the more common physiologic changes, disease states, and iatrogenic causes associated with aging that affect urinary tract function.

The risk of bladder calculi in patients with spinal cord injuries

A nonconcurrent prospective study of bladder calculi included 500 persons treated at the University of Alabama in Birmingham Spinal Cord Injury Care System between 1973 and 1981. Risk factors suspected of contributing to the development of bladder calculi were identified. Logistic regression analysis was used to estimate each risk factor's adjusted odds ratio and to develop a predictive model for bladder stone formation. Bladder calculi were most likely to develop within one year of injury. Patients developing bladder calculi prior to first definitive discharge were most likely to be white and have neurologically complete lesions and Klebsiella infections at admission. Patients developing bladder stones within two years of hospital discharge were most likely to be young and white and have indwelling urethral catheters and either Proteus or multiple-organism infections at discharge. The predictive model was 82% sensitive and 83% specific when applied to a validation sample of patients.