Voiding function study with ultrasound in male and female neonates

Assessment of lower urinary tract function in pediatrics using ultrasonography

Ultrasound imaging is a less invasive imaging modality without radiation exposure and is available for repeated tests. It is the gold standard examination for diagnosing and managing disorders of the urinary tract, including lower urinary tract dysfunction (LUTD) in pediatric urology. Ultrasound imaging is effective for screening underlying diseases and determining treatment strategies. Ultrasound examination at the bedside should focus on post-voided residual urine (PVR), bladder wall thickening, renal morphology, and rectal diameter. Since PVR must be tested immediately after voiding, examining infants who cannot complain of the urge to void is difficult. PVR measurement combined with a 4-h voiding observation or alarm system activated by urine is recommended for these infants. Early diagnosis is important because LUTD is associated with the risk of morbid residual urine and high voiding pressure, which can result in renal deterioration, urinary leakage, and febrile urinary tract infection.

Effectiveness of a voiding evaluation technique using a diaper equipped with a urination-activated alarm system to assess bladder function and voiding patterns in infants

PURPOSE

Four-hour voiding observation is a conventional method for evaluating bladder function in infants. However, it requires a diaper check every 5 min during the observation period, which creates an unusual environment for the infant, making the evaluation of natural urination difficult. This study aimed to investigate the parameters of urination before mature bladder function using a diaper equipped with a urination-activated alarm system.

METHODS

The study participants were 51 infants aged 0-4 years without bladder dysfunction. A urination-activated sensor was used to notify the inspector wirelessly when urination was detected, enabling the immediate assessment of ultrasonically measured residual urine. Bladder capacity was calculated as the sum of both residual urine volume and micturition volume, and the residual urine rate as the residual urine volume divided by bladder capacity.

RESULTS

A total of 36 boys and 15 girls were enrolled. The median (interquartile range) residual urine volume, bladder capacity, and residual urine rate were 3.0 mL (1.1-6.6), 53.0 mL (33.9-75.3), and 7.0% (2.1-15.0), respectively. Infants aged 0-1 and 2-4 years were then classified into Group A (N = 27) and Group B (N = 24), respectively. The residual urine rate was significantly higher in Group A (11.0% [5.4-21.2]) than in Group B (4.8% [0.6-8.9]; p < 0.01).

CONCLUSIONS

Voiding observation using a urination-activated alarm system allowed less invasive analysis in infants and revealed that the residual urine rate decreased with mature bladder function from about 2 years of age.

An approach to daytime wetting in children

Daytime wetting is a common problem with various causes that can usually be identified through a careful history, thorough physical examination, and urinalysis. Conservative approaches to therapy have a successful outcome in most children. Invasive diagnostic imaging studies and pharmacologic or surgical intervention are necessary only for carefully selected children.

Bladder dysfunction: diagnosis with dynamic US

PURPOSE

To evaluate the role of dynamic ultrasonography (US) in the diagnosis of bladder dysfunction and to compare dynamic US with urodynamic study, which is considered to be the standard in the diagnosis of bladder dysfunction.

MATERIALS AND METHODS

Images from 71 pairs of examinations in 63 patients (median age, 7.9 years; range 1.0-17.4 years) were included in the study. After the child consumed adequate fluids in an appropriate environment, natural filling of the bladder occurred, and dynamic US was used to evaluate detrusor activity, determine capacity of the bladder, and estimate residual urine volume. A urodynamic study was performed in every patient within 6 months of dynamic US and under the same treatment conditions. The paired Student t test was used to compare the maximal cystometric capacity values obtained with the two examinations. Analysis of validity was performed with the calculation of sensitivity, specificity, positive and negative predictive values, and their respective 95% confidence limits.

RESULTS

The bladder capacity was not significantly different between dynamic US and urodynamic study (P =.12). Analysis of validity for the determination of the presence of clinically substantial residual urine showed 97.7% sensitivity and 100% specificity for dynamic US. The sensitivity and specificity of dynamic US in the detection of involuntary detrusor contraction were 93.0% and 88.9%, respectively. In the analysis of involuntary detrusor contraction with urine leakage, dynamic US showed sensitivity of 100% and specificity of 97.8%.

CONCLUSION

Dynamic US is a sensitive method for the diagnosis of bladder dysfunction.

Meatus tightly covered by the prepuce is associated with urinary infection

BACKGROUND

Almost all newborns have phimosis, which is known as one of the risk factors for urinary infection. The present study analyzed which specific prepuce conditions correlated with the development of febrile urinary infection in Japanese male infants.

METHODS

The subjects consisted of 100 children, 64 boys and 36 girls, with febrile urinary infection. Prepuces were classified by their retractability in the male patients and in 714 healthy boys.

RESULTS

Ninety-four percent of first febrile urinary infections occurred before 7 months of age in boys, whereas only 37% of the girls had first infections by that age. The prepuce covered the external urethral meatus in 96% of the healthy boys aged 3 years or less. A gentle retraction maneuver could not uncover the urethral meatus in approximately 40% of the boys aged 0-6 months. The frequency started to decline spontaneously after that age. Male patients aged 0-6 months significantly more often had tightly covered meatus than did healthy neonates (85%vs 42%, P < 0.0001).

CONCLUSIONS

These findings indicate that it is specifically those boys whose external urethral meatus are tightly covered with foreskin who constitute the high-risk group for urinary infection. Awareness of this observation should help with diagnosing and managing urinary infection in young boys.

Does gender influence human cardiovascular and renal responses to water immersion?

We hypothesized that women and men exhibit similar cardiovascular and renal responses to thermoneutral water immersion (WI) to the neck. Ten women and nine men underwent two sessions in random order: 1) seated nonimmersed for 5.5 h (control) and 2) WI for 3 h, with subjects seated nonimmersed for 1.5 h pre- and 1 h postimmersion. We measured left atrial diameter, heart rate, arterial pressure, urine volume and osmolality, and urinary endothelin, urodilatin, sodium, and potassium excretion. No significant difference existed between groups in cardiovascular responses. The groups also exhibited mostly similar renal responses to immersion after adjustment for body mass. However, female urodilatin excretion per kilogram during immersion was over twofold that of men, and the female kaliuretic response to immersion was delayed and less pronounced relative to that in men. Men may excrete more potassium than women during immersion because men possess greater lean body mass (potassium per kilogram). Results obtained in men during WI may be cautiously extrapolated to women, yet urodilatin and potassium responses exhibit gender differences.