Surprising interobserver and intra-observer variability in pediatric testicular ultrasound volumes

INTRODUCTION

Testicular volume (TV) can be obtained by either scrotal ultrasound (SU) or orchidometer. Scrotal ultrasound allows for a more objective measurement; however, the interobserver and intra-observer variability of TV measurements has not been rigorously studied.

OBJECTIVE

The authors measured intra-observer and interobserver variability of SU TV measurements in pediatric patients to assess the reliability and reproducibility of SU. Special attention was paid to how often a 20% discrepancy in TV was noted as this has previously been utilized as an indication for varicocelectomy.

DESIGN

Patients with an indication for SU or undergoing an ultrasound for another reason were prospectively recruited. Two different urologic specific ultrasound technicians (A and B) performed SU to assess interobserver variability. A second measurement was taken by technician A within 90 days to assess intra-observer variability (A vs A1). The technicians were blinded to other ultrasound results.

RESULTS

Fourteen patients (28 testes, 56 volume measurements) were included in the intra-observer group and 17 patients (34 testes, 68 volume measurements) in the interobserver group. The mean time to repeat intra-observer ultrasound measurements (range) was 46 days (23-84). Mean age (range) in the intra-observer group was 14.3 years (11-19) and 14.1 years (11-19) in the interobserver group. Indication for ultrasound was varicocele (n = 6), scrotal pain (4), hydronephrosis (3), hydrocele (2), epididymal cyst (2), posterior urethral valves (1), and testis asymmetry (1). Utilizing Bland-Altman analysis and plots, variability was seen in both intra-observer and interobserver measurements. The mean values for testicular sizes for technician A and technician B were 13.0 ± 9.7 cm³ vs 13.8 ± 9.9 cm³, respectively. The mean values for TV measurement for technician A's first and second measurements (A, A1) were 14.3 ± 9.7 cm³ and 14.8 ± 8.9 cm³, respectively. An errant 20% difference in TV measurements for the same testis was seen in 25% (7 of 28) of intra-observer measurements and 35% (12 of 34) of interobserver measurements. These 20% differences were more common with a lower body mass index (odds ratio, OR = 0.74, p = 0.01) in the interobserver group, and lower TV was a predictor in the intra-observer group (OR: 0.82, p = 0.009).

CONCLUSIONS

Variability exists in both interobserver and intra-observer measurements of TV by dedicated urologic ultrasonographers, and greater than 20% of differences in measured TV in same testicles occurred in over 25% of cases. Caution should be exercised in basing operative decisions and scientific studies on limited measurements of TV.

Spinal anesthesia in children: most pediatric urologists are not on board

OBJECTIVE

In 2016, the Food and Drug Administration issued a warning on general anesthetic medications used for lengthy procedures (>3 h) in children younger than 3 years. Spinal anesthesia can be a safe alternative to general anesthesia for many pediatric urology procedures. It can shorten total operating room (OR) time, provide excellent pain control, and allow parents to reunite with their child immediately after surgery. However, use of spinal anesthesia can also directly affect the operating surgeon (awake patient, time constraints of spinal, and prolonged preoperative time). Members of the Societies for Pediatric Urology (SPU) and European Society of Pediatric Urology (ESPU) were surveyed to get their opinions on the use of spinal anesthesia for routine pediatric urology procedures. It was hypothesized that half of pediatric urologists would favor spinal anesthesia and that SPU members would be more likely to favor spinal anesthesia than their European colleagues.

MATERIALS AND METHODS

A short survey with five clinical scenarios was created. Scenarios assessed physicians' recommendations regarding timing and the type of anesthesia (general or spinal) for common pediatric urology procedures: undescended testicle, inguinal hernia, hypospadias, phimosis, and phimosis with penoscrotal webbing. Surveys were emailed to members of the SPU and ESPU. Responses and demographic information were collected and analyzed.

RESULTS

The survey was completed by 113 SPU members (46% response rate for members who opened the invitation) and 109 ESPU members. For all clinical scenarios, < 20% of pediatric urologists from the SPU and <25% from the ESPU favor doing any procedure with spinal anesthesia. The majority of respondents practice in children's hospitals with pediatric anesthesiologists, but roughly half of the responders (54% SPU and 43% ESPU) do not think their anesthesia colleagues would be comfortable performing spinal anesthesia. Furthermore, only 51% of SPU and 36% of ESPU members discuss the possible neurodevelopmental side-effects of anesthesia with parents; similarly, less than half of all respondents think their anesthesia colleagues address these potential side-effects when obtaining consent. The only significant difference between SPU and ESPU responses was that ESPU members tended to delay penile surgery more than SPU respondents.

CONCLUSION

Whether general anesthesia has any effect on the developing brain of children undergoing routine pediatric urology procedures is unclear. Yet, few pediatric urologists, independent of their region of practice, prefer spinal to general anesthesia. Collaboration in the OR is the key to success, and it is important that pediatric urologists and pediatric anesthesiologists work together to balance the benefits and risks of general and spinal anesthesia.

Pediatric penile surgery by a nurse practitioner in the operating room

INTRODUCTION

With the growing shortage of pediatric urological surgeons, it was our aim to streamline our system to get patients with less complex penile procedures performed in a timely manner. To do this, an advanced practice provider (APP) was trained to perform minor penile procedures in children in the operating room(OR).

OBJECTIVES

The goal of our study was to show that with proper training an APP could safely perform a circumcision in the OR.

STUDY DESIGN

After approval of the study center's credentialing committee, a NP was trained to perform revisions and initial circumcisions in children in the OR. The process involved: (1) observation, (2) first assisting and (3) performing the procedure with direct, and later in-direct, supervision. The first 100 cases were evaluated for surgical complications, post-operative complications and return rates to the OR.

RESULTS

100 independent cases were completed with 90 having only in-direct supervision. There were no operative complications, nor any documented emergency room or urgent care visits in the immediate post-operative period. There were no early returns to the OR and only 1 scheduled follow-up procedure for a penile skin bridge.

DISCUSSION

It was demonstrated that with proper training a NP can safely perform minor penile procedures in the OR. This allows us to free up our pediatric urology physicians to see and operate on more complex pediatric urology problems. In addition, it allows those with minor penile issues to be cared for more expeditiously. A concern related to training NPs to do circumcisions could be the loss of control by urologists. In this situation, the attending physician is ultimately responsible from a medico-legal standpoint. That would not be true if the NP was practicing independently. With a shortage of urologists, this significantly expands the ability to care for our patient population. In additional, attending surgeons will have a greater freedom to perform major procedures. A limitation of the study was that a patient satisfaction survey was not obtained to see if there were concerns over a APP doing their circumcision. Personal feedback on 30 of the patients that did not return for the follow-up visit was not obtained. The authors of the study are primary providers of pediatric urology care in the study region, thus any individual with concerns would have been referred.

CONCLUSIONS

It was demonstrated that a well-trained APP can safely perform minor penile procedures independently in the OR with indirect supervision.

Natural history of testicular size in boys with varicoceles

INTRODUCTION

Testicular size is commonly used as a proxy for future fertility in adolescent boys diagnosed with varicoceles. Surgery is often performed based on a 15-20% reduction in volume of the ipsilateral testicle when compared to the unaffected side. Recent European Association of Urology guidelines, however, have highlighted the risk of overtreatment. Data on the natural progression of testicular size discrepancy are limited in this population. To evaluate the role of a non-surgical approach, the present study reports on testicular size progression in 35 boys with left-sided varicoceles managed with observation alone.

METHODS

In the present study, 103 consecutive boys who were seen for varicocele were retrospectively evaluated; the 35 who were seen for at least three sequential visits by the same pediatric urologist for a unilateral left varicocele were selected. In the present practice, surgical management of varicoceles in teens is offered, but not recommended unless surgery is being performed for another reason (3/103). The Prader orchidometric testicular volumes that were documented for all visits were recorded and the volume of the left testicle as a percentage of the right was calculated. This analysis was performed for the entire population, and subgroup analysis was conducted for boys with a Grade 3 varicocele, with >10% asymmetry at diagnosis, and by dividing the population into prepubertal and pubertal age groups. Boys with bilateral varicoceles, concurrent testicular masses, or volumes recorded by a nurse practitioner were excluded from the study.

RESULTS

The mean left testicular volume in the population was found to measure 96%, 95% and 96% of the right at the first, second and third visit (median interval was 2.0 years), respectively. Among the 26 boys seen for a fourth visit (median 3.3 years) and the 15 seen for a fifth visit (median 4.3 years), the mean left testicular volumes were 98% and 97% of the right at diagnosis and 97% at both the fourth and fifth visits (Figure). Likewise, no differences were seen after dividing the population into prepubertal (9-11 years, n = 9) and pubertal (12-14 years, n = 26) groups. Among the 13 (37%) boys with a Grade 3 varicocele at presentation, the left testicular volume was 95% (SD 11.4) of the right and remained unchanged by the third visit (96%, P = 0.69). In addition, among the 11 boys (31%) with greater than 10% size difference at the first visit, the left testicle measured 82% of the right (SD 5.3) at diagnosis and increased to 92% (SD 6.3) by the third visit (P < 0.001).

DISCUSSION

In the 35 boys observed over a median of 2.0 years or three consecutive visits, there was no worsening of testicular asymmetry. This finding is consistent with some previous observational data on pediatric varicoceles, but carries the advantages of a narrower age range and longitudinal follow-up in all patients. At the same time, these results differ from other studies that show no improvement or worsening of asymmetry during follow-up. This difference is attributed to the inherent characteristics of the present study population and the choice of orchidometer for measurement. The present data have the advantage of excluding selection bias. Recognizing that this study is a retrospective, single-operator study with a small sample size, prospective, randomized trials are recommended to weigh surgery vs observation in adolescent varicocele patients.

CONCLUSIONS

No progression in atrophy/hypotrophy of the left testis was found in a series of 35 consecutive patients who were followed non-surgically for left-sided varicocele. Our data thus support observation as management for childhood varicocele in younger teens.

A comparison of palpable and impalpable cryptorchid testes using CD-99 immunohistochemistry

OBJECTIVE

To compare the clinical and morphological features of impalpable and palpable cryptorchid testes, as there is debate about how much effort is appropriate to bring an impalpable undescended testicle into the scrotum.

PATIENTS AND METHODS

We reviewed retrospectively 189 cases of undescended testicles in 168 patients who were explored surgically by one surgeon between August 1997 and September 2000. Operative findings of palpability, testicular size and location were collected. The mean tubular diameter (MTD), tubular fertility index (TFI) and mean number of germ cells per tubule (MGCT) were calculated using immunohistochemistry for CD-99, a Sertoli-cell marker, to classify germ cells more accurately.

RESULTS

Sixty-three testes (33%) were impalpable; the median age at the time of surgical exploration was 23 months for both groups. The mean (sd) testicular volume for the impalpable and palpable groups were 0.83 (0.38) and 1.22 (0.54) mL, respectively. Using fitted curves of size vs age, impalpable testes were smaller than palpable testes at all ages, with the difference nearly statistically significant (P < 0.06). The MTD, TFI and MGCT decreased with age in both groups, with no statistically significant differences between the groups. A sub-analysis of abdominal and extra-abdominal testes confirmed no significant differences.

CONCLUSION

Impalpable testes are smaller at the time of exploration than palpable cryptorchid testes. However, histological factors predict that impalpable testes have a significant chance of future fertility and therefore orchidopexy is appropriate. CD-99 immunohistochemistry makes objective morphological information easier to obtain.

Diuretic renogram clearance half-times in the diagnosis of obstructive uropathy: effect of age and previous surgery

Diuretic renography with radiotracers has been used successfully to diagnose obstruction in patients with hydronephrosis. Controversy persists with regard to the best approach for the interpretation of renogram curves: visual analysis or a quantitative index, i.e. the clearance half-time. The latter is often reported to be in the intermediate or non-diagnostic range. It is important to measure the incidence of equivocal half-times in various subsets of patients with hydronephrosis in order to determine in which settings the measurement of this index may be clinically useful. We performed a retrospective study of diuretic renograms performed at our institution between 1997 and 2000 for the evaluation of suspected uretero-pelvic junction (UPJ) obstruction. Vigorous intravenous hydration, exceeding current guidelines, was employed in these patients. Three hundred and seventy-seven renogram curves in 205 patients were analysed. Patients were divided into three groups: >1 year of age; <or=1 year of age; and those who had previously undergone surgical correction of obstruction regardless of age. Patients with reflux or anatomical abnormalities of the urinary tract, those with chronic renal failure, those with bilateral normal clearances before furosemide administration and those with unilateral normal clearances before furosemide administration with contralateral poor renal function were excluded. In the remaining 119 patients, 205 clearance half-times were classified as normal before furosemide, normal after furosemide (half-time, <10 min), prolonged (half-time, >20 min) or intermediate (half-time, 10-20 min). In patients >1 year of age, 37% of 101 renograms showed normal half-times before furosemide, 20% showed normal half-times after furosemide, 44% showed prolonged half-times and none (0%) showed an intermediate half-time. In patients </=1 year of age, there was a statistically significantly different distribution, with 48% of 64 renograms showing normal washout before furosemide, 16% showing normal clearance after furosemide, 19% showing abnormal half-times and 17% showing intermediate half-times. In 33 renograms from patients who had undergone corrective surgery, 49% had normal half-times, 24% had prolonged half-times and 27% had intermediate half-times. It can be concluded that, when using the selection criteria, hydration, acquisition and processing protocols and half-time definition employed in this study, the addition of a clearance measurement in patients older than 1 year with suspected UPJ disease enhances patient classification and may improve the diagnostic confidence. There was a significantly higher incidence of intermediate half-times in patients with native disease aged <1 year than in those >1 year. Caution is advised when interpreting this finding in this age group. The measurement of washout was less useful in patients who had undergone a corrective procedure, because of the high rate of 'indeterminate' and 'abnormal' values in spite of successful surgery. Vigorous intravenous hydration, exceeding current standards, may have contributed to the lower incidence of intermediate half-times than reported previously.

Aspirin treatment improves bladder function after outlet obstruction in rabbits

OBJECTIVES

To examine whether bladder smooth muscle dysfunction after outlet obstruction could be altered by treatment with aspirin. Long-term outlet obstruction causes contractile and metabolic dysfunction of the bladder in vivo and in vitro. The evidence is growing that a decrease in bladder perfusion is an important cause of this phenomenon. The platelet aggregation inhibitor, acetylsalicylic acid (aspirin), has been used to improve perfusion of the heart for decades.

METHODS

Ten male New Zealand white rabbits were obstructed for 4 weeks. Five rabbits received no further treatment (Obs), and 5 rabbits received 2 mg/kg/day aspirin (Obs+aspirin), administered by an osmotic pump implanted subcutaneously 1 week before the surgical obstruction. The bleeding time was measured to confirm the effectiveness of the aspirin treatment. Three different control groups were created: sham-operated rabbits, unobstructed rabbits with pumps containing DMSO (vehicle), and unobstructed rabbits with pumps containing aspirin. The contractile responses of bladder strips to field stimulation, adenosine triphosphate, carbachol, and KCl were determined. A section of each detrusor tissue was fixed in formalin and used to determine the smooth muscle and collagen (connective tissue) volume fraction.

RESULTS

No differences were found in the bladder weights or responses to stimuli in the different control groups, which were therefore combined. Partial bladder outlet obstruction caused significant increases in the bladder weight of the obstructed animals (Obs+aspirin, 10.15 +/- 0.87 g; Obs, 10.17 +/- 0.88 g; and controls, 2.87 +/- 0.21 g). The aspirin treatment increased the bleeding time from 1.7 +/- 0.3 minutes to 3.3 +/- 0.1 minutes. The responses to field stimulation were significantly reduced in all of the obstructed rabbits. However, the responses of the bladder strips from the Obs rabbits to field stimulation were impaired to a significantly greater degree than were those from the Obs+aspirin rabbits. The response to 32-Hz stimulation was reduced by 86% in the Obs group but by only 64% in the Obs+aspirin group. The responses to carbachol were significantly reduced by 62% in the strips from the Obs rabbits, but the responses of the strips from the Obs+aspirin rabbits were similar to the responses of the strips from the controls. The responses to KCl and adenosine triphosphate were reduced, although they just failed to achieve statistical significance using Bonferroni's analysis. The ratio of smooth muscle and connective tissue shifted slightly toward smooth muscle after 4 weeks of obstruction, but no difference was found with or without aspirin treatment.

CONCLUSIONS

Low-dose aspirin has a small but significant protective effect on the contractile dysfunction induced by bladder outlet obstruction in rabbits, although the increase in bladder mass was not altered. Bladders of the same weight showed improved responses to all forms of stimulation after pretreatment with aspirin. Already used by millions of patients with heart diseases, aspirin could be a useful protection against contractile dysfunction of the obstructed bladder.

Magnetic resonance imaging in the evaluation of congenital anomalies of the external genitalia

OBJECTIVES

To assess the value of magnetic resonance imaging (MRI) in the anatomic evaluation and management planning of complex congenital genitourinary anomalies.

METHODS

Multiplanar T(1) and T(2)-weighted MR images were obtained in 6 pediatric patients with congenital genitourinary anomalies, including aphallia, diphallia, ectopic scrotum, and epispadias. The imaging studies were read by experienced radiologists and discussed with the urologic surgeons in a multidisciplinary conference.

RESULTS

Each congenital anomaly was demonstrated in detail by MRI. The MR images of penile agenesis showed hypoplastic corpora cavernosa and a vestigial bulb. In patients with penile duplication, MRI was able to delineate the course of each corporal body and the varying degree of thickness of the tunica albuginea. For the patient with scrotal ectopia, detailed MR images excluded both the possibility of urethral and corporal duplications and the presence of viable testes in the ectopic scrotum. In the case of epispadias, MRI illustrated the precise spatial relationship between the erectile bodies and urethra. Additionally, MRI identified related aberrant pelvic organs and provided images of the external genital structures.

CONCLUSIONS

MRI, by rendering excellent anatomic interpretation of complex genital anomalies and associated abnormal pelvic tissues, assists surgeons in conceptualizing the anomalous structures and contributes to their formulation of management approaches.

The response of fetal sheep bladder tissue to partial outlet obstruction

PURPOSE

We characterized the response of fetal ovine bladder strips to stimulated contraction and relaxation, and compared this response to that of strips from the pregnant mother and those obtained after a short duration of fetal bladder outlet obstruction.

MATERIALS AND METHODS

Sham surgery or bladder obstruction was performed in fetal sheep at 90 days of gestation (term 147 days). Bladder tissue was obtained 3 and 5 days later. Isolated strips of full-thickness bladders from fetuses and pregnant females were mounted individually in Tyrode's solution containing glucose. The strips were subjected to electrical field stimulation. Alternate strips were stimulated by adding carbachol, adenosine triphosphate and KCl. Each strip stimulated by carbachol also underwent field stimulation in the presence of carbachol. Relaxation was also tested using isoproterenol and nitroprusside.

RESULTS

The response of isolated strips to field stimulation showed phasic contraction or biphasic response, consisting of initial phasic contraction followed by phasic relaxation and a return to control tension after the end of stimulation. In fetal bladder strips field stimulation at all frequencies after carbachol stimulation produced phasic relaxation or a biphasic response with an initial relaxation phase followed by phasic contraction. This field stimulated relaxant response was not present in adult female bladder strips. In addition, field stimulation stimulated relaxation was completely eliminated by pretreatment with N-nitro-L-arginine-methyl ester, indicating that relaxation was nitric oxide mediated. The fetal responses to all forms of stimulation and relaxation were significantly greater than those of pregnant females. After 5 days or greater of obstruction the responses to field stimulation were reduced significantly. In contrast, there were no significant differences in contractile responses to adenosine triphosphate, carbachol or KCl, or the relaxant response to field stimulation after obstruction. However, there was a significant reduction in relaxant responses to isoproterenol and nitroprusside.

CONCLUSIONS

In mid gestation sheep fetus contractile responses to field stimulation, adenosine triphosphate, carbachol and isoproterenol are well developed. The fetal ovine bladder shows a strong neuronal nitric oxide response that is not present in the pregnant mother and is maintained after short-term obstruction.

Increased blood flow after catheterization and drainage in the chronically obstructed rabbit urinary bladder

OBJECTIVES

To determine the effect of drainage on rabbit bladder blood flow after 4 weeks of partial outlet obstruction. Previous studies have shown that catheterization and drainage of the urinary bladder in control rabbits resulted in a significant nitric oxide-induced increase of blood flow to the bladder. It was also shown that 4 weeks' partial outlet obstruction caused a significant decrease in blood flow to the bladder.

METHODS

Male New Zealand White rabbits underwent partial outlet obstruction by standard methods. After 4 weeks, the blood flow to the bladder muscle and mucosa was determined by a microsphere technique. Within 1 to 2 minutes after transurethral catheterization and complete drainage of the bladder, the blood flow was again determined. Unobstructed animals served as controls. Four other control animals underwent a repetitive blood flow study during 10 minutes to determine the time frame of blood flow changes after drainage. Blood flow was also measured in 2 control rabbits after transurethral catheterization without drainage and in 2 control rabbits after drainage by suprapubic puncture. To exclude the possibility that increased intravesical pressure alters the blood flow measurements, the relationship between the intravesical volume and the bladder pressure was examined in the obstructed rabbits.

RESULTS

After drainage of the bladder, the blood flow to the bladder muscle increased 4.5-fold in the decompensated obstructed group (bladder weights greater than 15 g) and 2.5-fold in the compensated animals (bladder weights less than 5 g) and control animals. Blood flow to the mucosa followed the same pattern but without reaching significance. Blood flow returned to near baseline values within 5 minutes. Catheterization without drainage did not alter the blood flow. In contrast, drainage by puncture increased the blood flow significantly. Higher intravesical volumes increased the intravesical pressure slightly, but after opening the abdominal fascia, the intravesical pressure did not change with increasing volumes.

CONCLUSIONS

Although the previously shown decreased blood flow to the bladder smooth muscle may be an etiologic factor in bladder contractile dysfunction secondary to partial outlet obstruction, the bladder does have the ability to increase the blood flow after drainage. This ability could be a compensatory and possibly protective mechanism after outlet obstruction.

Placement of artificial urinary sphincter in children and simultaneous gastrocystoplasty

PURPOSE

Previous studies have described placement of an artificial urinary sphincter and simultaneous augmentation cystoplasty with a segment of bowel. Conclusions from these studies indicated that infection rates were higher and a staged approach should be undertaken. Others have suggested that concurrent urinary reconstruction with stomach and sphincter placement can be performed safely. Results comparing infection rates of simultaneous sphincter placement and gastrocystoplasty versus staged sphincter placement and augmentation cystoplasty using a segment of ileum or stomach versus sphincter placement alone in a pediatric population have not been previously described to our knowledge. We reviewed these various groups of patients to determine if the difference in infectious complications were clinically and statistically significant.

MATERIALS AND METHODS

A retrospective review of medical records from 1986 to 1999 identified 28 pediatric patients (age 18 years or less) who had undergone placement of an AS800dagger artificial urinary sphincter. Data points were collected focusing on etiology of the neurogenic bladder, age at time of surgery, types of surgery performed, length of followup and complication rates.

RESULTS

Complete data were available for 27 of the 28 patients. Neurogenic bladder was secondary to myelomeningocele in 25 cases, transverse myelitis in 1 and spinal cord injury in 2. Mean patient age at surgery was 12.7 years (range 6.1 to 18.2) and mean followup was 4.3 years (range 1 month to 13 years). Simultaneous gastrocystoplasty was performed in 7 cases (group 1), staged sphincter placement followed by augmentation cystoplasty with a segment of ileum or stomach was done in 8 (group 2) and 12 did not require bladder augmentation (group 3). Urethral device erosion requiring explantation was the most common complication, occurring in 3 patients in group 1 and 2 in group 3 (p = 0.101). Mean time to erosion was 22.1 months (range 2 to 46.4). Previous surgery (bladder neck or hernia repair) was a common factor in each group with complications. Urine cultures and culture of the explanted device were positive in 2 patients in group 1.

CONCLUSIONS

Simultaneous placement of artificial urinary sphincter at the time of gastrocystoplasty can be performed in carefully selected patients, although those undergoing staged procedures did well without complications. Prior bladder neck surgery seems to be a significant risk for infection. A staged approach to lower urinary tract reconstruction would be more advantageous due to the absence of infection and erosion in those undergoing staged sphincter placement and augmentation cystoplasty.

Placement of artificial urinary sphincter in children and simultaneous gastrocystoplasty

PURPOSE

Previous studies have described placement of an artificial urinary sphincter and simultaneous augmentation cystoplasty with a segment of bowel. Conclusions from these studies indicated that infection rates were higher and a staged approach should be undertaken. Others have suggested that concurrent urinary reconstruction with stomach and sphincter placement can be performed safely. Results comparing infection rates of simultaneous sphincter placement and gastrocystoplasty versus staged sphincter placement and augmentation cystoplasty using a segment of ileum or stomach versus sphincter placement alone in a pediatric population have not been previously described to our knowledge. We reviewed these various groups of patients to determine if the difference in infectious complications were clinically and statistically significant.

MATERIALS AND METHODS

A retrospective review of medical records from 1986 to 1999 identified 28 pediatric patients (age 18 years or less) who had undergone placement of an AS800dagger artificial urinary sphincter. Data points were collected focusing on etiology of the neurogenic bladder, age at time of surgery, types of surgery performed, length of followup and complication rates.

RESULTS

Complete data were available for 27 of the 28 patients. Neurogenic bladder was secondary to myelomeningocele in 25 cases, transverse myelitis in 1 and spinal cord injury in 2. Mean patient age at surgery was 12.7 years (range 6.1 to 18.2) and mean followup was 4.3 years (range 1 month to 13 years). Simultaneous gastrocystoplasty was performed in 7 cases (group 1), staged sphincter placement followed by augmentation cystoplasty with a segment of ileum or stomach was done in 8 (group 2) and 12 did not require bladder augmentation (group 3). Urethral device erosion requiring explantation was the most common complication, occurring in 3 patients in group 1 and 2 in group 3 (p = 0.101). Mean time to erosion was 22.1 months (range 2 to 46.4). Previous surgery (bladder neck or hernia repair) was a common factor in each group with complications. Urine cultures and culture of the explanted device were positive in 2 patients in group 1.

CONCLUSIONS

Simultaneous placement of artificial urinary sphincter at the time of gastrocystoplasty can be performed in carefully selected patients, although those undergoing staged procedures did well without complications. Prior bladder neck surgery seems to be a significant risk for infection. A staged approach to lower urinary tract reconstruction would be more advantageous due to the absence of infection and erosion in those undergoing staged sphincter placement and augmentation cystoplasty.

Effect of chronic bladder outlet obstruction on blood flow of the rabbit bladder

PURPOSE

Previous studies have shown that the initial reaction of the rabbit bladder to partial bladder outlet obstruction is increased blood flow at day 1 and a return to baseline blood flow at 1 week. Mucosal and muscle blood flow followed this pattern but mucosal blood flow was always 4 to 5-fold greater. In this study we examined the effect of 4 weeks of outlet obstruction on bladder blood flow and correlated it with the severity of bladder contractile dysfunction.

MATERIALS AND METHODS

A total of 14 male New Zealand White rabbits underwent partial outlet obstruction creation by standard methods. After 4 weeks the rabbits were anesthetized, and blood flow to the muscle and mucosa was determined by standard fluorescent microsphere technique. A section of each detrusor was used for in vitro contractility studies. Contractile responses to field stimulation, carbachol and potassium chloride were determined. A section of each detrusor tissue was fixed in formalin and used to determine the smooth muscle volume fraction.

RESULTS

Four weeks of partial bladder outlet obstruction caused a significant and variable increase in bladder weight and a decrease in blood flow to bladder muscle without changes in the blood flow to mucosa. There was a clear correlation between the severity of contractile dysfunction, bladder weight and the magnitude of the decrease in blood flow in muscle. The smooth muscle volume fraction remained stable at approximately 40%.

CONCLUSIONS

Bladder decompensation was associated with decreased blood flow to bladder smooth muscle. Because compensated obstructed bladders with relatively normal contractile function are also hypertrophied but have normal blood flow, decreased blood flow in decompensated bladders is not simply a response to bladder hypertrophy. From this study we hypothesize that decreased blood flow to bladder smooth muscle is an etiological factor in bladder contractile dysfunction (bladder decompensation) secondary to partial outlet obstruction.

Absorption of oxybutynin from vaginal inserts: drug blood levels and the response of the rabbit bladder

OBJECTIVES

Oxybutynin has been used for treatment of urge urinary incontinence for more than 20 years. However, one of the major problems with its use is uncomfortable anticholinergic side effects that can lead to discontinuation of treatment. Alternative forms of drug administration may reduce side effects and thus improve patient compliance.

METHODS

A cylinder-shaped, curved silicone elastomer insert containing oxybutynin was anchored in the vagina of female rabbits. The inserts were designed to release oxybutynin at rates of 0.5, 1.0, and 5.0 mg/day, respectively. Blood drug and metabolite levels were monitored for 1 to 7 days and cystometry was carried out after 7 days of treatment.

RESULTS

There was a consistent dose-dependent absorption of the oxybutynin resulting in stable plasma concentrations by 3 days. Levels of N-desethyloxybutynin, the active metabolite that is thought to be responsible for side effects, were less than 1.0 ng/mL in all groups. The cystometrograms showed a decrease in the detrusor pressures for the higher oxybutynin groups and a dose-dependent decrease in micturition pressure. The vaginal wall in contact with the insert showed no irritation.

CONCLUSIONS

The inserts produced stable blood levels and released sufficient amounts of oxybutynin to have measurable effects on the bladder. There was no irritating effect of the insert on the vaginal wall after a 1-week treatment. Vaginal inserts containing oxybutynin may be an interesting alternative method for the chronic delivery of oxybutynin.

Intraoperative pharmacological erection as an aid to pediatric hypospadias repair

PURPOSE

The intraoperative evaluation of erection is a major advance in hypospadias surgery. We determined the advantages of erections induced pharmacologically over those induced by intracorporeal saline injection for evaluating chordee during hypospadias surgery.

MATERIALS AND METHODS

During the repair of hypospadias or chordee without hypospadias 56 boys 6 months to 13 years old underwent pharmacological erection induced by 14 microg. alprostadil administered intracavernously. Phenylephrine (40 microg. ) was given for detumescence. We monitored the adequacy of erection and detumescence, changes in blood pressure and pulse, and in 3 cases intracorporeal pressure. Intraoperative artificial erection was also induced in 30 patients.

RESULTS

Erection occurred within 1 minute of injection. It was judged to be excellent in 47 cases and adequate in 6, while it failed in 3 probably due to injection outside of the corpora. Erection involved the whole penis, in contrast to artificial erection when tourniquet placement altered the erection and left the penile base flaccid. The degree of chordee remained stable during evaluation compared to artificial erection when curvature varied with the force of the saline injection. Erection persisted during chordee repair as long as the corpora were not opened. Detumescence occurred within seconds in all cases in which phenylephrine was given. There were no cases of priapism, and systemic blood pressure and pulse did not change. Intracorporeal pressure during pharmacological erection was 47 to 70 mm. Hg, whereas during artificial erection pressure was 50 to 250 mm. Hg depending on how much saline was injected and how rapidly fluid drained through the tourniquet. Chordee was induced by over injection.

CONCLUSIONS

Pharmacological erection in hypospadias repair is effective and reliable with no significant complications. It is especially valuable in severe hypospadias and in patients with a large suprapubic fat pad. Artificial erection with saline injection should be performed with only moderate force since over filling is unphysiological and may falsely induce chordee.

High urinary flow accelerates renal injury in young rats with partial unilateral ureteral obstruction

PURPOSE

We studied the effect of dietary manipulation and high urine flow on neonatal partial ureteral obstruction in a weanling rat preparation.

MATERIALS AND METHODS

A total of 40, 3-week old Sprague-Dawley rats underwent unilateral ureteral obstruction by burial of the right ureter in the psoas muscle and 13 underwent sham operation. Low, high and normal salt, and high sucrose diets were administered for 2 months. The glomerular filtration rate of each kidney was measured by iothalamate clearance. Intrapelvic pressure and renal blood flow were measured before and after acute volume loading.

RESULTS

Fluid intake and urine output were 8 to 10-fold greater in animals on high salt and high sucrose diets compared to those in rats on normal and low salt diets. Hydronephrosis was observed only in rats with partial obstruction and high urine flow. No difference in renal weight was noted. Relative glomerular filtration rate of the partially obstructed kidney was maintained when urine flow was normal but decreased significantly with high urine flow. Total glomerular filtration rate also decreased with high urine flow. Intrapelvic pressure was elevated significantly at baseline in partially obstructed kidneys with high urine flow. All kidneys with partial obstruction had significantly increased intrapelvic pressure with volume loading. Renal blood flow was not significantly decreased in rats with high urine flow.

CONCLUSIONS

Chronic high urine flow causes loss of renal function in partially obstructed weanling rat kidneys. Research should be done to determine whether human infants with hydronephrosis and partial ureteral obstruction would benefit from the prevention of increased fluid and salt intake.

Expression of the Wnt gene family during late nephrogenesis and complete ureteral obstruction

Because the Wnt-4, -7b, and -11 genes are expressed in metanephric kidneys and code for secreted glycoproteins that may serve as mediators of the transformation of renal mesenchyme to epithelium, we investigated the pattern of Wnt gene expression in late metanephrogenesis and after ureteral obstruction. Newborn and 10-, 20-, and 60-day-old rats underwent complete unilateral ureteral ligation or sham operation. The kidneys were collected bilaterally 1, 5, 10, 20, or 30 days later. RNase protection assays were used to quantify the amounts of mRNA encoding Wnt-4, -7b, and -11, E-cadherin, and cytokeratin-19. Renal development was assessed by histologic characterization of vimentin, cytokeratin, E-cadherin, and beta-catenin distribution. During normal development, the amounts of mRNA encoding Wnt-4 and Wnt-11 increased during gestation and then abruptly decreased after the completion of metanephrogenesis, 15 days after birth. In contrast, the amounts of mRNA encoding Wnt-7b, E-cadherin, and cytokeratin-19 increased during development and into adulthood. In neonatally obstructed kidneys, the expression of Wnt-4 was abnormally maintained when obstruction was induced before the completion of renal development and was reactivated when obstruction was induced after the completion of metanephrogenesis. Wnt-7b expression was minimally affected and Wnt-11 expression was only transiently affected by obstruction. In neonatally obstructed kidneys, the differentiation of mesenchyme to epithelium failed to proceed normally, with the majority of cells maintaining vimentin expression and some differentiated epithelial cells reverting to vimentin expression. In addition, the expression of E-cadherin and cytokeratin was increased in epithelial cells. Changes in the expression of Wnt genes were correlated with histologic changes. This study suggests that Wnt-4 and -11 are likely to be important mediators of the transformation of mesenchyme to epithelium in the kidney. Obstruction induced during metanephrogenesis disrupts the normal pattern of Wnt-4, -7b, and -11 expression and interferes with the normal transformation process in developing kidneys, by maintaining the mesenchymal component and inducing the transformation of epithelium to mesenchyme.

Upper ureteral reconstructive surgery

Upper ureteral reconstructive surgery encompasses a wide variety of procedures directed at the correction of abnormal processes and structural defects in the proximal ureter. Although some of these techniques have strict indications for specific causes, technical innovations have led to development of numerous alternatives in upper ureteral reconstructive surgery. These innovations provide the practicing urologist with various options from which to choose for the management of upper ureteral disease.

Growth factor expression in the obstructed developing and mature rat kidney

The purpose of this study is to evaluate the role of keratinocyte growth factor (KGF), transforming growth factor-alpha (TGF-alpha), and their receptors in altered renal growth caused by complete ureteral obstruction in the developing kidney. Neonatal and adult rats underwent complete unilateral ureteral ligation or sham operation. The kidneys were harvested at 1, 5, 10, 20, and 30 days after obstruction. Renal growth and development was assessed by histology and immunohistocytochemical localization of vimentin, cytokeratin and smooth muscle-alpha actin. Cellular proliferation was measured by [3H]thymidine labeling index of all cells. RNase protection assays were used to quantify mRNA encoding for KGF, KGF receptor, TGF-alpha, and epidermal growth factor (EGF) receptor. Ureteral obstruction in the developing kidneys resulted in decreased DNA synthesis, rapid parenchymal loss, myofibroblast proliferation in the interstitium, decreased tubular epithelial cells formation, and development of cystic dysplasia. In comparison, obstruction in the mature kidneys resulted in transient growth in the medullary ductal cells, parenchymal loss, and myofibroblast proliferation at a later time, lymphocytic infiltration in the interstitium but not cystic dysplasia. KGF and KGF receptor mRNA levels were increased in obstructed neonatal kidneys. Similarly, TGF-alpha and EGF receptor mRNA levels were increased. Delayed and more moderate increases in KGF, KGF receptor, and TGF-alpha expression were also seen in the obstructed mature kidneys. Of importance, the amount of EGF receptor mRNA was not increased in the obstructed compared with the contralateral or sham-operated adult kidneys. This study suggests that obstruction alters the normal expression pattern of KGF, TGF-alpha, and their receptors in renal development. These changes may be responsible for the impaired renal growth and altered development seen in ureteral obstruction of the kidneys. Although some changes are similar to those seen in the adult kidney, the increased expression of TGF-alpha and cystic dysplasia are unique to neonatal obstruction.

Neuroanatomical changes in the rat bladder after bladder outlet obstruction

OBJECTIVE

To investigate the histological changes in bladder innervation in response to partial bladder outlet obstruction in a rat model.

MATERIALS AND METHODS

Forty-eight adult female rats had their bladder outlet partially obstructed by ligating the proximal urethra over a 20 G angiocatheter; 18 shamoperated rats served as controls. Animals were killed after 1, 2 and 4 weeks, and their bladders evaluated using computerized morphometry. Immunohistochemical staining for neuronal protein gene-product 9.5 (PGP, a general neuronal marker) and enzyme histochemical staining of acetylcholinesterase, adrenergic fibres and nitric oxide synthase were performed.

RESULTS

Bladder wall changes after obstruction consisted of a six- to sevenfold increase in bladder volume and weight. Smooth muscle hypertrophy was evident equally at all sample times. Cystometry showed functional alterations in bladder capacity and voided pressures; obstructed animals had markedly increased bladder capacities and higher voiding pressures (obstructed, 80-100 cmH2O; normal, 30-40 cmH2O). Neuronal changes in the obstructed bladder were most dramatic within the cholinergic and adrenergic neurotransmitter systems within and surrounding the smooth muscle bundles, where there was less staining than in control animals. PGP immunoreactivity increased slightly. The L-arginine-nitric oxide pathway appeared unperturbed after obstruction.

CONCLUSIONS

These histological findings suggest that neuropathic changes in the bladder after outlet obstruction, including detrusor instability, are mainly the result of anatomical perturbations in the cholinergic and adrenergic pathways.

Gastrocystoplasty: long-term followup

PURPOSE

Gastrocystoplasty is no longer favored at many institutions due to complications, including the hematuria-dysuria syndrome and metabolic alkalosis. We reviewed our experience to determine the advantages and disadvantages of bladder augmentation using stomach body wall.

MATERIALS AND METHODS

We retrospectively reviewed the medical records, urodynamic studies, x-rays and laboratory evaluations of 47 children who underwent gastrocystoplasty at our institution between 1986 and June 1997. Parents and patients were contacted by telephone for detailed interviews to validate the medical record and determine whether there had been any changes since the last visit. Followup ranged from 9 months to 11 years (mean 4.4 years). Bladder dysfunction was secondary to spinal dysraphism in 38 children. Other diagnoses included cloacal and bladder exstrophy, posterior urethral valves, a persistent urogenital sinus and bilateral ectopic ureters.

RESULTS

Preoperative and postoperative ultrasound studies available for 79 renal units demonstrated a stable or improved upper tract in 75 (95%). Preoperative and postoperative serum sodium, potassium and creatinine levels showed no significant changes. Mean serum chloride decreased 2.7 mEq./l. and bicarbonate increased 3.3 mEq./l. In the 3 patients with renal insufficiency serum bicarbonate increased 8 mEq./l. Mean pressure specific bladder volume at less than 20 cm. water increased 177 cc and mean maximum bladder pressure decreased from 35 to 13 cm. water. Two-thirds of the patients had bacilluria and a fourth reported a symptomatic bladder infection. No patients had bothersome mucus or required routine bladder irrigation. Symptoms consistent with the hematuria-dysuria syndrome were present in 27% of the patients. No patients had symptoms more than once weekly. Symptoms occurred in 75% of the patients without a neurogenic bladder, such as exstrophy or posterior urethral valves, and in 14% of those with neurogenic bladder dysfunction. In 1 case a bladder stone developed 8 years after surgery. Five patients required reoperation for complications related to gastrocystoplasty. No patient had perforation.

CONCLUSIONS

Our data show that even after a mean of 4.4 years gastrocystoplasty has significant advantages over intestinal augmentation, including decreased chloride reabsorption, mucous production and urinary infection, and an extremely low incidence of stones and perforation. The gastric patch is associated with metabolic alkalosis and the hematuria-dysuria syndrome, which may be avoided and medically treated with proper patient selection and close followup. The procedure should be avoided in sensate patients with sufficient bowel.

Neonatal hydronephrosis

With fetal abnormalities diagnosed during maternal ultrasound becoming more commonplace, the management of neonatal hydronephrosis has become one of the most interesting and controversial subjects in pediatric urology. Although it is recognized that obstruction must be treated, it is also clear that hydronephrosis may well exist without significant obstruction. Numerous experimental and clinical studies of the urinary tract have failed to lead to a clear consensus. Our approach consists of careful observation of patients with moderate hydronephrosis in well functioning kidneys. In patients with reduced function or a renal pelvic diameter of greater than 3 cm and dilated calyces, we lean more towards surgical intervention. Overall, an individualized approach is necessary.

Length of stay for specialized pediatric urologic care

BACKGROUND

Pediatric urologic specialists have been excluded from many recent managed care contracts because they are believed to be more expensive and of no better quality than general urologists in managing common urologic problems in children. We believed this to be inaccurate.

OBJECTIVES

To compare the length of stay at the University of California, San Francisco Medical Center for 2 common pediatric urologic operative procedures with data from other northern California hospitals and to document our results and patient satisfaction.

DESIGN

Retrospective analysis of HCIA statewide database (HCIA Inc, Orange, Conn).

SETTING

Northern California, 1995.

SUBJECTS

Children younger than 12 years undergoing surgery for repair of an obstruction of the ureteropelvic junction or vesicoureteral reflux.

MAIN OUTCOME MEASURE

Length of stay.

RESULTS

The length of stay in our hospital was similar to that observed in other hospitals in which other full-time pediatric urologic specialists practiced and was significantly less than that observed in other northern California hospitals, even when adjusted for risk. In fact, a savings of 279 hospital days would have been realized if all patients had the same length of stay as that achieved at University of California, San Francisco Medical Center. In the 38 patients operated on at our center, there was uniform surgical success. Of the parents, 92% (11/ 12) were satisfied with their child's care and 92% (11/ 12) believed they received enough information to know what to expect and how to care for their child at home. There were no data available evaluating quality from other northern California hospitals for comparison.

CONCLUSIONS

Our finding that actual and risk-adjusted length of stay were shorter when patients were treated by full-time pediatric urologists, while excellent quality was maintained, suggests that these specialists achieve their results with more efficiency and lower resource utilization than do general urologists. The implication of these results is that exclusive contracting that prevents patients from receiving care from full-time specialists results in overuse of valuable resources and possibly reduced quality. If our results are generalizable, they have important implications for health care reform in the United States.

Gastrocystoplasty: is there a consensus?

The problems encountered with ileal and colocystoplasty have led to the use of the stomach for bladder augmentation, termed gastrocystoplasty. The advantages of gastrocystoplasty over intestinal segment augmentation include reduced chloride reabsorption, decreased mucus production, decreased urinary infection in the presence of acid urine, extremely low incidence of stones, and avoidance of complications from short bowel syndrome. The gastric patch provides comparable improvements in bladder volume, pressure, and continence. The thick muscular wall of the stomach facilitates ureteric reimplantation as compared with the small intestine, but the rate of stenosis and reflux may not be superior. The disadvantages of the gastric patch include complications of severe systemic alkalosis, which is usually manifest in dehydrated, renal compromised patients, and the hematuria-dysuria syndrome (HDS), which is more prevalent in patients with renal insufficiency, normal pelvic sensation, and urinary incontinence. The postoperative complication rate of gastrocystoplasty is comparable with that of other augmentation procedures and similarly warrants proper selection and close follow-up of patients. In this report we review the literature and present the results, including a discussion of the technique and the pathophysiology of its complications.

Renal hemodynamic changes after complete and partial unilateral ureteral obstruction in the fetal lamb

PURPOSE

Complete and partial ureteral obstruction decreases ipsilateral renal blood flow in neonatal and adult animals. However, the effects of obstruction that develops during gestation may be different from those in neonatal or adult animals. We determine whether complete or partial ureteral obstruction decreases ipsilateral renal blood flow in fetal sheep.

MATERIALS AND METHODS

We positioned an ultrasonic flow transducer around both renal arteries in 21 fetal sheep at 123 to 125 days of gestation. Unilateral ureteral obstruction was created in 16 fetuses, including complete and partial obstruction in 7 and 9, respectively. There were 5 controls. Renal blood flow and arterial blood pressure were measured daily for a minimum of 7 days.

RESULTS

All obstructed kidneys had hydronephrosis, partially obstructed kidneys had less obstruction and contralateral kidneys had none. Renal weight was similar in obstructed and contralateral kidneys in the sham operated, partial and complete obstruction groups. After partial ureteral obstruction renal blood flow in obstructed and contralateral kidneys was increased compared to that in sham operated kidneys up to 11 days after obstruction was created. After complete ureteral obstruction the blood flow in obstructed kidneys was significantly lower than in the unobstructed counterparts but it remained 124% of initial renal blood flow at 10 days. Elevated ureteral pressure was maintained in obstructed kidneys throughout the study period.

CONCLUSIONS

In our experiment partial ureteral obstruction in the fetus did not decrease renal blood flow to the ipsilateral kidney even after 7 days. Complete obstruction decreased blood flow in the affected kidney but not to same magnitude as that in previous adult animal studies. Our findings suggest that during gestation renal blood flow is maintained in the presence of obstruction.

Long-term benefits of early neurosurgery for lipomyelomeningocele

PURPOSE

Our previous experience with early neurosurgery for lipomyelomeningocele revealed that patients undergoing repair before age 1.5 years were more likely to have normal bladder function. We evaluate the durability of the urological benefits in patients with lipomyelomeningocele with longer followup.

MATERIALS AND METHODS

A retrospective chart review was performed on all patients who underwent urodynamic testing before and after primary neurosurgical repair of lipomyelomeningocele. A total of 43 patients presented between 1983 and 1995 with at least 12 months of followup (median 68, range 15 to 167).

RESULTS

Of the 43 patients 36 (84%) maintained stable clinical and urodynamic function, and 7 (16%) had late deterioration, which occurred between 9 months and 8 years postoperatively. Of 19 patients with normal urodynamic studies preoperatively 14 (74%) maintained normal function. Overall, 14 of 43 patients (33%) with lipomyelomeningocele had normal bladder and sphincter function during followup. The principal predictor of long-term normal bladder function was preoperative urodynamic status, since urodynamic studies were preoperatively normal in 13 of 14 patients (93%) who maintained normal bladder and sphincter function. Late neurosurgery was equally efficacious if urodynamic studies were normal.

CONCLUSIONS

Our data continue to support early diagnosis and neurosurgical intervention in patients with lipomyelomeningocele, since there is a higher likelihood of normal preoperative function that can be preserved. Furthermore, the results are durable in 84% of cases. However, close followup is necessary, since deterioration can occur up to 8 years postoperatively.

Multicenter experience with the Mitchell technique for epispadias repair

PURPOSE

We present a multicenter experience using the Mitchell epispadias technique to determine if satisfactory results could be obtained by various pediatric urologists at multiple centers using the same technique to repair epispadias. This particular technique involves complete disassembly of the penis into 2 separate hemicorporeal glandular bodies and a separate urethral plate, and relies on the unique blood supply to the epispadiac phallus.

MATERIALS AND METHODS

A total of 17 boys 11 months to 21 years old underwent the Mitchell procedure for epispadias at 4 institutions by 6 different surgeons between 1994 and 1996. One patient in this group had undergone prior epispadias repair, which had failed.

RESULTS

At followup (mean 13.5 months) 3 boys had pinpoint penopubic fistulas, which resolved spontaneously in 2. The 21-year-old patient had a complete wound dehiscence. All boys with intact repairs have straight erections, orthotopic meatus and satisfactory appearances. There were 15 boys with a conical glans appearance and 1 exhibiting glandular disproportion. There was 1 episode of postoperative pyelonephritis.

CONCLUSIONS

The Mitchell technique for repair of epispadias is reproducible and successful in the hands of pediatric urologists from different centers. Chordee is reliably corrected, erectile function preserved, the urethra ventrally situated in an anatomically precise fashion and satisfactory cosmesis achieved.

Neonatal management. Role for early intervention

Although performing pyeloplasty on an infant with a relatively healthy kidney prior to the onset of renal damage is not as well-accepted as "aggressive observation," the authors argue that early intervention is the more "conservative" or safe method of treatment for infants with ureteropelvic junction (UPJ) obstruction. Using experimental and clinical data, the authors demonstrate that prolonged partial UPJ obstruction in the developing kidney causes significant renal morbidity with time.

Changing the technique of background subtraction alters calculated renal function on pediatric mercaptoacetyltriglycine renography

PURPOSE

Although many operative decisions are based on apparent changes in function detected by serial diuretic renography, the reliability of relative renal function data has been questioned. We investigated the effect of background subtraction on calculated renal function.

MATERIALS AND METHODS

We reviewed 23 pediatric mercaptoacetyltriglycine renograms. Regions of interest for background subtraction were redrawn and relative renal function values were recalculated.

RESULTS

In patients with left hydronephrosis left differential renal function was consistently underestimated by 7.3% compared to the superior and 4.7% compared to the average background subtraction technique. In patients with right hydronephrosis, when considering lower pole background activity only, right differential renal function was consistently overestimated by 15.8% compared to the superior and 2.4% compared to the average background subtraction technique. In patients younger than 1 year at the time of study these differences were exaggerated.

CONCLUSIONS

Because of overlapping hepatic background activity, the position of regions of interest for background subtraction may greatly influence calculated renal function. We recommend that the preferred method of calculating background subtraction to minimize error be based on a region of interest surrounding the whole kidney. This method is especially pertinent in patients with right hydronephrosis and in those younger than 1 year. Reported relative renal function data should be interpreted with caution.

Hemodynamic changes after complete unilateral ureteral obstruction in the young lamb

PURPOSE

We studied renal hemodynamic changes after complete acute unilateral ureteral obstruction in the young lamb.

MATERIALS AND METHODS

Seven 4-week-old lambs underwent unilateral complete ureteral obstruction and renal blood flow was monitored in both kidneys with ultrasonic flow transducers. Ureteral and arterial blood pressure was measured.

RESULTS

In the obstructed kidney renal blood flow was stable for 5 hours and then decreased thereafter to 71% of baseline at 5 days (p < 0.05). In the contralateral kidney the pattern of renal blood flow constituted a mirror image, although the magnitude of the increase was decreased (122% of baseline at 5 days, not statistically significant). Mean arterial blood pressure did not change in 5 days. Mean ureteral pressure increased from a baseline of 9 to 37 mm. Hg (p < 0.001) 2 hours after obstruction but gradually decreased to 24 mm. Hg after 24 hours and remained elevated for 5 days (p < 0.001).

CONCLUSIONS

The pattern of renal blood flow and ureteral pressure response to obstruction in the young lamb is different from that previously reported. Renal blood flow does not increase after obstruction and it is relatively preserved at 5 days. This unexpected response may be a result of the compound caliceal sheep kidney, immaturity of the young vascular system or development differences in the mechanism of spontaneous decompression of the collecting system.

Smooth and striated muscle development in the intrinsic urethral sphincter

PURPOSE

The intrinsic urethral sphincter is composed of adjacent striated and smooth muscle. We studied the sequential expression of smooth and striated muscle proteins to gain insight into the ontogeny of intrinsic sphincter development.

MATERIALS AND METHODS

The intrinsic urethral sphincters of timed Fischer 344 rat embryos at 14, 16 and 18 days of gestation, neonates on postnatal day 1 and adult animals were examined. Serial sections of the urethra and adjacent levator ani muscles were studied histologically with hematoxylin and eosin, anti-alpha-smooth muscle actin, anti-alpha-sarcomeric actin and antistriated muscle myosin heavy chain antibodies.

RESULTS

The intrinsic urethral sphincter was identified within the periurethral mesenchyma as early as day 14 of gestation. Although striated myotubules were identified within the urethra by hematoxylin and eosin staining starting on postnatal day 1, striated muscle myosin heavy chain protein was absent in the embryonic and neonatal development of the sphincter, and it was expressed only in the mature myotubule of adults. alpha-Smooth muscle actin was expressed throughout the urethral sphincter of embryonic and neonatal animals. In adults alpha-smooth muscle actin was confined to the smooth muscle component of the urethra. Co-expression of alpha-smooth and alpha-sarcomeric muscle actin by the striated sphincter myotubule was noted only in neonates.

CONCLUSIONS

Development of the intrinsic urethral sphincter is characterized by sequential expression of well characterized muscle marker proteins. The co-expression of smooth and striated muscle markers by developing sphincter myotubule suggests the possibility that trans-differentiation of smooth to striated muscle occurs in the developing genitourinary tract.

Neurogenic bladder dysfunction due to myelomeningocele: neonatal versus childhood treatment

PURPOSE

We sought to determine whether the neonatal institution of treatment of neurogenic bladder dysfunction in myelomeningocele patients at high risk for urinary tract deterioration improves renal and bladder outcome.

MATERIALS AND METHODS

We reviewed the records of patients with bladder dysfunction believed to be at high risk for renal deterioration based on urodynamic studies. All patients were treated with clean intermittent catheterization. We compared rates of urinary infection, hydronephrosis, reflux, continence and surgical intervention in 46 patients in whom treatment was started in year 1 of life and 52 treated after age 4 years.

RESULTS

Renal outcome was similar in both groups with persistent hydronephrosis in 6 of 46 patients (13%) and 7 of 52 (14%), respectively. However, significantly fewer bladder augmentation procedures were required in patients started on treatment during year 1 of life (5 of 46, 11% versus 14 of 52, 27%, p < 0.05).

CONCLUSIONS

In addition to any psychological benefit, early intervention with clean intermittent catheterization in children with neurogenic bladder dysfunction may help to prevent irreversible bladder dysfunction and limit the need for bladder augmentation.

Vesicourethral function in mice with genetic disruption of neuronal nitric oxide synthase

PURPOSE

Nitric oxide is thought to play an important role in neuromodulation of the lower urinary tract. We therefore studied the lower urinary tract function of mice in whom the gene encoding for neuronal nitric oxide synthase had been disrupted (nNOS knockout).

METHODS

Female mice, both control and nNOS knockout, underwent voiding, urodynamic and muscle strip testing as well as histologic studies. Neuronal mechanisms assessed histologically included nitric oxide, cholinergic, adrenergic, vasoactive intestinal polypeptide (VIP), and nonspecific neuronal protein (protein gene product 9.5 [PGP 9.5]).

RESULTS

No differences in voiding were observed between normals and nNOS knockout mice. On urodynamic studies, bladder capacity was higher in the experimental than in the normal animals (25.3 +/- 11.8 vs. 17.4 +/- 5.6 ml./gm. x 1000, p < 0.05) as was the maximal bladder pressure at leakage (70.1 +/- 15.9 vs. 59.5 +/- 12.8 cm. H20, p < 0.05). After treatment with L-NAME or L-Arginine, there was no significant difference between the groups. Muscle bath studies showed no differences in bladder contractility or relaxation after chemical and electrical stimulation. Histologic studies confirmed virtually no nNOS or nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase in the nNOS knockout mice, but no difference in the total number of nerves (PGP 9.5) and of cholinergic, adrenergic or VIP-staining nerves was detected between groups.

CONCLUSIONS

Despite disruption of the main pathway for synthesis of neuronal nitric oxide, nNOS knockout mice voided normally, demonstrate normal muscle bath responses, and have normal numbers of all nerves studied (except those staining for NO). Further studies are underway to elucidate the compensatory mechanisms in these animals.

Plexiform neurofibroma involving the genitourinary tract in children: case reports and review of the literature

We report extensive genitourinary neurofibroma in two children who presented with massive bilateral hydroureteronephrosis and a thick-walled bladder. The best radiologic technique to stage the disease and determine treatment is magnetic resonance imaging. Management of extensive genitourinary neurofibroma is controversial. Based upon our experience and a review of the literature, aggressive surgery should be approached cautiously.

Clean intermittent catheterization in boys using the LoFric catheter

PURPOSE

We compared a recently developed hydrophilic catheter to the standard polyethylene catheter in regard to hematuria, infection and patient satisfaction.

MATERIALS AND METHODS

A hydrophilic LoFric or standard Mentor catheter was assigned at random to 17 and 16 boys, respectively, who were skilled in intermittent self-catheterization. They were evaluated by weekly urinalysis and a questionnaire.

RESULTS

Significantly fewer episodes of microscopic hematuria occurred in the LoFric than Mentor catheter group (9 episodes in 6 subjects versus 19 episodes in 11, p < 0.05). There were also fewer episodes of bacteriuria in the LoFric group but the difference was not statistically significant. Mean scores plus or minus standard deviation on a visual analogue scale with 0 equal to most and 10 equal to least favorable were LoFric 3.3 +/- 2.8 versus Mentor 4.9 +/- 2.7 for catheter convenience and 2.7 +/- 2.4 versus 4.2 +/- 2.6 for insertion comfort, significantly favoring the LoFric group (p < 0.05 for both). Of the 16 LoFric subjects 13 preferred to continue its use, particularly those with a history of urethral trauma or sphincteric spasm.

CONCLUSIONS

In boys the LoFric catheter appears to cause less trauma. Although it is not reusable and is more expensive than the standard catheter, satisfaction is higher with the LoFric device and for select patients it has significant advantages.

Therapeutic laparoscopy for the nonpalpable testicle

Laparoscopy is playing an increasingly important role in the management of boys with nonpalpable testes. We describe our technique of laparoscopy and laparoscopically assisted orchidopexy. Our early results in 24 patients with nonpalpable intraabdominal testes have encouraged us to recommend this option as the procedure of choice.

The effect of prepubertal androgen exposure on adult penile length

PURPOSE

Recent studies in the rat suggest that early exposure to exogenous testosterone accelerates the loss of androgen receptors and compromises eventual penile length. To determine whether this is true in men we measured adult penile length of patients treated in childhood for sexual precocity.

MATERIALS AND METHODS

We examined 21 men with sexual precocity due to true precocious puberty (12) or congenital adrenal hyperplasia (9) who had been followed at our institution since childhood. Penile lengths were compared with data from normal men.

RESULTS

Mean stretched penile length plus or minus standard deviation was 12.7 +/- 2.6 cm. in all patients, 12.1 +/- 2.6 cm. in those with true precocious puberty and 13.6 +/- 1.6 cm. in those with congenital adrenal hyperplasia. These lengths were not significantly different from those of normal men (12.4 +/- 2.7 cm.).

CONCLUSIONS

In contrast to findings in rats, exposure to endogenous testosterone during gestation and/or childhood does not reduce adult penile length in men. Thus, the use of testosterone to treat childhood genitourinary anomalies would likely not compromise mature penile size.

Efficacy of retrograde endopyelotomy in children

PURPOSE

Endopyelotomy has been performed extensively in adults for the treatment of ureteropelvic junction obstruction. To determine its applicability to the pediatric population we reviewed our experience with retrograde endopyelotomy in children.

MATERIALS AND METHODS

Eight children 4 to 15 years old were treated with retrograde endopyelotomy and results were compared to those of a concurrent group of 8 treated with open pyeloureteroplasty.

RESULTS

Retrograde endopyelotomy was done in all of our patients with lower ureteral dilatation (as an adjunct measure in 5). Seven patients had symptomatic and radiographic improvement. The patient in whom the procedure failed had a crossing lower pole vessel. Postoperative analgesia, length of hospitalization and cost were lower in the endopyelotomy group.

CONCLUSIONS

Retrograde endopyelotomy is feasible in children older than age 4 years and it results in reduced morbidity. The success rate is high but open surgery remains the standard, particularly when a crossing lower pole vessel is identified preoperatively.

Exogenous endothelin-1 causes renal vasodilation in the fetal lamb

PURPOSE

Endothelin-1 is known to be a potent vasoconstrictor. We investigated the effects and mechanisms of action of endothelin-1 and its receptors in regulating renal vascular tone in the fetal lamb.

MATERIALS AND METHODS

We observed the in vivo effects of endothelin-1, an endothelin-b receptor agonist (4-alanine-endothelin-1), endothelin-a receptor antagonists (BQ-610 and BQ-123), and the inhibition of prostaglandin and nitric oxide synthesis on the response of the renal circulation to endothelin-1 in a chronic preparation in third trimester fetal lambs.

RESULTS

After injection of 250 ng./kg. endothelin-1 into the descending aorta proximal to the renal arteries in 8 fetal animals, renal blood flow increased (4.4 +/- 0.7 ml. per minute per kg., p < 0.001 versus vehicle), as did mean arterial blood pressure (3.0 +/- 0.3 mm. Hg,p < 0.001 versus vehicle). Calculated renal vascular resistance decreased (-1.1 +/- 0.2 mm. Hg per minute per kg./ml., p < 0.001 versus vehicle). After injection of 1,725 ng./kg. 4-alanine-endothelin-1 in 5 animals renal blood flow increased (3.8 +/- 0.4 ml. per minute per kg., p < 0.05 versus vehicle) and mean arterial blood pressure was unchanged (1.6 +/- 1.7 mm. Hg). Calculated renal vascular resistance decreased (-0.8 +/- 0.2 mm. Hg per minute per kg./ml., p < 0.05 versus vehicle). After injection of 0.5 mg./kg. BQ-610 in 6 animals renal blood flow increased (2.3 +/- 0.7 ml. per minute per kg., p < 0.05) and mean arterial blood pressure decreased (-2.7 +/- 0.3 mm. Hg, p < 0.05 versus vehicle). Calculated renal vascular resistance decreased but this difference was not statistically significant (-0.7 +/- 0.3 mm. Hg per minute per kg./ml., p < 0.07). A dose of 1 mg./kg. BQ-123 in 2 animals decreased renal vascular resistance markedly. Infusion of a prostaglandin synthesis inhibitor (1 mg./kg. per minute meclofenamic acid) did not alter the decrease in renal vascular resistance after endothelin-1 (-0.7 +/- 0.4 mm. Hg per minute per kg./ml). In contrast, during infusion of a nitric oxide synthesis inhibitor (1.5 mg./kg. per minute N-omega-nitro-L-arginine) endothelin-1 increased renal vascular resistance (1.2 +/- 0.2 mm. Hg per minute per kg./ml., p < 0.001).

CONCLUSIONS

Endothelin-1 is a vasodilator in the fetal renal circulation, which acts primarily via endothelin-b receptors. Ongoing activity of endothelin-a receptors contributes to renal vascular tone in fetal lambs. The vasodilatory effects of endothelin-1 in the fetal lamb renal circulation are mediated via the nitric oxide system and not via prostanoids.

Lower urinary tract function in ambulatory children with spina bifida

OBJECTIVE

To investigate lower urinary tract function in ambulatory children with myelomeningocele.

PATIENTS AND METHODS

The urological course of 45 children with myelomeningocele who walked either independently (19 children) or with ankle-foot orthotics (26 children) was reviewed. Follow-up ranged from 9 months to 13.5 years (mean 4.75 years).

RESULTS

A normal pattern of voiding was observed both clinically and during urodynamic evaluation in only three of the 45 children, with the remainder displaying neurogenic lower urinary tract dysfunction. The independent walkers and those with orthotics did not differ in the spectrum of lower urinary tract dysfunction or other variables. Those patients with persistent incontinence underwent an initial urodynamic evaluation when older (mean 3.7 years versus 6.4 weeks in those who were continent).

CONCLUSION

Ambulatory children with myelomeningocele suffer the full spectrum of lower urinary tract dysfunction. Given the potential danger of untreated lower urinary tract dysfunction, ambulatory children with myelomeningocele should receive the same diagnostic and therapeutic attention as their peers with more overt neurological deficits.