Kidney Transplantation in Patients with Neurovesical Dysfunction

Background: Five renal recipients with neurovesical dysfunction (NVD) were retrospectively reviewed focusing on anatomical and urodynamic abnormalities of the lower urinary tract and their management prior to kidney transplantation.
Methods: The underlying anomalies in these 5 patients were a posterior urethral valve (1 with an imperforate anus; n = 2), meningomyelocele (n = 2) and a congenital short urethra with an imperforate anus (n = 1). Their urinary tracts were evaluated prior to transplantation with voiding cystourethrography, urethrocystoscopy, cystometrography and electromyography of the external urethral sphincter to identify a possible focus of urinary tract infection, urine storage and voiding function.
Results: All 5 patients had NVD proven by urodynamic studies or by documentation of urinary retention in the absence of mechanical outlet obstruction. Bilateral high grade vesicoureteral reflux was noted in all patients, requiring ureteroneocystostomy. Clean intermittent catheterization (CIC) was ultimately employed for bladder emptying in all patients. Two patients with poor bladder compliance underwent augmentation cystoplasty before transplantation. The Mitrofanoff procedure was used in 2 patients with structural urethral abnormalities to access the bladder for catheterization. After eradication of possible sources of infection and establishment of a low-pressure urine storage system with bladder emptying by CIC, kidney transplantation was performed. Following kidney transplantation, all of the recipients were asymptomatic for urinary tract infections using CIC. Although 1 patient lost his graft due to chronic rejection, the other 4 other patients have good renal function.
Conclusion: Kidney transplantation in patients with NVD can be performed provided that their urinary tract problems are properly resolved.     

CKD and bladder problems in children

Approximately 35% of children with CKD who require renal replacement therapy have a significant urological abnormality, including posterior urethral valves, a neuropathic bladder, prune belly syndrome, Hinman syndrome, or severe vesicoureteral reflux. In such children, abnormal bladder function can have a significant deleterious effect on the renal function. In children with bladder outlet obstruction, bladder compliance and capacity often are abnormal, and a sustained intravesical pressure of >40 cm H(2)O impedes drainage from the upper urinary tract. Consequently, in these conditions, regular evaluation with renal sonography, urodynamics, urine culture, and serum chemistry needs to be performed. Pediatric urological care needs to be coordinated with pediatric nephrologists. Many boys with posterior urethral valves have severe polyuria, resulting in chronic bladder overdistension, which is termed as valve bladder. In addition to behavioral modification during the day, such patients may benefit from overnight continuous bladder drainage, which has been shown to reduce hydronephrosis and stabilize or improve renal function in most cases. In children with a neuropathic bladder, detrusor-sphincter-dyssynergia is the most likely cause for upper tract deterioration due to secondary vesicoureteral reflux, hydronephrosis, and recurrent urinary tract infection (UTI). Pharmacologic bladder management and frequent intermittent catheterization are necessary. In some cases, augmentation cystoplasty is recommended; however, this procedure has many long-term risks, including UTI, metabolic acidosis, bladder calculi, spontaneous perforation, and malignancy. Nearly half of children with prune belly syndrome require renal replacement therapy. Hinman syndrome is a rare condition with severe detrusor-sphincter discoordination that results in urinary incontinence, encopresis, poor bladder emptying, and UTI, often resulting in renal impairment. Children undergoing evaluation for renal transplantation need a thorough evaluation of the lower urinary tract, mostly including a voiding cystourethrogram and urodynamic studies.     

Anterior urethral valve as a cause of end-stage renal disease

Although posterior urethral valves are predominant as a cause of obstructive uropathy in children, anterior urethral valves may also appear as the underlying etiologic factor in end-stage renal disease that results from obstruction. Two cases are presented of anterior urethral valve patients that were admitted with end-stage renal disease. The first case was successfully treated with diverticulectomy and urethral reconstruction in preparation for renal transplantation. The second case, however, had been on cystostomy drainage for 6 years and also had a contracted bladder. A more extensive lower urinary tract reconstruction was delayed. Children with poor stream and recurrent infections should be evaluated carefully and anterior urethral valve or diverticula should be considered in differential diagnosis of obstructive lesions.     

Myogenic bladder decompensation in boys with a history of posterior urethral valves is caused by secondary bladder neck obstruction?

OBJECTIVE: To investigate whether myogenic bladder decompensation in patients treated for congenital posterior urethral valves (PUV, the most serious cause of infravesical obstruction in male neonates and infants) may be secondary to bladder neck obstruction, as despite prompt ablation of PUV these patients can have dysfunctional voiding during later childhood or adolescence, the so-called 'valve bladder syndrome'. PATIENTS AND METHODS: The study comprised 18 boys (mean age 14 years, range 6.2-18.5) who had had successful transurethral ablation of PUV between 1982 and 1996, and had completed a follow-up which included serial assessment of serum creatinine, completion of a standard voiding diary, ultrasonography with measurement of urine before and after voiding, a urodynamic examination with simultaneous multichannel recording of pressure, volume and flow relationships during the filling and voiding phases, coupled with video-cystoscopy at least twice. The mean (range) follow-up was 9.3 (6-17) years. RESULTS: Urodynamic investigation showed myogenic failure with inadequate bladder emptying in 10 patients; five with myogenic failure also had unstable bladder contractions. On video-cystoscopy the posterior bladder neck lip appeared elevated in all patients but in those with myogenic failure it was strongly suggestive of hypertrophy, with evidence of obstruction. At the last follow-up one patient with myogenic failure who had had bladder neck incision and four others who were being treated with alpha-adrenergic antagonists had a significant reduction of their postvoid residual urine. CONCLUSION: Despite early valve ablation, a large proportion of boys treated for PUV have gradual detrusor decompensation, which may be caused by secondary bladder neck obstruction leading to obstructive voiding and finally detrusor failure. Surgical or pharmacological intervention to improve bladder neck obstruction may possibly avert this course, but further studies are needed to validate this hypothesis.     

Pediatric renal transplantation and the dysfunctional bladder

We retrospectively reviewed our long-term experience with pediatric renal transplantation into a dysfunctional lower urinary tract to evaluate graft survival, function, and special urological complications. Between 1967 and March 2000, a total of 349 renal transplantations were performed in children younger than 18 years. Malformations of the lower urinary tract were the reasons for end-stage renal failure in 66 children (18.6%). The cause of urinary tract disorders included: meningomyelocele connected with neuropathic bladder (n=4 transplantations); prune belly syndrome (n=5 transplantations); VATER association (n=2 transplantations); posterior urethral valves (n=27 transplantations); and vesico-uretero-renal reflux (n=28 transplantations). The majority of the patients underwent surgical interventions to preserve renal function or to prepare renal transplantation. The 1- and 5-year graft survival rate was evaluated with special reference to the underlying disease. The 1-year graft survival rate in all children with lower urinary tract malformations was 83.3%, compared with 88% for all children. In those children with vesico-ureteral reflux, it was 92.8% and in the children with Vater association and prune belly syndrome, it was 85.7%. One graft was lost in the children who had neurogenic bladder, so the 1-year graft survival rate was 75%. The worst 1-year graft survival rate was obtained for boys who had posterior urethral valves (1-year graft survival rate: 74%; 5-year graft survival rate: 62.9%). Concerning the 5-year graft survival rate, it was 70% for all children with malformations of the urinary tract. The best rate was obtained for children with reflux in the native kidneys (78.5%), followed by those with VATER association and prune belly syndrome. As an additional child with neurogenic bladder lost his graft, the 5-year graft survival rate was 50%. Pediatric renal transplantation into a dysfunctional bladder can be connected with high urological complication rates which may contribute to worse graft survival. The 1- and 5-year graft survival rate in children with malformations of the lower urinary tract is worse than in children without bladder dysfunction. We regarded a striking difference between graft survival and the urological disorders which led to renal insufficiency. We obtained the worst graft survival rates in children with posterior urethral valves which are usually connected with bladder emptying problems and dysfunctional voiding. Potential pediatric transplant recipients must be classified according to pathophysiological as well as anatomical abnormalities of the urinary tract and all urological problems have to be solved prior to transplantation. At our center, living donors are favored to plan transplantation of these children properly.     

Renal transplantation in children with severe bladder dysfunction

PURPOSE: Renal transplantation in children with bladder dysfunction carries a risk for the renal graft. We report our experience with transplantation in 15 patients 6 to 18 years old with severe abnormalities of the lower urinary tract. MATERIALS AND METHODS: A total of 18 renal transplants were performed in 15 children with bladder dysfunction secondary to myelomeningocele (3), occult spina bifida (1), malformation/agenesis of the sacrum (5), posterior urethral valves (4), female hypospadias (1) and bladder exstrophy (1) between 1979 and 2003. Urological surgery was performed before transplantation in 14 cases-7 bladder augmentations, 5 incontinent urinary conduits/reservoirs and 2 vesicostomies. Voiding was maintained by intermittent catheterization in 9 cases and incontinent ostomies in 6. Graft implantation was performed by extraperitoneal route with ureteral anastomosis to the native bladder in cases of bladder augmentation. Immunosuppression consisted of triple therapy with polyclonal/monoclonal antibodies. RESULTS: Urological complications consisted of urethral obstruction due to mucus hypersecretion (1), urinary fistula (1), ureterovesical obstruction (1), stone formation (3), urinary tract incrustation by Corynebacterium urealyticum (1) and pyelonephritis (2). Graft survival rates at 1 and 5 years were 77% and 62%, respectively, with a median of 79 months (95% CI 51 to 107). Three graft losses were related to urological disease. CONCLUSIONS: Renal transplantation in children with severe bladder dysfunction can achieve similar results to those obtained in the general population. Meticulous selection of patients and surgical reparative techniques ensuring voiding and adequate control of urinary infections are mandatory. Augmentation cystoplasty and intermittent catheterization are appropriate techniques currently used for achieving this outcome.     

Early ureteral surgery for posterior urethral valves

The obstruction caused by posterior urethral valves may be responsible for profound dysfunction of the entire proximal urinary tract. The pathophysiologic relations between the valves and function of the ureterovesical junction and upper urinary tract are key in determining the need for upper tract surgery. In most cases, function of the ureters and ureterovesical junction is directly related to high intravesical pressure and will normalize when pressures drop after valve destruction. However, upper tract function remains abnormal in some cases and leads to complications that necessitate early ureteral and upper tract surgical intervention. The second crucial relation in the management of patients with posterior urethral valves is that between renal dysfunction and urinary tract obstruction. The surgeon is compelled to maximize the potential for renal function. The relation between renal dysplasia, obstructive uropathy, and urinary tract obstruction complicates the management of patients with posterior urethral valves and challenges us to develop new methods to measure potential renal function. Patients born with posterior urethral valves are treated initially with bladder drainage, which is undertaken by placement of a urethral catheter at the time diagnosis is made with the voiding cystogram. During this initial period of evaluation and stabilization, the patient's medical status is optimized, giving the surgeon information concerning renal function and prognosis to allow the most efficient surgical management. In almost all cases, posterior urethral valves are destroyed primarily, most often by transurethral fulguration. This usually leads to rapid improvement of bladder, upper tract, and renal function. When primary fulguration is not advisable, drainage through a vesicostomy is a useful alternative. Utilizing either method, low-pressure bladder drainage is a primary goal in the initial management of patients in most centers. As with many problems in surgery, our ability to accurately identify patients who would benefit from surgery is more limited than our surgical effectiveness. Voiding cystograms allow us to diagnose reflux and to follow bladder emptying and function. Serial ultrasound scans, nuclear medicine scans, and pressure-perfusion studies give us insight into upper urinary tract function. Too often, however, limitations of the patient's condition and size and the severe degree of urinary tract abnormalities make the results difficult to interpret. Although diagnostic tests are invaluable in making decisions about upper tract surgery in patients with posterior urethral valves, these decisions are most often based on the classic clinical urologic problems of urinary extravasation, obstruction, infection, reflux, and azotemia.(ABSTRACT TRUNCATED AT 400 WORDS)     

Anterior and posterior urethral valves with subcoronal hypospadias: a rare association

Association of the anterior and posterior urethral valve is a rare congenital anomaly which can lead to various urinary tract symptoms. An 8-year-old boy was referred by his primary care physician for urinary dribbling, straining at micturition, and recurrent febrile urinary tract infection since the age of 2 years. Clinically, the bladder was palpable; both testes were normal, and, in addition, he had a subcoronal hypospadias. Diagnosis was confirmed by retrograde urethrogram and voiding cystourethrogram (micturating cystourethrogram) and urethroscopy. Cystoscopic ablation of both valves was done by electrocautery hook using low current at 5 o'clock and 7 o'clock directions. He voided with good flow and to completion. Urinary dribbling had completely subsided and renal function was normal at a follow-up period of 36 months with freedom from recurrent urinary tract infection.Both the anterior and posterior urethral valves develop from different embryological sources; thus, this association is rare. A case with this association has not been reported previously in the literature.     

Alternatives in the management of posterior urethral valves

The child with posterior urethral valves poses a continuing treatment dilemma because congenital infravesical obstruction may result in long-standing dysfunction of all segments of the urinary tract. Relief of the obstruction may not return bladder pressure to normal or completely resolve abnormalities of ureteral drainage. Dysplastic renal parenchyma cannot recover. Four issues affect the identification of those children who will benefit from therapy beyond transurethral valve destruction: the concept of transitional nephrology, the possibility of coexisting ureterovesical obstruction, the valve bladder syndrome, and prenatal urology.     

Rare combination of unilateral renal agenesis, congenital obstructive posterior urethral membrane, and enlarged prostatic utricle, with absence of hydroureteronephrosis

The existence of congenital obstructive posterior urethral membrane (COPUM), extending proximally from the verumontanum toward the bladder neck, has been widely debated. Although COPUM often leads to chronic renal disease, a milder degree of obstruction and protective pressure pop-off mechanisms have been reported. We present a male infant with a rare combination of unilateral renal agenesis, COPUM proximally from the verumontanum to the bladder neck, and enlarged prostatic utricle. The posterior urethra was dilated, without bladder abnormalities or hydroureteronephrosis, indicating milder obstruction. Moreover, the enlarged prostatic utricle could contribute in the urinary tract protection, serving as an uncommon pressure pop-off mechanism.     

Protective factors in posterior urethral valves

Patients with posterior urethral valves may present with or contract renal insufficiency. High intravesical pressure that is transmitted to the upper urinary tract in utero is a likely contributing cause. We have identified 3 anatomical associations with posterior urethral valves that provide a pressure "pop-off" mechanism resulting in preservation of better renal function: 1) the syndrome of posterior urethral valves, unilateral vesicoureteral reflux and renal dysplasia; 2) large congenital type bladder diverticula and 3) urinary extravasation with or without urinary ascites. Followup of 71 boys with posterior urethral valves was sufficient to permit long-term analysis. Serum creatinine was used as an index of renal function and prognosis. Of the 71 boys 20 (28 per cent) had 1 of the 3 protective mechanisms. Only 1 child (5 per cent) had a serum creatinine greater than 1.0 mg. per cent. Of the remaining 51 boys without a "pop-off" mechanism 20 (39 per cent) had serum creatinine greater than 1.0 mg. per cent and 7 had already progressed to renal dialysis and/or transplantation. The difference in serum creatinine was statistically significant (p less than 0.01). Thus, the syndrome of posterior urethral valves, unilateral vesicoureteral reflux and renal dysplasia; large congenital bladder diverticula and urinary extravasation can serve as a "pop-off" mechanism to buffer high pressures in the urinary tract and to lead to the preservation of better renal function in boys with posterior urethral valves.     

“Close-loop” urethral obstruction: Clinico-radiological features and management consideration in a resource-constraint environment

ObjectiveTo document our observation of “close-loop” obstruction among patients with dual urethral obstruction from BPH and urethral stricture disease.Materials and MethodsThe hospital records of all patients that presented to our centres with evidences of urethral stricture co-existing with BPH were retrospectively reviewed from January 2007 to December 2011. Among other things, the salient features in the contrast radiograph of those with “close-loop” obstruction and their treatment were documented and analysed.ResultsForty three patients were managed for radiological evidence of urethral stricture and elevated bladder base (dual obstruction). Thirty (69.7%) of these patients had open prostatectomy with easy dilatation of the urethral stricture. Twelve (27.9%) of the patients had urethroplasty for urethral stricture diseases; of these twelve, five patients presented with persistent LUTS (“close loop” obstruction). These five (11.6%) patients were aged between 50 to 80 years; they all had suprapubic cystostomy. In addition to delineating the anatomy of the urethral stricture and elevated bladder base, other salient features on the contrast radiographies included dilated prostatic urethral, visualization of the seminal vesicles and closed bladder neck on voiding cystogram. The initial treatment was urethroplasty but two each had combination therapy (with alpha adrenergic blocker and 5-alpha reductase inhibitor) and open prostatectomy respectively as further treatment while the last patient had perineal urethrostomy as first-stage redo-urethroplasty.Conclusion“Close-loop” urethral obstruction appears to be an entity that needs further evaluation.     

Kidney transplantation to patients with congenital malformations of the distal urinary tract

Abstract  Fourteen of 1000 consecutive kidney transplant patients had congenital malformations affecting the bladder or urethra: six had congenital valvulus of the urethra, two congenital sclerosis of the bladder outlet, and six a neurogenic bladder. Pretransplant surgey had been performed in all patients: reimplanta-tion of ureter ( n = 11), resection of congenital valvulus ( n = 7), and ne-phrectomy (n = 6). Four patients had an intestinal bladder. Age was 0–17 (median 1) years at diagnosis. Follow-up time was 3–10 (median 5) years. Special transplant surgery techniques were required in five patients. Patient survival after 2 years was 100 % and graft survival 93 %. No graft was lost due to outflow obstruction, infection or other causes related to the underlying disorder. Late technical problems were seen in two patients. Urinary tract infections were reported in 13 patients before transplantation and in eight after. Results of transplantation were excellent. Infections and surgical problems had a minor impact on outcome.     

Micturitional static urethral pressure profilometry in women

Micturitional static urethral pressure profilometry is an accurate method to identify the location and degree of bladder outlet and urethral obstruction in men. Described herein are the results of micturitional static urethral pressure profilometry in 17 women: 13 were nonobstructed, 3 were obstructed, and 1 voided by abdominal straining. The location of the static pressure drop was in the terminal urethral segment in all patients and was clearly distal to the location of the maximum urethral pressure determined on urethral closure pressure profilometry. It is concluded that the terminal urethral segment controls urinary flow, determines the voiding pressure, and that micturitional static urethral pressure profilometry can accurately identify the location of physiologic obstructions in the female urethra.     

Renal transplantation in children with severe lower urinary tract dysfunction

PURPOSE: Renal transplantation in children with end stage renal disease due to congenital urological malformations has traditionally been associated with a poor outcome compared to transplantation in those with a normal urinary tract. In addition, the optimal urological treatment for such children remains unclear. To address these issues, we retrospectively reviewed our experience with renal transplantation in this population. MATERIALS AND METHODS: Between 1986 and 1998, 12 boys and 6 girls a mean age of 8.4 years with a severe dysfunctional lower urinary tract underwent a total of 15 living related and 6 cadaveric renal transplantations. Urological anomalies included posterior urethral valves in 8 cases, urogenital sinus anomalies in 4, the prune-belly syndrome in 2, and complete bladder duplication, ureterocele, lipomeningocele and the VATER syndrome in 1 each. In 11 children (61%) bladder augmentation or continent urinary diversion was performed, 2 (11%) have an intestinal conduit and 5 (28%) have a transplant into the native bladder. RESULTS: In this group patient and overall allograft survival was 100 and 81%, respectively. These values were the same in all children who underwent renal transplantation at our center during this era. In the 17 children with a functioning transplant mean serum creatinine was 1.4 mg./dl. Technical complications occurred in 4 patients (22%), including transplant ureteral obstruction in 2 as well as intestinal conduit stomal stenosis and Mitrofanoff stomal incontinence. CONCLUSIONS: Renal transplantation may be successfully performed in children with end stage renal disease due to severe lower urinary tract dysfunction. Bladder reconstruction, which may be required in the majority of these cases, appears to be safe when performed before or after the transplant. A multidisciplinary team approach to surgery is advantageous.     

Role of the bladder in delayed failure of kidney transplants in boys with posterior urethral valves

PURPOSE: There is a tendency toward less favorable long-term graft function in patients with posterior urethral valves than in controls. We studied the role of the bladder in boys who underwent transplantation by simultaneously evaluating renal graft and voiding function. MATERIALS AND METHODS: Between 1972 and 1994, 66 boys with posterior urethral valves underwent kidney transplantation. Of these boys 44 with a mean age of 9.7 years who retained a functional renal graft did not undergo any surgery on the lower urinary tract except for the initial treatment of posterior urethral valves. Long-term evaluation included a voiding questionnaire, radiological assessment and serum creatinine measurement. RESULTS: Average followup was 9.01 years (range 2.4 to 19.6). There was no voiding dysfunction symptomatology in 23 boys, while 3 (14.2%) and 8 (38.1%) of the remaining 21 had daytime and nighttime frequency, respectively. Dysuria and incontinence were present in 11 (52.4%) and 12 (57.1%) patients, respectively. Urodynamics in 11 cases revealed a mean bladder compliance plus or minus standard deviation of 11.3+/-2.8 ml./cm. water. In boys with a voiding disorder mean serum creatinine increased after 5 years of followup. At 10 years after kidney transplantation mean serum creatinine was 140.3+/-36.0 and 285.7+/-36.2 micromol./l. in asymptomatic boys and those with a voiding disorder, respectively (p<0.01). CONCLUSIONS: Valve bladder has a role in the deterioration of renal transplants in boys with posterior urethral valves. In those with a voiding disorder closer followup is needed, including urodynamic and radiological studies. Bladder dysfunction, such as hypocompliance and/or hyperreflexia, requires medical or surgical treatment.     

Renal transplantation in children with posterior urethral valves

We compared retrospectively the outcome of renal transplantation in 18 children with a diagnosis of posterior urethral valves to 18 matched children with nonobstructed renal failure to identify the disadvantages of renal transplantation into the valve bladder. There was no statistical difference in patient survival. The 5-year graft survival rate was 62.3% in children with posterior urethral valves and 48% in the control group. The difference was not statistically significant (p = 0.32). A statistically significant increase in serum creatinine from 1.2 to 2.2 mg./dl. was noted in the patients with posterior urethral valves, which was not seen in the control group (p = 0.0009). The clinical significance of this finding is unknown. Renal transplantation can be performed successfully in patients with posterior urethral valves. A prospective study is required to determine the benefits of preoperative lower urinary tract urodynamic assessment and the true effect of the valve bladder.     

Results of kidney transplantation in children weighing less than 11 kilograms

Weigh and age are risk factors of graft failure. The aim of the study is to review the characteristics and the outcome of cadaver renal transplant in children weighing less than 11 Kg. From 1985 to 1999 10 cadaver renal transplant were performed in 10 children (7 boys and 3 girls). Primary renal disease were renal dysplasia(3), posterior urethral valves(5) and congenital nephrotic syndrome(2). All except two suffered end stage disease from birth. The cadaver donor age ranged from 4 to 45 years (mean 12.3). Cold ischaemia time was 14 to 30 hours (median 22.8 h). Grafts were placed extraperitoneally in the iliac fossa in all patients and special care was taken in aggressive intravascular volume expansion. In the first 5 children initial immunosuppression consisted of CyA, Pd and Aza. After 1991, the other five received sequential induction therapy with polyclonal antibodies and triple therapy (CyA, Pd, Aza). Renal function was evaluated as GFR yearly by Swartz formula and the actuarial and graft survival rates were obtained by Kaplan-Meier analysis. Patient survival was 90% at 1 and 10 years. Graft survival was 80% at 1 and 5 years; it decreased to 64% at 7 years. Seven continue with their first graft and the mean follow-up time is 6.6 years. Their renal function measured by the mean of GFR yearly decreased lightly from 102 ml/min/1.73 m2 at 1 year to 87.6 ml/min/1.73 m2 at 5 years. A successful patient and graft survival can be achieved in young receiving kidneys and small reciepients can improve their physical and mental development after transplantation.     

排尿期尿道压力测定在膀胱出口梗阻疾病诊断中的应用

目的　研究排尿期尿道压力测定 (MUPP)在膀胱出口梗阻 (BOO)疾病诊断中的应用。方法　下尿路梗阻患者 4 5例 ,其中良性前列腺增生 (BPH) 38例 ,前尿道狭窄 3例 ,女性尿道狭窄 4例。对照组为健康志愿者 4例。按常规方法行压力 流率测定 ,静态尿道压力测定 (UPP)及MUPP。以压力下降梯度计算梗阻程度。数据分析采用t检验。研究不同疾病梗阻患者尿道压力下降点及下降梯度 ,MUPP对梗阻部位的诊断价值 ,MUPP与压力 流率研究对可疑梗阻诊断的比较 ,MUPP与压力 流率研究判断梗阻程度的比较。　结果　对照组 2例男性 ,外括约肌以上尿道内压与膀胱内压力相等 ,尿道压在外括约肌处快速下降 ;2例女性 ,膀胱压与全部尿道压几乎相等 ,尿道末端 1cm处尿道压下降。 38例BPH患者最大排尿压增高 ,平均为 (99.33± 4 1.0 9)cmH2 O(1cmH2 O =0 .0 98kPa) ,尿道压力在膀胱颈或前列腺尖部下降。 3例前尿道狭窄患者后尿道近端压力与膀胱压相等 ,球部及远端尿道压力下降。 4例女性远端尿道狭窄患者尿道压力在狭窄远端区域下降。BPH、前尿道狭窄、女性远端尿道狭窄平均MUPP压力下降梯度分别为 (71.6 3± 37.4 1)cmH2 O、(43.5 1± 15 .71)cmH2 O、(41.4 8± 17.34)cmH2 O ,与正常对照组的 (2 4 .2 5± 2 .99)cmH2 O相比 ,差别有     

Urodynamic follow-up of experimental urethral obstruction in individual guinea pigs.

It is unknown whether changes in bladder function due to urethral obstruction follow a specific sequence. To answer this, we adapted a small animal model to allow repeated complete pressure-flow studies, enabling individual follow-up of changes in bladder function on urethral obstruction. Obstruction was induced in guinea pigs by placing a silver ring around the urethra. Urodynamic studies were repeated under anesthesia with ketamine/xylazine. Bladders were filled and bladder pressure measured through a single suprapubic catheter. Urine flow rate was measured using an ultrasound probe around the penis. Accurate measurements of bladder pressure and urine flow rates were obtained at 1-week intervals for 11 weeks in individual guinea pigs. In the control animals, the urodynamic parameters did not show significant changes. In the obstructed group, urethral resistance (P(low,ave)) increased from 20 to 35 cm H(2)O after 4 weeks and remained at that level. The maximum flow rate (Q(max)) increased from 0.17 to 0.24 mL/s after 2 to 3 weeks. After this peak, it gradually decreased to lower than the starting value after 10 to 11 weeks. The pressure at maximum flow rate (p(Qmax)) increased from 24 to 47 cm H(2)O after 6 to 7 weeks and thereafter declined. During weeks 1 through 4 of obstruction, unstable contractions were seen. All animals followed a similar sequence of patterns but at variable rates. Our animal model allows complete urodynamic follow-up of individual animals with urethral obstruction. We observed a specific sequence of changes in urodynamic patterns and parameters of bladder function.