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The relief of the impediment to urinary flow is the treatment of acute kidney failure due to urinary tract obstruction. However, there is a risk of inducing massive polyuria, which can be self-limited or produce severe contraction of the intravascular volume with pre-renal acute kidney failure and alterations in the internal environment. Polyuria, urine output > 3 L/d or > 200 mL/min for more than 2 hours, can have multiple causes, and can be classified as osmotic, aqueous or mixed. Post-obstructive polyuria obeys different pathogenic mechanisms, which overlap and vary during a patient's evolution. Initially, there is a decrease in vasoconstrictor factors and an increase in renal blood flow, which, added to the excess of urea accumulated, will cause intense osmotic diuresis (osmotic polyuria due to urea). Added to these factors are the positive sodium and water balance during acute renal failure, plus the contributions of crystalloid solutions to replace diuresis (ionic osmotic polyuria). Finally, there may be tubular dysfunction and decreased solutes in the renal medullary interstitium, adding resistance to the action of vasopressin. The latter causes a loss of free water (mixed polyuria). We present the case of a patient with post-obstructive polyuria where, by analyzing the clinical symptoms and laboratory alterations, it was possible to interpret the mechanisms of polyuria and administer appropriate treatment for the pathogenic mechanism.

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The relief of the impediment to urinary flow is the treatment of acute kidney failure due to urinary tract obstruction. However, there is a risk of inducing massive polyuria, which can be self-limited or produce severe contraction of the intravascular volume with pre-renal acute kidney failure and alterations in the internal environment. Polyuria, urine output > 3 L/d or > 200 mL/min for more than 2 hours, can have multiple causes, and can be classified as osmotic, aqueous or mixed. Post-obstructive polyuria obeys different pathogenic mechanisms, which overlap and vary during a patient's evolution. Initially, there is a decrease in vasoconstrictor factors and an increase in renal blood flow, which, added to the excess of urea accumulated, will cause intense osmotic diuresis (osmotic polyuria due to urea). Added to these factors are the positive sodium and water balance during acute renal failure, plus the contributions of crystalloid solutions to replace diuresis (ionic osmotic polyuria). Finally, there may be tubular dysfunction and decreased solutes in the renal medullary interstitium, adding resistance to the action of vasopressin. The latter causes a loss of free water (mixed polyuria). We present the case of a patient with post-obstructive polyuria where, by analyzing the clinical symptoms and laboratory alterations, it was possible to interpret the mechanisms of polyuria and administer appropriate treatment for the pathogenic mechanism.

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OBJECTIVE: To improve the model for establishment and evaluation of detrusor overactivity in female Wistar rats. MATERIALS AND METHODS: We ligated the perineal urethra of female Wistar rats and then performed filling cystometry. The probability of detrusor overactivity, bladder capacity, peak voiding pressure and histological changes were investigated. RESULTS: Detrusor overactivity ratio of the obstruction group was 32.4%. Bladder capacity increased from 0.273 ± 0.036 mL in control group to 0.89 ± 0.19 mL in detrusor overactivity group (P < 0.001), and peak voiding pressure increased from 45.9 ± 4.1 cm.H2O to 63.5 ± 17.4 cm.H2O (P = 0.007). For obstruction group, compared to no detrusor overactivity rats, detrusor overactivity rats had higher bladder capacity (0.89 ± 0.19 mL versus 0.43 ± 0.09 mL, P < 0.001) and higher peak voiding pressure (63.5 ± 17.4 cm.H2O versus 44.8 ± 6.2 cm.H2O, P = 0.005). Detrusor overactivity rats were classified according to peak voiding pressure (49.2 ± 4.2 cm.H2O versus 80.8 ± 7.1cm.H2O, P < 0.001). Moreover, bladder weight increased significantly in detrusor overactivity rats (P = 0.003, P = 0.028) and detrusor histological hypertrophy was observed. CONCLUSIONS: Ligating perineal urethra and filling cystometry with intra-urethral cannula approach is a simple and easily reproducible method to establish and evaluate the model of detrusor overactivity in rats.

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Objective To improve the model for establishment and evaluation of detrusor overactivity in female Wistar rats. Materials and Methods We ligated the perineal urethra of female Wistar rats and then performed filling cystometry. The probability of detrusor overactivity, bladder capacity, peak voiding pressure and histological changes were investigated. Results Detrusor overactivity ratio of the obstruction group was 32.4%. Bladder capacity increased from 0.273 ± 0.036mL in control group to 0.89 ± 0.19mL in detrusor overactivity group (P < 0.001), and peak voiding pressure increased from 45.9 ± 4.1 cm.H2O to 63.5 ± 17.4cm.H2O (P = 0.007). For obstruction group, compared to no detrusor overactivity rats, detrusor overactivity rats had higher bladder capacity (0.89 ± 0.19mL versus 0.43 ± 0.09mL, P < 0.001) and higher peak voiding pressure (63.5 ± 17.4cm.H2O versus 44.8 ± 6.2cm.H2O, P = 0.005). Detrusor overactivity rats were classified according to peak voiding pressure (49.2 ± 4.2cm.H2O versus 80.8 ± 7.1cm.H2O, P < 0.001). Moreover, bladder weight increased significantly in detrusor overactivity rats (P = 0.003, P = 0.028) and detrusor histological hypertrophy was observed. Conclusions Ligating perineal urethra and filling cystometry with intra-urethral cannula approach is a simple and easily reproducible method to establish and evaluate the model of detrusor overactivity in rats. .

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INTRODUCTION: Dilation of urinary tract occurs without the presence of obstruction. Diagnostic methods that depend on renal function may elicit mistaken diagnosis. Whitaker (1973) proposed the evaluation of urinary tract pressure submitted to constant flow. Other investigators proposed perfusion of renal pelvis under controlled pressure, making the method more physiological and reproducible. The objective of the present study was to evaluate the results of the anterograde pressure measurement (APM) of the urinary tract of children with persistent hydronephrosis after surgery suspected to present persistent obstruction. MATERIALS AND METHODS: Along 12 years, 26 renal units with persistent hydronephrosis after surgery (12 PUJ and 14 VUJ) were submitted to evaluation of the renal tract pressure in order to decide the form of treatment. Previous radionuclide scans with DTPA, intravenous pyelographies and ultrasounds were considered undetermined in relation to obstruction in 10 occasions and obstructive in 16. APM was performed under radioscopy through renal pelvis puncture or previous stoma. Saline with methylene blue + iodine contrast was infused under constant pressure of 40 cm H2O to fill the urinary system. The ureteral opening pressure was measured following the opening of the system and stabilization of the water column. RESULTS: Among the 10 cases with undetermined previous diagnosis, APM was considered non-obstructive in two and those were treated clinically and eight were considered obstructive and were submitted to surgery. Among the 16 cases previously classified as obstructive, nine confirmed obstruction and were submitted to surgery. Seven cases were considered non-obstructive, and were treated clinically, with stable DMSA and hydronephrosis. CONCLUSIONS: APM avoided unnecessary surgery in one third of the cases and was important to treatment decision in 100 %. We believe that this simple test is an excellent diagnostic tool when selectively applied mainly in the presence of functional deficit.

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INTRODUCTION: Dilation of urinary tract occurs without the presence of obstruction. Diagnostic methods that depend on renal function may elicit mistaken diagnosis. Whitaker (1973) proposed the evaluation of urinary tract pressure submitted to constant flow. Other investigators proposed perfusion of renal pelvis under controlled pressure, making the method more physiological and reproducible. The objective of the present study was to evaluate the results of the anterograde pressure measurement (APM) of the urinary tract of children with persistent hydronephrosis after surgery suspected to present persistent obstruction. MATERIALS AND METHODS: Along 12 years, 26 renal units with persistent hydronephrosis after surgery (12 PUJ and 14 VUJ) were submitted to evaluation of the renal tract pressure in order to decide the form of treatment. Previous radionuclide scans with DTPA, intravenous pyelographies and ultrasounds were considered undetermined in relation to obstruction in 10 occasions and obstructive in 16. APM was performed under radioscopy through renal pelvis puncture or previous stoma. Saline with methylene blue + iodine contrast was infused under constant pressure of 40 cm H2O to fill the urinary system. The ureteral opening pressure was measured following the opening of the system and stabilization of the water column. RESULTS: Among the 10 cases with undetermined previous diagnosis, APM was considered non-obstructive in two and those were treated clinically and eight were considered obstructive and were submitted to surgery. Among the 16 cases previously classified as obstructive, nine confirmed obstruction and were submitted to surgery. Seven cases were considered non-obstructive, and were treated clinically, with stable DMSA and hydronephrosis. CONCLUSIONS: APM avoided unnecessary surgery in one third of the cases and was important to treatment decision in 100%. We believe that this simple test is an excellent diagnostic tool when selectively applied mainly in the presence of functional deficit.

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INTRODUCTION AND HYPOTHESIS: Iatrogenic female urethral obstruction resulting from sling operations may be related to surgical inexperience and must be better understood. Although there are no widely recognized parameters for this type of study, a single-surgeon consecutive series offers an opportunity to study the role of expertise in sling operations over time. METHODS: This study consecutively examined 176 women who underwent an autologous fascial sling procedure. Postoperative urethral obstruction was identified by the occurrence of voiding dysfunctions. Clinically obstructed patients were invited to undergo a postoperative urodynamic evaluation after 3 months. To enable comparison, patients were placed into 6-month groups according to the time of surgery. RESULTS: A total of 159 cases were evaluated with a mean follow-up time of 32.4 ± 13.4 months. Stress continence was cured in 97.5% of cases. Although 29 patients were identified as obstructed, only 20 underwent a postoperative urodynamic evaluation. Only five of the clinically obstructed cases showed a high P(det)Q(max). All of the other cases met one or more of the non-classic parameters linked to obstruction. Overactive bladder was present in 14 (63.6%) of the obstructed cases. Iatrogenic urethral obstruction was more common among the early cases (30.4%) than among the later ones (5%) (P < 0.001). Postoperative urodynamic evaluation showed a trend toward obstruction on pressure flow studies. CONCLUSIONS: Autologous fascial sling operations require expertise and involve a clear surgical learning curve. Iatrogenic obstruction in females does not fit a single model and may be difficult to recognize. Obstruction in females must be identified through clinical indicators and postoperative urinary complaints rather than the high detrusor pressure observed in men. Furthermore, iatrogenic female obstruction can probably be minimized but not eliminated.

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OBJECTIVE: To compare the renal and cardiorespiratory effects of IV treatment with lactated Ringer's solution (LRS) or physiologic saline (0.9% NaCl) solution (PSS) in severely decompensated cats with urethral obstruction (UO). ANIMALS: 14 cats (4 cats were used only to establish infusion rates). PROCEDURES: An occluded urethral catheter was used to induce UO in each cat. After development of severe metabolic acidosis, hyperkalemia, and postrenal azotemia, the obstruction was relieved (0 hours); LRS or PSS (5 cats/group) was administered IV (gradually decreasing rate) beginning 15 minutes before and continuing for 48 hours after UO relief. Ten minutes before urethral catheter placement (baseline), at start of fluid therapy (SFT), and at intervals during fluid administration, various physical and clinicopathologic evaluations were performed. RESULTS: Metabolic acidosis was detected in the PSS-treated group at SFT and 2 hours after relief of UO and in the LRS-treated group only at SFT The PSS-treated group had significantly lower blood pH and bicarbonate concentrations at 8 through 48 hours and lower base excess values at 2 through 48 hours, compared with the LRS-treated group. Hypocalcemia and hypernatremia were detected in the PSS-treated group at 2 and 12 hours, respectively. Absolute serum potassium and chloride concentrations did not differ significantly between groups at any time point. CONCLUSIONS AND CLINICAL RELEVANCE: Treatment with LRS or PSS appeared to be safe and effective in cats with experimentally induced UO; however, LRS was more efficient in restoring the acid-base and electrolyte balance in severely decompensated cats with UO.

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The present study examined the factors responsible for triggering renal hemodynamic adjustments during acute volume expansion. The renal hemodynamic effects of graded volume expansion with 0.9% saline (Sal; 1, 2, and 4% of body wt), 7% BSA solution (0.35, 0.70, and 1.4% body wt), or whole blood from a donor rat (WBL; 0.35, 0.70, and 1.4% body wt) were compared in rats anesthetized with pentobarbital sodium. Neural influences on the kidney were eliminated by vagus nerves, baro/chemoreceptor afferents, and renal nerves section, and renal perfusion pressure was controlled at constant level (approximately 120 mmHg) throughout the experiments. In Sal- and BSA-expanded rats, renal blood flow (RBF) increased (Sal: 15, 40, 71%; BSA 17, 49, 107%) and renal vascular resistance (RVR) decreased in parallel with the degree of volume expansion (RVR: Sal 17, 31, 44%; and BSA: 15, 35, 54%). Renal hemodynamics remained unaltered after expansion with WBL. In rats expanded with Sal or BSA, correction of the fall of hematocrit restored RBF and RVR to control levels. Interference with tubuloglomerular feedback by uretheral obstruction had no effect on the decrease in RVR with Sal or BSA. Inhibition of the vascular tone by intrarenal papaverine infusion also did not alter the renal hemodynamic response to volume expansion with Sal or BSA. These findings suggest that the changes in renal hemodynamics after acute expansion are likely mediated by changes in rheologic properties of the blood rather than by changes in active vascular tone.

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Most of the urodynamic studies are conducted in the laboratory during a brief recording time and under nonphysiological conditions and, thus, may fail to unfold the nature of existing pathological conditions of the lower urinary tract; false positives and false negatives are possible. To overcome some of the difficulties associated with conventional P/F studies we have developed, with the cooperation of Medical Measurement System company, Entschede, The Netherlands, a portable system (UDS 2000) for ambulatory monitoring of intravesical pressure, abdominal pressure and EMG connectable with a weight-transducer flowmeter that allows to perform Holter P/F measurements. We compared the results obtained with conventional P/F studies and with Holter P/F studies in 58 BPH patients. During the filling phase we observed a slightly increased number of stable detrusors with Holter P/F recording (46 vs 42); conversely, the number of patients suffering from urge incontinence was the same (7 pts). During the voiding phase, out of 45 patients considered obstructed at conventional P/F study, only 42 were really urodynamically obstructed (93.3%), while other 3 patients had bordeline obstruction. 4 patients with bordeline obstruction at conventional P/F study were considered non-obstructed after Holter P/F. In conclusion, Holter P/F proved to be reliable in the assessment of bladder function during storage and emptying in BPH patients and to be more specific in defining outlet obstruction than the conventional study because of the physiologic filling, the reduction of urethral irritation, the lack of a urethral catheter either during filling or voiding, and the reduction of emotional stress.(ABSTRACT TRUNCATED AT 250 WORDS)

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Las valvas de uretra anterior como causa de obstrucción infravesical congénita son poco frecuentes en niños, pues se informan 47 casos en la literatura. En éste informe se presentan forma de aparición, evaluación sistemática, conductas terapéuticas y resultados obtenidos. El uso de vesicostomía en el periodo neonatal previene las potenciales complicaciones con el uso de eletrofulguración transuretral que pueden ocurrir por el tamaño pequeño de la uretra. Así mismo, se ofrece la clasificación de las valvas de uretra anterior de conformidad con los hallazgos radiográficos

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Durante la obstrucción ureteral se presentan cambios en el flujo arterial al riñon afectado. Este estudio tuvo como finalidad determinar estos cambios mediante ultrasonografía Doppler de la arteria renal. Estas determinaciones se llevaron a cabo en seis unidades renales con obstrucción ureteral, en las seis unidades renales contralaterales a la obstruida y en 14 unidades renales testigos. Se encontró que las características de flujo de la arteria renal manifestaban diferencias estadísticamente significativas entre la unidad renal obstruida y las unidades renales contralaterales y testigos

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Se revisaron 2184 expedientes de losw ingresos al servicio de urología y nefrología del Hospital General de México SS durante 1988 y se encontraron historias clínicas de 58 pacientes (2.65 porciento) con diagnóstico de obstrucción ureteropiélioca. Fueron 14 individuos (24 porciento) con afección de vasos aberrantes, a todos ellos se les solicitaron exámenes de laboratorio y gabinete, así como prueba de Whitaker. Según el tipo de vaso aberrante, arterial o venoso, y del lugar de urgencia se efectuó el tratamiento quirúrgico pertinente. El tratamiento postoperatorio se hizo con antimicrobianos y el promedio de días de hospitalización fue de seis. Los pacientes fueron citados a consulta externa; transcurridos tres meses se repitieron los exámenes de laboratorio, la urografía excretora y se practicó la prueba de Whitaker.

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