Robot-assisted reconstructive surgery of lower urinary tract in children: a narrative review on technical aspects and current literature.

Background and Objective: Robotic approach is used widely for paediatric upper tract urinary reconstruction. This is a narrative review looking at the current status of robotic approach in lower urinary tract reconstruction. The aim of this article is to highlight the important technical aspects of commonly performed robotic lower urinary tract reconstructive surgeries and review the current literature. Methods: MEDLINE database search was conducted using MeSH terms and Boolean operators from Jan 2000 to Jun 2022. Abstracts were screened to exclude those in languages other than English as also articles pertaining to (I) upper urinary tract surgery, (II) only laparoscopic surgery (not robot-assisted) and (III) non-urological topics. Selected articles were then reviewed and search expanded to include their references with a focus on advanced lower urinary tract reconstruction. Key Content and Findings: The technical aspects of robotic ureteric reimplantation, continent catheterisable channel and autoaugmentation are discussed in detail. The early outcomes are comparable to open surgery. The true advantage of robotic approach becomes apparent when performing lower urinary tract reconstruction, where space in the pelvis is limited and access is challenging. Only a few centres are currently performing bladder neck surgery and bladder augmentation. Conclusions: Robotic lower urinary tract reconstruction in children is feasible and safe. Robotic approach offers better access, especially in the limited space within the pelvis. It reduces blood loss and post-operative pain allowing early recovery and discharge. Long-term follow-up with increasing experience could further validate these early observations.

Dye-assisted lymphatic-sparing laparoscopic varicocelectomy in children.

INTRODUCTION: The ideal method for varicocelectomy in children remains controversial. We present our experience with dye-assisted lymphatic-sparing laparoscopic varicocelectomy (LSLV) in children, which overcomes the limitations of previously described techniques. MATERIALS AND METHODS: Twenty-five consecutive LSLVs were performed on children with a mean age of 15 years over a 4-year period. Varicocele grade was 3 in 21 cases and grade 2 in 4. Indications for intervention were hypotrophy in 12, pain in 11 cases and family preference in 2. A scrotal injection of lymphatic dye was utilized to spare at least one lymphatic and the remaining spermatic vessels were divided. RESULTS: Lymphatic sparing was accomplished in all cases. Operative time varied from 30 to 140 min (mean 85 ± 26). No perioperative complications were noted. On average follow-up of 13 months a residual varicocele was noted in 2 cases, with no hydrocele and resolution of pain. Mean testicular volume difference diminished from 33% pre to 18% postoperatively. CONCLUSION: This multi-surgeon experience demonstrates that dye-assisted LSLV is easily accomplished with promising results. It appears that preservation of a single spermatic lymphatic vessel is sufficient, although in some cases a second dye injection is required to visualize the lymphatics.

How do asymptomatic toilet-trained children void following tubularized incised-plate hypospadias repair?

PURPOSE: : To evaluate the functional outcome in the form of urinary flow rates in asymptomatic children following uncomplicated tubularized incised plate urethroplasty (TIPU) hypospadias repair. METHODS: : We reviewed the records of children who underwent TIPU at our institution between April 1997 and September 2007 and included only asymptomatic toilet-trained children who had an uncomplicated postoperative course and had undergone uroflometry not less than 1 year postoperatively. Unfavourable voiding parameters were either a plateau curve, a peak flow below the 5th percentile range in nomogram or a post-void residual (PVR) more than 20% of the total functional capacity of the bladder. Uroflowmetry findings were analyzed against variables, including the surgeon, the severity of hypospadias, the presence of a hypoplastic urethra, the use of double layer closure, the performance of a spongioplasty and the use of a stent. Serial uroflowmetries, when available, were compared with respect to the initial flow study. RESULTS: : In total, 59 patients were eligible for the study. The mean age at surgery was 2.4 years. Hypospadias was distal penile in 50 (85%) and mid and proximal penile in 9 (15%). Mean follow-up was 3.3±2 (1-9.5) years. The uroflow curve was bell-shaped in 18 (30%), interrupted in 8 (14%), slightly flattened in 27 (46%) and plateau in 6 (10%). Flow rate nomograms revealed that 40 (68%) were above the 20th percentile, 10 (17%) were below the 5th percentile and 9 (15%) were between these ranges. PVR was >20% of the pre-void volume in 9 children (15%). No patient demonstrated all three unfavourable parameters together. The groups of children with unfavourable functional voiding parameters were compared to the children with favourable parameters specifically with respect to the possible predictors of outcome. Follow-up uroflometry in 17 patients showed improvement in the flow curve, flow rate and PVR with significant improvement of maximum urinary flow rate (Qmax) and PVR values. CONCLUSIONS: : Asymptomatic, urodynamic abnormalities were observed in our study following uncomplicated TIPU repair. These abnormalities were not related to the variation of the technique among surgeons. Spontaneous improvement has been noted on serial flow studies.

A novel technique of stenting for laparoscopic pyeloplasty in children.

PURPOSE: We introduce the novel technique of a percutaneous pyelo-ureterostomy stent for laparoscopic pyeloplasty in children, which overcomes the limitations of previously described stenting techniques. MATERIALS AND METHODS: A Chiba needle is passed percutaneously across the anterior wall of the renal pelvis after completion of the anterior pyelo-ureteric anastamotic line. A guide wire is inserted through the trocar followed by an angiocatheter over the wire. The stent is passed through the angiocatheter, over the wire and across the wall of the renal pelvis. The wire is withdrawn and the stent distal tip is advanced to the mid-ureter. The posterior anastamotic line is then completed and the renal pelvis closed. The stent is capped on postoperative day 1 and removed in the office on postoperative day 10. RESULTS: Since 2007 we have used this approach for 14 laparoscopic pyeloplasties (5 right, 9 left) in children with a mean age of 8.8 years (range 5-17). Mean time of insertion was 9:55 min with no difficulties or perioperative complications noted. CONCLUSION: The antegrade pyelo-ureteral stent is easily and quickly inserted percutaneously as well as removed in the office, thus obviating the need for a second anesthetic.

The anterior approach to retroperitoneoscopic adrenalectomy in children: technique.

PURPOSE: Very limited literature exists on minimally invasive adrenalectomy in children. Retroperitoneoscopic adrenalectomy (RPA) has the advantage of avoiding intra-abdominal organ retraction, but concerns have been expressed regarding RPA on the right side. Herein, we describe the second reported experience with the anterior approach to RPA in children, which appears to overcome the limitations previously ascribed to right RPA. MATERIALS AND METHODS: Two children, aged 8 and 14-years, presented with incidental right adrenal masses. Both patients were placed in the lateral decubitus position with lumbar hyper-extension. A 5-mm, 3-port approach was used, as demonstrated in the video. RESULTS: Pathology revealed a 7-cm ganglioneuroma and a 5-cm pheochromocytoma with intact surgical margins. Operative time with these large masses and first experience with this technique was 5 h in the first case and 3.5 h in the second. No intraoperative or postoperative complications were noted, with minimal blood loss and a hospital stay of 36 h in both cases. CONCLUSION: The anterior approach to RPA is feasible even in children with a smaller retroperitoneal space and a large adrenal mass. It provides excellent exposure of the adrenal gland and vein, even on the right side.

How much does the midline incision add to urethral diameter after tubularized incised plate urethroplasty? An experimental animal study.

PURPOSE: We objectively quantified the gain in urethral diameter and the effect of stenting after tubularized incised plate urethroplasty in a rabbit hypospadias model. MATERIALS AND METHODS: We created a hypospadias model in 12 New Zealand white male rabbits by excising the ventral urethra. A 3 cm tattoo line was made longitudinally in the dorsal urethral plate midline. Two weeks later a 2 cm relaxing incision was made in the middle part of the tattooed line. The stretched incision width between the tattooed edges was measured, followed by urethral plate tubularization. Six rabbits were stented and 6 were nonstented. Two weeks later the animals were sacrificed and the distance separating the tattoo was measured at the midpoint of the tattooed line. Transverse sections at this point were examined histologically. RESULTS: All animals survived the procedures. Stents were removed at 7 days in 4 rabbits and fell out in 2 at 4 and 2 days, respectively. The mean ± SD incision width of 5.5 ± 1.6 mm (range 3 to 8) at tubularization became 2 ± 0.5 mm (range 1 to 3) after healing (p <0.002). Mean width of the healed incision was 1.7 ± 0.4 (range 1 to 2) vs 2.3 ± 0.5 mm (range 1.5 to 3) in the nonstented and stented groups, respectively (p <0.06). Rabbits with a stenting duration of less than 7 days were excluded from the last analysis. Histologically all incisions healed completely with an intact epithelium. CONCLUSIONS: The initial width of the midline relaxing incision significantly decreased after complete epithelialization. The average gain in urethral width was only 2 mm. Stenting appeared to increase the width of the healed incisions but not in a statistically significant manner.

Risk factors for re-operation following tubularized incised plate urethroplasty: a comprehensive analysis.

OBJECTIVES: To review our 10-year experience with tubularized incised-plate (TIP) urethroplasty and determine the risk factors for reoperation. METHODS: The hospital records of 391 patients underwent the TIP procedure from April 1997 to September 2007 were reviewed retrospectively. Data were collected with respect to patient demographics, characteristics of the hypospadias malformation, intraoperative factors and postoperative outcome. Complications requiring reoperation were identified. Univariate and multivariate analyses were used to identify risk factors for reoperation. RESULTS: Median age at surgery was 2 years (range, 0.5-16). Median follow-up was 11 months (range, 3-96). Neourethral complications requiring re-operation developed in 48 patients. A total of 52 reoperations were required because of fistulae (25/6%), neourethral disruption (13/3%), meatal stenosis (13/3%), and stricture (1/0.3%). The re-operation rate was significantly higher in the presence of interrupted sutures, chordee requiring dorsal plication, penoscrotal or proximal shaft defects, a lack of neourethral vascular tissue coverage, and in children over 4 years of age. Multivariate analysis identified the last 3 of these variables as independent risk factors for reoperation. CONCLUSIONS: In addition to position of the urethral meatus and the absence of vascular covering flaps, we found that an age over 4 years at the time of surgery is an additional independent risk factor for neourethral complications requiring reoperation.

Is routine renography required after pyeloplasty?

PURPOSE: We assessed whether renography should be performed routinely following pyeloplasty. MATERIALS AND METHODS: We identified the records of all patients undergoing pyeloplasty at our hospital between 1989 and 2005. Patients were eligible for the study if they had undergone preoperative ultrasound and renal scan, and postoperative ultrasound and renal scan within 3 months and 1 year postoperatively, respectively. Patients were excluded if they had associated anomalies or high grade reflux. Postoperative downgrading or decompression of the pelvicaliceal dilatation within the same grade was recorded as "improved," while unchanged or worsening hydronephrosis was recorded as "no improvement." All information was obtained from the official radiologist reports rather than from the postoperative surgeon notes. Data obtained from the postoperative renal scan included the presence or absence of obstruction as well as split renal function. We compared postoperative ultrasound and renal scan, as well as changes between preoperative and postoperative split renal function in patients with a normal contralateral kidney. Fisher's exact test was used for comparison. RESULTS: A total of 97 patients who underwent 101 pyeloplasties at a median age of 18 months were eligible for review. Mean +/- SD followup was 4.5 +/- 2 years. Of the 91 kidneys with improvement on postoperative ultrasound 2 (2%) had an obstructive postoperative renal scan, which spontaneously resolved during followup. In contrast, of the 10 kidneys with postoperative ultrasound showing no improvement 4 (40%) had an obstructive renal scan, of which 2 (50%) required a second procedure (p <0.001). Of the 46 kidneys with downgraded hydronephrosis none had an obstructive postoperative renal scan, compared to 6 of 55 (11%) without downgrading (p <0.03). Of the 49 patients with preoperative split renal function greater than 45% none demonstrated changes of more than 5% postoperatively, compared to 15 of 35 (43%) with split renal function less than 45% (p <0.001). CONCLUSIONS: Patients in whom postoperative ultrasound reveals downgrading may not require postoperative renal scan to rule out obstruction. However, those with preoperative function less than 45% may exhibit functional changes greater than 5% that can be determined by postoperative renal scan.

Nonoperative management of grade 5 renal injury in children: does it have a place?

BACKGROUND: Nonoperative treatment of blunt renal trauma in children is progressively gaining acceptance; grade 5 renal trauma is associated with a significant rate of complications. OBJECTIVE: To assess the feasibility and outcome of initial nonoperative management of grade 5 blunt renal trauma in children. DESIGN, SETTING, AND PARTICIPANTS: This retrospective study included 18 children (12 boys and 6 girls; mean age: 8.4+/-3.4 yr) who presented to the authors' institutes with grade 5 blunt renal trauma between 1990 and 2007. MEASUREMENTS: An intravenous contrast-enhanced computed tomography (CT) scan demonstrated grade 5 renal trauma in all patients. Associated major vascular injuries were suspected in four patients. All were initially managed conservatively. Indications for intervention included hemodynamic instability, progressive urinoma, or persistent bleeding. Dimercaptosuccinic acid (DMSA) scans were performed at a mean time of 3.1 yr (range: 1-17) following the injury in nine patients. RESULTS AND LIMITATIONS: Four patients (22%) with suspected major vascular injuries required nephrectomy 1-21 d following the trauma. Two patients with continuing hemorrhage required selective lower-pole arterial embolization (11%). Three patients (17%) had their progressive urinoma drained percutaneously, and two of them required delayed reparative surgery for ureteropelvic junction (UPJ) avulsion. Nine patients (50%) were successfully managed nonoperatively. Kidneys were salvaged in 78% of patients. DMSA scanning showed a split function >40% in 44% of evaluated kidneys. Two patients (22%) had split function <30%. At last follow-up, none of the children were hypertensive or had any abnormality on urine analysis. CONCLUSIONS: Nonoperative management of grade 5 renal trauma is feasible. Prompt surgical intervention is required for those with major vascular injuries. Superselective arterial embolization can be an excellent option in patients with continuing hemorrhage and who have pseudoaneurysms. Patients with UPJ disruption can be salvaged by initial drainage of the urinoma followed by deferred correction.

Prospective study of the long-term effects of shock wave lithotripsy on renal function and blood pressure.

PURPOSE: We clarified the long-term effects of extracorporeal shock wave lithotripsy on renal function and blood pressure, and its relation to body mass index and type of lithotriptor. MATERIALS AND METHODS: A total of 100 patients with a single radiopaque renal stone 2 cm or less in length were followed for 18 to 57 months (mean 43.6 +/- 13.8) after being stone-free by extracorporeal shock wave lithotripsy monotherapy using 2 lithotriptors. Mean patient age was 47.9 +/- 9.1 years (range 23 to 66). Nuclear scintigraphy using (99m)technetium-mercaptoacetyltriglycine was done for all patients before extracorporeal shock wave lithotripsy, as well as at the last followup visit to estimate glomerular filtration rate, clearance and split renal function. Blood pressure measurements were recorded at admission and at each followup visit. RESULTS: Before extracorporeal shock wave lithotripsy treated side mean (99m)technetium-mercaptoacetyltriglycine clearance, glomerular filtration rate and split function were 146.22 +/- 59.48, 52.66 +/- 13.69 and 49.7 +/- 7.31, respectively. At the last followup visit they were 145.1 +/- 58.82 (p = 0.842), 54.85 +/- 15.75 (p = 0.114) and 49.96 +/- 8.68 (p = 0.577), respectively. Of 100 patients 18 were hypertensive before extracorporeal shock wave lithotripsy and 21 were hypertensive at the last followup visit. Mean diastolic blood pressure before extracorporeal shock wave lithotripsy was 80.2 +/- 6.2 vs 80.6 +/- 7.8 mm Hg (p = 0.674) at the end of followup. Mean systolic blood pressure before extracorporeal shock wave lithotripsy was 121.2 +/- 9 vs 121.55 +/- 10.2 mm Hg by the end of the study (p = 0.748). There were no statistically significant differences among body mass index groups or lithotriptor groups. CONCLUSIONS: Extracorporeal shock wave lithotripsy is a safe procedure and has no significant long-term effects on renal function or blood pressure regardless of the type of machine used or body mass index.

Use of oxidized cellulose for corporal body grafting and suture-less correction of severe penile chordee: an experimental study in rabbits.

OBJECTIVE: To evaluate the efficacy of oxidized cellulose, Surgicel(TM) (Johnson & Johnson Medical, New Brunswick, NJ, USA) for patching defects in the tunica albuginea in a rabbit model, with a future application to correct chordee. MATERIALS AND METHODS: The study comprised nine New Zealand white male rabbits; a rectangular 15 x 5-mm defect was created in the ventral tunica albuginea that was covered by Surgicel. The skin was closed with no catheters left in situ after the procedure. The rabbits were killed in groups of three at 2, 6 and 12 weeks after surgery. The evaluation included cavernosography and histopathological examination of sections of the penis stained with haematoxylin and eosin, and Masson's trichrome. RESULTS: No deaths were caused by the procedure, and none of the rabbits developed bleeding or haematoma after surgery. Cavernosography at 2 weeks showed contrast medium leaking from the site of the Surgicel, but at 6 and 12 weeks all rabbits had a straight erection with patent corpora and no evidence of narrowing or venous leak. Histopathological evaluation revealed evidence of the remnants of Surgicel surrounded by acute inflammatory cell infiltrate with early neovascularization at 2 weeks. At 6 and 12 weeks, there was complete normal regeneration of the tunica albuginea with no foreign-body reaction. CONCLUSIONS: In this pilot study, Surgicel had a clear haemostatic effect when covering a defect in the tunica albuginea. Moreover, normal tunica albuginea regenerated by 6 weeks and was maintained at 12 weeks. These results suggest that Surgicel might be considered a safe and effective grafting material for tunica albuginea substitution, including the surgical management of penile chordee.

Treatment of renal stones in children: a comparison between percutaneous nephrolithotomy and shock wave lithotripsy.

PURPOSE: We compared the results of percutaneous nephrolithotomy and shock wave lithotripsy for the treatment of 1 to 2 cm renal stones in children. MATERIALS AND METHODS: The study included 166 children with renal stones 1 to 2 cm. A total of 75 patients (82 kidneys) were treated with percutaneous nephrolithotomy and 91 (93 kidneys) were treated with shock wave lithotripsy. Mean followup was 31 +/- 10 months (range 6 to 84). Both groups were compared regarding stone-free rate, re-treatment rate, complications and incidence of stone recurrence. RESULTS: Both groups were comparable regarding preoperative characteristics. Of the units treated with percutaneous nephrolithotomy 4 (4.9%) were associated with minor complications. Stone-free rate after a single session of percutaneous nephrolithotomy was 86.6% (71 units), and the remaining 11 kidneys with residual stones were successfully treated with repeat percutaneous nephrolithotomy in 7 and shock wave lithotripsy in 4. Therefore, a total of 78 units (95%) were stone-free after percutaneous nephrolithotomy monotherapy, and the overall stone-free rate at 3 months was 100%. Of the patients undergoing shock wave lithotripsy 1 (1.1%) had development of steinstrasse and was successfully treated with ureteroscopy. The overall re-treatment rate after shock wave lithotripsy was 55%. A total of 79 units (84.9%) were stone-free after shock wave lithotripsy monotherapy, whereas 7 (7.5%) with no gross response to treatment were treated with percutaneous nephrolithotomy and 7 with insignificant stones less than 4 mm were followed. Therefore, the overall stone-free rate at 3 months was 92.5%. The differences in stone-free rates and re-treatment rates significantly favored percutaneous nephrolithotomy, while the incidence of complications and stone recurrence at last followup were not significantly different between the groups. CONCLUSIONS: For treatment of 1 to 2 cm renal stones in children percutaneous nephrolithotomy is better than shock wave lithotripsy, yielding higher stone-free and lower re-treatment rates.

Diagnosis of ureteral obstruction in patients with compromised renal function: the role of noninvasive imaging modalities.

UNLABELLED: We compared the role of noncontrast computerized tomography (NCCT), magnetic resonance urography (MRU), and combined abdominal radiography (KUB) and ultrasonography (US) in the diagnosis of the cause of ureteral obstruction in patients with compromised renal function. MATERIALS AND METHODS: The study included 149 patients, of whom 110 had bilateral obstruction and 39 had obstruction of a solitary kidney. Therefore, the total number of renal units was 259. All patients had renal impairment with serum creatinine greater than 2.5 mg/dl. Besides conventional KUB and US all patients underwent NCCT and MRU. The gold standard for diagnosis of the cause of obstruction included retrograde or antegrade ureterogram, ureteroscopy and/or open surgery. The sensitivity, specificity and overall accuracy of NCCT, MRU, and combined KUB and US in the diagnosis of ureteral obstruction were calculated in comparison with the gold standard. RESULTS: The definitive cause of ureteral obstruction was calculous in 146 and noncalculous in 113 renal units, including ureteral stricture in 65, bladder or ureter in 43, extraurinary collection in 3 and retroperitoneal fibrosis in 2. The site of stone impaction was identified by NCCT in all 146 renal units (100% sensitivity), by MRU in 101 (69.2% sensitivity), and by combined KUB and US in 115 (78.7% sensitivity) with a difference of significant value in favor of NCCT (p <0.001). Ureteral strictures were identified by NCCT in 18 of the 65 cases (28%) and by MRU in 54 of 65 (83%). Bladder and ureteral tumors causing ureteral obstruction could be diagnosed in approximately half of the patients by NCCT (22 of 43) and in all except 1 by MRU (42 of 43). NCCT and MRU could identify all extraurinary causes of obstruction. Overall of the 113 kidneys with noncalculous obstruction the cause could be identified by MRU in 101 (89% sensitivity), by NCCT in 45 (40% sensitivity), and by combined KUB and US in only 20 (18% sensitivity) with a difference of significant value in favor of MRU (p <0.001). CONCLUSIONS: In patients with renal impairment due to ureteral obstruction NCCT has superior diagnostic accuracy for detecting calculous causes of obstruction but MRU is superior for identifying noncalculous lesions.

Diagnosis of noncalcareous hydronephrosis: role of magnetic resonance urography and noncontrast computed tomography.

OBJECTIVES: To evaluate the role of magnetic resonance urography (MRU) and noncontrast computed tomography (NCCT) in the diagnosis of noncalcareous hydronephrosis when excretory urography (intravenous urography) is either contraindicated or inconclusive. METHODS: A total 108 consecutive patients with noncalcareous hydronephrosis were included in this study. In all patients, intravenous urography was either contraindicated or could not determine the diagnosis. In all patients, calculus obstruction was excluded by NCCT and all underwent heavily T2-weighted MRU. The final definitive diagnosis was established by retrograde or antegrade ureterography, endoscopy, or open surgery and was considered the reference standard for the diagnosis of obstruction. Normal kidneys in patients with unilateral obstruction were considered the reference standard for the absence of obstruction. The results of MRU were compared with those of NCCT regarding sensitivity, specificity, and overall accuracy. RESULTS: Of the 108 patients, 5 had bilateral obstruction and the remaining 103 had unilateral obstruction. Of the latter group, 5 had a solitary kidney; therefore, the total number of renal units was 211 (113 obstructed and 98 normal units). Ureteral strictures were identified by NCCT in 15 (28%) of 54 and by MRU in 45 (83%) of 54 patients. Bladder, ureter, or prostate tumors causing ureteral obstruction could be diagnosed in one half of the 54 patients with such tumors by NCCT (27 of 54) and in all but 2 patients by MRU (52 of 54). Both NCCT and MRU could identify all extraurinary causes of obstruction. Overall, of the 113 kidneys with noncalculus obstruction, the cause could be identified by MRU in 102 (sensitivity of 90%) and by NCCT in 47 (sensitivity of 42%), a difference of statistically significant value in favor of MRU (P <0.001). The specificity of T2-weighted MRU and NCCT was 100% and 99%, respectively (not a statistically significant difference). The overall accuracy of T2-weighted MRU and NCCT was 95% and 68%, respectively (P <0.001). CONCLUSIONS: In patients with ureteral obstruction in whom intravenous urography is not helpful and after NCCT has excluded stone disease, heavily T2-weighted MRU is a sensitive and specific method in the identification of the cause of obstruction.

Noncontrast computed tomography in obstructive anuria: a prospective study.

OBJECTIVES: To evaluate the role of noncontrast computed tomography (NCCT) in the determination of the cause of obstructive anuria and to compare its accuracy with that of the traditional methods of combined plain abdominal x-ray (KUB) and gray-scale abdominal ultrasonography (US). METHODS: The study included 40 consecutive patients with obstructive anuria. In addition to the routine evaluation, which included history, clinical examination, biochemical profile, KUB, and US, all patients underwent NCCT. The study patients were tested against an age and sex-matched control group that included the normal contralateral kidneys of 57 consecutive patients who underwent KUB, US, and NCCT for acute flank pain during the same study period. The reference standard for the determination of the cause of obstruction was retrograde or antegrade ureterography with or without ureteroscopy or open surgery. The absence of obstruction in the control group was confirmed by nonequivocal normal intravenous urography of the side free of flank pain. Both NCCT and combined KUB and US were compared regarding the sensitivity, specificity, and overall accuracy. RESULTS: The study group had 48 renal units, because obstruction was bilateral in 8 patients and of a solitary kidney in 32. Of the 42 renal units with calculus obstruction, the site of stone impaction was identified in all renal units by NCCT (sensitivity 100%) and in only 25 by combined KUB and US (sensitivity 59.5%)-a significant difference (P = 0.0001). Of the 6 renal units with noncalcular obstruction, both NCCT and US diagnosed the cause of obstruction in 3. The overall sensitivity of NCCT in the determination of the cause of obstructive anuria was 94% and that of combined KUB and US was 58%-a significant difference (P = 0.0001). The specificity of NCCT was not significantly different from that of combined KUB and US (96.5% versus 93%, respectively). The overall accuracy of NCCT was 95% and that of combined KUB and US was 77%-a significant difference (P = 0.0003). CONCLUSIONS: In patients with obstructive anuria, conventional KUB and US could not identify the cause of ureteral obstruction in about 40% of the patients. Under such conditions, NCCT can accurately provide the diagnosis, obviating the need of invasive and expensive diagnostic procedures.

Recoverability of renal function after relief of acute complete ureteral obstruction: clinical prospective study of the role of renal resistive index.

OBJECTIVES: To study the values of the renal resistive index (RI) before and at different points after relief of obstructive anuria and to correlate these values with the corresponding values of serum creatinine and with the recovery of renal function after release of obstruction. METHODS: A total of 32 consecutive patients with obstructive anuria were prospectively evaluated by measurement of RI before drainage and at 3 days, 1 week, 2 weeks, and 4 weeks after drainage. Serum creatinine was measured at all points of the RI examination. Moreover, RI was measured in an age and sex-matched control group of 24 consecutive healthy donors and volunteers. RESULTS: The study included 40 obstructed and 48 normal kidneys. In the obstructed kidneys, the mean RI values decreased significantly from 0.78 +/- 0.05 before drainage to 0.70 +/- 0.09 at 3 days after drainage (P <0.001) with an additional significant reduction to 0.68 +/- 0.08 at 7 days after drainage (P <0.01) and stabilized thereafter. Serum creatinine decreased significantly from 8.4 +/- 4.4 mg/dL before drainage to 4.7 +/- 3.8 mg/dL 3 days after drainage (P <0.001) and then to 3.6 +/- 3.7 mg/dL 7 days after drainage (P <0.001) and stabilized thereafter. The correlation between the RI and serum creatinine at the overall points of measurement was good. Obstructed kidneys were classified into two groups according to the recovery of renal function after obstruction relief: those that showed significant improvement of serum creatinine (24 kidneys, group 1) and those with no significant improvement of serum creatinine (16 kidneys, group 2). In group 1, the difference between the mean RI values before and after drainage was statistically significant (0.78 +/- 0.05 versus 0.64 +/- 0.06, P <0.001); in group 2, the difference between the before and after drainage RI values was not significant (0.781 +/- 0.040 versus 0.779 +/- 0.039). The mean RI of the normal kidneys was 0.66 +/- 0.04. A comparison between the mean RI values of the control group and the mean RI values of the obstructed patients after drainage showed no significant difference in group 1; markedly higher values were noted in group 2 at all points after drainage. CONCLUSIONS: In the setting of acute complete renal obstruction, the RI has a good positive correlation with serum creatinine. Recovery of renal function could not be predicted from the changes in RI before obstruction release. However, a reversal of a previously elevated RI could be used as an early indicator that renal function recovery is likely.