Renal function before and after pyeloplasty: does it improve?

Renal cortical transit time in the evaluation of prenatally detected presumed pelvi ureteric junction like obstruction: A systematic review

Introduction

Differentiating nonobstructive from obstructive dilatation of the kidney is a clinical dilemma in prenatally detected hydronephrosis. Many radionuclide renogram parameters have been used to differentiate obstructed from non-obstructed units, including cortical transit time (CTT). We evaluate the role of CTT in identifying obstruction through a systematic review.

Methods

A literature search of the MEDLINE, MEDLINE In-Process, and MEDLINE Epub Ahead of Print, EMBASE, Google scholar, Pub Med, and Cochrane Library was done using key words - radionuclide renogram, CTT, parenchymal transit time, cortical transit, renography to identify articles on the subject. The identified articles were assessed for appropriateness and reviewed.

Results

The initial search yielded a total of 1583 articles, after adding the articles from references and applying the inclusion and exclusion criteria a total of 28 articles were selected. CTT showed good inter observer agreement in identifying obstruction. The use of CTT as a single parameter for determining the need for surgery and to identify those kidneys which will have functional improvement after surgery has been evaluated and has been found to be useful. CTT is best used in conjunction with ultrasonography to make clinical decisions.

Conclusion

The commonly used visual method of estimating the CTT, is a promising parameter for the evaluation of prenatally detected pelviureteric junction obstruction. Further well-designed multicenter prospective studies are needed to establish it as the most specific parameter to differentiate obstructive from nonobstructive dilatation of the pelvicalyceal system.

Does relative renal function improve after intervention for chronic ureteric obstruction?

Introduction

Unilateral renal function often deteriorates with chronic ureteric obstruction. Our objectives were to determine the change in relative renal function (RRF) by MAG3 renography after intervention for ureteric obstruction, and to identify clinical/epidemiological factors which influence long-term outcomes.

Material and methods

We identified 228 patients from 2006 to 2017 who underwent MAG3 renography before and after intervention for unilateral ureteric obstruction. Patients were grouped into categories preoperatively - with normal RRF (43–57%) through mild (29–42%), moderate (15–28%) and severe (<15%) impairment of RRF. Patient demographics, types of obstructive uropathy and intervention employed were analysed. Each group was assessed for the absolute change in RRF and change in RRF category postoperatively.

Results

The mean patient age was 50.4 years (SD 16.7), and 62.3% were female. Overall, the mean pre- and post-intervention RRF of the obstructed kidney did not differ significantly (32.30% vs. 32.20%, P = 0.835). Most patients remained in their preoperative RRF group: 85.9% of normal, 67.4% of mild, 64.4% of moderate and 73.3% of patients with severe RRF impairment did not change category.

Patients with mildly impaired preoperative RRF showed a significant worsening postoperatively (36.37% vs. 34.58%, P = 0.024). The other three groups showed no significant change in RRF following intervention.

Multivariate logistic regression analysis showed no statistically significant association between type of intervention, age, gender or diagnosis and improvement in postoperative RRF category.

Conclusions

Our results show that RRF does not improve significantly after intervention for ureteric obstruction. The aim should therefore be to maintain existing renal function and relieve symptoms.

Uretero-Pelvic Junction Stenosis: Considerations on the Appropriate Timing of Correction Based on an Infant Population Treated with a Minimally-Invasive Technique

There is no univocal consensus about timing of intervention and best surgical approach for infants with asymptomatic uretero-pelvic junction obstruction (UPJO). We conducted a retrospective analysis of patients undergoing one-trocar-assisted pyeloplasty (OTAP) in a 13 year range period by creating two homogenous groups (indications for surgery were the same for all patients): patients operated on in the first 90 days of life (34 patients; Group 1) and patients operated on between 3 and 12 months of life (34 patients; Group 2). We observed no statistically significant differences between groups in regard to mean operative time, conversion rate to open surgery, mean hospital stay, early complications (urinary leakage) rate and mean antero-posterior diameter (APD) reduction rate. Moreover, no statistical improvement was seen between groups in regard to separate renal function (SRF) at 1-year-follow-up renogram. Thanks to the HSS calculated before and 1 year after surgery, we registered an important improvement in Group I patients (p = 0.023). In our study, there was no significant evidence, in terms of intraoperative data and early postoperative outcomes, between patients who underwent an early pyeloplasty and those who underwent a delayed correction. Nevertheless, we registered a significant improvement in those patients with an impaired SRF that underwent an early surgical correction, especially in terms of urinary flow. Even though this study cannot definitely establish the superiority of early timing of correction, it is evident that further research is needed to clarify this aspect.

Factors Accountable for Unabated Obstruction Following Pyeloplasty

Purpose:

Split renal function (SFR) and frusemide washout (FWO) are assessed by the DTPA renogram to measure the renal parenchymal functions as well as the evidence of obstruction, both for diagnosis and to treat the pelviureteric junction obstruction. In good number of renal units, both these parameters remain unaltered even after surgery and cause anguish to parents and referring physicians and are usually attributed toward “defective pyeloplasty.” In this study, we have tried to single out the bona fide responsible factor for the bad outcome; either the nonreversible kidney or the restenosis of pyeloplasty.

Patients and Methods:

We studied file of 69 patients in whom a double “J” (DJ) stent was left in situ for internal drainage for a duration of 8 weeks in the postoperative period. DTPA scans were performed preoperative, at 8 weeks with a stent in place, and at 12 and 24 months postremoval of the stent to assess renal function.

Results:

In our study, 45 patients (65.2%) showed improvement either in SRF or in FWO or in both after 8 weeks following pyeloplasty and 24 of 69 units (34.8%) did not show any change in renal function with DJ stent in place. Only in six units (8.7%), out of 69 units had deterioration of renal function after removal of DJ stent.

Conclusions:

In our opinion, no improvement of renal function found in 24 units (34.8%) even with internal drainage with DJ indicates irreversible renal damage. In 45 units (65.2%), renal function reversed after pyeloplasty and DJ stent. However, after the removal of the DJ, functions deteriorated in six units (8.7%) due to restenosis following pyeloplasties.

Retroperitoneal laparoscopic non-dismembered pyeloplasty for uretero-pelvic junction obstruction due to crossing vessels: A matched-paired analysis and review of literature

OBJECTIVE

To compare laparoscopic Anderson-Hynes pyeloplasty (LAHP) and retroperitoneal laparoscopic YV-pyeloplasty (LRYVP) in ureteropelvic junction obstruction (UPJ) in presence of a crossing vessels (CV).

METHODS

Our database showed 380 UPJO-cases,who underwent laparoscopic retroperitoneal surgery during the last 2 decades including 206 non-dismembered LRYVP, 157 dismembered pyeloplasties LAHP, and 17 cases of laparoscopic ureterolysis. Among them 198 cases were suitable for a matched-pair (2:1) analysis comparing laparoscopic retroperitoneal non-dismembered LRYVP (Group 1, n = 131) and dismembered LAHP (Group 2, n = 67) in presence of a crossing vessel. Patients were matched according to age, gender, kidney functions, and obstruction grade. Complications were graded according to modified Clavien-classification.

RESULTS

Comparative data were similar between both groups (LRYVP vs. LAHP) including mean operating time (112 min vs. 114 min), complication rates (4.2% vs. 7.3%) mainly Grade 1-2 according to Clavien classification, and success rates (90% vs. 89%). These results reflected in the reviewed literature indicate that LRYVP provides the advantage of minimal dissection in case of CV with similar outcome. However, redundant pelvis and anteriorly crossing vessels still require a dismembered pyeloplasty LAHP.

CONCLUSION

LRYVP has achieved similar results compared with the previous golden standard of open surgery, especially in case of crossing vessels apart from presence of a redundant pelvis or anteriorly crossing vessel. This can be further improved when using the small access retroperitoneoscopic technique respectively mini-laparoscopy.

Is decreased diameter of renal pelvis in prone position an indicator of successful pyeloplasty?

OBJECTIVE

To evaluate patients who had undergone pyeloplasty for pelviureteric junction obstruction, by measuring the anteroposterior diameter (APD) of the renal pelvis in supine and prone positions, and determine whether a decrease in APD in prone position can exclude obstruction in dilated renal system.

MATERIALS AND METHODS

From January 2012 to December 2013, patients who had undergone pyeloplasty were evaluated by ultrasound in two centers. The difference of APD of the renal pelvis in supine and prone positions was obtained. Correlation was made with the pre- and post-pyeloplasty renal function by radionuclide renogram.

RESULTS

There were 42 patients (31 males, 11 females; age range 5 months to 18 years). Residual hydronephrosis was detected in 41 patients of whom 35 patients (85%) showed decrease in APD by >10% in prone position. These patients and the one without hydronephrosis showed either no deterioration or improvement in renal function. Six patients (15%) showed either no change or increase in APD in prone position. Three patients (7.5%) were confirmed to have decrease in renal function indicating obstruction. Three patients (7.5%) showed no deterioration of renal function, but sluggish drainage on radionuclide renogram.

CONCLUSION

Demonstration of decreased APD of renal pelvis in prone position by ultrasound is useful to differentiate obstructed from non-obstructed dilated renal system, and it correctly identified 85% candidates with successful pyeloplasty. In patients with no decrease or increase in APD at prone position, further follow-up is recommended to rule out obstruction.

Pelvis/cortex ratio: A sonographic marker of pelvi ureteric junction obstruction in children

Objectives

The aim of the study is to document pelvis/cortex ratio (P/C ratio) in children presenting with antenatally detected hydronephrosis and determine whether it could be used as a sonographic marker of Pelvi ureteric junction (PUJ) obstruction.

Materials and Methods:

All the children presenting with unilateral fetal hydronephrosis (PUJ) between Jan 2007 and March 2008 were included. Ultrasonogram was performed by the same sonologist and P/C ratio was determined by dividing maximum anteroposterior pelvic diameter with maximum cortical thickness.

Results:

Among a total of 111 children, 87 (78%) improved on conservative management while 24 (22%) required pyeloplasty. The mean (± SD) P/C ratio was 2.7 ± 2.18 in those improved on conservative management while 13.5 ± 1.48 in those who required surgery (P < 0.01). All (22/22) children with P/C ratio of 12 or above required pyeloplasty, while 2/5 with P/C ratio 8-12 and none (0/84) with P/C ratio less than 8 required pyeloplasty (P<0.01).

Conclusions:

P/C ratio could be used as a marker of PUJ obstruction in children with hydronephrosis.

Evaluation of UPJ obstruction before and after pyeloplasty using MR urography

This article builds on the previous article in this symposium and shows how MR urography contributes to the postoperative evaluation of children with UPJ obstruction. By analyzing the postoperative results, we derived new insights into their preoperative evaluation. With MR urography we combine simultaneous physiological and anatomic evaluation that enables us to identify changes in renal pathophysiology that occur in association with impaired drainage and obstruction. We studied 35 children before and after pyeloplasty. The pyeloplasty was considered successful in 30 and unsuccessful in 5. Both anatomic and functional criteria were used. The anatomic parameters included the degree of hydronephrosis, the appearance of the renal parenchyma, the quality of the nephrogram and the presence of crossing vessels. The functional criteria included the renal transit time, the calyceal transit time, the volumetric differential function, the Patlak differential function, the difference between the volumetric and Patlak differential function and the Patlak number per milliliter of renal tissue. No single parameter was sufficient to fully characterize UPJ obstruction, but by synthesizing all the information we were able to subdivide UPJ obstruction into compensated, decompensated and uropathic kidneys. Decompensated systems had the most significant improvement following successful pyeloplasty. Compensated systems showed little improvement in renal function, and uropathic kidneys were associated with a poor prognosis. It is clear that not all UPJ obstructions are the same, and it seems logical that treatment should be individually tailored rather than using a standard approach for all cases. Because MR urography can identify pathophysiological differences in children with UPJ obstruction that are occult to renal scintigraphy, it has an important potential role in identifying those who will benefit most from pyeloplasty and those who are probably best observed.

The change in renal function in the supranormal hydronephrotic kidney after pyeloplasty

OBJECTIVE

To investigate changes in the differential renal function (DRF) before and after pyeloplasty in renal units with unilateral pelvi-ureteric junction obstruction (PUJO) with supranormal function, and to evaluate the clinical significance.

PATIENTS AND METHODS

We reviewed the medical and radiographic records of 29 children (26 boys and three girls) with unilateral PUJO with a DRF (estimated by (99m)Tc-mercaptoacetyltriglycine renal scintigraphy) of >/= 50% in the affected renal unit, who had pyeloplasty and were followed for >1 year after surgery. Patients were divided into two groups according to the degree of change in their DRF to compare the clinical variables, anteroposterior pelvic diameter and parenchymal thickness measured by renal ultrasonography. The mean (range) follow-up after pyeloplasty was 35 (12-89) months.

RESULTS

After pyeloplasty, although the mean DRF reduced from 53.8% to 51.4%, in seven (24%) patients the DRF decreased significantly (>5%) while most (76%) showed a change of </= 5% of the preoperative function, or further improvement. In the seven patients with a DRF of >/= 55% before surgery, the DRF afterward was >55% in four and 50-55% in one. Between those with and with no significant reduction in DRF, only the preoperative renal parenchymal thickness differed significantly (2.78 vs 5.00 mm, P = 0.006).

CONCLUSION

Supranormal DRF exists and represents the true split function of the affected renal unit in patients with adequate renal parenchyma; these units maintained the supranormal function after pyeloplasty. Parenchymal thickness might be useful to differentiate between the true and false estimates and predict surgical outcome before surgery.

Dismembered pyeloplasty in children: A review of 5 years single center experience

AIM

Dismembered pyeloplasty is the treatment of choice for significant ureteropelvic junction obstruction in children. In the present study, we review our experience in 103 pediatric patients and present the clinical characteristics, the surgical treatment and its complications and the long term results.

METHODS

We have reviewed the medical charts of 103 consecutive patients who underwent dismembered pyeloplasty in a 5-year period, from 1997 to 2002. Preoperative data, short- and long-term complications and outcome were recorded. Imaging studies included urinary tract sonography and dynamic renal scans, the results of which were compared pre- and postoperatively.

RESULTS

Most of our patients were boys (81%), diagnosed prenatally (78%). We had no major complications and acceptable incidence of minor complications. Postoperative outcome was excellent, with decreased hydronephrosis (81%), improved renal drainage (87%) and preserved or improved renal function (89%).

CONCLUSION

Dismembered pyeloplasty can be performed with a low incidence of minor complications, no major complications and excellent long-term outcome.

MR imaging of kidneys: functional evaluation using F-15 perfusion imaging

BACKGROUND

Children with hydronephrosis are typically investigated by a combination of diuretic renal scintigraphy, ultrasound, and voiding cystourethrography. Unfortunately, there is no gold standard to assess obstruction.

PURPOSE

The purpose of our study was to evaluate the utility of dynamic contrast enhanced MR urography in the investigation of children with hydronephrosis to define urinary tract anatomy, to calculate differential renal function and to assess urinary tract obstruction.

MATERIALS AND METHODS

Dynamic contrast-enhanced MR imaging was performed in 40 children with unilateral hydronephrosis. There were 14 girls and 26 boys with an age range of 1 month to 14 years (mean 1.4 years). The information from traditional imaging modalities was compared to the information obtained from the single MR study.

RESULTS

The anatomic imaging with MR urography was superior to other modalities. The split renal function was estimated with MR urography by calculating the volume of enhancing renal parenchyma and was comparable to renal scintigraphy ( r=0.98). By using surgery versus non-surgery as the decision point, with MR urography the sensitivity was 100%, specificity 71%, positive predictive value 86%, negative predictive value 100%, and diagnostic efficiency 90%. For renal scintigraphy the sensitivity was 96%, the specificity 56%, positive predictive value 76%, negative predictive value 90%, and diagnostic efficiency 79%.

CONCLUSIONS

Dynamic contrast-enhanced MR urography provides superior anatomic and functional information when compared with ultrasound and diuretic renal scintigraphy. The information is gathered in a single study that does not use ionizing radiation. It is likely that MR urography will replace renal scintigraphy in the evaluation of hydronephrosis in children.