Pattern of renal function deterioration as a predictive factor of unilateral ureteropelvic junction obstruction treatment

Managing Ureteropelvic Junction Obstruction in the Young Infant

In the last decade, management of congenital UPJ obstruction has become progressively observational despite the lack of precise predictors of outcome. While it is clear that many children will have resolution of their hydronephrosis and healthy kidneys, it is equally clear that there are those in whom renal functional development is at risk. Surgical intervention for the young infant, under 6 months, has become relatively infrequent, yet can be necessary and poses unique challenges. This review will address the clinical evaluation of UPJO in the very young infant and approaches to determining in whom surgical intervention may be preferable, as well as surgical considerations for the small infant. There are some clinical scenarios where the need for intervention is readily apparent, such as the solitary kidney or in child with infection. In others, a careful evaluation and discussion with the family must be undertaken to identify the most appropriate course of care. Further, while minimally invasive pyeloplasty has become commonly performed, it is often withheld from those under 6 months. This review will discuss the key elements of that practice and offer a perspective of where minimally invasive pyeloplasty is of value in the small infant. The modern pediatric urologist must be aware of the various possible clinical situations that may be present with UPJO and feel comfortable in their decision-making and surgical care. Simply delaying an intervention until a child is bigger may not always be the best approach.

Diuretic renography in hydronephrosis: a retrospective single-center study

PURPOSE

Ureteropelvic junction obstruction (UPJO) is one of the most common causes of hydronephrosis other than transient hydronephrosis. In children with unilateral hydronephrosis, mercaptoacetyltriglycine-3 diuretic renography (MAG₃) is used to calculate differential renal function and to assess drainage. The aim of our study is to examine whether anteroposterior pelvic diameter on renal ultrasound (US) scan can predict both differential renal function (DFR) and obstruction in pediatric patients, and whether an US adequately identifies those patients who need further investigation. We also aimed to design a study with a larger sample size than previous studies investigating the relationship between MAG₃ and US.

METHODS

We retrospectively reviewed the MAG₃, US, dimercaptosuccinic acid scan (DMSA) findings, and medical records of pediatric patients with hydronephrosis and/or atrophy who were at follow-up between January 2013 and December 2016 in our center which is located in the south-east region of Turkey.

RESULTS

Two hundred and twenty-five pediatric patients (M/F = 156/69) with unilateral hydronephrosis but without VUR were enrolled in this study. The mean age of the children was 45.4 ± 48.3 months (range 2-173 months). Sixty-nine patients had obstructive pattern on ^99mTc-MAG₃. With respect to obstructive pattern, there was a significant difference between the hydronephrosis groups both with 15 and 20 mm border. An APD of greater than 20 mm had 15.8 times (95% CI 5.72-43.69) higher likelihood of having obstruction MAG3 findings. On the other hand, an APD of greater than 15 cm had 9.2 times (95% CI 3.01-28.57) higher likelihood of having obstruction MAG₃ findings. The incidence of urinary tract infections was lower than in the obstructive group than the other groups. The regression analysis showed that an APD of greater than 20 mm was a risk factor for low DRF (OR = 5.208, 95% CI 1.529-17.743, p = 0.008). However, the regression analysis showed that an APD of greater than 15 mm was not a risk factor low DRF.

CONCLUSIONS

The combination of ultrasound and MAG₃ provides the necessary anatomical and functional information to follow the degree of obstruction and to decide between surgical intervention and conservative follow-up. Our study supports a threshold of 20 mm rather than 15 mm for severe obstruction and a low DRF. An APD threshold greater than 15 mm did not have a predictive value in DRF estimation.

Primary non-surgical management of unilateral ureteropelvic junction obstruction in children: a systematic review

Ureteropelvic junction obstruction (UPJO) is the most common obstructive uropathy and its optimal management remains controversial. However, there is a current trend towards non-surgical management. We aimed to determine the effects of the non-surgical management in children with unilateral UPJO. For a systematic review, we searched MEDLINE, EMBASE, CENTRAL, clinical trials registries, and selected conference proceedings for eligible studies. Any type of study reporting the outcomes renal function, secondary surgical intervention, drainage pattern or hydronephrosis of non-surgical management in children with unilateral UPJO was included. Data from 20 studies were extracted and evaluated by two independent authors. The pooled prevalence was 21% for split renal function deterioration, 27.9% for secondary surgical intervention, 3.2% for progressive hydronephrosis, and 82.2% for improved drainage pattern. Not all patients with surgical intervention regained split renal function from enrolment. Renal imaging methods did not strongly correlate with each other. Many studies had to be excluded because of a lack of detection of an obstruction or mixed populations with bilateral UPJO or other uropathies. The variable definitions of UPJO, different criteria for surgical intervention, incongruity of management protocols, and the imprecise reporting of outcomes were limiting factors in the comparability of the results, leading to heterogeneity in meta-analyses. Although the available evidence cannot recommend or refute the current non-surgical management, the systematic review clarifies aspects of the ongoing controversy by providing realistic estimates for non-surgical management in children with unilateral UPJO. Additionally, it reveals unclear potential risks, particularly for long-term outcomes, which were rarely reported.

Predictors of Renal Functional Improvement After Pyeloplasty in Ureteropelvic Junction Obstruction: Clinical Value of Visually Assessed Renal Tissue Tracer Transit in 99mTc-mercaptoacetyltriglycine Renography

OBJECTIVE

To determine the clinical value of visually assessed renal tissue transit time (TTT) in ^99mTc-mercaptoacetyltriglycine (^99mTc-MAG3) renography for patients undergoing pyeloplasty.

MATERIALS AND METHODS

Medical records of 164 patients who underwent dismembered pyeloplasty were retrospectively reviewed. Baseline and postoperative renal ultrasonography and ^99mTc-MAG3 renography were performed. Two urologists blinded to clinical data evaluated the renography and classified TTT as timely or delayed based on visualization of the tracer in the kidney pelvis between 2 and 10 minutes. Renal functional change after pyeloplasty was compared between patients in the timely and delayed groups.

RESULTS

A total of 126 patients (median age, 9 months) were evaluated after excluding patients with bilateral ureteropelvic junction obstruction, a single functioning kidney, duplicated ureter, or <3 months of follow-up. There were no differences between 89 patients with timely TTT and 37 patients with delayed TTT in mean preoperative hydronephrosis grade (3.7 vs 3.8) and pelvic diameter (3.1 cm vs 3.4 cm). Although the pre- and postoperative mean values of differential renal function (DRF) were significantly higher in the timely group than in the delayed group (47.2% vs 38.3% and 47.9% vs 44.6%), DRF change was greater in the delayed group (6.3% vs 0.6%). In multivariate analysis, delayed TTT was the only significant predictor of >5% improvement in renal function after pyeloplasty.

CONCLUSION

Delayed TTT in ^99mTc-MAG3 renography was a significant predictor of renal functional improvement after pyeloplasty in ureteropelvic junction obstruction. Because substantial improvement of renal function is anticipated, we recommend immediate pyeloplasty in patients with delayed TTT and decreased DRF.

Delayed renal tissue tracer transit in Tc-99m-DTPA renography correlates with postoperative renal function improvement in UPJO patients

OBJECTIVE

The aim of the study was to explore the potential parameters for evaluating the improvement in relative renal function (RRF) in patients with unilateral ureteropelvic junction obstruction (UPJO) who underwent surgery. In this regard we observed the RRF expressed as the obstructed kidney's percentage contribution to overall renal function in technetium-99m diethylenetriaminepentaacetic acid (Tc-99m-DTPA) diuretic renography.

MATERIALS AND METHODS

Data on 47 patients, who underwent Anderson-Hynes pyeloplasty for diagnosed unilateral UPJO during the period of February 2003 to October 2014, were retrospectively collected. Tc-99m-DTPA diuretic renography was performed on all patients before and after surgery, and no morphological or functional abnormalities were detected on the contralateral kidney. Several parameters, especially renal tissue tracer transit (TTT), the response to furosemide stimulation, and RRF, were evaluated. All data were analyzed with the statistical software SPSS, 17.0, and a value of P less than 0.05 was considered statistically significant.

RESULTS

Data on 42 patients were eventually retained for further analysis; five patients were excluded because of indeterminate TTT. All patients showed obstructive response to furosemide stimulation with a preoperative RRF of 41±12%. Postoperative RRF of the obstructed kidneys was 47±11%, significantly higher than the preoperative RRF (P<0.05). Postoperative RRF improvement (absolute increment≥5%) was seen in 18/42 (43%) patients, and 24/42 (57%) of them manifested with postoperative drainage improvement. After surgery, both the RRF increment and the percentage of patients with postoperative RRF improvement in the preoperative delayed TTT group were significantly higher than those in the normal TTT group (12±7 vs. 2±4%, and 81 vs. 19%, respectively; P<0.05), but no significant difference in postoperative drainage improvement was detected between the two groups (56 vs. 54%, P>0.05). None of the other factors, including the preoperative RRF, obstructed kidney location, surgical method, sex, and age, had a significant influence on postoperative RRF improvement (P>0.05).

CONCLUSION

Preoperatively delayed TTT of Tc-99m-DTPA diuretic renography was an independent factor that correlated with RRF improvement of unilaterally hydronephrotic kidneys, and might provide valuable information for surgical decisions pertaining to UPJO patients.

Postnatal evaluation of intrauterine hydronephrosis due to ureteropelvic junction obstruction

PURPOSE: Fetal hydronephrosis is a frequent finding due to advances in prenatal ultrasonography. The definition of fetal and neonatal urinary tract obstruction is a very difficult task requiring confirmation of reduced renal function and hydronephrosis. In this study we followed a series of consecutive patients with intrauterine hydronephrosis that persisted during post-natal life. METHODS: 116 newborns with antenatal hydronephrosis diagnosed by ultrasound and submitted to a specific post-natal evaluative protocol with a follow-up period of 6 years. RESULTS: In 45 (38.8%) of 116 patients, ureteropelvic junction (UPJ) obstruction was confirmed and surgical correction of the UPJ obstruction was done in 19 patients. From 26 children who were initially submitted to non-surgical treatment, only 6 (23%) needed a surgical approach during follow up. Overall analysis showed that surgery was performed in 25 patients with UPJ obstruction, and the others 20 patients were kept under clinical observation, since normal renal function was confirmed by scintigraphy scans. CONCLUSION: Fetal hydronephrosis due to UPJ obstruction deserves careful postnatal evaluation. UPJ obstruction is the most frequent anomaly and its surgical treatment has very precise indications. The evaluative protocol was useful in identify patients that could be followed-up with a non-surgical approach.

[Thickness of the renal pelvis smooth muscle indicates the postoperative course of ureteropelvic junction obstruction treatment]

OBJECTIVE

To investigate the relationship between the histopathologic findings and the postoperative course of children surgically treated for ureteropelvic junction (UPJ) obstruction.

MATERIAL AND METHODS

Twenty-eight patients operated for unilateral UPJ obstruction from 1998 to 2005 with adequate histopathologic specimens and postoperative follow up were retrospectively reviewed. Specimens were stained using elastic van Geisson to differentiate smooth muscle from collagen and elastin. Postoperative follow up included renal ultrasound (U/S) and diuretic renogram studies.

RESULTS

Twelve patients with mean renal pelvis smooth muscle thickness (mRPSMT) of 136.97 ± 34.17 improved on the 6(th) postoperative month. Nine patients that improved after 9 months postoperatively had mRPSMT=173.61 ± 33.91. The rest 7 patients that improved on the 12(th) postoperative month had mRPSMT=258.78 ± 96.09. Correlation between renal pelvis smooth muscle and time of postoperative improvement was extremely significant (r = 0.7928, p < 0.0001).

CONCLUSION

The thickness of the renal pelvis smooth muscle is significantly correlated to the postoperative course of patients with UPJ obstruction and can be used as a prognostic tool for the onset of their improvement.

Diuretic renography in hydronephrosis: renal tissue tracer transit predicts functional course and thereby need for surgery

PURPOSE

The recognition of those hydronephrotic kidneys which require therapy to preserve renal function remains difficult. We retrospectively compared the 'tissue tracer transit' (TTT) of (99m)Tc-mercaptoacetyltriglycine ((99m)Tc-MAG(3)) with 'response to furosemide stimulation' (RFS) and with 'single kidney function < 40%' (SKF < 40%) to predict functional course and thereby need for surgery.

METHODS

Fifty patients with suspected unilateral obstruction and normal contralateral kidney had 115 paired (baseline/follow-up) (99m)Tc-MAG(3) scintirenographies. Three predictions of the functional development were derived from each baseline examination: the first based on TTT (visually assessed), the second on RFS and the third on SKF < 40%. Each prediction also considered whether the patient had surgery. Possible predictions were 'better', 'worse' or 'stable' function. A comparison of SKF at baseline and follow-up verified the predictions.

RESULTS

The frequency of correct predictions for functional improvement following surgery was 8 of 10 kidneys with delayed TTT, 9 of 22 kidneys with obstructive RFS and 9 of 21 kidneys with SKF < 40%; for functional deterioration without surgery it was 2 of 3 kidneys with delayed TTT, 3 of 20 kidneys with obstructive RFS and 3 of 23 kidneys with SKF < 40%. Without surgery 67 of 70 kidneys with timely TTT maintained function. Without surgery 0 of 9 kidneys with timely TTT but obstructive RFS and only 1 of 16 kidneys with timely TTT but SKF < 40% lost function.

CONCLUSION

Delayed TTT appears to identify the need for therapy to preserve function of hydronephrotic kidneys, while timely TTT may exclude risk even in the presence of an obstructive RFS or SKF < 40%.

Is it always necessary to treat a ureteropelvic junction syndrome?

The term ureteropelvic junction (UPJ) obstruction covers different morbid entities, and the old aphorism, "A UPJ is not a UPJ" remains true. Hydronephrosis is readily seen on antenatal ultrasonography but does not necessarily imply obstruction. Although most cases will resolve spontaneously, the probability of a significant pathology is related to the degree of pyelectasis, as seen on the third trimester study. Criteria of obstruction are difficult to define with precision, but two that are well-accepted are size of the renal pelvis (> 15 mm) and relative renal function, as determined by adequate isotopic studies. A new therapeutic standard has been established, and minimally invasive surgery has finally dethroned its open rival. Possibly facilitated by robotic assistance, laparoscopic dismembered pyeloplasty is the present gold standard, albeit endopyelotomy remains the least invasive with similar results in carefully selected patients.