Temporal Trends and Practice Patterns for Inpatient Management of Malignant Extrinsic Ureteral Obstruction in the United States

Serum creatinine trajectory after drainage of kidneys with bilateral malignant ureteral obstruction: a prospective non-randomized comparative study

BACKGROUND

Serum creatinine trajectory (SCr-Tr) is a neglected prognostic tool for chronic and acute kidney injury. We aimed to assess the predictors of SCr-Tr during the time-to-nadir and serum creatinine (SCr) normalization rate after drainage, using percutaneous nephrostomy in patients with bilateral malignant ureteral obstruction.

METHODS

A prospective non-randomized study was performed on SCr-Tr in patients with bilateral malignant ureteral obstruction from August 2019 to March 2022. The primary outcome was SCr-Tr during the time-to-nadir.

RESULTS

This study included 102 patients with a mean age ± SD of 59.6 ± 14.7 years. SCr-Tr was non-linear with a mean ± SD (range) of 0.5 ± 0.4 (0.03-2.3) mg/dl/day. Multivariate analyses revealed that female gender (p = 0.016), body mass index (BMI; p = 0.005), and SCr at presentation (p < 0.001) were predictors of rapid SCr-Tr during the time-to-nadir. However, age (p = 0.008) and low urine output at presentation (p = 0.015) were associated with a lower SCr-Tr. In contrast, laterality of drainage (p = 0.544) and mean parenchymal thickness (p = 0.066) were not associated with mean SCr-Tr. Also, only the mean parenchymal thickness (p = 0.002) was a predictor of rapid SCr-Tr at ≥ 0.5 mg/dl/day. However, low BMI (p = 0.023) was associated with a high SCr normalization rate, while unilateral drainage (p = 0.045) was associated with a lower rate.

CONCLUSIONS

Female gender, low BMI, and SCr at presentation were predictors of rapid SCr-Tr during the time-to-nadir. Bilateral drainage was an independent predictor of SCr normalization rate, but not of rapid SCr-Tr. The mean parenchymal thickness was the only independent predictor for rapid SCr-Tr at ≥ 0.5 mg/dl/day.

Acute kidney injury due to bilateral malignant ureteral obstruction: Is there an optimal mode of drainage?

There is a well-known relationship between malignancy and impairment of kidney functions, either in the form of acute kidney injury or chronic kidney disease. In the former, however, bilateral malignant ureteral obstruction is a surgically correctable factor of this complex pathology. It warrants urgent drainage of the kidneys in emergency settings. However, there are multiple controversies and debates about the optimal mode of drainage of the bilaterally obstructed kidneys in these patients. This review addressed most of the concerns and provided a comprehensive presentation of this topic from the recent literature. Also, we provided different perspectives on the management of the bilateral obstructed kidneys due to malignancy. Despite the frequent trials for improving the success rates and functions of ureteral stents, placement of a percutaneous nephrostomy tube remains the most recommended tool of drainage due to bilateral ureteral obstruction, especially in patients with advanced malignancy. However, the disturbance of the quality of life of those patients remains a major unresolved concern. Beside the unfavorable prognostic potential of the underlying malignancy and the various risk stratification models that have been proposed, the response of the kidney to initial drainage can be anticipated and evaluated by multiple renal prognostic factors, including increased urine output, serum creatinine trajectory, and time-to-nadir serum creatinine after drainage.

Magnetic resonance imaging of in vitro urine flow in single and tandem stented ureters subject to extrinsic ureteral obstruction

OBJECTIVE

To quantify the relative volumetric flows in stent and ureter lumina, as a function of stent size and configuration, in both unobstructed and externally obstructed stented ureters.

METHODS

Magnetic resonance imaging was used to measure flow in stented ureters using a phantom kidney model. Volumetric flow in the stent and ureter lumina were determined along the stented ureters, for each of four single stent sizes (4.8F, 6F, 7F, and 8F), and for tandem (6F and 7F) configurations. Measurements were made in the presence of a fully encircling extrinsic ureteral obstruction as well as in benchmark cases with no extrinsic ureteral obstruction.

RESULTS

Under no obstruction, the relative contribution of urine flow in single stents is 1-10%, while the relative contributions to flow are ~6 and ~28% for tandem 6F and 7F, respectively. In the presence of an extrinsic ureteral obstruction and single stents, all urine passes within the stent lumen near the extrinsic ureteral obstruction. For tandem 6F and 7F stents under extrinsic ureteral obstruction, relative volumetric flows in the two stent lumina are ~73% and ~81%, respectively, with the remainder passing through the ureter lumen.

CONCLUSIONS

Magnetic resonance imaging demonstrates that with no extrinsic ureteral obstruction, minimal urine flow occurs within a stent. Stent lumen flow is significant in the presence of extrinsic ureteral obstruction, in the vicinity of the extrinsic ureteral obstruction. For tandem stents subjected to extrinsic ureteral obstruction, urine flow also occurs in the ureter lumen between the stents, which can reduce the likelihood of kidney failure even in the case of both stent lumina being occluded.

Predictors of nadir serum creatinine after drainage of bilaterally obstructed kidneys due to different etiologies

PURPOSE

To identify the predictors of nadir serum creatinine (SCr) after drainage of bilaterally obstructed kidneys (BOKs) by different modes: double-J stent (JJ) versus percutaneous nephrostomy (PCN) and unilateral versus bilateral drainage.

METHODS

A prospective non-randomized study was performed on patients with BOKs and raised SCr during December 2019-November 2021. Relevant variables were studied for improvement and non-improvement and for benign and malignant underlying obstructions (BUO and MUO).

RESULTS

This study included 107 patients with BOKs including 68 (63.6%) males and 39 (36.4%) females. After drainage, 86 (80.4%) patients get improved, while 21 (19.6%) patients failed to reach a nadir SCr. Drainage by PCN was significantly higher in MUO, while JJ was significantly higher in BUO (p < 0.001). Also, bilateral drainage was a significant predictor of improvement in MUO (p = 0.03). In contrast, mode of drainage had no significant effect on improvement in BUO (p = 0.84), but bilateral drainage was a significant factor of rapid time to nadir (p = 0.02). Univariate analyses revealed no significant effects on the improvement in SCr from the studied variables, except the male gender (p = 0.01), old age (p < 0.001), MUO (p = 0.01), unilateral drainage (p < 0.001), and use of PCN for drainage (p < 0.001). By multivariate analysis, unilateral drainage (p = 0.01) and MUO (p < 0.001) were independent predictors of non-improvement in patients with BOKs.

CONCLUSIONS

Male gender, old age, MUO, unilateral drainage, and drainage by PCN were significant predictors of non-improvement in SCr after drainage of BOKs. However, unilateral drainage and MUO were the only independent predictors of non-improvement.

Treatment efficacy and prognosis analysis in locally advanced or metastatic colorectal cancer patients with hydronephrosis

The effect of hydronephrosis, a common complication of metastatic colorectal cancer (CRC), on the treatment outcome and prognosis of locally advanced or metastatic CRC remains to be elucidated. The present study investigated the clinical characteristics, outcomes, and prognoses of patients with locally advanced or metastatic colorectal cancer (CRC) with hydronephrosis. Clinical data of patients with locally advanced or metastatic CRC who were attending Peking University Shenzhen Hospital and Shenzhen Cancer Hospital between January 2016 and December 2020 were retrospectively collected. A total of 52 patients with hydronephrosis based on CT or MRI findings were selected, and their clinical characteristics, treatment outcomes, and survival times were analyzed. Of the 52 patients, 33 were male (63.5%), and the median age was 49 years (range, 31-76 years). A total of 15 (28.8%) patients with CRC had synchronous hydronephrosis and the remaining 37 patients had metachronous hydronephrosis. Ureters were either compressed by peritoneal or abdominal cavity metastatic lymph nodes in 34 cases (65.4%) or by direct tumor invasion in 18 cases (34.6%). However, objective response rate (ORR) was higher in the group in which ureters were compressed by peritoneal or abdominal cavity metastatic lymph nodes; ORR, disease control rate and median progression-free survival (PFS) between the two groups were not statistically different. (P>0.05). The median survival period was only 27.0 months (95% CI, 20.549-33.451) in patients complicated with malignant hydronephrosis. Univariate and multivariate analyses showed that CA19-9 might be a prognostic factor for locally advanced and metastatic CRC patients with hydronephrosis. Metachronous metastatic CRC has a high incidence rate of complicated hydronephrosis. Targeted drugs in combination with chemotherapy improve the treatment efficacy and prognosis of patients. Notably, the present study found that CA19-9 level might be a prognostic factor in CRC patients with hydronephrosis.

Influence of Single Stent Size and Tandem Stents Subject to Extrinsic Ureteral Obstruction and Stent Occlusion on Stent Failure

Background and Purpose: Drainage of obstructed kidney due to extrinsic ureteral obstruction (EUO), required to prevent renal damage, is often achieved using double-J ureteral stents. But these stents fail frequently, and there is considerable debate regarding what stent size, type and configuration offer the best option for sustained drainage. Here, we examine the impact of stent diameter and choice of single/tandem configuration, subject to EUO and various degrees of stent occlusion, on stent failure. Methods: Computational fluid dynamics (CFD) simulations and an in vitro ureter-stent experiment enabled quantification of flow behavior in stented ureters subject to EUO and stent occlusions. Various single and tandem stents under EUO were considered. In each simulation and experiment, changes in renal pressure were monitored for different degrees of stent lumen occlusion, and onset of stent failure as well as simulated distributions of fluid flow between stent and ureter lumina were determined. Results: For an encircling EUO that completely obstructs the ureter lumen, with or without partial stent occlusion, the choice of stent size/configuration has little effect on renal pressure. The pressure increases significantly for ~90% stent lumen occlusion, with failure at >95% occlusion, independent of stent diameter or a tandem configuration, and with little influence of occlusion length along the stent. Conclusions: Stent failure rate is independent of stent diameter or single/tandem configuration, for the same percentage of stent lumen occlusion, in this model. Stent failure incidence may decrease for larger diameter stents and tandem configurations, because of the larger luminal area.

Comparative study of renal drainage with different ureteral stents subject to extrinsic ureteral obstruction using an in vitro ureter-stent model

BACKGROUND

To compare the efficacy of different ureteral stents subject to extrinsic ureteral obstruction (EUO), in a controlled in vitro stented ureter experiment.

METHODS

We employ an in vitro ureter-stent experimental set-up, with latex tubing simulating flexible ureters attached to vessels simulating renal units and bladders. The flow behavior of five ureteral stents-polymeric 8F, tandem 6F, tandem 7F, endopyelotomy and metal-was tested under a ureteral deformation configuration of 40°, with 2000 g external force over a 3.5 cm length of the ureter. A constant fluid flow was applied through the ureter-stent configurations, and pressure fluctuations in the renal unit were monitored. We considered a renal unit pressure of 10 cmH₂O or flow discontinuation in the bladder as stent failure. Urine containing debris was mimicked by use of a colloidal solution.

RESULTS

Of all assessed ureteral stents, under EUO conditions, only the single 8F stents remained patent throughout the length of the experiment. All other stents-tandem 6F and 7F, single 7F, metal and endopyelotomy-displayed limitations.

CONCLUSIONS

Tandem and metal stents show no superiority over large luminal polymeric stents for EUO treatment in this in vitro model. Larger luminal stents offer excellent resistance to external pressure and allow adequate colloidal flow. The need for frequent exchange and bladder irritation should also be considered in the choice of stent configuration for treatment of kidney drainage under EUO.

Periureteral Marginal Zone Lymphoma Resulting in Hydronephrosis and Flank Pain in the Absence of Disseminated Disease: Case Report of Two Patients Presenting with Rare But Important Differential

Background: Extrinsic compression of the ureter can result from multiple different malignancies, typically in the presence of known or disseminated disease. Rarely, hydroureteronephrosis and flank pain can occur as the presenting sign and symptom of lymphoma. In this study, we present two cases of primary ureteral obstruction in patients without a prior diagnosis of lymphoma and without bulky retroperitoneal lymphadenopathy. Case Presentation: Case #1 was a healthy 58-year-old man who presented with acute left flank pain. He was found to have left hydroureteronephrosis secondary to a proximal periureteral mass. Diagnostic ureteroscopy demonstrated this to be an extrinsic compression on the ureter and preoperative imaging was negative aside from one enlarged periaortic node. Laparoscopic ureterolysis and biopsy were remarkable for periureteral dystrophic tissue concerning for lymphoma. Case #2 was a 47-year-old woman with a solitary kidney secondary to prior left nephrectomy who presented with hydronephrosis of her solitary kidney and acute kidney injury. Retrograde pyelogram showed high-grade obstruction at the junction of the mid- and distal ureter. Periureteral thickening was noted, but no definitive masses were seen on cross-sectional imaging. Robotic ureterolysis showed dense fibrosis around the ureter. Pathology report from Cases #1 and #2 were both remarkable for marginal zone lymphoma and both patients received bendamustine and rixuximab with resolution of ureteral obstruction and their lymphoma. Conclusion: Ureteral compression as the primary presentation of periureteral lymphoma is a rare but important etiology of extrinsic malignant ureteral obstruction. These cases emphasize that malignant obstruction can occur even in the absence of disseminated disease.

Ureteral Stent and Percutaneous Nephrostomy in Managing Malignant Ureteric Obstruction of Gastrointestinal Origin: A 10 Years’ Experience

Background: Malignant ureteral obstruction (MUO) is variable in presentation and there is no consensus on its management, especially when caused by gastrointestinal (GI) malignancies. Our aim was to describe our experience with this oncological complication. Methods: We retrospectively analyzed the outcomes of ureteral stent and nephrostomy tube (NT) positioning for GI-related MUO from 2010 to 2020. We performed descriptive analysis, survival analysis, and uni- and multi-variate analysis. Results: We included 51 patients. NT was mainly used when bladder involvement occurred and when MUO revealed an ex novo cancer diagnosis. Survival was poorer in patients with new diagnoses and in those receiving no treatment after decompression. Moreover, MUO caused by upper-GI tumors was related to shorter overall survival. Conclusions: GI tumors causing MUO should be considered of poor prognosis. Treatment decisions should be weighted accurately by both specialists and the patient.