NIHR Signal Uncertainty over the use of stents after telescopic surgery for kidney stones

Published on 8 November 2016

Inserting a stent, a narrow tube, after ureteroscopic surgery for removal of kidney stones reduces unplanned hospital readmissions but causes more pain upon urination.

This review compared outcomes for patients having ureteroscopic surgery for stones who had a stent placed in the ureter (the tube connecting the kidney with the bladder) with patients who had the stent left out. There was significant variability in the results of the individual studies, and it is possible that clinical judgment was influencing the decision of whether or not to place a stent.

The review shows there is a balance between the pros and cons of using a stent, and therefore a need for clinical judgment and a discussion during the consent process to decide which patients might be more suited to a less invasive treatment approach.

Share your views on the research.

Why was this study needed?

Kidney stones alone are responsible for more than 12,000 hospital admissions every year. Many smaller stones become stuck in the ureter. They are often removed using a ureteroscope and it has been common practice to leave a stent in the ureter to make sure there is free drainage of urine from the kidney.

Stents can cause bothersome symptoms which affect patient quality of life and there has been debate about the best course of action. European guidelines suggest that, if the surgery is uncomplicated, the stent may be left out but there is no consensus on the definition of “uncomplicated” surgery.

This research was undertaken to summarise results from trials to identify which patients need stent placement, and who may benefit from having the stent left out. This understanding will help surgeons decide the best treatment for each individual patient.

What did this study do?

This systematic review included 17 studies - 13 trials and four observational studies (1,943 adults) - that examined outcomes following ureteroscopic removal of kidney stones with or without stent placement.

The main outcome of interest was unplanned hospital, emergency or physician visit within 30 days following surgery. Other outcomes included postoperative pain, infection, pain on urination, average time of the operation and further obstruction of the ureter. The researchers carried out subgroup analyses, including looking at the effect of how long the stent was left in place and analysing trials and observational studies separately.

The main sources of bias were that patients and physicians were aware of treatment allocation. In the observational studies, and also some trials, there was also the potential that treatment choice was being influenced by patient characteristics.

What did it find?

  • Stent omission increased the odds of unplanned medical visit by over 60% compared with stent placement (odds ratio [OR] 1.63, 95% confidence interval [CI] 1.15 to 2.30). However, there were important differences (heterogeneity) between the results of the individual studies.
  • Pooling the trials only reduced between-study variability, and stent omission was still associated with more than double the odds of unplanned visit (OR 2.12, 95% CI 1.38 to 3.25). There was no significant effect in observational studies only.
  • Looking at type of visit, patients without a stent had almost four times the odds of hospital readmission (OR 3.75, 95% CI 2.09 to 6.74). Odds of emergency doctor visit was not statistically significant (OR 0.89, 95% CI 0.53 to 1.51), and there was greater variability in this result between studies.
  • Stent omission reduced pain or irritation upon urination (relative risk [RR] 0.39, 95% CI 0.25 to 0.62) and reduced operative time by an average of 3.19 minutes (95% CI ‑5.64 to -0.74).
  • There was no statistically significant effect on postoperative pain or infection.

What does current guidance say on this issue?

The European Association of Urology 2013 Guideline states that routine stenting following uncomplicated ureteroscopy to remove kidney stones is not necessary. However, a stent should be inserted in patients at increased risk of complications, which can include trauma to the ureter, residual fragments, bleeding or perforation.

What are the implications?

Omitting a stent may increase the risk of hospital readmission and place a greater demand on hospital services. Readmission may disrupt patients’ lives, but this needs to be weighed against a reduction in postoperative urinary symptoms.

An important limitation to the included studies is the influence of the surgeon’s clinical judgment over whether or not to place a stent. This highlights the need to identify the patients that will gain the most benefit from stent placement or omission, and to develop clear criteria for surgeons to follow.

In the meantime, it remains important to consider the context of this surgery, what resources are available and whether patients are prepared to accept a slightly increased risk of short term discomfort or pain with a stent, for a reduced risk of hospital readmission.

Citation and Funding

Pais VM, Jr, Smith RE, Stedina EA, Rissman C M. Does omission of ureteral stents after ureteroscopy increase risk of unplanned return visit? A systematic review and meta-analysis. J Urol. 2016; 196(5):1458-66.

No funding information was provided for this study.

Bibliography

European Association of Urology. Urolithiasis; 3. Guidelines. Arnhem: European Association of Urology; 2016.

Hughes B, Wiseman OJ, Thompson T, et al. The dilemma of post-ureterescopy stenting. BJU Int. 2014; 113(2):184-5.

The British Association of Urological Surgeons. I think I might have…Kidney stones. London: The British Association of Urological Surgeons.

Why was this study needed?

Kidney stones alone are responsible for more than 12,000 hospital admissions every year. Many smaller stones become stuck in the ureter. They are often removed using a ureteroscope and it has been common practice to leave a stent in the ureter to make sure there is free drainage of urine from the kidney.

Stents can cause bothersome symptoms which affect patient quality of life and there has been debate about the best course of action. European guidelines suggest that, if the surgery is uncomplicated, the stent may be left out but there is no consensus on the definition of “uncomplicated” surgery.

This research was undertaken to summarise results from trials to identify which patients need stent placement, and who may benefit from having the stent left out. This understanding will help surgeons decide the best treatment for each individual patient.

What did this study do?

This systematic review included 17 studies - 13 trials and four observational studies (1,943 adults) - that examined outcomes following ureteroscopic removal of kidney stones with or without stent placement.

The main outcome of interest was unplanned hospital, emergency or physician visit within 30 days following surgery. Other outcomes included postoperative pain, infection, pain on urination, average time of the operation and further obstruction of the ureter. The researchers carried out subgroup analyses, including looking at the effect of how long the stent was left in place and analysing trials and observational studies separately.

The main sources of bias were that patients and physicians were aware of treatment allocation. In the observational studies, and also some trials, there was also the potential that treatment choice was being influenced by patient characteristics.

What did it find?

  • Stent omission increased the odds of unplanned medical visit by over 60% compared with stent placement (odds ratio [OR] 1.63, 95% confidence interval [CI] 1.15 to 2.30). However, there were important differences (heterogeneity) between the results of the individual studies.
  • Pooling the trials only reduced between-study variability, and stent omission was still associated with more than double the odds of unplanned visit (OR 2.12, 95% CI 1.38 to 3.25). There was no significant effect in observational studies only.
  • Looking at type of visit, patients without a stent had almost four times the odds of hospital readmission (OR 3.75, 95% CI 2.09 to 6.74). Odds of emergency doctor visit was not statistically significant (OR 0.89, 95% CI 0.53 to 1.51), and there was greater variability in this result between studies.
  • Stent omission reduced pain or irritation upon urination (relative risk [RR] 0.39, 95% CI 0.25 to 0.62) and reduced operative time by an average of 3.19 minutes (95% CI ‑5.64 to -0.74).
  • There was no statistically significant effect on postoperative pain or infection.

What does current guidance say on this issue?

The European Association of Urology 2013 Guideline states that routine stenting following uncomplicated ureteroscopy to remove kidney stones is not necessary. However, a stent should be inserted in patients at increased risk of complications, which can include trauma to the ureter, residual fragments, bleeding or perforation.

What are the implications?

Omitting a stent may increase the risk of hospital readmission and place a greater demand on hospital services. Readmission may disrupt patients’ lives, but this needs to be weighed against a reduction in postoperative urinary symptoms.

An important limitation to the included studies is the influence of the surgeon’s clinical judgment over whether or not to place a stent. This highlights the need to identify the patients that will gain the most benefit from stent placement or omission, and to develop clear criteria for surgeons to follow.

In the meantime, it remains important to consider the context of this surgery, what resources are available and whether patients are prepared to accept a slightly increased risk of short term discomfort or pain with a stent, for a reduced risk of hospital readmission.

Citation and Funding

Pais VM, Jr, Smith RE, Stedina EA, Rissman C M. Does omission of ureteral stents after ureteroscopy increase risk of unplanned return visit? A systematic review and meta-analysis. J Urol. 2016; 196(5):1458-66.

No funding information was provided for this study.

Bibliography

European Association of Urology. Urolithiasis; 3. Guidelines. Arnhem: European Association of Urology; 2016.

Hughes B, Wiseman OJ, Thompson T, et al. The dilemma of post-ureterescopy stenting. BJU Int. 2014; 113(2):184-5.

The British Association of Urological Surgeons. I think I might have…Kidney stones. London: The British Association of Urological Surgeons.

Does omission of ureteral stents after ureteroscopy increase risk of unplanned return visit? A systematic review and meta-analysis

Published on 12 June 2016

Pais, V. M., Jr.,Smith, R. E.,Stedina, E. A.,Rissman, C. M.

J Urol , 2016

PURPOSE: Post-ureteroscopy ureteral stent omission remains controversial. Although omission is associated with reduced postoperative discomfort, concern remains for early obstruction. We performed a systematic review and meta-analysis of trials that compare the risk of unplanned visits with and without stent following ureteroscopy for nephrolithiasis. METHODS: Randomized controlled trials (RCT) and observational studies comparing post-ureteroscopic stent omission versus placement and reporting unplanned visits within 30 days were identified via a search of MEDLINE (1946-2015), CENTRAL (1898-2015), EMBASE (1947-2015), ClinicalTrials.gov (1997-2015), AUA Annual Meetings abstracts (2011-2015), and reference lists of included articles, last updated in October 2015. Two reviewers independently extracted data and assessed methodological quality. Odds ratios (OR), relative risks (RR), and weighted mean differences (WMD) were calculated as appropriate for each outcome. RESULTS: Of the initial 1,992 studies, 17 (involving 1,943 participants) met inclusion criteria. Unstented patients were significantly more likely to have an unplanned medical visit compared to those who received a post-ureteroscopy stent (OR 1.63, 95% CI 1.15-2.30). Unstented patients had shorter operative time (WMD -3.19 minutes, 95% CI -5.64 to -0.74) and were less likely to experience dysuria (RR 0.39, 95% CI 0.25-0.62). They were also less likely to experience postoperative infection (OR 0.89, 95% CI 0.59-1.33) and pain (OR 0.64, 95% CI 0.39-1.05), although these results were not significant. CONCLUSIONS: Stent omission is associated with an increased risk of unplanned medical visits, despite reduced symptoms compared to stented patients. Patients and physicians should weigh these tradeoffs when considering post-ureteroscopy stent placement.

Kidney stones are lumps of minerals that form in the urinary tract and can cause symptoms like irritation or infection, or extreme pain (renal colic) if they get stuck and block urine flow.

Ureteroscopy is a surgical procedure that can be used to remove kidney stones from the ureters, the tubes that connect the kidney with the bladder. A long, thin tube is inserted through the urethra, up into the bladder, and then through to the ureters.

A stent is a small, thin tube that can be left in the ureter after the stone is removed to help pass urine and prevent new stones from blocking the tube.

Expert commentary

This relevant review attempts to analyse a heterogeneous group of patients in terms of available RCT evidence, and determine the question about whether to or not to stent after ureteroscopy - a question that remains challenging even for experienced ureteroscopists.

The drawbacks of this sort of assessment include the diversity of healthcare systems/challenges, such as availability of beds (whether to admit overnight, eg ureteric catheter then feasible), staff resources (someone trained to help with removal of stent on string), office settings (for LA stent removal cystoscopically), etc - these are alluded to in the discussion of 'real-world' management. I suspect these variables will perpetuate the difficulties in strong recommendations in any guidelines, given these differences.

The authors suggest the use of a quasi-standardised ureteric injury scale (initially devised by Traxer), though again this is also somewhat subjective based on an intra-op visualised assessment. The debate regarding the use of stenting will likely continue.

Mr Ranan DasGupta, Consultant Urologist, Imperial College Healthcare NHS Trust