What are kidney stones?
Kidney stones are collections of calcium-containing material that are usually hard and can form in one or both kidneys. Kidney stones can form when high levels of certain minerals form crystals in the urinary tract. These stones can be as small as a grain of sand or as large as a pea. In rare cases they can be as big as golf balls. Small kidney stones may not cause symptoms or severe pain. Larger stones can block urine from leaving the kidney.
How are kidney stones treated?
People with large kidney stones often need treatment. Two common ways to treat them are called percutaneous nephrolithotomy (PCNL) and retrograde intrarenal surgery (RIRS). PCNL involves placing a small tube from the skin into the kidney and then using different instruments to break up and remove the stones. RIRS involves placing a long viewing tube through the urethra (the tube connecting the bladder to the outside of the body) and the ureter (the tube connecting the bladder and the kidney) into the kidney, then using different instruments to break up and remove the stones. It is unclear how the two treatments compare.
What did we want to find out?
We wanted to know if PCNL was better than RIRS for treating kidney stones. We were mainly interested in the following results.
• Complete removal of stones
• Serious complications
• Need for another procedure to remove stones
• Unplanned medical visits
• Length of hospital stay
• Narrowing (stricture) of or injury to the ureter
• Quality of life
What did we do?
We searched for studies that compared PCNL with RIRS in adults with kidney stones of any size and located in any part of the kidney. We compared and summarized the results of the studies and rated our confidence in the evidence, based on factors such as study methods and sizes.
What did we find?
We found 42 studies that randomly allocated participants to either PCNL or RIRS. There were 4571 participants in total. The average age of participants was between 27.7 years and 59.3 years, and the average stone size was between 10.1 mm and 39.1 mm.
Main results
We found that compared with people treated with RIRS, people treated with PCNL may be more likely to be free of stones after the procedure and less likely to need another procedure to remove remaining stones. PCNL probably does not increase the risk of serious complications, although it may result in a longer hospital stay. We also found that people treated with PCNL may be no more likely to have a stricture of the ureter than people treated with RIRS. We did not find any evidence for unplanned medical visits or quality of life.
What are the limitations of the evidence?
We have little confidence in the evidence for most results, mainly because the studies were not well planned or carried out and because the results varied considerably across studies.
How up to date is this evidence?
The findings of this review are up to date to 23 March 2023.
Based on a large body of evidence from 42 trials, we found that PCNL compared with RIRS may improve stone-free rates and may reduce the need for secondary interventions, but probably has little or no effect on major complications. PCNL compared with RIRS may have little or no effect on ureteral stricture rates and may increase length of hospital stay. We found no evidence on unplanned medical visits or participant quality of life. Because of the considerable shortcomings of the included trials, the evidence for most outcomes was of low certainty.
Access size for PCNL was less than 24 Fr in most studies that provided this information. We expect the findings of this review to be helpful for shared decision-making about management choices for individuals with renal stones.
Kidney stones (also called renal stones) can be a source of pain, obstruction, and infection. Depending on size, location, composition, and other patient factors, the treatment of kidney stones can involve observation, shock wave lithotripsy, retrograde intrarenal surgery (RIRS; i.e. ureteroscopic approaches), percutaneous nephrolithotomy (PCNL), or a combination of these approaches.
To assess the effects of percutaneous nephrolithotomy (PCNL) versus retrograde intrarenal surgery (RIRS) for the treatment of renal stones in adults.
We performed a comprehensive search of the Cochrane Library, MEDLINE, Embase, Scopus, and two trials registries up to 23 March 2023. We applied no restrictions on publication language or status.
We included randomized controlled trials that evaluated PCNL (grouped by access size in French gauge [Fr] into three groups: ≥ 24 Fr [standard PCNL], 15–23 Fr [mini-PCNL and minimally invasive PCNL], and < 15 Fr [ultra-mini-, mini-micro-, super-mini-, and micro-PCNL]) versus RIRS.
Two review authors independently selected studies and extracted data from the included studies. Our primary outcomes were stone-free rate, major complications, and need for secondary interventions. Our main secondary outcomes were unplanned medical visits to emergency/urgent care or outpatient clinic, length of hospital stay, ureteral stricture or injury, and quality of life. We performed statistical analyses using a random-effects model. We rated the certainty of evidence using GRADE criteria. We adopted a minimally contextualized approach with predefined thresholds for minimal clinically important differences (MCIDs).
We included 42 trials assessing the effects of PCNL versus RIRS in 4571 randomized participants. Twenty-two studies were published as full-text articles, and 20 were published as abstract proceedings. The average size of stones ranged from 10.1 mm to 39.1 mm. Most studies did not report sources of funding or conflicts of interest. The main results for the most important outcomes are summarized below.
Stone-free rate
PCNL compared with RIRS may improve stone-free rates (risk ratio [RR] 1.13, 95% confidence interval [CI] 1.08 to 1.18; I2 = 71%; 39 studies, 4088 participants; low-certainty evidence). Based on 770 participants per 1000 being stone-free with RIRS, this corresponds to 100 more (62 more to 139 more) stone-free participants per 1000 with PCNL (an absolute difference of 10%, where the predefined MCID was 5%).
Major complications
PCNL compared with RIRS probably has little or no effect on major complications (RR 0.86, 95% CI 0.59 to 1.25; I2 = 15%; 34 studies, 3649 participants; moderate-certainty evidence). Based on 31 complications in the RIRS group, this corresponds to six fewer (13 fewer to six more) major complications per 1000 with PCNL (an absolute difference of 0.6%, where the predefined MCID was 2%).
Need for secondary interventions
PCNL compared with RIRS may reduce the need for secondary interventions (RR 0.31, 95% CI 0.17 to 0.55; I2 = 61%; 21 studies, 2005 participants; low-certainty evidence). Based on 222 secondary interventions in the RIRS group, this corresponds to 153 fewer (185 fewer to 100 fewer) secondary interventions per 1000 with PCNL (an absolute difference of 15.3%, where the predefined MCID was 5%).
Unplanned medical visits
No studies reported unplanned medical visits.
Length of hospital stay
PCNL compared with RIRS may extend length of hospital stay (mean difference 1.04 days more, 95% CI 0.27 more to 1.81 more; I2 = 100%; 26 studies, 2804 participants; low-certainty evidence). This effect size is greater than the predefined MCID of one day.
Ureteral stricture or injury
PCNL compared with RIRS may have little or no effect on the occurrence of ureteral strictures (RR 0.93, 95% CI 0.39 to 2.21; I2 = 0%; 13 studies, 1574 participants; low-certainty evidence). Based on 14 ureteral strictures in the RIRS group, this corresponds to one fewer (nine fewer to 17 more) ureteral strictures per 1000 with PCNL (an absolute difference of 0.1%, where the predefined MCID was 2%).
Quality of life
No studies reported quality of life.