Super-Mini Percutaneous Nephrolithotomy for Nephrolithiasis: A Systematic Review and Meta-Analysis

Abstract

We aimed to conduct a systematic review and meta-analysis to summarize the current evidence regarding the role of super-mini percutaneous nephrolithotomy (SMP), which refers to a 7-Fr nephroscope placed through a tract sized 10-14 Fr, in treating renal stones and compare its outcomes with the standard mini-percutaneous nephrolithotomy (PCNL) techniques. A systematic literature search was conducted on the Medline database via PubMed and SCOPUS until May 2022 to retrieve the relevant studies. The titles and abstracts of unique records were screened for eligibility, followed by the full-text screening of potentially eligible abstracts. Data extraction was performed by two independent reviewers. The risk of bias assessment was conducted based on the study design. Open Meta (Analyst) and Review Manager 5.4 were used to perform all analyses. A total of 14 studies (n = 4,323 patients) were included, with two randomized controlled trials, one single-arm trial, and 11 cohort studies. The stone-free rate (SFR) of SMP was 91.4%. The pooled analysis showed no significant difference between SFR in mini-PCNL (mean difference (MD) = 1.03, 95% confidence interval (CI) = (0.99, 1.06), p = 0.12) and flexible ureteroscopy (MD = 0.84, 95% CI = (0.4, 1.76), p = 0.65]. On the other hand, SMP had a better SFR rate when compared with retrograde intrarenal surgery (MD = 1.3, 95% CI = (1.01, 1.66), p = 0.04). The pooled mean operative time of SMP was 49.44 minutes (95% CI = (41, 57.88), p < 0.001), which was longer than mini-PCNL (MD = 1.92, p < 0.001) and shorter than ureteroscopy (MD = -17.17, p < 0.00001). In the SMP group, the postoperative complications included fever (>38°C), pain, and hematuria, with an incidence of 7.6%, 2.3%, and 3.4%, respectively. The mean length of hospital stay after SMP was 2.4 days (95% CI = (2.17, 2.7), p < 0.001). The current evidence suggests that SMP is a safe and effective technique in the management of renal stones in both children and adults.

Keywords: mini-pcnl; pcnl; pediatric urinary stone disease; stone surgery; super-mini pcnl; urinary stones.

Figure 1. Identification of the included studies.

Figure 2. Average operation time of the included studies.

Forest plot of the single-arm pooled analysis of operative time in patients who underwent super-mini percutaneous nephrolithotomy [5-18]. 95% CI = 95% confidence interval

Figure 3. Initial after-operation stone-free rate of the included studies.

Forest plot of the single-arm pooled analysis of stone-free rate in patients who underwent super-mini percutaneous nephrolithotomy [5-15,17]. 95% CI = 95% confidence interval

Figure 4. Average postoperative hospital stay.

Forest plot of the single-arm pooled analysis of postoperative hospital stay in patients who underwent super-mini percutaneous nephrolithotomy [5-7,9-12,14-18]. 95% CI = 95% confidence interval

Figure 5. Operative time of the included studies.

Forest plot of the pooled analysis of operative time in patients who underwent SMP versus RIRS [7,15,17], mini-PCNL [8,9,11,13], ureteroscopy [14,18], and sPCNL [12]. SMP = super-mini percutaneous nephrolithotomy; mini-PCNL = mini-percutaneous nephrolithotomy; sPCNL = standard percutaneous nephrolithotomy; RIPS = retrograde intrarenal surgery; 95% CI = 95% confidence interval; IV = inverse variance

Figure 6. Stone-free rate (%).

Forest plot of the pooled analysis of stone-free rate in patients who underwent SMP versus RIRS [7,15,17], mini-PCNL [8,13], ureteroscopy [9,14], and sPCNL [12]. SMP = super-mini percutaneous nephrolithotomy; mini-PCNL = mini-percutaneous nephrolithotomy; sPCNL = standard percutaneous nephrolithotomy; RIRS = retrograde intrarenal surgery; 95% CI = 95% confidence interval; M-H = Mantel-Haenszel