الفهرس 
AcknowledgmentOnly 14 pages are availabe for public view
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Abstract
Minimally invasive endourological procedures, namely fURS and mPCNL, are gaining much credibility for treatment of small and mid-sized renal stones, especially those in the lower pole. Although flexible ureteroscopy achieves lower complication rates than mini-PCNL, as well as shorter hospital stay and less postoperative pain, its poor durability and high costs remain major limitations.
Due to insufficient randomized studies with large sample sizes that compare between the two modalities for treatment of renal stones less than 2cm, we conducted a randomized, comparative study conducted from January 2019 to July 2021 across three tertiary care urology centers in two governorates in Egypt, Assiut and Alexandria. Inclusion criteria were adult patients with renal stone(s) of ≤ 2cm total burden with inappropriateness or failure of SWL. Exclusion criteria were pregnancy and uncorrectable bleeding diathesis.
The study assessed two primary outcomes: (1) stone-free rate (SFR), which was measured on the 1st and 30th post-operative days using KUB and ultrasound and at the 3rd month using a NCCT. Cases were considered stone-free if they had no residual stones or stone fragments > 2mm. (2) complications, which were reported according to the Modified Clavien-Dindo classification system. Secondary outcomes included operative times, auxiliary procedure and blood transfusion rates and haemoglobin drop.
The study included 118 procedures for 109 patients. Mini-percutaneous nephrolithotomy achieved a final SFR of 98.3%, and fURS achieved 94.9%, which are higher than most of the reported rates in the literature. The current study agrees with nearly all the studies that compared fURS and mPCNL in that the latter achieves higher stone free rates than fURS. However, the difference in our study, unlike most studies, was not statistically significant.
Complications occurred significantly more frequently with mPCNL than f.URS. When applying the Modified Clavien-Dindo Classification System, all complications in the two groups were minor (grade I-II) except two cases that underwent mPCNL and required termination and re-treatment due to intraoperative bleeding (grade IIIb).
Similar to our study, six randomized clinical trials (RCT) and three metanalyses showed mPCNL was associated with significantly higher SFR than fURS when treating lower pole stones. Flexible ureteroscopy was also more effective than m.PCNL in treatment of multiple stones (either at a single or multiple locations), which is a frequent observation in literature.
In his study, stones with low density yield significantly higher SFRs when treated with f.URS rather than m.PCNL. To the best of our knowledge, there is a single study that compares the effect of stone HU on SFR between mPCNL and fURS, and it confirmed our observation. There are other studies that found the same negative effect of low stone density on the SFR after PCNL.
Patients that underwent either simultaneous ipsilateral ureteral pathology treatment or simultaneous contralateral renal unit stone treatment and patients whose ureters had been stented before operation were more effectively treated with fURS compared to mPCNL with statistically significant differences. To our knowledge, none of the studies that compared mPCNL and fURS correlated those factors with SFR.
Limitations of this study include inability to conduct subgroup analysis of SFR according to stone burden due to limited numbers and non-uniform distribution of some pre-operative variables.
Based on the findings of this study, we recommend using f.URS for renal stones ≤ 2cm over m.PCNL due to lower morbidity with comparable effectiveness.
To conclude, Flexible ureteroscopy achieves comparable SFR and operative time to mPCNL, with significantly lower morbidity. Possible parameters that favor mPCNL over fURS include renal pelvic and lower calyceal stones, high stone density, and those that favor fURS are multiple stones, low stone density, pre-stented ureters, and the need for simultaneous treatment of ipsilateral ureteral pathology or contralateral renal unit stones.