Prospective comparative study of Miniperc and standard PNL for treatment of 1 to 2 cm size renal stone


Mahesh Desai, Department of Urology, Muljibhai Patel Urological Hospital, Dr V.V Desai road, Nadiad, Nadiad Gujarat 387001, India. e-mail:


Study Type – Therapy (case series)

Level of Evidence 4

What’s known on the subject? and What does the study add?

Standard PNL is known to have higher clearance rates for stones 1–2 cm. However, it is not promoted because of its associated morbidity, especially bleeding. Minitiarization of the PNL has spawned a new interest in this modality for treating small bulk urolithiasis.

The study adds to a growing body of evidence in a prospective manner that smaller tract PNL “miniperc” is associated with a similiar efficacy of achieving stone-clearance rates while decreasing the invasiveness of the procedure and associated morbidity.


• To evaluate the results of miniperc vis-à-vis standard PNL in the treatment of stones of 1–2 cm in size. Miniperc may represent a reasonable procedure in patients with nonbulky urolithiasis offering a similar outcome as standard percutaneous nephrolithotomy (PNL) with advantage of reduced morbidity.


• 55 procedures including 27 miniperc and 28 standard PNL were performed for renal stones 1–2 cm in size. Pediatric patient, active urinary tract infection, renal malformation, uncorrected coagulopathy and morbid obesity patients were excluded from the study.

• The parameters studied were demography, operative time, postoperative analgesic requirement, hemoglobin drop, complications and stone clearance.


• Mean tract size was 18.2 ± 2 F (15–20) and 26.8 ± 2 F (24–30), P value <0.0001 in the miniperc and standard PNL, respectively. Holmium LASER and pneumatic lithotripter were the main energy sources used in miniperc and standard PNL, respectively.

• Miniperc operative time was longer than that of standard PNL (45.2 ± 12.6 vs 31 ± 16.6 min, P= 0.0008 respectively).

• Conversely, there was an advantage of miniperc over standard PNL in terms of a significantly reduced hemoglobin drop (0.8 ± 0.9 vs 1.3 ± 0.4 gram%, P= 0.01), analgesic requirement (55.4 ± 50 vs 70.2 ± 52 mg tramadol, P= 0.29) and hospital stay (3.2 ± 0.8 vs 4.8 ± 0.6 days, P≤ 0.001), respectively.

• Intra- operative conversion of the procedure into a tubeless PNL was significantly more in the miniperc group (P≤ 0.001). The miniperc and standard PNL group had clearance rates of 96% and 100%, respectively at 1 month follow up.


• This study demonstrated significant advantages of the miniperc procedure in terms of reduced bleeding leading to a tubeless procedure and reduced hospital stay.

• The stone free rates and the complications were similar in either group.