Percutaneous nephrolithotomy (PCNL) is a minimally invasive procedure considered as the treatment of choice for the management of large-scale and fully-formed kidney stones.This procedure has a 5% risk of complications including bleeding, the lesion of the collecting system, the risk of urinary infection and bacteremia. New surgical tools such as dilatation of the nephrostomy tract with mechanical dilatation contribute to the reduction of these risks, together with an improvement in the operative times and a lower rate of complications.

At present there are multiple scales measuring the lithiasic morphology (Guy, the STONE nephrolitometry score system and the nomogram of the Office of Clinical Investigation of the Endourology Society - CROES) which allow to evaluate the degree of complexity of the stone, the possibility of residual stones and the risk of complications. These tools allow us to do a better analysis of the risk factors of the patient who will be taken to this type of endoscopic procedure in order to decrease morbidity and complication rates.

Hypothesis:

The use of pneumatic dilators during percutaneous nephrolithotomy reduces the rates of intraoperative and postoperative complications, which would have an impact on hospitalization times and surgical success for the management of renal stone.

Nephrolithiasis is a major worldwide source of morbidity, constituting a common urological disease affecting 10-15% of the world population, with a subsequent clinical relapse rate of approximately 50%. Recent technological and surgical advances have reduced the need for open surgery with less invasive procedures, such as percutaneous nephrolithotomy (PCNL), extracorporeal shock wave lithotripsy (SWL) and retrograde ureteroscopy. The selection of the surgical procedure generally depends on the size, composition, location of the renal stone, the existence of obstruction and anatomical variations of the urinary system. Today, PCNL is the established procedure for stone greater than 2 cm; The procedure usually involves three main stages: it begins with the insertion of a ureteral catheter to perform a retrograde study with contrast medium where the anatomy of the kidney is evaluated, then the puncture is performed by inserting a surgical needle on the skin to the specific location of the stone, with subsequent dilatation of the tract to the collecting system, and once this access has been made it is proceeded to carry out the fragmentation and extraction of the stone through various types of instruments.

The success and results of the treatment of surgery are very well known and highly dependent on precision in the puncture stage (the stones must be achieved with a precise and direct path), make this step is the most challenge for surgeons. The ideal access is one that allows complete removal of the stones while minimizing intraoperative bleeding. Needle punctures and their complications, such as kidney injuries and adjacent organs, eventually impair the overall surgical success and outcome of the patient. Although PCNL is considered minimally invasive surgery (MIS) with many associated benefits, such as the production of small incisions in the patient, reducing hospitalization time and postoperative recovery, some complications still occur frequently. The dilation of the nephrostomy tract is the second step in which there are more complications, since it depends on an optimal puncture of the collecting system and a precise manual control to avoid damages of the collecting system or to increase the risks of bleeding.

Restricted vision, difficulty in handling the Instrumental, restrictive mobility within the kidney, skill levels of hand-eye coordination of the surgeon, deviation of the needle, moving anatomical objective, are a constant challenge for the surgeon. Several technological advances have been proposed to improve the effectiveness of this procedure. In regard to puncture and dilatation, relevant contributions have been provided by the improvement in medical imaging techniques, as well as the fusion of multiple imaging procedures.

Main goal

To determine the highest rate of intraoperative and early postoperative complications (bleeding, pain) with the use of the various methods of access to the renal collecting system during percutaneous nephrolithotomy for the treatment of kidney stones greater than 2 cm than 2 cm between April 2017 and January 2018.

Inclusion Criteria:

• Patient over 18 years old
• Non-staghorn kidney stones greater than 2 cm

Exclusion Criteria:

• Coagulopathies
• Solitary Functioning Kidney
• Pyonephrosis
• Pregnancy
• Urinary tract infection
• Cardiopulmonary Restrictions Limiting Prone Position
• BMI greater than 35
• More of 2 puncture of the excretory tract
• STONE score equal or greater than 12