A Prospective Comparison of Fluoroscopic, Sonographic or Combined Approach for Renal Access in Percutaneous Nephrolithotomy

Purpose:

Recently, PCNL or MPCNL is widely used as the most popular choice to treat patients with all types of renal stones. Successful puncture to the desired renal calyx is the key step for the operation. Nowadays puncture for renal access can be achieve using not only US guidance but fluoroscopy guidance as well. However, it is clear that there is a lack of randomized controlled data comparing fluoroscopy, US and US combined with fluoroscopy in the guidance of MPCNL. Consequently, we performed this randomized controlled trial to obtain higher grade evidence.The aim of this present study is to compare the result of fluoroscopy, US and US combined with fluoroscopy in the guidance of MPCNL.

Methods:

We will enroll 450 patients who are candidates for MPCNL in our study. By simple random sampling technique, patients will be assigned to three 150-patient groups (group 1, US-guided MPCNL, group 2, fluoroscopy-guided MPCNL and group 3, US combined with fluoroscopy-guided MPCNL).

All the patients will be diagnosed definitely before operations with kidney, ureter, and bladder (KUB), intravenous pyelography (IVP), US and/or CT.

All procedures are performed by urologists in our center, with assistance from an endourology fellow.

Surgical technique:

Under general or epidural anaesthesia, each patient is initially placed in the lithotomy position, and a 5 Fr ureteric catheter is advanced to the kidney and fixed with a 16 Fr Foley catheter. Then the patient is turned to the prone position.

Group 1: US-guided MPCNL The puncture is made with an 18-gauge needle using an ultrasound probe. After the desirable calix is reached, a flexible-tip guidewire is introduced. We attempt to manipulate the guidewire down to the ureter. If this is not successful, the second choice is to allow the guidewire to coil in a more distant calix. The length of the needle from skin to the collecting system is measured to ensure that the length of dilator is appropriate. The access tract is dilated from 8 Fr to a maximum 18/20 Fr using fascial dilator. We defined access to the collecting system as gaining entry to the targeted urinary system and desired calix.

Lithotripsy is performed using either pneumatic lithotriptor or holmium laser. When multiple nephrostomy tracts are necessary to remove the stones, same technique is employed for each of the tracts.

Complete stone clearance is confirmed using US at completion of the procedure. We routinely put a double J ureteral catheter into the ureter which is to be removed about 3-4 weeks later after the operation in the out-patients clinic. At the end of the procedure nephrostomy tubes are placed in both groups. The tubes are removed when the drainage from nephrostomy tubes being grossly clear.

Group 2 fluoroscopy-guided MPCNL Patients in group 2 have the standard fluoroscopy-guided renal access before MPCNL. Air or contrast medium is injected through the ureteral catheter, the target calix is identified. For tract dilatation fascial dilators are used under fluoroscopic guidance.

Complete stone clearance is confirmed fluoroscopically at completion of the procedure.

The rest of the procedure is the same as described for patients in group 1.

Group 3 US combined with fluoroscopy-guided MPCNL:

Under the guidance of ultrasound, the coaxial needle is placed in the desired calyx. A floppy-tipped guidewire is then passed through the needle into the collecting system. The working channel is then dilated under X-ray.

US and X-ray check for residual stone fragments are performed at the end of the procedure.

The rest of the procedure is the same as described for patients in group 1.

Data collection:

Data for the three groups -demographic characteristics, access success, access time, duration of radiation exposure, site of target calix, site of access, Hb decrease, duration of postoperative hospital stay, complications (modified Clavien system), stone clearance (SFR after single procedure and final SFR) and the need for auxiliary treatment - are compared.

The primary end point of the study is the comparison of outcome of procedure including stone free rate, transfusion rate, operation time, access time, length of stay and complications.

Inclusion criteria

• Normal renal function.
• American society of Anesthesiology (ASA) score 1 and 2.
• Absence of congenital abnormalities.
• Kidney stones of diameter > 2.0cm (including multiple and staghorn stones)

Exclusion criteria

• Patients with congenital anomalies, e.g. ectopic kidney, polycystic, horseshoe, or malrotated kidney.
• Patients who underwent transplant or urinary diversion.
• Patients with solitary kidney.
• Patients will be excluded from the study if they undergoing MPCNL have purulent fluid in the initial puncture.