A new percutaneous nephrostomy technique in the treatment of obstructive uropathy.

Purpose: To describe the percutaneous nephrostomy technique used at our centre in the treatment of supravesical urinary tract obstruction and to analyse the results obtained.

Materials And Methods: Three-hundred and seventy-three patients underwent 412 percutaneous nephrostomies, most of which (78%) in an emergency setting, performed with a newly devised "mixed" technique. The procedure combines the positive elements of the two techniques employed to date in the management of upper urinary tract obstruction: the Seldinger angiographic technique and the Goodwin technique. Once the site for the placement of the nephrostomy catheter has been established, the kidney is punctured with an 18-gauge trocar needle to reach the renal pelvis. This occurs under real-time ultrasonographic (US) guidance. After having removed the mandrin and performed a pyelography with a small volume of contrast material, both a 0.038-inch Teflon-coated J-tipped guide wire and a 7-8 French catheter are introduced.

Results: The procedure time is from 7 to 15 minutes; the fluoroscopy time usually lasts less than 30 seconds. Only in one case of a mobile kidney with a non-dilated collecting system was it not possible to position the nephrostomy catheter. In 38 patients (9.2%) a second renal puncture with an 18-gauge needle was necessary, due to the absence of dilatation of the collecting system. In three cases the procedure had to be repeated because of a kinking of the wire which could not be corrected, even with the use of a fine soft dilator. We encountered five major complications (three cases of sepsis and two of haemorrhage requiring transfusion), 119 minor complications (50 cases of nephrostomy catheter dislodgement, three of malpositioning, 12 of mild infection, 20 of pelvicalyceal haemorrhage, five of subcapsular haematoma, 29 of renal pelvis perforation).

Discussion And Conclusions: The technique adopted has a high success rate in the treatment of supravesical obstructive uropathy and very short procedure times, thanks to US guidance and elimination of the steps involving the use of dilators of progressive diameter. In addition, the radiation exposure was low, being limited to confirming the proper placement of the needle, the wire, and the catheter in the renal pelvis. In all the other steps of the procedure we used US guidance which enabled us to choose the puncture site and follow the needle advancement. The major limit to our "mixed" technique is the need to small-diameter catheters, which entails having to replace them with larger ones with greater biocompatibility.