Dilation of the Puncture Track

After the puncture needle has reached the desired calyx, a flexible guide wire (Seldinger) or a semi-stiff guide wire (Lunderquist) is led through the needle and advanced deep into the kidney (Fig. 38). The track is then dilated, which one can facilitate by dividing the muscles all the way to the renal surface with the double blade knife (see Fig. 26). For this purpose, the distance between the skin and the surface of the kidney is measured beforehand with the ultrasound probe and the distance disc is set accordingly. To cut the track even further than the designated 10 mm, which might be necessary when there is hard scar tissue, the double blade is twisted about 90° at a selected depth and is pulled out. Then the central leading rod of the telescope dilator set or, if teflon dilators are used, the thin dilator is advanced. Since dilatation is done in one plane only, a soft Seldinger guide wire can easily kink in the second plane or can even be pulled out of the kidney through the leading rod or through the first dilator. The wire can be pushed back and forth in the central track with short, quick motions. The wire’s refusal to be moved anymore indicates that it has kinked, in which case the affected portion of the wire has to be pulled out through the track. This complication alone makes it advisable, when using Seldinger wires, to advance as much wire as possible into the cavity system.