Fig. 14.1
Brodel’s avascular plane
Before positioning the patient and individuating the point of access, it is important to check that the operative trolley contains all the instruments needed to complete the procedure. It must contain a support for the needle guide, to be attached to the ultrasound probe, skin disinfectant, a drape/drapes to outline the operative field, sterile gel, local anesthetic, a scalpel with a pointed blade, a bowl of physiological solution, a metal guidewire, fascia dilators, nephrostomic stents of a suitable caliber, drainage tubes, silk sutures, and sterile gauzes for dressings (Fig. 14.2).
Fig. 14.2
Surgical kit
14.3 Description of the Technique
The control system when positioning a nephrostomic catheter relies largely on ultrasound guidance, using 3.5 or 5 MHz probes. The advantages of the ultrasound guidance system are the ease of localization of the renal cavities and of determining the depth of the kidneys; the possibility of using this system even in pregnant women and in subjects who are allergic to contrast medium, or with a reduced renal function; and the fact that it can be used in a dedicated outpatients clinic. When possible, it is better to associate the US guidance with radiological control: this association guarantees a success rate exceeding 98 %.
The possible access techniques include Seldinger’s angiographic approach (Video 14.1), the one step or the combined technique, with the catheter equipped with a metal cannula and pointed obturator so as to insert it in the renal cavity.
The method most commonly employed is Seldinger’s technique that involves explorative puncture of the renal cavity and then positioning of the nephrostomy. After copious disinfection of the skin, the operative field is outlined with sterile drapes, and local anesthesia of the superficial and deep planes is given with 2 % Xylocaine or Carbocaine (Fig. 14.3). Sterile gel can be used for the contact between the skin and US probe that has previously been immersed, with its needle guide in sterile solution. The needle (generally 18 ch) is passed through the collimator, and then the procedure can commence.
Fig. 14.3
Local anesthetic injection
In Seldinger’s technique, the needle with the obturator is followed (thanks to the reflecting echo), under ultrasound guidance the whole way (Video). When the needle arrives at the renal capsule, a deformity will be noted, caused by the pressure of the needle on the parenchyma about to be penetrated. Once the excretory tract is reached, generally the inferior calyx, the obturator is withdrawn, and urine can be seen running down. The skin is incised up to the fascia with the pointed scalpel. The metal guidewire is inserted through the needle sheath that is then withdrawn, and the dilator or progressive dilators are inserted, up to a caliber of one size greater than the caliber of the nephrostomic catheter to be used. After the last dilator has been withdrawn, the nephrostomy is inserted and the metal guidewire removed. Then the nephrostomic stent is fixed to the skin plane, normally with silk sutures (Fig. 14.4). Lastly, the wound is dressed, covering the nephrostomy with sterile gauze and taking care to avoid bending it or provoking stricture.
