Coaxial Needle Technique for Percutaneous Nephrostomy

Renal access for urinary diversion is typically achieved by means of percutaneous nephrostomy. Other indications for percutaneous nephrostomy include treatment of nephrolithiasis and complex urinary tract infections, ureteral intervention, and nephroscopy and ureteroscopy. Typically the kidney is accessed in the avascular plane of Brodel to prevent bleeding complications [1]. Visualization of the collecting system is imperative for successful needle placement and can be performed either using a blind-stick approach with contrast opacification, using intravenous pyelography (IVP) and triangulation, or more commonly using direct ultrasound guidance. Currently, ultrasound guidance is the preferred method because it allows for visualization of both the needle and the targeted collecting system throughout the initial needle placement, without the need for contrast, resulting in more accurate guidance of the needle towards its target and avoidance of critical structures both inside and outside of the kidney [2]. After localization using ultrasound, either an 18or a 21/22 gauge needle is typically guided into the posterior pole calyx of the kidney. Once the collecting system is accessed, dilation from an 0.018” system to an 0.035” system is performed before the catheter is finally placed [3]. There are times when visualization using ultrasound guidance may fail and reverting back to the blind-stick or IVP method for percutaneous nephrostomy is necessary. Typically this occurs when a patient is obese, edematous, generally echo-unfriendly, or when the ultrasound equipment used provides adequate, but low image quality.