The Air Technique to Determine Appropriate Posterior Calyx for Puncture

A posterior calyx is the preferred point of entry into the urinary collecting system during percutaneous nephrostomy procedures. Although ultrasonographic guidance is the preferred modality to gain this initial access, confident identification of a posterior calyx can be challenging using sonography alone, particularly in obese patients without hydronephrosis. In this setting, air or carbon dioxide can be introduced into the prone patient’s collecting system in order to fluoroscopically guide a confident puncture of the posterior calyx of the renal collecting system. This chapter presents a technique employing the introduction of air into the urinary collecting system to permit facile identification of a posterior calyx using fluoroscopic guidance during percutaneous nephrostomy procedures.