Placement and / or replacement of percutaneous nephrostomy
When is this exam indicated?
Nephrostomy is used whenever there is evidence of renal distress due to mechanical obstruction to the progression of urine to the bladder. In many cases, this situation occurs due to the presence of a stone or urothelial tumor within the ureter or due to the presence of a variety of pathologic conditions that cause ab extrinsic obstruction of the ureter. The consequent dilatation of the upper excretory tract resulting from an obstruction to the outflow of urine can be an acute process, which usually causes a colic-like symptomatology (e.g. in case of ureteral stones) or a chronic process (e.g. in case of urothelial tumor or ab extrinsic compression), which usually does not cause an acute algic symptomatology. Nephrostomy allows recovery of renal function and provides immediate relief to the patient if symptoms occur. Nephrostomy may also be indicated to aid in the healing of urinary fistulas following demolitive and/or reconstructive surgery.
How is it performed?
The patient is placed in a prone position on a radiology bed. It is performed by pricking the skin in the lumbar region with a specific needle, which is moved forward under ultrasound and fluoroscopic guidance until it reaches the excretory cavities, crossing the renal parenchyma. A catheter is then inserted and connected to an urinary collection bag.
The procedure is performed under local anesthesia.
The nephrostomy is generally removed once the disease that had caused the obstruction has resolved. However, if prolonged use of the nephrostomy is anticipated, periodic replacement of the nephrostomy catheter (every 3-4 months) is recommended to prevent urinary tract infections.
A concomitant oral anticoagulant therapy is an absolute contraindication, as it significantly increases the risk of renal bleeding. For this reason it is recommended the suspension of such therapy in view of the procedure, to be replaced with low molecular weight heparin therapy allowing the return to normal range of coagulation values. However, antiplatelet therapy is considered a relative contraindication. In fact, patients at high thrombotic risk, should continue antiplatelet therapy, despite the increased risk of post-procedural renal bleeding.