WHAT IS A PERCUTANEOUS NEPHROSTOMY?
Kidneys filter the blood and produce urine. The ureter is a smooth muscular tube which takes urine from the kidney to the bladder. This leaves the bladder when we pass urine. The ureter may be blocked from intrinsic lesions such as stones, strictures, clot or tumour: or from extrinsic causes such as masses from adjacent organs, or enlarged lymph glands. A percutaneous nephrostomy is a way of accessing an obstructed urinary system through the skin (percutaneous) to obtain images of the urinary collecting system (nephrostomy).
HOW DO YOU DIAGNOSE A BLOCKED KIDNEY?
A history and examination of the patient may demonstrate back/loin/groin pain. There may be a pre-existing history of kidney stones, or other renal disease. Blood tests may reveal signs of deteriorating kidney function or signs of infection. A urinary tract ultrasound may show a dilated kidney. This is normally performed as a first line imaging investigation. A CT scan of the abdomen may be undertaken. This will show the kidneys in greater detail. This may also reveal the source of the obstruction, ranging from intrinsic lesions or from extrinsic compressive lesions, as discussed earlier.
WHY TREAT A BLOCKED KIDNEY?
An obstructed kidney places back-pressure on the kidney, reducing its function and it may result in kidney failure. An obstructed urinary system is also at increased risk of becoming infected.
HOW DO WE TREAT A BLOCKED KIDNEY?
A blocked kidney requires decompression in order to restore kidney function and to avoid infection. This is done with a percutaneous nephrostomy. A percutaneous nephrostomy may be performed under a combination of ultrasound and fluoroscopic guidance. The kidney is precisely punctured under imaging guidance in order to minimise injury to blood vessels and to minimise bleeding risk. Once the kidney is accessed, a flexible plastic tube may be inserted (a catheter) in order to drain the obstructed system into a collection bag outside the body. This reduces “back pressure” onto the kidney and aims to restore kidney function.
WHAT IS A URETERIC STENT?
A ureteric stent is a thin plastic tube which is coiled at both ends. The superior end lies within the kidney and the inferior end is coiled within the bladder. The stent traverses the ureter. This restores flow from the kidney to the bladder.
HOW IS A URETERIC STENT INSERTED (Stent Surgery)?
A ureteric stent may be inserted from the bladder by a Urological surgeon. If the patient is not an operative candidate, or there has been a failed attempt from the bladder, an Interventional Radiological approach would be undertaken.
A percutaneous nephrostomy would be performed initially in order to access the blocked kidney. The obstruction would then be crossed and a ureteric stent deployed in order to restore urine flow from the kidney to the bladder.