Interventional Uroradiology Procedures

Chapter 8


Interventional Uroradiology Procedures


Tariq Ali and Andrew Winterbottom


Interventional radiology is a subspecialty of radiology that uses minimally invasive, image-guided techniques to both diagnose and treat conditions throughout the body. Within urology, the applications and usefulness of interventional radiology has increased significantly in recent years. There are many emergency situations where radiological procedures are safer and more effective than surgical options, and indeed other situations where interventional radiology offers the only valid treatment option. For this reason it is very important that urology and radiology departments work cohesively with one another. Outlined below are some common interventional radiology procedures used in emergency urology situations. An understanding of each procedure and its potential complications will be important when making management decisions, in preparing and communicating with the patient, and when looking after the patient after any procedure.


NEPHROSTOMY


This is a minimally invasive urinary diversion procedure, whereby, under image guidance, a drainage tube is inserted percutaneously into the renal collecting system.


Indications


In the emergency setting, a nephrostomy is usually used as a temporary urinary diversion technique to relieve obstruction and to help treat acute kidney injury or systemic sepsis (Box 8.1). Early intervention is crucial, particularly in the setting of a single functioning kidney (including renal transplants) to prevent progression to obstructive nephropathy.


Box 8.1 Indications for nephrostomy.



Urinary diversion in an obstructed system (stone, tumour, clot).


Urinary diversion away from a leak or fistula.


Treatment of sepsis in an obstructed system that is infected.


Access for antegrade ureteric stenting.


Access for hybrid urological procedures (percutaneous nephrolithotomy [PCNL]).


Patient preparation


As for any procedure, baseline blood tests are essential, particularly to identify any derangement in clotting that would require correction prior to starting the procedure (Box 8.2). Intervening in an obstructed system increases the risk of bacteraemia and therefore adequate antibiotic cover against Gram-negative organisms is essential.


Box 8.2 General requirements for interventional procedures.



Full blood count (FBC).


Creatinine.


Clotting screen.


Antibiotic cover.


Procedure


Planning the case is essential to prevent avoidable complications. Previous computed tomography (CT) images can be helpful to identify the anatomy and to demonstrate the location of the bowel in order to prevent injury during the procedure. The procedure is usually performed with the patient in a prone position but in certain cases it may be performed in the semi-prone or supine position. The nephrostomy is performed using a combination of ultrasound (US) and fluoroscopic guidance. US is used to identify the dilated target calyx within the kidney. Adjacent bowel and pleura can also be visualised in order to prevent injury. Once the calyx has been punctured, fluoroscopy is used to image the opacified collecting system. Using a standard Seldinger technique over a guidewire, the tract is dilated and a drain inserted (Figure 8.1). Complications associated with the procedure are summarised in Box 8.3.



images


Figure 8.1 Nephrostomy insertion. Fluoroscopic images showing (a) initial lower pole calyx puncture; (b) advancement of the sheath into the renal pelvis; and (c) insertion of a pigtail drain into the renal pelvis.


Box 8.3 Complications of nephrostomy insertion.



Bleeding.


Injury to the renal tract and urine leak.


Sepsis.


Bowel injury.


Pneumothorax (upper pole puncture).


Outcome


Nephrostomy tubes are used not only for diversion of urine in an obstructed kidney; they also provide a means of renal access for antegrade ureteric stenting and hybrid urological procedures such as percutaneous nephrolithotomy (PCNL). In some instances a nephrostomy can provide long-term renal drainage.


ANTEGRADE URETERIC STENT INSERTION


Ureteric stenting is the process by which an indwelling endoluminal tube is inserted into the ureter to ensure drainage of urine to the urinary bladder.


Indications


The indications for antegrade ureteric stenting generally follow the usual causes for obstruction of any tubular viscus, i.e. luminal causes (e.g. stone, tumour, clot), mural pathology (e.g. inflammation, tumour) or extrinsic compression (e.g. tumour, collection, fibrosis) (Box 8.4). The stent used is the same whether inserted antegrade using US and fluoroscopy or retrograde via cystoscopy.


Box 8.4 Indications for ureteric stenting.



To relieve obstruction.


To maintain ureteric patency in ureteric injuries or leak.


To maintain ureteric patency during stone treatment.


Patient preparation


As for any procedure, baseline blood tests are essential, particularly to identify any derangement in clotting that would require correction prior to starting the procedure (Box 8.2). Intervening in an obstructed system increases the risk of bacteraemia and therefore adequate antibiotic cover against Gram-negative organisms is essential.


Procedure


Planning the case is essential to prevent avoidable complications. A CT scan is usually used to make a diagnosis, to demonstrate the level of obstruction and to identify relevant anatomy (adjacent bowel and lung). The procedure is usually performed with the patient in a prone position but in certain cases it may be performed in the semi-prone or supine position, particularly if there is pre-existing nephrostomy access. Ureteric stenting may be performed as a primary procedure or as an adjunct to an existing nephrostomy. Following renal access, a guidewire and catheter are used to negotiate the obstruction/stenosis and gain access into the urinary bladder (or conduit). The stent is then advanced over a stiff guidewire into the urinary bladder, followed by careful withdrawal of the wire and the use of a pusher/suture system to ensure a pig-tail forms both within the bladder and the renal pelvis (Figure 8.2). Complications associated with the procedure are summarised in Box 8.5.



images


Figure 8.2 Ureteric stent. Fluoroscopic images showing (a) lower pole renal access with an antegrade ureterogram showing distal ureteric obstruction; (b) a wire has been manipulated across the ureteric obstruction into the bladder; (c) a ureteric stent with pigtails positioned in the renal pelvis and bladder.

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May 4, 2018 | Posted by in ABDOMINAL MEDICINE | Comments Off on Interventional Uroradiology Procedures
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