**2. Indications and contraindications of percutaneous nephrostomy**

In essence, percutaneous nephrostomy may be performed for diagnostic or therapeutic purposes. For example, an antegrade pyelography can be performed following percutaneous nephrostomy to diagnose urinary tract obstruction. Its therapeutic uses on the other hand, can be seen to fall under two broad groups. Typically, the procedure is carried out to provide urinary diversion, and for a large number of cases this is related to urinary tract obstruction due to various causes. Secondly, the nephrostomy can be used to provide access to the urinary tracts for further intervention such as endopyeloscopy and nephrolithotomy. This is usually performed in collaboration with a urologist.

#### **2.1 Indications**

The following is a list of indications recognised by the Society of Interventional Radiology (SIR) (Ramchandani, Cardella et al. 2003):

Percutaneous Nephrostomy 299

complications are higher in these patients, and they are ideally treated as an inpatient to ensure adequate planning prior to the procedure as well as providing periprocedural

Fluoroscopic or CT-guided percutaneous nephrostomy may be contraindicated in pregnant patients in the first trimester in order to minimize radiation exposure to the fetus. Percutaneous nephrostomy performed using only ultrasound guidance has been described with good success rates (Gupta, Gulati et al. 1997; Ozden, Yaman et al. 2002), with Gupta reporting an overall success rate of 98.5%. However minimum radiation exposure should always be borne in mind even in non-pregnant patients in accordance with ALARA (As

Following assessment of the primary diagnosis and indication for percutaneous nephrostomy for each particular case, the procedure should not be performed without adequate review of all relevant imaging performed prior to the procedure. Percutaneous nephrostomy is usually performed using ultrasound or fluoroscopic guidance, although in many cases, CT may have been performed to arrive at the diagnosis prior to the procedure

The primary diagnosis should be reviewed thoroughly, and this should include the cause and level of obstruction, degree of pelvicalyceal dilatation, as well as the most accessible renal calyx for catheter placement. If urinary calculi are present within the renal pelvis, their exact nature and location must be elucidated. The success rate for percutaneous nephrostomy has been reported to be lower in patients with a non-dilated collecting system, complex calculus disease and staghorn calculus (Ramchandani, Cardella et al. 2003). The kidney itself must also be assessed for the presence of anatomical variants or congenital

Equally important to note is the vascular anatomy of the target kidney. Its precise delineation, as well as the presence of abnormal vascular malformations or aneurysmal dilatation should be noted. Injury to the first order segmental renal arteries may occur in the region of the renal pelvis, particularly if the puncture is made too medially. To prevent vascular injury and bleeding complications, the safest approach has been described by approaching the cusp of the papilla as far peripherally as possible, and by entering the kidney via the Brodel's line (Dyer, Regan et al. 2002). Brodel's line is a zone of relative avascularity and watershed territory, which is located just posterior to the lateral convex margin of the kidney, between the major anterior and posterior divisions of the renal artery. Care should be taken to avoid a through-and-through two-wall puncture of the renal pelvis

The position of the affected kidney relative to the surrounding abdominal viscera should be thoroughly assessed as this has a bearing in determining the safest and most effective approach for renal puncture. Under normal circumstances, the posterolateral margins of the kidneys are immediately adjacent to the posterolateral aspects of the abdominal wall with no organs to interpose in between. Hence, a posterior approach is advantageous in avoiding the surrounding organs (Hruby 1990). Although the spleen, liver, pancreas and the adrenal glands are in close proximity to the kidneys, they are usually not shown to interpose

monitoring.

Low As Reasonably Achievable) principle.

and correlation with these images may prove to be beneficial.

as this runs the risk of injury to the anterior segmental renal artery.

**3. Anatomical considerations** 

anomalies such as horseshoe kidney.


The above indications can be applied to both native as well as transplanted kidneys.

#### **2.2 Contraindications**

Percutaneous nephrostomy has a good safety profile, and there is no single recognizable absolute contraindication (Ramchandani, Cardella et al. 2003). Relative contraindications however do exist, for which the benefits and potential risk must be weighed for each individual case.

Patients with known renal vascular malformations or arterial aneurysm are at risk of severe hemorrhage should there be accidental injury to these affected vessels. Nevertheless these patients may still require emergent decompression particularly in cases of urinary tract obstruction complicated by pyonephrosis. Careful preprocedural planning is vital, taking into account the nature of vascular malformations or aneurysm in detail by using the appropriate imaging method such as CT when determining approach and puncture tract. The performing physician should be aware of the potential need for angiographic embolization in these cases, particularly if bleeding becomes difficult to control and there is risk of hemodynamic instability. Similarly, patients with severe coagulopathy or bleeding diathesis are exposed to risks of severe hemorrhage. For these patients, thorough assessment of their coagulation profile as well as appropriate correction of coagulopathy may be necessary prior to the procedure.

Electrolyte imbalances such as severe hyperkalaemia may frequently be encountered particularly in cases of background chronic renal disease, and in whom the concomitant urinary tract obstruction may need to be urgently treated. In these cases, appropriate medical therapy is required to correct the electrolyte imbalance in order to reduce the risk of developing complications such as cardiac arrhythmia or cardioplegia (Ramchandani, Cardella et al. 2003).

Special attention should also be made to those patients with significant underlying morbidity or terminal illness who are deemed unsuitable for conventional surgery but yet there may be a role for percutaneous nephrostomy to provide a temporary measure. Risks of

1. Provision of urinary diversion in cases of urinary tract obstruction, which may be secondary to intrinsic or extrinsic ureteral obstruction. This may be related to urinary calculi, malignancy or iatrogenic causes. The obstruction may be diagnosed incidentally on imaging studies, or patients may present with features of obstructive uropathy. 2. In cases of pyonephrosis, where there is urgency in providing immediate drainage as these patients are at risk of developing fulminant sepsis and shock. This may be suspected in patients with clinical features of sepsis, accompanied by flank pain and

3. Urinary diversion in cases of urinary leakage or fistula, which may in turn be related to

5. Providing access for urological interventions and endoscopy (nephrolithotomy and removal of urinary calculus, ureteral stent placement, delivery of chemotherapeutic agents e.g. for upper tract transitional cell carcinoma, foreign body retrieval e.g. migrated ureteral stents). Percutaneous nephrostomy has been shown to provide adequate treatment of various types of urinary calculi including staghorn calculi.

Percutaneous nephrostomy has a good safety profile, and there is no single recognizable absolute contraindication (Ramchandani, Cardella et al. 2003). Relative contraindications however do exist, for which the benefits and potential risk must be weighed for each

Patients with known renal vascular malformations or arterial aneurysm are at risk of severe hemorrhage should there be accidental injury to these affected vessels. Nevertheless these patients may still require emergent decompression particularly in cases of urinary tract obstruction complicated by pyonephrosis. Careful preprocedural planning is vital, taking into account the nature of vascular malformations or aneurysm in detail by using the appropriate imaging method such as CT when determining approach and puncture tract. The performing physician should be aware of the potential need for angiographic embolization in these cases, particularly if bleeding becomes difficult to control and there is risk of hemodynamic instability. Similarly, patients with severe coagulopathy or bleeding diathesis are exposed to risks of severe hemorrhage. For these patients, thorough assessment of their coagulation profile as well as appropriate correction of coagulopathy may be

Electrolyte imbalances such as severe hyperkalaemia may frequently be encountered particularly in cases of background chronic renal disease, and in whom the concomitant urinary tract obstruction may need to be urgently treated. In these cases, appropriate medical therapy is required to correct the electrolyte imbalance in order to reduce the risk of developing complications such as cardiac arrhythmia or cardioplegia (Ramchandani,

Special attention should also be made to those patients with significant underlying morbidity or terminal illness who are deemed unsuitable for conventional surgery but yet there may be a role for percutaneous nephrostomy to provide a temporary measure. Risks of

The above indications can be applied to both native as well as transplanted kidneys.

evidence of urinary tract obstruction on imaging.

4. Urinary diversion for hemorrhagic cystitis.

trauma for example.

**2.2 Contraindications** 

necessary prior to the procedure.

Cardella et al. 2003).

individual case.

complications are higher in these patients, and they are ideally treated as an inpatient to ensure adequate planning prior to the procedure as well as providing periprocedural monitoring.

Fluoroscopic or CT-guided percutaneous nephrostomy may be contraindicated in pregnant patients in the first trimester in order to minimize radiation exposure to the fetus. Percutaneous nephrostomy performed using only ultrasound guidance has been described with good success rates (Gupta, Gulati et al. 1997; Ozden, Yaman et al. 2002), with Gupta reporting an overall success rate of 98.5%. However minimum radiation exposure should always be borne in mind even in non-pregnant patients in accordance with ALARA (As Low As Reasonably Achievable) principle.
