Iftikhar Ahmed ( Departments of Radiology, The Aga Khan University Medical Centre, Karachi. )
Imtiaz Hussain Rizvi ( Departments of Radiology, The Aga Khan University Medical Centre, Karachi. )
Asif Aslam ( Departments of Community Health Sciences, The Aga Khan University Medical Centre, Karachi. )
Mohammad Nadeem Ahmed ( Departments of Radiology, The Aga Khan University Medical Centre, Karachi. )
Yusuf A. Hussain ( Departments of Radiology, The Aga Khan University Medical Centre, Karachi. )
A retrospective analysis of 34 patients of obstructive renal failure, initially managed by percutaneous nephrostomy was performed. Pre procedure blood biochemical profile was compared with upto one week follow-up of blood chemistry. There was a decline of 71.1% and 56.08% (P-values 0,0001 and 0.0028) in the mean values of serum creatinine and blood urea nitrogen respectively at 7 days after the procedure. Improvement in blood biochemical profile was solely dependent on performance of percutaneous nephrostomy (JPMA 45:16,1995).
Percutaneous nephrostomy is a commonly performed image guided intervention to relieve urinary obstruction1-4. In the modern radiological practice, most common indication for this procedure is obstructive uropathy thatis frequently caused by calculus disease5. Percutaneous nephrostomy itself is the definitive therapeutic intervention in cases where transient supra-vesical urinary diversion is needed. Percutaneous access to the renal collecting system is also used for other endourological procedures6,7. Elective surgical management may be deferred until the blood chemistiy has returned towards normal in patients who cannot be offered definitive percutaneous management. Nephrostomically produced urinary diversion helps reverse the changes in the renal parenchyma related to back pressure. Improvement in biochemical profile after relief of obstruction is well known in experimental animals and humans8-10. Literature review, however, has revealed a lack of studies, quantitatively analyzing the change in blood chemistry in response to supra- vesical urinary diversion provided by percutaneous nephrostomy. In this paper, the effectiveness of percutaneous nephrostomy was assessed in reversing the biochemical manifestations of obstructive renal failure in clinical settings.
Patients and Methods
This is a descriptive study of patients who had percutaneous nephrostomy performed within a period of two years from January, 1990 at the Department of Radiology, The Aga Khan University Medical Centre. Two criteria of case selection were used for the study: a) All cases of obstructive renal failure initially treated by percutaneous urinary diversion, b) All cases in which the complete biochemical profile was available for retrospective evaluation. A total of34 cases were thus selected. The nephrostomies were perfonned either as an emergency or elective procedure by the staff and the senior residents having different levels of expertise. The procedure was first explained to the patient. Local anaesthesia was used in all the cases except one 3 year old child who was given inhalational anaesthetics. Premedication with antibiotics and sedatives was used selectively in patients in whom the need was clinically obvious. In all cases, initial localization was performed by ultrasound11,12. This in most cases was followed by antegrade pyelogram13 with the patient in prone oblique position14. For catheter insertion, angiographic guidewire exchange or catheter sheathed needle insertion techniques15,16 were used underfluoroscopic cover. The catheters were pulled from 7Fr radio- opaque polyethylene tubing (Cook Inc.) in the Department of Radiology. For securing the catheters to the skin, silk stay sutures were used. Baseline biochemical investigations included serum electrolytes, creatimne and blood urea nitrogen levels. Blood urea nitrogen and serum creatinine were selected as renal function parameters17. These tests are routinely performed on patients suspected of having deranged renal functions. Serum creatinine and blood urea nitrogen levels were analyzed before the insertion of the nepluDstomy tube and were followed-up at one, three and seven days intervals after the tube placement. The analysis was performed using "Excel" computer software and paired student t test of statistical significance was applied.
Out of 34 patients studied, 29 were males and 5 females, between 3 and 78 years of age. Percutaneous nephrostomy was achieved in all the 34 patients without failure in first attempt. Thiiteen patients needed bilateral tube placement. Twenty-six nephrostomy tubes were placed in patients having calculus disease; of these, 8 presented in emergency service for acute urinary obstruction while 18 suffered chronic renal obstruction. Urinary diversion was perfomied in 8 patients to relieve chronic obstruction caused by urinary tract malignancy. The procedures were relatively free of complications, two patients needing long term drainage, dislodged their nephrostomy tubes after discharge from the hospital. All patients had transient hematuria which did not require transfusion and lasted less than 48 hours. In all the patients, a gradual decline in serum creatimne and blood urea nitrogen values (Figure) was observed.
At one week follow-up, 71.1% and 56.0% decline in the serum creatinine and blood observed (P values 0.0001 and 0.0028 respectively). All the patients showed marked clinical improvement evidenced by biochemical profile and symptomatic relief.
Obstructive uropathy is a backpressure phenomena which leads to renal parenchymal damage. The extent of damage is dependent on duration, completeness and level of obstruction and the vascular status of the kidney18. The gradual decline in the mean values of serum creatinine and blood urea nitrogen as depicted in the figure demonstrates the effectiveness of percutaneous nephrostomy in obstructive renal failure patients. In general, patients with higher baseline serum creatinine and blood urea nitrogen values did not return to normal. All these patients had long standing disease resulting in renal parenchymal damage. There was, however, a statistically significant decrease in their serum creatinine and blood urea nitrogen values (P value 0.0001 and 0.0028 respectively), thus showing a direct relationship between the performance of percutaneous nephrostomy and the change in biochemical profile. This study shows that supra-vesical urinmy diversion provided by percutaneous nephrostomy is extremely effective in restoring the renal functions towards normal in patients having obstructive renal failure. Nephrostomy is a very effective intervention for patients requiring definitive urinary surgery, but with high risk of anaesthetic complications and those in need of urgent urinary diversion.
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