INVESTIGATIVE UROLOGY

Comparative Study of Degree of Renal Trauma between Amplatz Sequential Fascial Dilation and Balloon Dilation during Percutaneous Renal Surgery in an Animal Model
Al-Kandari AM, Jabbour M, Anderson A, Shokeir AA, Smith AD
Department of Urology, Urology and Nephrology Center, Mansoura University, Mansoura, Egypt
Urology. 2007; 69: 586-9

• Objectives: To compare two commonly used methods of dilation, the Amplatz sequential fascial (ASF) and the balloon dilator, in a porcine model.
• Methods: Fourteen kidneys from 9 female pigs were used for this experiment. One kidney of each pig underwent ASF dilation and the other underwent balloon dilation using the Nephromax balloon. This was achieved after percutaneous renal puncture with an 18-gauge needle under fluoroscopic guidance. The effects of both methods of dilation were assessed immediately in 1 pig, after 24 hours in 3 pigs, at 4 weeks in 4 pigs, and at 6 weeks in 1. The animals were killed, and the kidneys were removed for gross and histologic examination.
• Results: Grossly, the ASF dilated tracts appeared rounded and the balloon dilated tracts appeared V-shaped with lateral fragmentation within 24 hours. No obvious gross differences were noted at 4 to 6 weeks between the two methods of dilation, with both appearing as fine scars. Histologically, minor differences were seen at 4 to 6 weeks, with slightly more abscesses and larger scar formation in the kidneys that underwent ASF dilation than in the balloon dilation group.
• Conclusions: In this porcine animal model, the degree of renal trauma induced by the ASF dilators and the balloon dilators during percutaneous renal surgery seems to be comparable. The acute and chronic renal parenchyma effects of both methods of tract dilation were almost similar. The choice of nephrostomy tract dilation should be by physician preference.
  
  
• Editorial Comment
  This is an interesting animal model study comparing the two most common methods of nephrostomy tract dilation in USA; Amplatz sequential fascial (ASF) dilators and balloon dilators. The study aimed to determine whether any significant differences in renal trauma were present between the two techniques both acutely (immediate to 24 hours) and chronically (at 4 to 6 weeks) in pgs. The authors chosen the best animal model for this kind of analysis, since the renal collecting system, the intrarenal arteries and the kidney morphometric parameters are very similar between pigs and humans (1,2).
  The analysis was macroscopic and microscopic. The histologic examination at 24 hours showed no apparent differences, except for the degree of hemorrhage, which was slightly more in the ASF dilated tracts. However, in the specimen removed at 4 to 6 weeks after ASF dilation, slightly more inflammation with abscess formation was present in the ASF dilated tracts than in the balloon-dilated tracts.
  The slight differences were not significant and the authors demonstrated that the use of either method of dilation had no difference in terms of the degree of renal parenchymal trauma. Therefore, they concluded that the method of dilation is a matter of physician preference and experience.

References

1. Sampaio FJ, Pereira-Sampaio MA, Favorito LA: The pig kidney as an endourologic model: anatomic contribution. J Endourol. 1998; 12: 45-50.
2. Pereira-Sampaio MA, Favorito LA, Sampaio FJ: Pig kidney: anatomical relationships between the intrarenal arteries and the kidney collecting system. Applied study for urological research and surgical training. J Urol. 2004; 172: 2077-81.

Dr. Francisco J.B. Sampaio
Full-Professor and Chair, Urogenital Research Unit
State University of Rio de Janeiro
Rio de Janeiro, RJ, Brazil
E-mail: sampaio@urogenitalresearch.org