Indian Journal of Urology
LETTER TO EDITOR
Year
: 2015  |  Volume : 31  |  Issue : 4  |  Page : 375--376

Re: Sharma G, Sharma A. Determining the angle and depth of puncture for fluoroscopy-guided percutaneous renal access in the prone position. Indian J Urol 2015;31:38.41


Nikhil Choudhary, Mahendra Singh 
 Department of Urology, Indira Gandhi Institute of Medical Sciences, Patna, India

Correspondence Address:
Nikhil Choudhary
Quarter 3/5 Old MDH, Mch Urology Third Year Resident, Indira Gandhi Institute of Medical Sciences, Patna
India




How to cite this article:
Choudhary N, Singh M. Re: Sharma G, Sharma A. Determining the angle and depth of puncture for fluoroscopy-guided percutaneous renal access in the prone position. Indian J Urol 2015;31:38.41.Indian J Urol 2015;31:375-376


How to cite this URL:
Choudhary N, Singh M. Re: Sharma G, Sharma A. Determining the angle and depth of puncture for fluoroscopy-guided percutaneous renal access in the prone position. Indian J Urol 2015;31:38.41. Indian J Urol [serial online] 2015 [cited 2021 Apr 11 ];31:375-376
Available from: https://www.indianjurol.com/text.asp?2015/31/4/375/166480


Full Text

Dear Editor,

We have read the original article by Sharma et al. with great interest.[1] The authors have to be congratulated for highlighting a neglected area of urology. Although establishing a percutaneous tract is essential to the success of percutaneous nephrolithotomy, the techniques to do this have sparsely been described. Most standard endourology textbooks describe two techniques – "bull's eye" and "triangulation."[2] Both these techniques rely on advancement of puncture needle under C arm guidance in two planes in an almost hit-and-trial manner. No objective criteria of access angle, depth of puncture, standard landmarks or maneuverability have been described.

However, some points of the article need clarification. The law of sines used by the authors states that: a/sin A=b/sin B=c/sin C=D [3] where a, b and c are three side of the triangle, A, B and C are the opposite angles and D is the diameter of the triangle's circumcircle [Figure 1]. As is clearly seen in Figure 1 of the original article, the triangle ABC is placed inside the patient's body with its apex on the targeted calyx and base on the back. However, in Figure 2 of the original article, the protractor is placed parallel to the patient and is measuring the angle between the horizontal surface (patients back) and the puncture needle. To measure the actual angle ABC, the protractor would have to be placed upside down. Alternatively, we can assume that the patient's back and the line CB are two parallel intersecting lines, in which case the angle measured from the horizontal and the intratriangle angle would become corresponding opposite angles and would be roughly equal. As the patient's back is not a strictly horizontal parallel line, there would be a variation between the two angles in actual measurement. A more accurate value could be obtained by measuring the angle between the needle and the back on the medial aspect and subtracting it from 1800 to obtain the desired angle. As the line CB is clearly a straight line, which would be traversed by the puncture needle, this angle would be more representative.{Figure 1}

We hope that these points enable the authors to improve the success rate of their technique.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest

References

1Sharma G, Sharma A. Determining the angle and depth of puncture for fluoroscopy-guided percutaneous renal access in the prone position. Indian J Urol 2015;31:38-41.
2Bernardo NO. Percutaneous renal access under fluoroscopic control. In Smith's Textbook of Endourology. 3rd ed. United States: Wiley-Blackwell; 2012. p. 180-8.
3LAW OF SINES. WIKIPEDIA, the free encyclopedia. en.wikipedia.org/wiki/Law_of_sines.