Re: Wei Gan JJ, Lia Gan JJ, Hsien Gan JJ, Lee KT. Lateral percutaneous nephrolithotomy: A safe and effective surgical approach. Indian J Urol 2018;34:45-50

Dear Sir,

With immense interest, we read the article by Gan et al.[1] and commend the authors for presenting a large retrospective series of 347 percutaneous nephrolithotomy (PCNL) cases performed from the lateral approach over a period of 14 years. They have very well analyzed the advantages and disadvantages of lateral PCNL over prone PCNL. After reviewing the article, we have a few comments to make.

Upper portions of both the kidneys are generally located anterior to the 11^th and 12^th ribs. In about 85% of the cases, the upper pole calyces are located above the 12^th rib.[2] Hence, anatomically, it is always easier to access the upper pole calyx through a supracostal puncture (above 12^th rib) which will provide the shortest and the straightest path to the pelvicalyceal system. This supracostal puncture rate has been reported to be around 25%–50% in various series.[3,4] In the index article by Gan et al.[1], it is mentioned in Table 2 that the upper polar puncture was made in 254 cases out of the total of 347 cases. However, it was surprising that supracostal puncture (above 12^th rib) was required in only 4 out of the 347 (1.1%) cases. Is it due to the use of the triangulation technique, use of the kidney break, an anatomical variation in the patient population included or just by chance, this has not been explained in the text. If the lateral position of the patient with the table broken makes access to the upper pole calyx by a subcostal approach easier, then it is a significant advantage of lateral position PCNL over prone position and has implications in avoiding thoracic complications.

Upper pole puncture is preferred in the majority of the cases as it provides an easy access to the pelvic and lower calyceal stones. Upper pole can also be accessed by the subcostal approach and a percutaneous tract can be created. However, such an access will neither be the shortest or nor the straightest path to the pelvicalyceal system. Such an oblique access can cause significant torque while accessing the lower polar calyces and may result in infundibular injuries with rigid instruments.[5] Such injuries can only be avoided with the use of flexible instruments. The authors should discuss a valid reason for selecting the subcostal approach to the upper polar calyx in majority of their cases (77.4%) and whether they encountered any similar problems in their experience?

In the results, the authors mention that four cases were abandoned in their series. It will be interesting and informative for the readers to know the reasons for abandoning these procedures and whether they were related to the lateral positioning of the patient or not.