The needle entry for the PCNL procedure is usually guided by fluoroscopy. The standard method uses the Bull's eye technique or carnio-caudal technique. 
Using USG guidance for percutaneous access for PCNL is a well-established, safe, and effective method. (1)
Some urologists use ultrasound guidance for the entry. Standard probes have an external needle guide, which may target 35 to 45’. This high-degree angle makes it difficult to align with the calyceal axis. 
Our novel method involved a hockey stick-shaped special convex probe with a needle guide at a 5’ and 25’ angle to make perfect and easy calyceal punctures.

The plain and contrasted CT scan images are evaluated from all angles. The best possible entry path is an imaginary straight line with optimum access to the renal stone. 
After anesthesia induction, an ultrasound is done to evaluate which point/s the needle might be entering the Calyx. All these points are marked. 
The supine position is fully flat or has some upward tilt, so the needle enters, avoiding any vital organ surrounding the kidney. 
After painting and dripping, dye and saline are injected to inflate the PC system. An ultrasound is performed to finalize the entry point. There may be more than one way to go. The best calyceal entry should not traverse the extensive length of renal parenchyma, and the tract should be almost perpendicular to the cup of the calyx. 
Once finalized, a small stab incision is placed. The USG probe is fixed, and the needle is advanced into the kidney under the ultrasound guide at a 5’ or 25’ angle, as per the plan, with intermittent fluoroscopy shoots as required. Once the needle enters the calyx, the entry is confirmed by fluoroscopy. The USG probe should be fixed and not moved. The needle hub is held steady, and the stylet of the needle is removed. Urine—saline will come out. If it does not, re-confirm the needle tip position. It is better to undershoot than to overshoot the target.
Once the needle is in, the USG probe’s connectors are removed to free the needle. The guide wire is inserted. The remaining steps are as per any renal tract dilatation protocol and Amplatz sheath placement. 
The color Doppler is rarely used when a patient has a solitary kidney or is at a high risk of bleeding. To check the renal vessels in the entry tract, one may use color Doppler to avoid perforating through major renal vessels.

After using this method, the total operating time is reduced by 45 to 60 minutes, as there is no change in the supine to prone position and the use of two sets of drapes. Radiation exposure is reduced from an average of 7 minutes to 3 minutes. Due to precise and targeted puncture, in 95% of cases, the first passage of the needle was the successful entry. For others who failed the first entry, 4 % of cases needed a second passage, and 1% needed more than two trials.

It is easy to learn, reproducible, and user-friendly. This reduces radiation to the patient and all operating room staff. (2) One can also quickly perform complex renal entries.

1.	Chu C, Masic S, Usawachintachit M, Hu W, Yang W, Stoller M, et al. Ultrasound-Guided Renal Access for Percutaneous Nephrolithotomy: A Description of Three Novel Ultrasound-Guided Needle Techniques. J Endourol. 2016;30(2):153-8.
2.	Beiko D, Razvi H, Bhojani N, Bjazevic J, Bayne DB, Tzou DT, et al. Techniques - Ultrasound-guided percutaneous nephrolithotomy: How we do it. Can Urol Assoc J. 2020;14(3):E104-E10.