Safety and Efficacy of a Superior Caliceal Puncture in Pediatric Percutaneous Nephrolithotomy

Introduction

T he management of renal calculi in children is associated with concerns about immediate morbidity of the surgical procedure and possible long-term implications of access technique and residual stones, particularly because of the small size of the kidney. Shockwave lithotripsy (SWL) had previously been considered the treatment of choice in pediatric stone disease, primarily because of its noninvasive nature. Certain stones that are resistant to SWL or are not suitable for this treatment because of their size or location, however, require different treatment modalities such as percutaneous nephrolithotomy (PCNL).

Since its first description in 1985 by Woodside and associates, ¹ pediatric PCNL has been established as a good modality of treatment for pediatric nephrolithiasis. The indications include large or complex stone burden, obstructed kidney, hard stones (cystine), and residual stones after failed SWL. ² The increasing acceptability of PCNL as a first-line therapy for pediatric stone disease has resulted from the continuous improvement in instrumentation, including smaller nephroscopes, energy sources for lithotripsy, anesthetic techniques, and improved surgeon skills. ^{3 –6} Although PCNL is a safe and effective method for maximal stone clearance in preschool children with staghorn calculi, ⁷ the superior caliceal approach has always been feared because of concerns about safety and morbidity, particularly in the pediatric population because of short stature and a greater risk of complications. ⁸

We thus evaluated the safety and efficacy of the superior caliceal approach to PCNL among a cohort of children who were undergoing PCNL at our center and compared their outcomes with others within the same cohort who had a nonsuperior caliceal access.

Patients and Methods

Between October 2007 and October 2009, operative and recovery data for all pediatric patients (under 16 years) who were undergoing PCNL for renal calculi were prospectively entered into a database and reviewed. PCNL was performed for standard indications, the most common being stone size or location being unsuitable for SWL. All patients had normal renal function. The stone area was derived by multiplying the largest vertical and horizontal dimensions on plain radiography. Patients in whom the primary puncture was made into the superior calix were compared with those in whom the superior calix was not punctured. The decision to make a superior calix puncture was based on the stone location, dilatation of the calix, likelihood of maximal clearance using a single puncture, and the certainty of staying below the 11th rib. All procedures were performed with the patient in the prone position after retrograde catheterization of the ureter with a 5F catheter.

Punctures were made by the urologist under fluoroscopy guidance. Biplanar fluoroscopy was used in all patients. Puncture was made using 18-gauge needle with diamond tip. After confirming accurate placement of the needle in pelvicaliceal system, an 0.038-inch straight-tip guidewire was introduced, and the tract was dilated to either 24F or 30F using Teflon or telescoping metallic dilators, per surgeon preference. An Amplatz sheath was used in all cases. A rigid nephroscope was used in all patients. We did not use a flexible nephroscope in any of our patients.

All stones were fragmented using a pneumatic lithoclast. Stone clearance was assessed by intraoperative fluoroscopy and postoperative radiography in all patients on postoperative day 1. In a few patients, ultrasonography or noncontrast CT scans were performed to confirm clearance and look for perinephric extravasation. In patients with complete stone clearance, the nephrostomy tube was clamped on postoperative day 1 and subsequently removed on postoperative day 2. Patients with residual calculi were planned to undergo relook PCNL, either through the same tract or through an additional puncture, if needed. In addition to intraoperative fluoroscopy, a postoperative chest radiography was performed on the evening of surgery in patients with supracostal punctures to rule out hydropneumothorax.

Results

During the study period, 26 pediatric patients (mean age 11.12 years; range 4–16 years) underwent 27 PCNLs (Table 1). Thirteen patients (14 renal units) had primary superior calix access with 13 of these being supracostal (above the 12th rib) while 13 did not receive a superior calix puncture. Nine patients had staghorn calculi, and another seven had multiple stones. Previous SWL had failed in two patients. Operative data are presented in Table 2. Three of the 10 patients in whom a superior calix puncture was made needed additional punctures in the middle or lower calix.

Overall, there was no difference in the two groups in terms of efficacy or complications. One patient in each group had residual calculi after completion of therapy. Major complications developed in one patient in each group—hydrothorax and ascites. Both resolved with no sequelae. One patient in each group needed second-look surgery. The patient in the superior calix group had a staghorn stone that was completely cleared in the second-look procedure through an additional puncture. The second patient who needed second-look surgery also had a staghorn stone but no superior calix access. He further needed ureteroscopy to clear migrated fragments from the ureter. One patient achieved complete clearance after SWL. Five of the superior calix access patients had no nephrostomy tube after surgery. The decision to leave no nephrostomy tube was based on the surgeon's assessment of an uncomplicated procedure, no significant bleeding, and complete clearance on intraoperative fluoroscopy and nephroscopy.

Discussion

A good initial puncture is key to a successful PCNL. An ideal puncture would allow direct access to the desired point with a straight, short tract through the fornix of a calix. A straight tract not only allows clear initial visualization of the stone, it also minimizes torquing of the nephroscope. This decreases intraoperative bleeding, keeping the vision clear; this may aid in achieving better stone clearance.

The superior calix is often the most suitable entry point for stones in the superior calix, staghorn stones, upper ureteral stones, or large pelvic stones. An additional advantage of the upper-pole puncture is manipulation of instruments along the long axis of the kidney because the upper role is more posteromedial than the lower pole. Universalization of the guidewire is easy in superior caliceal punctures, because of straight access to the pelviureteral junction. Golijanin and colleagues ⁸ observed that the supracostal approach provides direct access and facilitates stone clearance with the least requirement for additional tracts and lower blood loss because of minimal or no torquing during the procedure.

The superior caliceal approach, however, is generally avoided because of a fear of additional complications. ⁹ A superior calyceal puncture is often supracostal. Earlier publications suggested that the supracostal access was associated with a higher risk of intrathoracic complications with the reported incidence being above 12.5%. ^10,11 The majority of hydrothoraxes are asymptomatic, however, and intervention is necessary in only a small percentage of patients. ¹² Recent publications have further attested to the safety and advantages of the supra-12th rib approach in the adult population. ¹³ Among the supracostal access sites, the supra-11th rib is associated with a greater incidence of complications than the supra-12th rib approach. Munver and coworkers ¹⁴ reported a 16 times greater risk of intrathoracic complications with supra-11th rib puncture when compared with a supra-12th rib approach (23% vs 1.4%). Other thoracic complications included pneumothorax, hydrothorax, hemothorax, and nephropleural fistula in 8% of patients, and the authors recommended avoiding supra-11th puncture to minimize complications.

Hopper and Yakes ¹⁵ noted that with intercostal punctures between the 11th and 12th ribs, with the patient prone and in full expiration, the left lung would be punctured in 14% of cases and the right in 29%. Radecka and associates ¹⁶ used CT-guided placement of a nephrostomy tract to minimize complications. Finneli and Honey ¹⁷ described a combination of fluoroscopy and thoracoscopy through the 5th or 6th intercostal space to allow direct visualization when placing an upper-pole puncture track (through the 9th or 10th intercostal space).

Among the pediatric population, Zeren and colleagues ¹⁸ reported a 24% incidence of hemorrhage necessitating transfusion and a 30% incidence of transient fever after PCNL. In contrast, Fraser and coworkers ¹⁹ reported no complications in a small series of children undergoing PCNL. We have previously published our experience with the superior calix approach for PCNL and found it extremely useful in a large number of cases. ²⁰ This prompted our attempt at specifically evaluating this approach for children. Our indications for the superior calix approach for children are the same as those for adults, the primary aim being the straightest tract to the stone. We specifically avoid the supra-11th approach because of its higher risk of complications and did not use it for any of our patients.

Hydrothorax developed in one of our patients with supracostal superior caliceal puncture; it was managed by tube thoracostomy. In one patient with the nonsuperior caliceal approach, abdominal collection was noted. Signs of peritonism developed in this patient on postoperative day 2 after nephrostomy removal. Ultrasonography and noncontrast CT revealed mild to moderate perinephric extravasation. This patient, however, recovered with conservative management, and no active intervention was needed. We performed all punctures under fluoroscopic guidance and did not use CT guidance or thoracoscopy in any of our patients.

Tract size has been considered a potential issue of consequence in pediatric PCNL. Bilen and colleagues ²¹ observed a lower blood transfusion rate with smaller tracts. We dilated the tract up to 24F in 21 patients (22 renal units) and up to 30F in 5 patients. We did not encounter any difference in postoperative outcome of these two groups of patients. The number of patients with dilation tract size 30F is only five, however, thereby making it difficult to arrive at any conclusion about effect of tract size on postoperative outcome in terms of bleeding or long-term renal function. None of our patients had any major postoperative complication, and only one patient with a staghorn calculus needed blood transfusion.

Our study was not designed to determine differences in stone clearance rate with the approach. It is likely that we chose the superior caliceal approach for stones more likely to benefit from this approach, thus minimizing a potentially poor outcome with the nonsuperior calix approach. We achieved complete stone clearance in 92.85% of patients with the superior caliceal approach. This compared favorably with the reported stone-free rates for larger (staghorn) and complex calculi of 78% to 87%. ¹⁰ We did not notice any significant difference between our two groups is terms of blood loss, overall clearance, analgesia requirement, or hospital stay. Our findings are very similar to a recent publication by El-Nahas and associates ²² who compared the supracostal with the subcostal approach in a pediatric population. They found no difference in these parameters between the two groups. Because our only criterion for case selection was surgeon decision based on fluoroscopy, we believe that this can be used reliably to determine the puncture site.

Conclusions

The superior caliceal approach to PCNL in pediatric patients is associated with excellent stone clearance rates. It is associated with minimal additional complications and should be used when it appears to provide the best site for a good access.