Editorial Comment on: Percutaneous Nephrolithotomy and Spina Bifida: Complex Stone Surgery? by Mitchell et al .

The article entitled “Percutaneous Nephrolithotomy and Spina Bifida—Complex Stone Surgery?” by Mitchell et al. is a single center, retrospective study comparing preoperative comorbidities, intraoperative challenges, and postoperative complications between spina bifida (SB) patients and neurologically intact patients (controls) undergoing percutaneous nephrolithotomy (PCNL) for nephrolithiasis. ¹ The authors compared 13 (mean age 29.2 years) SB patients (34 PCNL) with 50 (mean age 50.7 years) controls (62 PCNL). In this study, PCNL on SB patients was associated with longer anesthesia time (median 95 minutes vs 55 minutes) and more intraoperative complications (23.5% vs 4.8%). The SB cohort also had increased postoperative complications (47% vs 11%), which includes longer length of hospital stay, need for intensive care, transfusion rates (11.8% vs 1.6%), and postoperative sepsis (38% vs 1.6%). The authors also report three nephrectomies in the SB cohort for symptomatic, nonfunctioning kidneys secondary to recurrent stone disease and repeated interventions. The authors conclude with four recommendations for the management of SB patients with PCNL: preoperative pulmonary function testing, 24 hours of preoperative antibiotics, treatment at specialized high-volume centers with intensive care units, and lastly counseling regarding an increased risk for postoperative complications and nephrectomy for “end-stage” stone disease.

I commend the authors' effort in this unique study. However, on the authors' own acknowledgment, certain important factors (data points) relating to the technical complexity of PCNL were not feasibly collected or available. These include incomplete Cobb angle measurements, unavailable measures of preoperative stone burden, and imperfect reporting of stone composition. The Cobb angle, for example, is an objective measure of the severity of scoliosis and kyphosis that may predict a more technically challenging PCNL. ² Although the Cobb angle may not have been feasible to control for, it would be interesting to see how the two cohorts would compare if the stone burden and stone compositions were matched. Similarly, I am curious to know how the results would change if the two cohorts were matched for preoperative factors such as age, obesity and chronic renal impairment. Fuller et al. using the CROES database found longer operative times, decreased stone-free rates, and higher retreatment rates in obese patients. ³ Although I am in agreement with most of the authors' four recommendations, I would caution against drawing a definitive conclusion regarding an increased risk for nephrectomy in SB patients because of recurrent stone disease and repeated interventions. The data from this small study may not be comprehensive enough to make this claim, as there was a higher proportion of “at-risk” patients in the SB cohort with preoperative chronic renal impairment (23.5% vs 8.0%) and a history of reconstructive surgery (70.6% had bladder augmentations vs 0%). Furthermore, the article does not explicitly report the evidence of progressive renal impairment with repeated PCNL. Although SB patients may be at an increased risk for progressive renal impairment and subsequent nephrectomies, this is commonly attributed to multiple etiologies.