Pelvicaliceal Anatomical Variation Between Stone Bearing and Normal Contralateral Kidneys—Does it Have an Impact on Stone Formation in Pediatric Patients With a Solitary Lower Caliceal Stone?

Impact of pelvicalyceal anatomical variation on surgical outcomes of endoscopic combined intrarenal surgery

Objectives

The objective of this work is to investigate the impact of the pelvicalyceal anatomical system (PCS) on calyceal stone formation and surgical outcomes of endoscopic combined intrarenal surgery (ECIRS) for renal and/or proximal ureteral stones with a diameter >15 mm.

Patients and methods

PCS was classified as Type I (single pelvis) or Type II (divided pelvis) according to the simple anatomical Takazawa classification. Using prospectively collected data from January 2016 to April 2020, 219 patients were retrospectively reviewed. After excluding patients who underwent a staged procedure, had hydronephrosis greater than grade 2, prior nephrostomy tubes, and failed to access the renal collecting system, 115 patients (Type I: 81, Type II: 34) were included, and the distribution of calyceal stones and surgical outcomes in ECIRS were compared between Types I and II PCS.

Results

The median number of renal stone calyces in the Type II group was significantly more than that in the Type I group (p = 0.016). In particular, the Type II group possessed more upper stone calyces. Multivariate logistic regression analysis revealed that Type II PCS was associated with an increased odds ratio (OR) for the presence of upper stone calyces (OR: 2.93, p = 0.018). The stone-free (SF) status at 1 month after surgery, confirmed by abdominal plain radiography, was significantly higher in the Type I group compared with that in Type II (67.9% vs. 39.4%, respectively; p = 0.006). The requirement for additional surgical interventions was significantly higher in the Type II group compared with that in Type I (35.4% vs. 7.4%, respectively; p < 0.001). Multivariate analysis revealed that the number of stone calyces (OR: 4.26; p = 0.001) and Type II PCS (OR: 3.43; p = 0.009) were independent predictors of residual stones after ECIRS.

Conclusion

We first revealed that the anatomic properties of PCS play a role in both upper calyceal stone formation and in the success of the ECIRS procedure. Because the SF rate in Type II PCS was significantly lower than that in Type I PCS, additional percutaneous nephrolithotomy tracts might be required, even for ECIRS.

Anatomic predictors of formation of lower caliceal calculi: is it the time for three-dimensional computed tomography urography?

OBJECTIVE

To evaluate the various anatomic factors, using computed tomography urography (CTU), that predispose to a lower-pole kidney stone formation on one side compared with the other.

MATERIALS AND METHODS

The study included 51 patients with a solitary lower-pole stone. Lower-pole infundibulopelvic angle (IPA), infundibular width (IW), infundibular length (IL), caliceal volume (CV), and number of minor calices of the affected lower calyx and normal contralateral kidney were measured based on CTU. The IPA was measured according to the methods of Sampaio and Elbahnasy. A comparison was made using multivariate analysis to determine whether any of these measurements predisposed one side to form stones.

RESULTS

The mean IPA was 80.9 degrees (Sampaio), and 52.3 degrees (Elbahnasy) on the affected kidney and 87.5 degrees (P = 0.39) and 54 degrees (P = 0.36) on the normal side. The mean IW was 2.6 mm on affected side and 3.15 mm on the normal side (P = 0.03). The mean IL was 19.7 mm and 15.3 mm (P < 0.001) on the affected and normal kidneys, respectively. Mean CV was 1123 mm(3) on affected side and 286 mm(3) on the normal side (P < 0.001). The mean number of minor calices was comparable (n = 3) on both sides with no statistical significance. Using multivariate analysis, only caliceal volume and IW sustained their significance in the final model.

CONCLUSIONS

CTU is a very useful imaging modality in the diagnosis of intrarenal anatomic variation. Larger caliceal volume and narrower IW are associated with stone formation in lower calyx.

The impact of pelvicaliceal features on problematic lower pole stone clearance in different age groups

AIM

Our aim was to evaluate the impact of pelvicaliceal variables in pediatric and adult age groups who underwent SWL for lower caliceal calculi.

METHODS

25 pediatric and 78 adult patients treated with extracorporeal shock wave lithotripsy (SWL) between 1996 and 2004 were enrolled into the study after exclusion of patients with hydronephrosis, major renal anatomic anomalies, non-calcium stones, history of recurrent stone disease and previous renal surgery. Lower pole infundibulopelvic angle (IPA), infundibular length (IL), infundibular width (IW) and pelvicaliceal volume were measured from pre-SWL intravenous urography. The pelvicaliceal stone load (PSL) index implicating the stone burden of each patient described as the relationship between stone volume and total estimated pelvicaliceal volume for stone-bearing kidney was also calculated.

RESULTS

Sixty-eight percent of adult and 80% of pediatric patients became stone-free after SWL. The statistical insignificance between PSL index (p=0.097) of two groups shows that both groups shared a similar stone burden. According to SWL outcome, mean IPA values of stone-free and residual patients were 46.85 degrees and 30 degrees in pediatric group, respectively (p=0.01), whereas these values were 48.08 degrees and 43.06 degrees in the adult group, respectively (p=0.352). In the pediatric age group, stone-free and cumulative success rates increased with increasing IPA but this correlation was statistically insignificant (p: 0.263).

CONCLUSIONS

Lower caliceal anatomy has a higher impact on stone clearance after SWL in pediatric patients and urologists can expect better SWL outcomes from pediatric population with solitary lower caliceal stone than adults under the same conditions.