Factors that predict the spontaneous passage of ureteric stones in children

What predicts spontaneous passage of ≤1 cm ureteral stones in children?

PURPOSE

The aim of this study is to determine what factors predict spontaneous passage of ≤1 cm ureteral stones in children.

METHODS

Files of the patients diagnosed with a single ureteral stone on a given side between 2008 and 2017 were retrospectively reviewed. Patients with congenital obstructive uropathy, neurogenic bladder, vesicoureteral reflux and those with a stone diameter of >1 cm were excluded. Detection of ureteral stones was done using ultrasonography (US) primarily, and computed tomography when US findings were inconclusive. Patients were treated either conservatively or surgically. Conservative treatment included adequate hydration and pain management whereas surgical treatment included ureteroscopic intervention. Apart from those who required urgent intervention, patients were referred for surgical treatment after 2-4 weeks of follow-up with no spontaneous passage. Factors analyzed for association of spontaneous passage included age, gender, type of hematuria, stone localization, laterality, presence of concomitant kidney stone, degree of hydronephrosis, stone size and stone composition.

RESULTS

A total of 70 patients (38 males, 32 females); median age 4.7 years had a ≤ 1 cm ureteral stone (median diameter 7 mm). US was able to diagnose the ureteric stone in 47 patients while computed tomography was required in 23 patients. Spontaneous passage was observed in 40 patients (57.1%). Median time for stone passage was 8 days (3-34 days). Stone size and presence of hematuria (macroscopic and microscopic combined) were factors associated with spontaneous passage and 6.7 mm was found to be the cut-off (AUC = 0.953; 95% CI 0.905-1.000; sensitivity 96.7%, specificity 82.5%, p < 0.001). Moreover, age, degree of hydronephrosis or stone location were not associated with spontaneous passage.

CONCLUSION

Patients with a ureteric stone size <6.7 mm can safely be followed conservatively, with a spontaneous passage rate of 82.5%. Type of Study Case series with no comparison group. Level of Evidence IV.

A fluid-structure interaction (FSI)-based numerical investigation of peristalsis in an obstructed human ureter

Urine moves from the kidney to the bladder through the ureter. A series of compression waves facilitates this transport. Due to the highly concentrated mineral deposits in urine, stones are formed in the kidney and travel down through the urinary tract. While passing, a larger stone can get stuck and cause severe damage to ureter wall. Also, stones in the ureter obstructing the urine flow can cause pain and backflow of urine which in turn might require surgical intervention. The current study develops a 2D axisymmetric numerical model to gain an understanding of the ureter obstruction and its effects on the flow, which are critical in assessing the different treatment options. Transient computational analysis involving a two-way fully coupled fluid-structure interaction with the arbitrary Lagrangian-Eulerian method between the ureteral wall and urine flow is conducted with an obstruction in the ureter. The ureter wall is modeled as an anisotropic hyperelastic material, data of which, is based on biaxial tests on human ureter from previous literature, while the incompressible Navier-Stokes equations are solved to calculate urine flow. A finite element-based monolithic solver is used for the simulations here. The obstruction is placed in the fluid domain as a circular stone at the proximal part of the ureter. One of the objectives of this study is to quantify the effect of the ureteral obstruction. A sharp jump in pressure gradient and wall shear stress, as well as retrograde urine flow, is observed as a result of the obstruction.

Experience of a Tertiary-Level Urology Center in the Clinical Urological Events of Rare and Very Rare Incidence. VI. Unusual Events in Urolithiasis: 1. Long-Standing Urethral Stones without Underlying Anatomical Abnormalities in Male Children

OBJECTIVES

The study aimed to present our center's experience with long-standing urethral stones in male children with normal urethra.

MATERIALS AND METHODS

Retrospective search of our center data was done for the cases of long-standing urethral stones with normal urethra in male children during the period July 2001 - June 2016. Demographic and clinical data were studied.

RESULTS

Of more than 54,000 urolithiasis procedures, 17 male children (0.031%) were operated for long-standing urethral stones with normal urethra. In 14 cases (82.4%), residence was rural and parental education levels were low or none. All children were regularly prompted voiding with a history of difficulty or dysuria. All the stones lodged in the posterior urethra with an approximate mean duration of 2 months. The mean stone size of 11.29 ± 3.88 mm and rough surfaces in 88.2% of cases represented the main predisposing factors. Major complications included rectal prolapse in 1 case and vesicoureteral reflux in 3 cases. Endoscopic push-back was followed by disintegration in 76.5% or cystolithotomy in 17.7%, while it failed in 1 case that was treated by cystolithotomy.

CONCLUSIONS

Long-standing urethral stones in male children with normal urethra are very rare misdiagnoses. Stone topography and sociocultural factors predisposed to their lodgments and negligence. Endoscopic treatment is the best approach.

Predicting Spontaneous Stone Passage in Prepubertal Children: A Single Institution Cohort

INTRODUCTION

No method currently exists for predicting which young child with a renal or ureteral stone will require surgery as opposed to pass the stone. Our goals were to analyze practice patterns at a major pediatric center and to identify factors that predicted spontaneous stone passage.

METHOD

A retrospective review of all prepubertal patients (≤ 11 years) presenting to our institution from January 2005 to July 2014 with symptomatic nephrolithiasis was performed. Demographic data and stone details were reviewed, including anatomic location, size, and outcomes. Spontaneous stone passage was determined by parental report and/or stone absence on imaging obtained within 6 months after initial diagnosis.

RESULTS

A total of 119 eligible patients were identified, with an average age of 88.7 months (4-143). Forty eight (40.3%) patients spontaneously passed their stone and the remaining 59.7% required endoscopic intervention. Overall, 79.0% had symptomatic presentation (flank pain, hematuria) and 39.5% of patients were obstructing stones. Symptomatic presentation was more common with ureteral (86.5%) than with renal (66.7%) stones, but was not associated with increased passage of stones in general (p-value 0.1765). Of the 48 patients who spontaneously passed stones, 11 (24.4%) were renal stones compared with 37 (50.0%) ureteral stones. The average size of spontaneously passed stones was 3.5 mm (2-8) for renal and 3.4 mm (1-7) for ureteral stones. Based on logistic regression, the single most important predictor of stone passage was stone size (p-value <0.001). The odds of passage were 3.1 times higher for ureteral stones compared with renal stones (p = 0.0070) when not controlling for size.

CONCLUSION

In prepubertal patients, ureteral stones with an average size of 3.5 mm or less are more likely to pass spontaneously. Based on this information, watchful waiting is a reasonable option in clinically stable nonseptic patients with renal/ureteral stones of this size.

Factors predicting the spontaneous passage of a ureteric calculus of ⩽10 mm

Objective

To evaluate the outcome of the expectant management of ureteric stones and to determine the factors predictive of the spontaneous passage of stones.

Patients and methods

We retrospectively reviewed the medical records of patients who had ureteric stones of ⩽10 mm and who were treated conservatively at our institutions during the period 2008–2013. The stone-passage rate and time, and different clinical, laboratory and radiological variables, were analysed.

Results

In all, 163 patients with ureteric stones were enrolled in the study, of whom 127 (77.9%) passed their stones spontaneously, with a mean (SD) passage time of 24.0 (8.09) days. The cumulative stone-passage rate was 1.6%, 15%, 41.7%, 72.4%, 89.8% and 98.4% at 7, 14, 21, 28, 35 and 42 days from the first presentation, respectively. Patients with a high pain-scale score, stones of ⩽5 mm, a lower ureteric stone, a high white blood cell count and those with absent computed tomography (CT) findings of perinephric fat stranding (PFS) and tissue-rim sign (TRS) had a higher likelihood of spontaneous stone passage. Patients with stones of ⩽5 mm, stones in the lower ureter and those with no PFS had a shorter spontaneous passage time. In a multivariate analysis the absence of PFS and TRS were the only significant predictors for spontaneous stone passage (P < 0.001 and 0.002, respectively).

Conclusions

The spontaneous ureteric stone-passage rate and time varies with different factors. The absence of CT findings of PFS and TRS are significant predictors for stone passage, and should be considered when choosing the expectant management.

Evaluation and medical management of kidney stones in children

PURPOSE

We review the current literature on the diagnostic evaluation and dietary and pharmacological management of children with nephrolithiasis.

MATERIALS AND METHODS

We searched MEDLINE(®), Embase(®) and the Cochrane Library from their inceptions to March 2014 for published articles in English on kidney stones and therapy in children 0 to 18 years old. Based on review of the titles and abstracts, 110 of the 1,014 articles (11%) were potentially relevant to the diagnostic evaluation and medical management of nephrolithiasis in children. We summarized this literature and drew on studies performed in adult populations to augment areas in which no studies of sufficient quality have been performed in children, and to highlight areas in need of research.

RESULTS

During the last 25 years the incidence of nephrolithiasis in children has increased by approximately 6% to 10% annually and is now 50 per 100,000 adolescents. Kidney stones that form during childhood have a similar composition to those that form in adulthood. Approximately 75% to 80% of stones are composed of predominantly calcium oxalate, 5% to 10% are predominantly calcium phosphate, 10% to 20% are struvite and 5% are pure uric acid. The recurrence rate of nephrolithiasis in patients with stones that form during childhood is poorly defined. Ultrasound should be used as the initial imaging study to evaluate children with suspected nephrolithiasis, with noncontrast computerized tomography reserved for those in whom ultrasound is nondiagnostic and the suspicion of nephrolithiasis remains high. Current treatment strategies for children with kidney stone disease are based largely on extrapolation of studies performed in adult stone formers and single institution cohort or case series studies of children. Tamsulosin likely increases the spontaneous passage of ureteral stones in children. Increased water intake and reduction of salt consumption should be recommended for all children with a history of kidney stones. Potassium citrate is a potentially effective medication for children with calcium oxalate stones and concomitant hypocitraturia, as well as children with uric acid stones. However, long-term compliance with therapy and the effect on decreasing stone recurrence in children are unknown. Based largely on efficacy in adult populations, thiazide diuretics should be considered in the treatment of children with calcium based stones and persistent hypercalciuria refractory to reductions in salt intake.

CONCLUSIONS

The incidence of kidney stone disease in children is increasing, yet few randomized clinical trials or high quality observational studies have assessed whether dietary or pharmacological interventions decrease the recurrence of kidney stones in children. Collaborative efforts and randomized clinical trials are needed to determine the efficacy and effectiveness of alternative treatments for children with nephrolithiasis, particularly those with calcium oxalate stones and concomitant hypercalciuria and hypocitraturia. Additional areas in need of study are the optimal length of time for a trial of stone passage in children, the cost-effectiveness of medical expulsive therapy vs analgesics alone, and the size and location of stones for which medical expulsive therapy is most effective.