Urinary Stones in Children Hard to Sidestep

Neil Osterweil

March 20, 2019

BARCELONA, Spain — The treatment of children with urinary tract stones can be a challenge because young people are smaller to work on than adults, there is an absence of suitable instruments, and there is a paucity of evidence suggesting which form of therapy is optimal, experts explained here at the European Association of Urology (EAU) 2019 Congress.

"We know that the miniaturization of instruments is important, but optimization of instruments is important, too. You cannot use a large sheath and a large nephroscope for an infant," said Selçuk Silay, MD, from Istanbul Medeniyet University, who comoderated the session on pediatric urolithiasis.

Approximately 5% of urinary tract stones in the Western world are bladder stones, but that figure is much higher in developing countries, said James Donaldson, MD, from the Aberdeen Royal Infirmary in the United Kingdom.

The prevalence of bladder stones is 10 times higher in males than females, and the peak incidence in children occurs at the age of 3 years, he reported.

There are three principal types of bladder stones: primary endemic, which occur in the absence of other urinary tract pathologies and are associated with poor nutrition; secondary stones that develop after another pathology, such as a bladder outlet obstruction, neuropathy, or chronic bacteriuria; and migratory stones, which form in the upper urinary tract and migrate to the lower tract.

Because no national or international guidelines or systematic reviews provide best-practice evidence for pediatric bladder stones, Donaldson and his colleagues conducted a systematic review at the request of the EAU guidelines committee, which he presented during the session.

Pediatric Bladder Stones

"The most important finding from our study in terms of change in practice comes from a large nonrandomized controlled trial from India showing that endemic stones can potentially can be treated without having to place a drain or a catheter," Donaldson told Medscape Medical News.

That was one of five studies and six full-text papers, covering the treatment of 814 children with stones, used in the systematic review. They were the only English-language studies available on the subject, he said.

The researchers found that stone-free rates after either transurethral cystolithotripsy (TUCL) or percutaneous cystolithotripsy (PCCL) were similar to rates after open surgery. Although both cystolithotripsy procedures took longer than surgery, catheter duration and hospital stays were shorter.

In contrast, they note, shockwave lithotripsy appears to be associated with low stone-free rates.

Rates of urethral stricture with both TUCL and PCCL were low in all studies that provided those data, and there were no significant differences between the treatment types, although the quality of the evidence supporting the findings was "very low."

Further research is required to determine whether patient age and stone size are associated with outcomes after endoscopic intervention, the team concludes.

A second presentation examined the use of mini and ultramini percutaneous nephrolithotomy (PNCL) in 24 patients at Nottingham University Hospital NHS Trust, United Kingdom.

Kidney Stones

sheath size against subsequent stone-free and complication rates has been a challenge, Susannah La-Touche, MBBS, and her colleagues write in their abstract.

Because the definition of stone-free rate is not standard, comparing outcomes from different studies can be difficult, they point out. For their study, they defined stone-free as "no visible residual calculi on follow-up imaging."

At their center, mini PCNL is performed with a 16.5 F sheath and ultramini PCNL is performed with an 11 F sheath. In each procedure, a 365 μm laser fiber is used.

Complete data were available for seven girls and 17 boys, with a median age of 7 years.

Mean procedural time in the study cohort was 196 minutes (range, 85 - 300 min). Mean procedure time was longer for calcium phosphate stones than for calcium oxalate monohydrate stones, and, in one patient, a struvite stone in a transplanted kidney (300 vs 285 min).

One patient developed urinary tract infection, for a complication rate of 4%, and no perioperative blood transfusions were required. Of the six patients with residual stone fragments, four underwent subsequent extracorporeal shockwave lithotripsy, one underwent ureteroscopy, and one received conservative treatment.

"We get better clearance rates with mini PCNL and ultramini PCNL in the pediatric patient," La-Touche told Medscape Medical News.

"It is a better clearance rate, actually, than in our adult population with the same balance, and the stone composition is the same as in our adult population," she said.

When La-Touche was asked why the incidence of stones is increasing in both children and adults in the Western world, she explained that the increase is probably related to environmental factors, which include socioeconomic status and nutrition.

Little Bodies, Big Instruments

These and other studies presented highlight some of the challenges pediatric urologists face, said Anne-Françoise Spinoit, MD, PhD, from Ghent University Hospital in Belgium, who comoderated the session.

"The problem of pediatrics is always the same: the instruments are generally made for adults and they have to be adapted for children. That's why we sometimes have big problems treating these patients," Spinoit told Medscape Medical News.

However, two recent developments are likely to improve the management of stones in children, Silay told Medscape Medical News. The so-called "superperc" technology uses suction to remove residual fragments, and high-powered lasers can now fragment stones more effectively.

The Donaldson study was supported by the EAU. The La-Touche study was internally supported. Silay, Donaldson, La-Touche, and Spinoit have disclosed no relevant financial relationships.

European Association of Urology (EAU) 2019 Congress; Abstracts 435 (La-Touche) and 443 (Donaldson). Presented March 17, 2019.

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