Difficult stones: Facts of case dictate treatment approach

May 15, 2006

Brisbane, Australia-A diverse array of difficult stone cases discussed at the Urological Society of Australasia meeting here made two points very clear. First, no single treatment strategy will be appropriate for every case. Second, treatment approach should be decided upon only after comprehensively reviewing multiple factors, including the patient's age, weight, general health, and comorbidities in addition to stone size, number, and location.

John Denstedt, MD, professor of urology, University of Western Ontario, London, ON, Canada, reviewed and commented on a number of cases presented by Damien Bolton, MD, director of urology at Austin Health, Victoria, Australia, and John Preston, MD, director of endoscopy at Princess Alexandra Hospital, Brisbane. Five of the cases were chosen for discussion by Urology Times.

Case 1: Pregnancy

Because of radiation concerns in early-stage pregnant women, Dr. Denstedt said he would have carried out an MRI, rather than an ultrasound examination, in this patient. He noted that the ureter is usually blind to ultrasound.

"When you see a stone on ultrasound, it almost routinely doubles in size" compared with what is measured by MRI, Dr. Denstedt said.

About 80% of stones occurring during pregnancy pass spontaneously and, if the woman had been afebrile, he would have followed her instead of intervening. Some patients can facilitate stone passage just by taking fluids.

Although the cause of the abortion is unclear, sepsis or the anesthetic may have been contributing factors, he said. In this case, he would have given intravenous sedation instead of a general anesthetic.

With respect to carrying out a stented ureteroscopy, Dr. Denstedt said that because of the increased risk of encrustation during early pregnancy that requires stents to be changed frequently, he does not recommend this option. However, at 20 weeks of pregnancy, stent placement would have been the preferable procedure. After 22 weeks, a percutaneous nephrostomy is barely more invasive than a stent, he said.

"What you have in pregnancy cases is a perfect storm, with an almost malignant stone formation," he said.

Case 2: Multiple stones

A 55-year-old woman had a 2-year history of recurrent hematuria, left pyelonephritis, and multiple stones appearing on x-ray.

"The concept of this patient being stone-free is a fantasy," Dr. Denstedt said, but efforts to remove all of her stones should be attempted.

Ureteroscopy and shock wave treatments were not possible in this case because the stones were located up to 12 cm anteriorly in the kidney. Therefore, surgery with a percutaneous approach was the preferred option. Dr. Denstedt recommended starting with the left side, where one stone may have been in the renal pelvis, but operating on both kidneys at the same time if the procedure went smoothly. Antibiotics should be given pre- and postoperatively, he said.

Case 3: Morbid obesity

A morbidly obese 48-year-old paraplegic man presented with multiple calculi in both kidneys, recurring urinary tract infections, a creatinine level of 230 μmol/L, and ongoing anticoagulation.

Stones were detected on routine imaging, so the patient's situation was not critical, Dr. Denstedt noted. He recommended carrying out a renal scan on the right kidney and removing it laparoscopically if it was functioning below 10%, although he acknowledged that laparoscopic surgery would be difficult in an obese patient.