Bianchi G et al, 2018: Ultrasound follow up: Is an undetected spontaneous expulsion of stone fragments a sign of extracorporeal shock wave treatment failure in kidney stones?
Bianchi G, Marega D, Knez R, Bucci S, Trombetta C.
Department of Urology, University of Trieste, Cattinara Hospital, Trieste.
INTRODUCTION: After extracorporeal lithotripsy (SWL), a spontaneous expulsion of fragments is often reported. The aim of this study is to demonstrate the presence of a stone free status or the presence of clinically insignificant residual fragments (CIRFs, defined as "asymptomatic, noninfectious, ≤ 3 mm fragments") in people with undetected spontaneous expulsion.
MATERIALS AND METHODS: Between May and September 2017, we performed a total of 87 treatments. The device used was a Storz Medical Modulith® SLK. All the patients were treated in prone position to reduce respiratory movements and underwent sonography before and four to eight weeks after the treatment. An in line ultrasound targeting was possible with all the stones. People lost to follow up or with ureteral stones were excluded. Patients were divided in groups according to gender, previous treatments, stone diameter and position.
RESULTS: We enrolled 73 patients. 57 patients had a single stone and 16 multiple stones. A mean number of 3044 shock waves was administered with a maximum average energy of 0.68mj/mmq. At follow up, 41 patients (56.2%) were found stone free or with CIRFs. The association between undetected expulsion and the presence of CIRFs is considered to be not statistically significant (p = 0.89). Among patients with CIRFs, 25/41 didn't report expulsion. Taking in account the groups our population was divided in, according to gender (p = 0.36), previous treatments (p = 0.44), stone diameter (p = 0.28) and stone position (p = 0.35), the association between undetected spontaneous expulsion and presence of CIRFs was never statistically significant.
CONCLUSIONS: An undetected spontaneous expulsion of stone fragments could not be considered a sign of SWL treatment failure. The association between undetected expulsion and presence of CIRFs is never statistically significant if gender of the patients, previous treatments, stone diameter and stone position are considered.
Arch Ital Urol Androl. 2018 Sep 30;90(3):166-168. doi: 10.4081/aiua.2018.3.166.
I have difficulties to understand exactly what the authors really want to demonstrate with this study of a small group of patients.
To detect expulsion of stone fragments it is necessary to have a method for this purpose. The patients might for instance be given a sieve or asked to pass urine in a vessel followed by careful inspection.
Expulsion can be expected in all patients rendered stone-free, but it is not mentioned if all these patients (n=?) had observed stone fragments in their urine. Or did all patients have either CIRF or failed treatment? Moreover expulsion of fragments also should be the consequence of disintegration leading to CIRFs as well as when there was partial disintegration and residuals > 3 mm (n=12). According to Table 2; CIRFs or complete stone clearance were recorded in 41 patients.
It is possible that the authors have been insufficiently careful with the definition of stone-free and CIRF. Irrespective of that reservation, it is obvious that the patients’ report on stone/fragment passage or its absence was a too weak variable for clinical conclusions.