Research Article: Management of Clinically Insignificant Residual Fragments following Shock Wave Lithotripsy

Date Published: May 31, 2012

Publisher: Hindawi Publishing Corporation

Author(s): Elisa Cicerello, Franco Merlo, Luigi Maccatrozzo.


Clinically insignificant residual fragments (CIRFs) are small fragments (less than 5 mm) that are present in upper urinary tract at the time of regular post-SWL followup. The term is controversial because they may remain silent and asymptomatic or become a risk factor for stone growth and recurrence, leading to symptomatic events, and need further urologic treatment. Although a stone-free state is the desired outcome of surgical treatment of urolithiasis, the authors believe that the presence of noninfected, nonobstructive, asymptomatic residual fragments can be managed metabolically in order to prevent stone growth and recurrence. Further urologic intervention is warranted if clinical indications for stone removal are present.

Partial Text

With the introduction of shock wave lithotripsy (SWL) in 1980, the treatment of renal calculi was revolutionised. Few medical innovations have had the dramatic effect of SWL which quickly became the treatment of choice for most upper-tract calculi [1]. However, as our approach to the treatment of urinary calculi has changed, so has our concept of what constitutes successful treatment. When open surgery was the standard treatment for the management of renal calculi, the presence of residual stones suggested a failed procedure, even if those remaining stones were small [2]. SWL does not remove stones; it disintegrates them producing fragments which must be passively excreted. However, the clearance of the fragments produced by shock waves is not immediate since as many as 85% of patients have radiological evidence of residual fragments when discharged from hospital [3]. The residual fragments are defined as all fragments remaining in the kidney 3 months after the last session of SWL. Among these fragments, those larger than 5 mm are generally considered as failures of the SWL session. The residual fragments with diameter less than 5 mm that are asymptomatic and noninfected are expected to pass spontaneously without further treatment, leading to the definition of clinically insignificant residual fragments (CIRFs) [4]. In case of persistence within the upper urinary tract, these fragments may grow and gain clinical relevance again, becoming symptomatic or requiring intervention [5].

Residual fragments are common after SWL. At the discharge, fragments less than 5 mm have been described in 85% to 96% of patients with calcium [3, 6] and in 92% with infected stones [7]. The majority of these fragments will be passed within a few weeks. With increasing renal persistence of residual fragments, the probability of stone clearance seems to decrease [8].

While the presence of residual fragments is usually reported as a function of the findings on plain abdominal radiographs, plain films have significant limitations.

Residual fragments may be important for a variety of reasons: they may act as a nidus for recurrent stone growth, they can become acutely dislodged and cause significant obstruction with pain and infection, or they may be the source of persistent infection.

The management of residual fragments is controversial, especially given the potential for these fragments to grow and become clinically significant.