To identify the possible complications after extracorporeal shock wave lithotripsy (SWL) and to suggest how to manage them, the significant literature concerning SWL treatment and complications was analyzed and reviewed. Complications after SWL are mainly connected to the formation and passage of fragments, infections, the effects on renal and nonrenal tissues, and the effects on kidney function. Each of these complications can be prevented adopting appropriate measures, such as the respect of the contraindications and the recognition and the correction of concomitant diseases or infection, and using the SWL in the most efficient and safe way, tailoring the treatment to the single case. In conclusion, SWL is an efficient and relatively noninvasive treatment for urinary stones. However, as with any other type of therapy, some contraindications and potential complications do exist. The strictness in following the first could really limit the onset and danger of the appearance of others, which however must be fully known so that every possible preventive measure be implemented.
Since its appearance at the beginning of the 1980s [
In essence, we are not talking about a procedure that is altogether benign, but rather one that may bring about lesions to kidneys and/or its neighbouring organs. Moreover, even a technically successful lithotripsy may determine subsequent morbidity due to related fragmented products. In light of this, the few contraindications that do actually exist should clearly be kept in mind [ pregnancy; uncontrolled infections in the urinary system; uncontrolled alterations of coagulation; aortic or renal artery aneurism; serious skeletal malformations; serious obesity.
Complications after an SWL come from: the formation and passage of fragments; infections; the effects on renal and nonrenal tissues: the effects on kidney function; hypertension.
The main aim of an SWL is the pulverisation of stones and asymptomatic elimination of fragments. This procedure may not always be completely successful due to
To illustrate this, the formation of fragments <4 mm is present in up to 59% of the cases, with a risk of a symptomatic episode, an operation, or even both, equal to 43% [
Factors responsible for the level of fragmentation after a lithotripsy, and therefore real risk factors for SWL failure are the
The stones made by Struvite, uric acid, and dehydrated calcium oxalate tend to fragment into tiny parts that may be easily passed. On the other hand, dehydrated calcium phosphate stones (brushite) and monohydrate calcium oxalate stones tend to produce larger fragments which are hence much harder to pass. Particularly difficult to treat are the stones made by cystine which, like any organic compound, has acoustic features similar to those in the surrounding tissues.
The chance of SWL treatment success is related to the volume of the stones being treated. For stones <2 cm, the percentage of success reported, considered as “stone free rate,” has been in the range of 66–99%, which drops to 45–70% for stones of 2-3 cm and even further again for staghorn stones [
Moreover, stones >2 cm almost always require multiple treatments and have a tendency to shatter incomplete: the risk of complication is greater with an incidence of partial obstruction between 19–50% [
For this reason, SWL as a monotherapy for cystine stones >15 mm is currently not recommended [
The chances of success are less, all other characteristics being equal, for stones located in the lower pole of the kidney. Recorded success rates have been in the region of 29% for stones of 11–20 mm and 20% for stones >20 mm [
Although the effects of shock wave frequency on the efficacy of the treatment were not clinically widely evaluated [
One complication directly related to incomplete fragmentation is the pileup of fragments, otherwise known as
Different options exist to deal with the problem once it has been established. As we have already seen, in some cases, complications are asymptomatic and may simply be followed over time with spontaneous resolution of the problem in 2 to 4 weeks, always ensuring of course that renal function is maintained [
In other cases, above all where larger distal fragments are present, steinstrasse has effectively been treated with repeated sessions of SWL showing positive results in 90% of cases [
During extracorporeal lithotripsy, one of the forces applied to the stone comes from a cavitation bubble collapse. This force, however, may cause damage to the small renal vessels that would result in a microhaemorrhage, the release of cell mediator of phlogosis, and the infiltration by inflammatory response cells.
These tiny lesions may also allow the passage of bacteria, which may be present in the urine or inside the stones themselves, into the blood stream which could thus develop into other related problems.
To simplify things here, we will define “infection” as a harmful colonization of a species unknown to the host organism that responds to the infection with inflammation. By the term “sepsis,” on the other hand, we refer instead to a serious medical condition characterised by a generalised state of inflammation, called SIRS (systematic inflammatory response syndrome), and by the definite or suspected presence of an infection [
The development of sepsis after bacteremia is relatively low in absolute terms, <1% of cases [
There are no truly trustworthy signs that attest to the early onset of bacteremia or bacteriuria: white cells blood count, speed of erythrosedimentation, and a positive culture are all useful signs, unfortunately they generally tend to show up positive when the patient is already symptomatic. In terms of reduction of infective complications and the expense connected to their treatment, the use of antibiotic prophylaxis has therefore been proposed, but this use has not been confirmed in other randomised controlled studies for patients without preexisting UTI or infected stones [
To sum up then, antibiotics should only be administered to patients with positive urine culture, with staghorn or low density struvite stones, with a history of struvite stones or recurring urinary infections, to patients who will undergo a contemporary instrumental procedure, and finally to those with a nephrostomy or a stent in place [
The most evident expression of kidney trauma is haematuria that generally passes in a few days.
Collections of symptomatic fluids or perirenal, subcapsular, or intrarenal haematomas are rare and occur in less than 1% of patients; if, however, patients have systematically undergone a CT scan or MRI then evidence of haematoma rises to 25% [
A microscopic examination shows up characteristic evidences: haemorrhagic lesions are preferentially localised in the corticomedullar joint, probably due to differences in the density of the tissue at that level [
The incidence of arrhythmia during an SWL varies from between 11% and 59%, and is, in general, related to minor premature ventricular beats. Evidence of ischemic lesions is very rare, and this incidence may be further reduced by synchronising the supply of shock waves with pulsations [
The association between SWL and arterial hypertension has always been a controversial argument and debated. The diagnosis of hypertension after SWL has been reported in 8% of cases, that does not differ greatly however from the incidence of about 6% of new diagnosis in the overall population [
A large retrospective study has analysed patients who underwent an SWL, controlled against patients who underwent an ureterorenoscopy or a percutaneous lithotripsy without being able to show, within one year of the treatment, any significant differences in the incidence of hypertension (2.4% versus 4%), and even after 4 years, the differences were not particularly significant (2.1% versus 1.6%); however, a statistically significant increase in diastolic pressure showed up after SWL [
Many of the studies that have been documented are retrospective. Limiting oneself to randomly controlled studies there is no evidence that SWL treatment determines changes in arterial pressure [
Several gastrointestinal lesions of various types have repeatedly been recorded following an SWL with a global incidence of 1.8% [
A sufficiently high amount of clinical and experimental evidence exists to exclude any permanent effects on testicular or ovarian function to thus confirm that there are no existing correlations between SWL and fertility [
Extracorporeal lithotripsy is an efficient and relatively noninvasive treatment for urinary stones: the large number of cases treated using this procedure, and its widespread use, testifies to this. However, as with any other type of therapy some contraindications and potential complications do exist. The strictness in following the first could really limit the onset and danger of the appearance of others, which however must be fully known in order that every possible preventive measure be implemented.
Extracorporeal shock wave lithotripsy
Systematic inflammatory response syndrome
Urinary tract infections
Computerised tomography
Magnetic resonance imaging.