Background and Purpose:
There are no definite data indicating which modality to use to assess the efficacy of shockwave lithotripsy (SWL). Usually, plain abdominal radiography (PAR) is recommended in percutaneous nephrolithotomy (PCNL) afterward and in the follow-up of asymptomatic stones, whereas noncontrast CT (NCCT) is recommended in cases of residual fragments. We compared the efficacies of PAR and NCCT in terms of assessing the outcome of SWL treatment for radiopaque ureteral stones.
Patients and Methods:
Those patients with renal colic and a radiopaque ureteral stone of 5 to 20 mm that was detected on PAR were included in the study; body mass index (BMI) values were calculated and recorded. Patients whose PAR revealed opacities suspicious for ureteral stones were evaluated with NCCT at 3-mm slices. Stone status was assessed with PAR and NCCT on post-SWL day 3. Detection of no stone, a residual fragment of ≤4 mm, and a residual fragment of >4 mm was defined as success, clinically insignificant residual fragments, and failure, respectively.
On post-SWL day 3, both PAR and NCCT revealed stones in 31 patients, and no stones were seen in either modality in 29 patients. NCCT revealed stones whereas PAR had negative results for stones in two patients. These patients had upper ureteral stones of 7.5 mm (6-9 mm) before SWL. Mean stone size on NCCT after SWL was 2.5 mm (1-4 mm). Mean BMI of these two patients was 27.72, and mean BMI of the patients with upper ureteral stones that were revealed by both PAR and NCCT was 27.68; these two values were statistically similar.
PAR is capable of detecting clinically significant residual fragments, and patients can be followed up with PAR alone after SWL treatment for radiopaque ureteral stones. This approach both decreases the cost and prevents excessive radiation exposure.
J Endourol. 2012 Jul;26(7):803-6. doi: 10.1089/end.2011.0624. Epub 2012 Mar 2
PMID: 22250983 [PubMed - indexed for MEDLINE]
In view of the currently extensive use of NCCT examinations in patients with urolithiasis, both for primary evaluation and for follow-up after different forms treatment this report is highly interesting. It is reassuring that very similar resukts were obtained when NCCT and plain abdominal radiography (PAR, KUB) were compared. Accordingly evaluation of outcome of ESWL advantageously can be made with PAR. This is an important finding in order to keep the exposure of the patient to radiation low. Another point of note was the finding that similar results on stone size were obtained with the two radiological modalities.