Characterization of ureteral lesions associated with impacted stones

Background: Few studies have addressed the various types of ureteral lesion s apparent in patients treated for ureteral stones, especially in those wit h impacted stones. Macroscopic and microscopic analyses of ureteral lesions associated with impacted stones were therefore undertaken. Methods: From May 1994 to October 1996, 36 patients with ureteral stones, 2 1 of whom showed stone impaction, were treated with transurethral ureteroli thotripsy. After ureteroscopic examination, biopsied specimens were obtaine d from six patients with impacted stones and were examined microscopically by conventional hematoxylin and eosin staining. Results: Ureteroscopy revealed two types of mucosal lesions in the patients with impacted stones: Type 1 lesions were defined as edematous or cystic h emispheric lesions and occurred in 18 patients, whereas type 2 lesions had a villous appearance and were present in three patients. Microscopically, t ype 1 lesions appeared as submucosal edema without specific findings, where as type 2 lesions appeared as columnar mesenchymal tissue coated with sever al layers of transitional epithelium. With regard to factors that might con tribute to lesion formation, duration of stone presence was significantly g reater for patients with impacted stones than for those with-nonimpacted st ones. However, no differences in such parameters were apparent between pati ents with type 1 lesions and those with type 2 lesions. Conclusions. Two types of ureteral lesions associated with impacted stones were confirmed microscopically. The duration of stone presence is a potenti al contributing factor in the development of ureteral lesions, but factors that determine the type of ureteral lesion remain unclear.