Nonopaque crystal deposition causing ureteric obstruction in patients with HIV undergoing indinavir therapy.

OBJECTIVE: We describe the unique CT features of ureteric calculi in six HIV-infected patients receiving indinavir, the most commonly used HIV protease inhibitor, which is associated with an increased incidence of urolithiasis. CONCLUSION: Ureteric obstruction caused by precipitated indinavir crystals may be difficult to diagnose with unenhanced CT. The calculi are not opaque, and secondary signs of obstruction may be absent or minimal and should be sought carefully. Images may need to be obtained using i.v. contrast material to enable diagnosis of ureteric stones or obstruction in patients with HIV infection who receive indinavir therapy.