OBJECTIVES
To characterize the clinical course following cutaneous vesicostomy (CV) in megabladder (mgb−/−) mice with functional urinary bladder obstruction.
MATERIALS AND METHODS
Forty-five mgb−/− males underwent CV at a median age of 25 days. The 34 animals that survived longer than 3 days after CV were evaluated by serial observation and renal ultrasound. Moribund animals were euthanized. Urinary bladders and kidneys were analyzed by histopathology, and urine biochemical studies were performed.
RESULTS
At a median of 11 weeks after CV, 35% (12/34) of mgb−/− males became moribund with pelvic masses, which were identified as bladder stones at necropsy. Urine pH was alkaline and microscopy demonstrated struvite crystals. Urine contained Gram-positive cocci, while urine cultures were polymicrobial. Stone composition was chiefly struvite (88–94%) admixed with calcium phosphate. In 40% (2/5) of cases, retained intravesical polypropylene suture was identified as the presumed nidus. No stones were detected in over 100 males prior to CV or in 25 cases when CV was performed using polydioxanone suture. Kidneys from 33% (4/12) of animals with bladder stones contained staghorn calculi. Histopathology from animals with struvite stones demonstrated active cystitis, pyelitis, and chronic pyelonephritis.
CONCLUSIONS
These findings attest to the importance of the nidus in lithogenesis and provide a novel murine model for struvite urolithiasis and chronic infection of the diverted urinary tract.