STONE FORMATION AFTER AUGMENTATION CYSTOPLASTY - THE ROLE OF INTESTINAL MUCUS

Purpose: We evaluated the role of mucus in urine after bladder augment ation and hypothesize that mucus acts as a possible etiological factor in stone formation. Materials and Methods: Mucus was collected via ce ntrifugation from the 24-hour urine specimens of 8 stone forming and 1 0 nonstone forming patients who were randomly selected from our augmen tation population. The mucus and stones were lyophilized, and then ana lyzed via scanning electron microscopy and energy dispersive x-ray spe ctrometry for calcium, phosphate, magnesium and sodium. The 24-hour ur ine collections were also analyzed to determine any metabolic differen ces between the 2 groups. Results: Scanning electron microscopy and en ergy dispersive x-ray spectrometry spectra showed increased calcium, p hosphate, and magnesium, and significantly higher (p <0.05) calcium-to -phosphate ratios in the mucus of stone versus nonstone forming patien ts. Of the 8 stones examined all had viscous fluid (mucus) centers ric h in calcium, phosphate and magnesium. Calcium-to-phosphate ratios in the corresponding mucus recovered from stone centers were similarly hi gh. Urinary citrate levels were low in both groups, and calcium, phosp hate and magnesium were within normal ranges. Conclusions: Mucus appea rs to have an important role in the genesis of bladder stones after au gmentation, possibly acting as a nidus. Metabolic changes following au gmentation were similar in stone and nonstone forming populations. Our data suggest that mucous calcium-to-phosphate ratios may be predictiv e of future stone formation. Furthermore, there may be a benefit in in stituting more aggressive measures aimed at clearing mucus from the bl adder.