My fiance is a quad and can urinate on his own, but can't empty his bladder. is it safe for us to try the condom catheter at night?

Yes and no: It is safe but will be ineffective. The condom catheter is only effective for those unable to control their urine. He can't empty his bladder so he needs a catheter in his bladder past the sphincter. A foley, straight, or supra pubic catheter is best in this case.

CIC better: Clean intermittent self catheterization if possible or by partner might achieve urinary control possible with addition of anticholingeric medication (eg oxybutinin er or Detrol (tolterodine) la is a better choice. Might be a candidate for an appendicovesicostomy to facilitate catheterization. Codom catheter in presence of retained urine is risky. ? Fiance have a neurourologist.