Accurate measurement of post-void residual (PVR) volumes requires accurate determination of the timing of voiding, which is challenging in non-verbal patients. As a proof of principle, we sought to test the feasibility, safety and efficacy of using an enuresis alarm to indicate voiding in ten infants. Each infant was observed for 4 h with alarm in the diaper, and diapers checked every 15-30 min to confirm voiding. The alarm activated in 31 of 33 voids (93.9%). No adverse events occurred. Further work will investigate whether this approach may improve accuracy of PVR measurement.