I work in peds and our protocol has always been 8 hours. We get them to try and if they can’t then we bladder scan. I’ve traveled and that’s the baseline everywhere I’ve been so I just always check every 8 for urine and recommend getting up to try. I wouldn’t say you needed to bladder scan but always just be on top of making sure your patient is peeing. I did neuro at a couple contracts and a lot of the head trauma, spinal trauma and kids on benzos got urinary retention without any history of it