Intermittent cathing as a 70 yo man

Hello friends! Asking for my dad (71) who is recovering from Spinal Dural AVF and has urinary retention. Does age play a factor in how comfortable or uncomfortable it is to self cathe? My dad is petrified of trying it. He had bad experience with indwelling foley catheter when he was at the hospital.

His post void residual keeps varying in ultrasound tests. I think he has detrussor spincter disynergia (DSD) so if the radiologist doesn’t test him immediately after voiding (which is again not really in his control), the reports sometimes show high PVR, other times when he is called in immediately after voiding, his PVR is still there but a little lower. Example, today he had to wait 45 mins after voiding to redo the sonography and his PVR was 280. 1 month ago he was taken in immediately after voiding and his PVR was 160. This journey is so confusing to navigate.