My baby boy was born with a severe hydronephrosis. i need to cath him once a day. but how long i keep catheterising him? he has anal incontinence

As long as necessary: The treatment plan for tour child is likely a complex one that involves testing & consulting with pediatric urologists/nephrolgists & your primary pcp.You do not mention the main diagnosis, but there are situations where intermittent cathing is done indefinitely. The option of a continuous catheter may lead to frequent urinary tract infections.

Long term: Depending on the cause of the hydronephrosis, and if it can be corrected, this will probably be a lifetime course, especially with stool incontinence as well (more a neurologic problem, i would guess).

Depends: It all depends on the diagnosis: both anatomic and neurologic. Although cathing only once a day is occasionally appropriate, it is much more common to cath 4-5 times a day. If he has anal incontinence as well, it increases the probability of a neurologic problem. Make sure you are evaluated by a pediatric urologist.

Wait a minute: Actually cathing once daily is almost never recommended. All the risks of cathing (introducing bacteria) and the bladder only gets emptied completely once. At the very minimum it needs to be twice daily and typically more. With all these issues, it sounds like he has something severe like valves or exstrophy. The bladder may take a long time to recover.