If the UTI is recurrent, ie. occurring more than two episodes in six months, a trip to the urologist would be recommended.
If you have a history of urinary tract stones or you suspect you may have stones, you should also see a urologist. An example of stone symptoms would be a loin ache radiating to the groin.
Pregnant ladies with a UTI should also be evaluated by a urologist.
Men with a UTI would also need to see a urologist.