A couple of things please me about your efforts to find a topic -- and the teacher in me feels compelled to point it out.
1. You are thinking in terms of "narrowing it down." That's smart. Too many students (and staff members new to research) start by picking a very specific topic -- and persist in pursuing it even if it is not appropriate or practical.
2. You are learning a valuable lesson while you search. Not all health care research questions are "nursing" questions. Some topics are more appropriately researched by our colleagues in other disciplines (e.g. medicine, pharmacology, psych, etc.). The best questions for you to pursue at this point of your career are ones that relate directly to things that nurses do and decisions that nurses make. While a nurse can choose to be an advocate for circumcision or an opponent of the routine performance of the procedure ... and/or ... a nurse would be interested in its relationship to UTI's ... it's a specific topic that might not be the best for a novice researcher to tackle.
I recommend taking a step back and taking a look at the nursing role in circumcision. What do nurses do in relation to this procedure? What decisions about it do nurses make? What issues exist in relation to the nursing role in circumcision? Those are ones that might lead to a good topic for you to explore further. You might want to review the nursing literature and see what experienced nurses are talking about (and concerned about) to find out what they see as being a problem or issue for nurses practicing in the field -- so that your work will produce something useful to them.