Shaykh Bin Baz was asked:
“Is it permisible to make Istikhaarah without praying two rakahs or without Wudhu? And is it permissible for a menstruating [woman] or one in postpartum period to make Istikhaarah?
Yes, it is permissible to make Istikhaarah as she pleases. She can make Istikharah as much as she likes without Salaah, as (i.e. in the manner) one asks one’s Lord and makes Istikhaarah to one’s Lord, whether male or female, while mensturating and whatever she has relating to menstruation. In all these cases, there is no problem in making Istikhaarah [without Salaah/Wudhu]. However, if it is done after the Salaah, then that is better and more virtuous. Her doing Istikhaarah with Salaah is an act of Sunnah. So one prays two rakahs and then asks and makes Istikhaarah to one’s Lord, whether one is male or female. Yet [again we mention] if she is menstruating or is in a state of rush, and thus one makes Istikharah without Salaah, then there is no problem in one asking one’s Lord, and all praise is for Allaah.
ادْعُونِي أَسْتَجِبْ لَكُمْ
‘Invoke Me, [i.e. believe in My Oneness (Islamic Monotheism)] (and ask Me for anything) I will respond to your (invocation).’
” End translation. [Reference]