I still have concern about amount of menstrual blood that has to be present to infect with hiv. My previous question was that I had sexual relations and female was menstruating after 2 minutes I stopped. Then I took off condom with a lot of blood present decides to wash my hands and finished by masturbating myself. The question would be how much blood has to be present outside of body to infect during masturbation and does it have to go in through urethra or can it infect if you are uncircumsized in cut or abrassions in penus.
Having sex with a condom reduces any chances that you may have transmitted from the menstrual blood. If this person was HIV positive, and you had blood on your hands, it cannot enter your system through your hands, and would die within seconds of being exposed to oxygen.
So to directly answer your question, no amount of blood really can transmit HIV through masturbation. Masturbation under any set of circumstances cannot transmit HIV, regardless of circumcision or not, abrasions or not. It does indeed need to enter through the urethra, but it also needs to enter during unprotected intercourse.
Keep in mind you did everything right in this situation, from wearing a condom to washing up, to checking with us. All in all, I would not necessarily recommend testing for this particular situation, as the person needs to be HIV positive in order for her to transmit HIV to you. However, regular testing would be recommended for any persons engaging in regular sexual activity. Just to ensure your own safety and the safety of your future partners.
Feel free to follow up with any new questions you may have.
All the best!