Pre-ejaculate (also commonly known as precum) is a clear fluid secreted by glands in the urethra, during sexual arousal before ejaculation Pre-ejaculate is an alkaline fluid containing numerous enzymes and mucus but no sperm.
Despite this lack of sperm, any fluid from the penis prior to ejaculation could be contaminated with sperm and therefore should be regarded as potentially fertile and capable of resulting in an unwanted pregnancy. This has been shown in studies where up to 40% of men had viable sperm in their pre-ejaculate. This is part of the reason for the high failure rate of the withdrawal method as a contraceptive method.
Urination before unprotected sex may lower the number of sperm in the urethra, but we cannot be absolutely sure that it eliminates the risk of an unwanted pregnancy.
It is best not to rely on the withdrawal method as a form of contraception. Typical failure rates of the withdrawal method are up to 27%. This means roughly 27 out of every 100 women using this method for a year will become unintentionally pregnant.
I would also remind you besides the risk of unwanted pregnancy, that unprotected sex also puts you at risk of sexually transmitted infections.
