Confirming whether sperm has entered the vagina can be important for individuals concerned about pregnancy risk. Here are some methods how to confirm whether sperm went inside:

1. Check for ejaculation: If you are engaging in sexual activity with a partner, observe whether ejaculation occurs. Ejaculation is the release of semen, which contains sperm, from the penis.
2. Use a condom: If a condom is used during intercourse, inspect it afterward for any signs of breakage or leakage. A broken condom can result in sperm entering the vagina.
3. Consider withdrawal method: If withdrawal (pulling out) is used as a contraceptive method, it's crucial to ensure that ejaculation occurs outside the vagina to minimize the risk of sperm entering.
4. Monitor vaginal discharge: After intercourse, pay attention to any changes in vaginal discharge. While not foolproof, an increase in cervical mucus or discharge may indicate sperm entry.
5. Take a pregnancy test: If pregnancy is a concern, consider taking a pregnancy test a few weeks after intercourse. Pregnancy tests detect the presence of human chorionic gonadotropin (hCG) hormone, which is produced by the body after fertilization occurs.

It's important to note that these methods may not guarantee complete certainty, and consulting with a healthcare professional for personalized advice and guidance is recommended for pregnancy prevention and reproductive health concerns.