_ refers to the internal organs

Visceral: Referring to the viscera, the internal organs of the body, specifically those within the chest (as the heart or lungs) or abdomen (as the liver, pancreas or intestines). In a figurative sense, something "visceral" is felt "deep down." It is a "gut feeling."

hope this helps !!!

So that you don't get baby's but also prevents stis such as hiv