I'm only 20 years old, and want to get pubic liposuction. Can I do this without my parents knowing about it?

You are over 18 and can have surgery done without your parents consent.  I think it is best however, for everyone to know in case something were to happen.  I suggest seeing an expert as treatment in this area requires meticulous skill and expertise, especially if done with hi definition.  Best, Dr. Emer.

If you are 18 years or older, a physician would require your consent before discussing your health with your parents. However, successful liposuction often requires wearing of a garment over the treated area and there is some discomfort involved. Possibly you will be taking pain medications. These issues could tip one off that you have had an intervention of some sort.

For the purposes of healthcare decisions, you are an adult at 18.  So the simple answer is yes. You do not need parental consent.  The better question is whether or not you should do it without informing your family and my answer is an enthusiastic no.  While complications of liposuction for healthy individuals are rare, they do happen.  Your family needs to know what to look for and they need to be able to communicate your surgical history to your healthcare team if you are unable to do so.  You don't have to seek their approval for your decision, but I highly recommend informing them of your decision.  If you have liposuction of your mons pubis alone, I would expect your recovery to be rather quick - a week or two.