Couple questions:
You are 19 and cannot go to MD alone? Why?
Are you assuming it is a varicocele from a picture or something (as you have said you have not been to an MD)?
Why not just tell your parents you need a check up...if they really have to be there....then tell the MD in private.
Here is some info I found for you...link below:
"Do Varicoceles Cause Permanent Damage?
Although there is no way to prevent a varicocele, it usually needs no special treatment. A varicocele is usually harmless and more than likely won't affect a guy's ability to father a child. Some experts believe, though, that in some cases a varicocele might damage the testicle or decrease sperm production. In those cases, a doctor will probably recommend surgery.
What If the Doctor Finds a Varicocele?
Varicoceles are generally harmless, but if there is any pain and swelling the doctor may prescribe an anti-inflammatory medication to relieve it. If the varicocele is causing discomfort or aching, wearing snug underwear (like briefs) or a jock strap for support may bring relief. If pain is persistent and support doesn't help, the doctor may recommend a varicocelectomy (a surgical procedure to remove the varicocele).
A varicocelectomy is done by a urologist (pronounced: yoo-rah-luh-jist), a doctor who specializes in urinary and genital problems. The procedure is usually done on an outpatient basis (meaning there's no need for an overnight stay in hospital). The patient usually undergoes general or local anesthesia. To fix the problem, the doctor simply ties off the affected vein to redirect the flow of blood into other normal veins.
After surgery, the doctor probably will recommend that a guy wears a scrotal support and places an ice pack on the area to bring down any swelling. There may be discomfort in the testicle for a few weeks, but after that, any aches and pains will go away and everything should be back in full working order."