When does a inguinal hernia need to be operated on? in a 16 year old male, plays hockey, and is on 20mg accutane once daily

Soon: If the diagnosis is correct, then it should be operated as soon as possible.

Sooner Or Later...: The timing of hernia surgery is dependent on the risk of bowel getting stuck in the hernia ("incarceration") & the severity of the symptoms associated w/the hernia. If the hernia is small and causing no pain, it is possible to wait until a convenient time in one's life to have the surgery. Of course, this is best answered by a surgeon after formal examination. Good luck!

During stable health: This won't self heal & at least at that age the kid can recognize if the hernia becomes trapped & tell you. This gives you some time to schedule the procedure during a period of good health, avoiding conflicts of school or other pursuits. A full recovery interval of 6-8 weeks should be anticipated before resumption of sports. If it's big, it should be done sooner & contact sports avoided.

Do it now: While Junior is healthy. Being a teenager is hard enough without having to worry about the hernia getting incarcerated and requiring a difficult emergency surgery. The last thing an athletic boy needs is a groin problem for which repair is routine. It's not going to fix itself and ultimately will become more and more of a problem, and harder to manage.