I had surgery for an inguinal hernia three weeks ago and my left testicle has swollen badly over the two days is it serious?

Possibly: It is not uncommon for some swelling to get into the scrotum after inguinal hernia surgery. It is unusual, though, for there to be a change 3 weeks after the operation. You should be checked by your surgeon if this has not resolved.

No: The swelling happens when the venous drainage from the hernia is compromised by swelling after surgery.