Hello. Welcome to Healthcare Magic. Although it isn't possible to diagnose your condition without an examination, it sounds like you may have a communicating hydrocele
, which is a pocket of fluid that collects beside your testicle when you're upright and then disappears when you lie down. The fluid that collects in a communicating hydrocele originates in your abdominal cavity: when you're standing or when you bear down the fluid follows a weakness in your groin, percolates through a thin channel leading to your scrotum
, and collects beside your testicle. When you lie down, the fluid goes the other way, allowing the hydrocele to shrink.
Hydroceles aren't cancerous, and they usually aren't dangerous. However, the weakness in your groin that permits the fluid to pass through could also admit a loop of intestine, causing a hernia
. Therefore, if you do have a communicating hydrocele it might be wise to get it repaired. A urologist
(a doctor who specializes in the genitourinary tract) can help you with this.
I hope that helps, and good luck!