Urine in the semen: Semen travels through the urethra, which is the same tube that urine travels through. It is possible that some yellow-tinted urine can mix with semen, which would give semen a yellow tint or cast.
Jaundice: This results when the liver has difficulty breaking down bilirubin, a by-product of red blood cell destruction.Jaundicemost commonly causes yellowing of the eyes but can cause the skin and the semen to appear yellow too.
Abnormally high white blood cells: Inflammation can produce excess white blood cells. These can be released via the semen, a condition known as pyospermia or leukocytospermia. Additional white blood cells can cause semen to appear yellow. These can be the result of an infection.