Male infertility can be caused by many factors that negatively impact sperm quality and production. A semen analysis examines sperm shape, count, volume, and motility to assess fertility. Common issues include varicoceles (enlarged veins in the scrotum), infections, genetic abnormalities, environmental toxins, smoking, drinking, and marijuana use - all of which can lower sperm count or damage sperm. Varicoceles are treated with surgery to repair damaged veins and improve sperm health.