A varicocele is an enlargement of the veins within the loose bag of skin that holds your testicles (scrotum). With time, varicoceles might enlarge and become more noticeable. The condition might cause a swollen testicle, almost always on the left side. Varicoceles are a common cause of low sperm production and decreased sperm quality, which can cause infertility.
 
Causes
Veins contain one-way valves that push blood in one direction, toward larger veins. When valves inside the veins in the testicles and scrotum don’t work properly, blood backs up and causes these veins to swell. A varicocele is the result.
 
Diagnosis of Varicocele

• Self-examination of the scrotum, above the testicles, can reveal a mass that feels like a bag of worms. Some patients may experience swelling or tenderness in the area, or a feeling of pressure in the groin when standing for long periods.
• The doctor may detect varicoceles as part of a visit for a general health screening or fertility issues.
  • Physical examination or ultrasound examination of the scrotum if it appears larger than normal, revealing veins that are larger than 2 millimeters in diameter.
  • Enlarged veins along with abnormalities of the sperm, such as low motility (less than 60%), low sperm count, or abnormal sperm shape.
  • Enlarged veins and abnormally small testicles in children.