A varicocele is an abnormal enlargement of the pampiniform venous plexus in the scrotum due to increased venous pressure. It is the most common cause of scrotal enlargement in adult males. Varicoceles are more common on the left side, since the left spermatic vein drains at a right angle first into the left renal vein and then into the inferior vena cava (IVC). The right angle causes less laminar flow than on the right side, where the spermatic vein drains directly into the IVC. A right-sided varicocele should always raise suspicion for renal cell carcinoma. Varicoceles can lead to infertility by raising local temperature, which damages the Sertoli cells of the seminiferous tubules. On scrotal examination, a 'bag of worms' appearance is seen. The lesion does not transilluminate. Doppler ultrasound will show increased blood flow. Treatment is with varicocelectomy or embolization.