A 23-year-old healthy man has been unable to father a child. He and his wife have a workup for infertility. His wife’s reproductive function is normal. On physical examination both his testes are palpable in the scrotum and the testes and scrotum are normal in size, with no masses palpable. However, the spermatic cord on the left has the feel of a ‘bag of worms’. Laboratory studies show oligospermia. Which of the following conditions is this man most likely to have? Explain your answer.

A Hydrocele

B Testicular torsion

C Spermatocele

D Varicocele

E Seminoma