Causes of Male infertility - Cryptorchidism

The undescended testis is a very common urologic problem, observed in 0.8% of boys at 1 year of age. It is considered a developmental defect and places the affected testis at higher risk of developing cancer. Although the newborn undescended testis is morphologically fairly normal, deterioration in early germ cell numbers is often seen by 2 years of age. The contralateral, normally descended testis is also at increased risk of harboring germ cell abnormalities. Thus, males with either unilaterally or bilaterally undescended testes are at risk for infertility later in life. Prophylactic orchidopexy is generally performed by 2 years of age to allow the testis to be palpated for cancer detection. It is unclear whether orchidopexy alters fertility potential in cryptorchidism.

Varicocele

A varicocele is defined as dilated and tortuous veins within the pampiniform plexus of scrotal veins. It is the most surgically correctable cause of male subfertility. The varicocele is a disease of puberty and is only rarely detected in boys under 10 years of age. A left-sided varicocele is found in 15% of healthy young men. In contrast, the incidence of a left varicocele in subfertile men approaches 40%. Bilateral varicoceles are uncommon in healthy men (< 10%) but are palpated in up to 20% of subfertile men. In general, varicoceles do not spontaneously regress. The cornerstone of varicocele diagnosis rests on an accurate physical examination.

Several anatomic features contribute to the predominance of left-sided varicoceles. The left internal spermatic vein is longer than the right; in addition, it usually joins the left renal vein at right angles. The right internal spermatic vein has a more oblique insertion into the inferior vena cava. This particular anatomy in the standing man may cause higher venous pressures to be transmitted to the left scrotal veins and result in retrograde reflux of blood into the pampiniform plexus.

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