The testis biopsy is a useful adjunct in the infertility evaluation because it provides a more precise clinical diagnosis for several infertility disorders. Most commonly, the technique involves a small, open incision in the scrotal wall and testis tunica albuginea under local anesthesia. A small wedge of testis tissue is removed and examined histologically. Abnormalities of seminiferous tubule architecture and cellular composition can be assessed and categorized into several patterns. A testis biopsy is most useful in the azoospermic patient. It is often difficult to distinguish between a failure of sperm production and obstruction within the reproductive tract ducts in such patients. A testis biopsy allows delineation between these 2 conditions. In obstruction, formal investigation of the reproductive tract is warranted, beginning with a vasogram. A vasogram involves the injection of dye or contrast media into the vas deferens toward the bladder from the scrotum (

Figure 42-11). In plain film radiographs, contrast material can delineate the proximal vas deferens, seminal vesicle, and ejaculatory duct anatomy and determine whether obstruction is present. Sampling of vasal fluid during the same procedure can also determine whether sperm exist within the scrotal vas deferens. Vasal sperm presence implies that there is no obstruction in the testis or epididymis. With this information, the site of obstruction can be accurately determined.

Whether a biopsy is indicated for oligospermia is controversial. Rare cases of partial reproductive tract obstruction may be diagnosed by biopsy, but the incidence of these disorders is low. While unilateral testis biopsies are usually sufficient, the finding of 2 asymmetric testes may warrant bilateral testis biopsies. This situation may reflect a unilateral unobstructed failing testis paired with a normal obstructed testis. Testis biopsies may also be indicated to identify patients at high risk for intratubular germ cell neoplasia. This premalignant condition exists in 5.5% of men with a contralateral germ cell tumor of the testis and is more prevalent in infertile than fertile men.

A relatively new indication for the testis biopsy is to determine whether men with atrophic, failing testes and elevated FSH levels actually have mature sperm that may be used for IVF and intracytoplasmic sperm injection (ICSI). A single testis biopsy can detect the presence of sperm in 30% of men with azoospermia, elevated FSH levels, and atrophic testes. Testicular sperm that are harvested by biopsy are now routinely used to help men with severe male-factor infertility to achieve fatherhood.