HISTORICAL BACKGROUND

As its name implies, testicular biopsy consists of the operative removal of a piece of tissue from the testis, so small as to have no deleterious effect on the gland yet large enough to include a representative group of tubules.¹ Along with a carefully performed history, physical examination, semen analyses, and appropriate assessment of endocrinologic variables, testicular biopsy can afford the clinician the opportunity for more precise diagnosis and treatment of many male infertility disorders.² The technique was first applied to human beings and published by Charny in 1940.¹ This open surgical technique consisted of the removal of a minute piece of tissue from the periphery of the testis through a small incision in the scrotum. No undesirable side effects were reported. Rowley et al,³ however, reported a transient decrease in sperm concentration in humans associated with testicular biopsy. The drop was observed in 39 of 100 men studied. The decrease occurred within 10 weeks of treatment; recovery began by 10 weeks of treatment and was complete at 18 weeks after bilateral testicular biopsy. With the development of gonadotropin radioimmunoassays (RIAs) in the 1970s and the demonstration of the relationship between serum follicle-stimulating hormone (FSH) concentrations and the histologic appearance of biopsy specimens in humans, a reappraisal of the value of testicular biopsy was made.⁴ At present, testicular biopsy is recommended only for those cases in which serum FSH concentrations and clinical evaluation are inconclusive.⁴ Fine needle aspiration (FNA) is the most recently described technique and currently is used clinically in human medicine.⁵

In recent years, methods have been developed for direct surgical sperm sampling from either the epididymis or the testis to be used for intracytoplasmic sperm injection (ICSI).⁶ The main approach, proven to be effective for the retrieval of spermatozoa from the epididymis in patients with obstructive azoospermia, is microsurgical epididymal sperm aspiration, although recently the retrieval of spermatozoa by FNA was shown to be equally effective.⁶ Recovery of spermatozoa also is now performed in patients with severely deficient spermatogenesis using open testicular biopsy as well as FNA.⁶ Araki et al⁷ reported success with use of spermatids in ICSI from patients with total lack of normal testicular sperm. Thirty-six males diagnosed with azoospermia underwent testicular biopsy; the spermatids thereby acquired from nine of these patients were used to fertilize oocytes by ICSI. Three of the procedures resulted in pregnancy with childbirth.

In veterinary medicine, testicular biopsy was first described in 1944 by Erb et al.⁸ This group of investigators performed testicular biopsy by the open method to study vitamin A deficiency in bulls. The investigators did not assess the effect of testicular biopsy on the testicle. Testicular biopsy can lead to a decrease in sperm output secondary to sperm granuloma formation or intratesticular hemorrhage and an attendant increase in intratesticular pressure. Interference with spermatogenesis can occur. which can be permanent in some cases; in others, however, seminal values return to normal if given adequate time.⁹

Later in the 1940s, Sykes et al¹⁰ investigated the consequences of testicular biopsy by the open method in bulls. They concluded that testicular biopsy in mature bulls led to a marked decrease in seminal sperm concentration. They also observed that further biopsies were associated with an increase in the number of abnormal spermatozoa and with morphologic changes in the tubules of the testis. Roberts,¹¹ who used the same method of biopsy in bulls, wrote in 1953 that testicular biopsy was of little use in veterinary medicine because it induced hemorrhage, making it difficult to perform. In the same year, Byers¹² concluded that the open method of testicular biopsy in bulls was in fact a useful technique and that it did not appreciably reduce the semen quality. He also suggested that testicular biopsy might be used to evaluate a bull’s ability to produce high-quality semen. Veznik,¹³ also using the open method in bulls, found it reliable provided that careful surgery and homeostasis were employed. However, he also observed a drop in sperm production on approximately day 23 after the testicular biopsy procedure. Heath et al¹⁴ used a 14-gauge needle biopsy instrument in one testicle of six bulls and reported no changes in semen quality over a 90-day period.

In rams, Stipancevic¹⁵ reported that the open method caused surgical trauma, which also affected spermatogenic function. Lunstra and Echternkamp¹⁶ looked at the effects of repeated testicular biopsy in the ram during pubertal development. Unilateral testicular “open method” biopsy was performed, and bilateral castration was later performed. No difference was found in testicular development between control testes and the testes subjected to open biopsy. These investigators claimed that the success of their technique was due to avoidance of hemorrhage achieved with use of blunt dissection during biopsy to minimize damage to the vascular layer of the tunica albuginea.

Joshi et al¹⁷ demonstrated a marked transient reduction in spermatozoal counts in men after unilateral or bilateral testicular biopsy. The reduction was observed in all patients, and normal values appeared after 4 weeks. These results are in contrast with the work of Rowley et al,¹⁸ who observed a reduction in sperm count in only 39% of human beings, with a normal sperm count reappearing at 10 weeks after the initial procedure.

In 1971, Galina,¹⁹ using the 12-gauge Vim-Silverman split needle biopsy method, performed testicular biopsy in boars, rams, bulls, and pony stallions. Clinical and histologic parameters were studied in all four species. In the boars, detailed weekly seminal examinations were made before and after testicular biopsy. No deleterious effects were observed. Paufler and Foote²⁰ studied the effect of repeated testicular biopsy (open method) of the same testis three times at 4-week intervals in rabbits and found that testis size, sperm output, and sperm motility and morphology did not differ from those in the controls.

The use of testicular biopsy in the horse was first discussed by Galina.¹⁹ Smith²¹ addressed the importance of defining a more precise site for the testicular biopsy in the stallion, to avoid the main branches of the testicular artery and thus the occurrence of undesirable hematomas. He concluded that testicular biopsy in stallions should be taken from the craniolateral quarter of the testicle to avoid damaging the lateral testicular artery. Many clinicians have alluded to the complications of testicular biopsy but have not presented adequate evidence to justify this concern. Cahill²² reported that owners of famous Kentucky stallions with infertility problems did not consider that testicular biopsy aided in the diagnosis of the problem “for obvious reasons.” Other investigators have found that testicular biopsy did not lead to deleterious effects. DelVento et al²³ evaluated the effects of unilateral testicular (open method) biopsy in stallions by recording changes in testicular width, gross appearance, and echogenicity from biopsied and nonbiopsied testes at 27 days. This group concluded that the open method of biopsy does not greatly alter the process of spermatogenesis or function of the testis in stallions. Threlfall and Lopate²⁴ found no histologic lesions after biopsy.

Hillman et al²⁵ reported for the first time the use of the Biopty gun procedure for testicular biopsy in stallions. No histopathologic or seminal changes due to the testicular biopsy procedure were identified. Faber and Roser²⁶ also reported that the use of the Biopty instrument to obtain biopsy samples was not detrimental to testicular function or spermatogenesis in the stallion. FNA currently is used successfully in veterinary medicine in dogs, mink, and horses^27–29 and appears to be the least invasive method.

TESTICULAR BIOPSY: TECHNIQUES, ADVANTAGES AND DISADVANTAGES

Several techniques to obtain a testicular biopsy specimen have been described: standard open surgical biopsy (or incisional biopsy), needle punch biopsy, Biopty gun needle biopsy, and FNA. All techniques provide material for study, but each approach has advantages and limitations.

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