9.3.4 Sonography

For diagnosis of testicular dysfunction, ultrasonography of the scrotal content has become a standard procedure in patients attending an andrology clinic (1, 2). In addition, transrectal ultrasonography of the prostate and seminal vesicles is a recommended procedure for the diagnosis of infertility and for pretreatment dia-gnosis and monitoring of testosterone therapy.

Two-dimensional ultrasonography of the scrotal content is best performed using a longitudinal or sector scanner allowing a high resolution (7.5 MHz or more). Scrotal ultrasonography is systematically performed using various longitudinal, transverse, and oblique scans with patients lying in the supine position. The examination always includes measurement of testicular volume, documentation of testicular homogeneity and echogenicity, epididymal morphology, and evaluation of the plexus pampiniformis. Three-dimensional ultrasonography of the scrotal content seems to be of limited value.

Exact measurement of testicular volume by ultrasonography has been shown to be useful, especially when palpation is difficult, as in the case of large hydroceles, acute epididymitis, or maldescended testes (Fig. 9.3.4.1a) (3). Testicular volume correlates with daily sperm production, and therefore, azoospermia with normal testicular volume is a diagnostic hint of obstructive azoospermia.

Objective and accurate measurement of testicular volume is especially advantageous in longitudinal monitoring of patients undergoing therapy regimens to increase spermatogenesis, e.g. treatment of hypogonadotropic hypogonadal patients by pulsatile gonadotropin-releasing hormone (GnRH) or gonadotropins. In such cases, a small but objective increase of testicular volume is a valuable indicator of therapeutic efficacy (4).

The largest prospective evaluation of the incidence of path-ological findings in infertile patients attending an andrological referral clinic showed that in about half of the patients, various scrotal pathologies can be detected by ultrasonography (Table 9.3.4.1) (5).

The leading ultrasonographic diagnosis in infertile patients is a varicocele (Table 9.3.4.1). Its presence can be documented by increased diameter of the veins of the plexus pampiniformis during the Valsalva manoeuvre (1). Velocity and duration of the retrograde blood flow can be quantified by Doppler sonography and—if available—directly visualized by colour-coded duplex sonography (Fig. 9.3.4.2) (6).

Increased epididymal size is seen in about 10% of infertile patients (Table 9.3.4.1), of whom around 33% have an enlarged epididymis on both sides. A diameter of more than 10 mm of the caput epididymis or more than 3 mm of the corpus or cauda epididymis can be considered as increased.

About 4% of patients show a single cyst or spermatocele in either the left or the right caput epididymis; less than 1% have cysts or spermatoceles in the cauda or corpus epididymis. Similarly to congenital bilateral absence of the vas deferens (CBAVD), obstruction of the epididymis may be associated with dilatation of the rete testis.

Hydroceles surrounding the testes can be found in approximately 8% of infertile patients. Hydroceles can result from infection, in which case they often show a septical structure. Small hydroceles are usually not palpated, while large hydroceles are easy to detect by diaphanoscopy. However, large hydroceles may hinder palpation of correct testicular volume and consistency. Although no significant difference in palpated and ultrasonographically determined testicular volume is detected in the presence of small hydroceles, testicular volume is generally overestimated by palpation in the presence of large hydroceles (1).

The main advantage of testicular ultrasonography is the possibility of characterizing the homogeneity and echogenicity of the testicular parenchyma. Changes in homogeneity may reflect changes in the functional activity of a testis or might lead to the suspicion of testicular tumour. Inhomogeneity is characterized by single or multiple hypoechogenic or hyperechogenic spots or areas (Fig. 9.3.4.1b), or a combination of hyper-hypoechogenic lesions demarcated from homogeneous surrounding testicular tissue.

Testicular inhomogeneity with hyperechogenic spots can be detected in patients with fibrotic changes (e.g. after mumps orchitis or testicular biopsy) and in patients with microlithiasis testis (1). Because of the frequent association of microlithiasis testis with testicular tumours or testicular intraepithelial neoplasia (TIN), detailed ultrasonography is especially important in these patients (7). Isolated focal testicular lesions, which appear hypoechoic or, more frequently, hyperechoic, can be found in patients after testicular sperm extraction (TESE) (8).

Homogeneous reduction of echogenicity of the testes, alone or in combination with inhomogeneity, is commonly observed in patients with maldescended testes or a past medical history thereof, in patients with Kallmann’s syndrome, with isolated hypogonadotropic hypogonadism (IHH) or with pituitary dysfunction, and in patients with Klinefelter syndrome (1).

In about 1% of infertile patients, intratesticular single or multiple cysts can be found. These are characterized by well-defined hypo-echogenic round areas with posterior enhancement (Fig. 9.3.4.1c). Follow-up examinations in these patients do not reveal any changes in ultrasonographic cystic findings.

In about 1 out of every 250 infertile patients, testicular tumours are detected by ultrasonography, presenting with the typical irregular hypoechogenic areas demarcated from the normal testicular tissue (Table 9.3.4.1) (Fig. 9.3.4.1d). In general, a testicular tumour is suspected only in about half of these patients by palpation, because of hard consistency or irregular surface of the testis.

The increased rate of testicular tumours among patients attending infertility clinics was recently confirmed in a large-scale study of 22 562 men (9). Men with male factor infertility showed a 2.8-fold higher risk of subsequently developing testicular cancer compared to men without male factor infertility. In another large-scale study, it was demonstrated that the risk for infertile patients with compromised semen parameters remained significantly increased, even when only men without cryptorchidism—a well-known additional risk factor for testicular tumours—were considered (10).

Ultrasonography of the scrotal content is an important diagnostic tool in the routine examination of andrological patients, and should be performed in every patient with compromised fertility.

Ultrasonography of the prostate and seminal vesicles can be performed using a transrectal linear or sector scanner (7.5 MHz or more). Transverse and longitudinal scans are applied for the screening of the prostate and the seminal vesicles. Prostate volume is measured by the ellipsoid or the planimetric method (1, 11).Accuracy of prostate volume measurement can be increased by three-dimensional ultrasonography of the prostate (12).

Transrectal ultrasound scanning of the prostate should be performed in hypogonadal patients prior to testosterone therapy, in combination with palpation and prostate specific antigen (PSA) measurement, to exclude a preexisting prostatic pathology that could deteriorate under testosterone treatment. In addition, transrectal prostate ultrasonography has proved to be a valuable tool for monitoring the efficacy of testosterone treatment (Fig. 9.3.4.3). Effective testosterone treatment in hypogonadal men results in PSA levels and prostate volumes that are comparable to age-matched normal men (11). The initially stimulated growth of the small prostate in hypogonadal men is a biological response to effective testosterone treatment; it does not exceed the prostate volume in age-matched men and should not preclude hypogonadal men from effective substitution therapy.

Transrectal ultrasonography of the prostate is valuable when differentiating between obstructive and non-obstructive azoospermia. In these patients, transrectal ultrasonography of the prostate might show intraprostatic cysts (e.g. utricular cysts) or intraprostatic ejaculatory duct dilatations as a cause or result of obstructive male infertility.

Pathological seminal vesicles may either be increased in diameter, be asymmetric or may be hypoplastic or atrophic. Measurement of the diameter of seminal vesicles before and after ejaculation can be performed to evaluate the contractility of the organ. Urogenital infections are a leading cause of abnormal sonographic appearance of the seminal vesicles. In patients with CBAVD, low ejaculate volume, azoospermia, and low seminal fructose are often combined with aplasia, hypoplasia, or cystic dilatation of the seminal vesicles.