Abnormalities of the Male Genital Tract

Chapter 126


Abnormalities of the Male Genital Tract




Overview


Ultrasound, including Doppler imaging in all its forms, is the main diagnostic imaging tool for evaluating the scrotum. Computed tomography (CT) is used predominantly to evaluate metastatic spread of testicular or other intrascrotal tumors. Magnetic resonance imaging (MRI) has been used in the search for undescended testes that remain in an intraabdominal position. MRI, like CT, can be used to analyze metastatic spread of testicular tumor. Its uses in intraabdominal, intrapelvic, and intrascrotal imaging are evolving.1



Ultrasound Technique


Scrotal ultrasound is performed with use of a high-frequency transducer. The superficial position of testes in the normally thin-walled scrotum allows excellent imaging with a transducer of 7.5 MHz or higher. Longitudinal, transverse, and coronal views are taken of each hemiscrotum. Transverse views, with the addition of a convex array transducer (e-Fig. 126-1), allow the best side-by-side comparison of both testes and their adnexa, especially when checking for differences in size, echogenicity, and vascularity (e-Fig. 126-2).16






Normal Findings


The testes should be ovoid, nearly symmetric in size (Box 126-1), and homogeneously echogenic. A highly echogenic linear focus (seen posteriorly and superiorly) represents the mediastinum testis (Fig. 126-3), which is the inward extension of the tightly adherent covering of the testis, the tunica albuginea. Fibrous septa extending from the mediastinum testes divide the testes into more than 250 lobules. The spermatic cord, draining veins, lymphatics, nerves, vas deferens, and a single testicular artery run within the mediastinum testis.69




The head of the epididymis (e-Fig. 126-4) sits atop the superior pole of each testis. The head is continuous with the epididymal body and tail, which travel inferiorly along the posterolateral margin of the testis. The echogenicity of the epididymis is normally homogeneous. It may be of equal or of slightly greater or lesser echogenicity than that of the testes.69




The scrotal wall should be between 3 and 6 mm thick. Beneath the scrotal wall are the two layers of the tunica vaginalis (Fig. 126-5), the outer (parietal) and the inner (visceral) layers, which are the residua of the processus vaginalis (i.e., peritoneum that descended with the testis from the abdomen). The visceral layer covers the testis on its anterior border and is attached to the tunica albuginea. Between the tunica’s two layers is a potential space that normally may contain as much as 1 to 2 mL of fluid. It is here that the fluid of a hydrocele may accumulate.69



Three small, persistent, vestigial remnants of the mesonephric and müllerian duct systems occasionally may be seen, usually only when a normal testis is surrounded by hydrocele fluid. These remnants are the appendix testis (e-Fig. 126-6) (a remnant of the müllerian duct), which is attached to the upper pole of the testis (and the most common one to potentially undergo torsion); the appendix epididymis (a remnant of the mesonephron), which is attached to the head of the epididymis; and the vas aberrans (a remnant of the mesonephron), which is attached to the epididymis at the junction of its body and tail.69





Cryptorchidism







Imaging: Ultrasound is the initial procedure for localization of a testis that is not palpable within the scrotum (e-Fig. 126-7). The undescended testes may be smaller and hypoplastic, although usually it is of equal echogenicity compared with the normal testis. MRI with fat-suppression techniques generally is more effective than CT for intraabdominal testes. Normal testes have a homogeneous high signal on T2-weighted images.1,6,10





Treatment: Surgical treatment for undescended testes is orchiopexy. It is performed, especially in cases of intraabdominal testes, because of the increased risk for the development of testicular neoplasia (a 10 to 40 times greater risk, with a seminoma being the most common neoplasm).11 Spontaneous descent during the first year of life may occur from an endogenous surge of luteinizing hormone, and thus surgical correction typically is delayed until 18 to 24 months.1,6,12 After orchiopexy, 53% of the testes are reported to be abnormal by either position, volume, structure, or perfusion.1,1316



Hydrocele






Overview: A hydrocele, which is the most common scrotal mass in a child (Fig. 126-8), results from fluid accumulated within the layers of the tunica vaginalis. Several types of hydroceles are identified (Fig. 126-9). The processus vaginalis is closed in 50% to 75% of persons by the time they are born and in most of the remainder of children by the end of the first year of life. Residual fluid from testicular descent is responsible for the noncommunicating hydroceles reported in at least 15% of male fetuses beyond 28 weeks of life. If the processus fails to close, a communicating hydrocele can develop.




In a hydrocele of the cord (a funicular hydrocele), the processus vaginalis is obliterated in its proximal and distal end and the hydrocele is contained in the patent space between these two points. In an inguinoscrotal hydrocele, the processus vaginalis is obliterated only at the internal inguinal ring and the hydrocele extends cephalad from the scrotum into the inguinal canal. In an abdominoscrotal hydrocele (e-Fig. 126-10), closure of the funicular process at the internal inguinal ring also occurs and forms a dumbbell-shaped cystic mass that protrudes into the extraperitoneal space above the inguinal area.1,17




In most cases, the etiology of a hydrocele found in the child or adolescent is idiopathic. Acquired hydroceles occur after scrotal trauma or as a complication of epididymitis-orchitis, testicular torsion, or intrascrotal neoplasm (reactive hydrocele). Increasing size of a hydrocele without an intrascrotal cause suggests a patent processus vaginalis and an associated inguinal hernia.1



Imaging: Scrotal ultrasound shows the cystic nature of the hydrocele as it appears to surround the normal homogeneously echogenic testes. Septations and debris may be present, particularly if the hydrocele is infected (i.e., a pyocele) or hemorrhagic (i.e., a hematocele) (e-Fig. 126-11). Echogenic debris (e.g., cholesterol crystals) often is seen in the fluid of chronic hydroceles (Fig. 126-12), along with occasional calcifications.1







Testicular Torsion






Overview: Torsion may occur at any age but is seen most often in adolescent boys between 11 and 18 years of age, perhaps because of the increase in testicular growth and weight during this time. The normal testis is strongly attached to the epididymis, which in turn is applied to the posterior scrotal wall. If these attachments fail to develop properly (the “clapper-in-a-bell” phenomenon), the testis, suspended within the tunica vaginalis, may rotate and the spermatic cord undergoes torsion. A person with acute torsion experiences sudden acute scrotal pain, accompanied by nausea and vomiting. An important finding on physical examination is a change in testicular axis from the normal vertical positioning of the testis in the scrotum to a more horizontal positioning. Within hours of torsion, a reddened scrotum develops, with or without enlargement.1



Imaging: Ultrasonography is the only diagnostic tool necessary to make the diagnosis of torsion and suggest surgical exploration. The testis is normal-sized to enlarged, with normal to decreased echogenicity (Fig. 126-13). Enlargement and hypoechogenicity are thought to be due to venous congestion. The echogenicity pattern is usually homogeneous. Epididymal enlargement may be an early finding in some cases of torsion. At least 10% of cases of torsion have associated reactive hydroceles. Ultrasound performed more than 48 hours after symptomatology (e-Fig. 126-14) may show a heterogeneous or hyperechoic testis from hemorrhage or hemorrhagic necrosis.1





State-of-the-art color or power Doppler imaging methods have made ultrasound the gold standard for the imaging and preoperative diagnosis of testicular torsion. Venous flow is lost before arterial flow ceases. Color flow comparison to the contralateral testis is helpful and necessary, particularly when torsion is incomplete, in which case the diagnosis may be suggested not by absence of arterial flow but by blood flow asymmetry. The spermatic cord always should be seen, and it should be straight. When torsion is present, a spiral twist or Whirlpool sign is seen. Flow may be normal or increased in a torsed testis that spontaneously detorses.20–23


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Dec 20, 2015 | Posted by in PEDIATRIC IMAGING | Comments Off on Abnormalities of the Male Genital Tract
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