Scrotal 4 T’s Dr/ Ahmed Bahnassy MBCHB-MD-FRCR Consultant Radiologist-RMH
Normal anatomy • The testicles and associated structures are located within the scrotum, formed by fusion of three fascial layers and divided by a median septum. The septum is contiguous with the dartos muscle underneath the scrotal skin..
Normal ultrasound • In the adult, the normal testis is roughly 20 cm3, with an approximate diameter of 3 to 5 cm. • The mediastinum testis can be seen as a linear echogenic band.
The rete testis • The mediastinum divides the testis into lobules and serves as a conduit through which the blood vessels, lymphatics, and spermatic tubules enter and leave the testis.
Epididymis • The epididymal head is located superior to the testis, while the body and tail run posterior to the testis. • The epididymis has an echogenicity similar to or slightly hyperechoic to the testis. The epididymal head may be round or triangular, measures 5 to 12 mm in length. • The efferent ducts converge and, from the epididymal tail, become a single vas deferens, which continues in the spermatic cord.
Tunical sac• The tunica vaginalis is a potential space formed from the processus vaginalis, an outpouching of the fetal peritoneum that descends into the scrotum along with the testis.• An inner visceral layer covers the testis and epididymis, and an outer parietal layer lines the scrotum. The layers join at the posterolateral aspect of the testis where it attaches to the scrotal wall.
Tunica albuginea • The tunica albuginea forms a dense capsule around the testis, and a reflection of this capsule along the posterior border (the mediastinum testis) runs along the superior inferior axis of the testis.
Color doppler examination • The main blood flow to the testicle is via the testicular artery. The testicular artery pierces the tunica albuginea, forming capsular arteries that, in turn, form recurrent rami that course centrifugally toward the mediastinum.
Transmediastinal artery • In 10% to 50% of normal testes, a single transmediastinal artery can be seen unilaterally running directly within the mediastinum and coursing in an opposite direction from the recurrent rami
Appendix testisFour testicular appendages, include theappendix testis, appendix epididymis, vas • Testicular appendagesaberrans, and the paradidymis; 92% of are remnants of the para-males have an appendix testis, and 34%have an appendix epididymis mesonephric ducts and are found at the upper pole of the testes in a groove between the testis and the head of the epididymis.They are usually of similar reflectivity to the epididymal head and are ovoid or sessile shaped, but may be pedunculate.
The 4 T’s• Torsion• Trauma.• Tumor.• Testiculitis (orchitis)
I-Testicular Torsion• Torsion usually occurs in the absence of any precipitating event .• But factors that can precipitate torsion includes 1. Trauma (4 to 8 percent of cases ) 2. Increase in testicular volume (often associated with puberty) 3. Testicular tumor 4. History of cryptorchidism 5. Spermatic cord with a long intrascrotal portion
Torsion• Torsion initially obstructs venous return. Subsequent equalization of venous and arterial pressures compromises arterial flow, resulting in testicular ischemia• The degree of ischemia depends on the duration of torsion and the degree of rotation of the spermatic cord• Ischemia can occur as soon as four hours after torsion and is almost certain after 24 hours
Torsion• In one study, investigators quoted a testicular salvage rate of 90 percent if detorsion occurred less than six hours from the onset of symptoms• this rate fell to 50 % after 12 hours, and• to less than 10 % after 24 hours
Torsion• Color Doppler imaging provides both structural and physiologic information about the vascular integrity of the testis. Unilateral diminished or absent flow is the most accurate sign of testicular torsion .
Within 6 hours, the affected testis may be slightly enlarged, with normal or decreased echogenicity .After 24 hours, echogenicity ofthe testis becomesheterogeneous, a sign of loss ofviability. The epididymal headmay be enlarged because ofinvolvement of the deferentialartery.
II-Trauma • Ultrasound shows heterogeneous echogenicity within the testis due to areas of hemorrhage or infarction. Other findings include irregular, poorly defined borders, scrotal wall thickening, and hematocele . • The tunica is disrupted with testicular rupture, and there may be diminished blood flow in the disrupted capsule.
III-Scrotal tumors• Testicular cancer has 3 main types—• (1) germ cell tumors,• (2) non–germ cell tumors,• and (3) extragonadal tumors.• Germ cell tumors, which are the most common, are classified as either seminoma or nonseminoma, based on histology.
Seminoma• Scrotal ultrasonography commonly shows a homogeneous hypoechoic intratesticular mass. Larger lesions may be more inhomogeneous.• Calcifications and cystic areas are less common in seminomas than in nonseminomatous tumors.
Non Seminomatous Germ Cell tumours• NSGCTs refer to the germ cell tumors that contain embryonal stem cells.• The 4 histologic classifications of NSGCTs include (1) embryonal carcinoma, (2) teratoma, (3) choriocarcinoma, and (4) yolk sac tumor.
In patients with testicular tumors, scrotal sonograms usually demonstrate a mass in the testis, usually confined by the tunica albuginea. This mass may contain microcalcifications and areas of hemorrhage and is typically heterogeneous in appearance.
Non Germ cell TumorsGonadoblastoma; granulosa cell tumor; leydig cell tumor; sertoli cell tumor. Sertoli-cell tumors are the most common gonadal stromal tumors in prepubertal children. These tumors tend to appear as painless masses in boys younger than 6 months and produce no endocrinologic effects; 14% of patients present with gynecomastia. Leydig-cell tumors are the second most common gonadal stromal tumors in children and are also benign. These tumors most often occur in boys aged 5-10 years, and the synthesis of testosterone may produce precocious puberty.
Other pre—Pubertal umoursJuvenile granulosa-cell tumors appear as cystic, painless testicular masses.They almost exclusively appear in the first year of life and most appear byage 6 months. These tumors are hormonally inactive and benign.Gonadoblastoma occurs in association with disorders of sexualdevelopment (intersex).Cystic dysplasia of the testis is a benign lesion that is often associated withipsilateral renal agenesis or dysplasia.Leukemia and lymphoma are the most common malignancies to affect thetestis secondarily and account for 2-5% of all testis tumors; most presentbilaterally.Paratesticular structures can give rise to various benign (lipoma, leiomyoma,hemangioma, or fibroma) and malignant tumors; however, these areextremely rare. Rhabdomyosarcoma is the most common malignant tumor(17%) and may arise from the distal spermatic cord and appear as a scrotalmass or hydrocele.
Venous infarction• Venous infarction of the testis may occur in patients with severe epididymo-orchitis where localized oedema occludes the venous drainage of portions of the testis or the entire testis.• The testis appears of low reflectivity, is swollen, and there is an absence of colour Doppler flow.• Indirect evidence of venous infarction is suggested by reversal of arterial flow in diastole when the testicular artery in the spermatic cord is interrogated with spectral Doppler ultrasound.
Fournier gangrene Fourniers gangrene is a aggressive necrotizing fasciitis of the perineum, which occurs most frequently in males aged 50–70 years, associated with diabetes mellitus. Fourniers gangrene usually arises secondary to local infection with multiple organisms involved: Klebsiella spp., Streptococcus spp., Proteus spp. and Staphylococcus
Polyorchidism.• Polyorchidism is a rare anomaly described as the presence of more than two testes.• type A: the supernumerary testis lacks either an epididymis or vas deferens.• Type B: the supernumerary testis has an epididymis but no vas deferens, and the epididymis may be connected to the normal ipsilateral testis (type B2) or have no connection (type B1).• Type C: the supernumerary testis has a separate epididymis, but shares the vas deferens with the ipsilateral testes either in a parallel or longitudinal fashion.• Type D: the supernumerary testis may have a completely separate epididymis and vas deferens, and is the least common.
Cystic transformation of rete testis• Dilatation of the rete testis is very common and mostly seen in patients over 50 years of age. Rete testis dilatation is often associated with either post-infectious or post-traumatic epididymal obstruction.• Frequently an epididymal abnormality such as a spermatocele or dilated efferent ducts following a vasectomy can be found on ultrasound
Two-tone testes• The two-tone testis is an eloquent term, used to describe the appearance of a normal testis that is transacted by trans- mediastinal vessels, resulting in a neatly divided manifestation of different reflectivity.• The portion nearest the probe is of normal expected testicular reflectivity whereas the portion distal to the vessel is of decreased reflectivity caused by imaging obliquely through the walls of the trans-mediastinal vessels.
Segmental testicular infarction• Segmental testicular infarction is rare Predisposing factors to segmental infarction include polycythaemia, intimal fibroplasia of the spermatic artery, sickle cell disease and trauma, or idiopathic origin.• Clinically segmental infarction usually presents with testicular pain, whereas a malignant lesion presents as a painless lump.• The ultrasound features are those of a low reflective area, which may be wedge-shaped, with no posterior acoustic enhancement and may be associated with focal expansion of the testes. There is poor or absent colour Doppler flow whereas malignant lesions normally demonstrate increased colour Doppler flow.
Intra-testicular varicocele• An intra-testicular varicocele is an uncommon ultrasound finding with an incidence quoted at <2% in a symptomatic population. The ultrasound appearances of an intra- testicular varicocele are anechoic serpiginous or cystic structures radiating from the mediastinum testis. An intra-testicular varicocele will behave in a similar fashion to an extra-testicular varicocele, increasing in size and demonstrating retrograde flow on Valsalva manoeuver.
Splenogonadal fusion• Two types of splenogonadal fusion are described: in the more common continuous type, a cord, which may be beaded with small splenunculi, connects the accessory spleen to the actual spleen whereas in the discontinuous type no cord is present • If the diagnosis is considered preoperatively, a 99mTc- sulphur colloid scan is diagnostic, demonstrating tracer uptake within the accessory spleen and splenic tissue
Epidermoid cyst• The “onion-ring” appearance corresponds to alternating layers of compacted keratin and loosely dispersed desquamated squamous cells.• A similar appearance has been described in a teratoma.• The absence of colour Doppler flow and negative tumour markers increases diagnostic confidence.
Testicular oedema• Testicular oedema results in fluid tracking into the interstitial tissues of the testis as a consequence of marked subcutaneous oedema of the scrotal sac. This gives rise to low reflective linear branching throughout the testes giving a ‘crazy paving’ appearance. The linear branching low reflective areas demonstrate no colour Doppler signal.
Dancing megasperm’• An unusual appearance, estimated at 0.6%, is that of multiple small echoes within an enlarged epididymis, with apparent independent movement.Patients with this appearance had a history of a vasectomy or previous surgery to the scrotum, and all were symptomatic for scrotal pain
Torsion of an appendix testis• The ultrasound appearances of a torted appendix testis are a rounded mass with variable reflectivity at the superior aspect of the testicle with surrounding increased Doppler flow and a small hydrocele. ultrasound will demonstrate the appendix within a small localized hydrocele.
‘Snowstorm’ hydrocele• This appearance is attributed to the presence of cholesterol crystals circulating within the fluid or to high protein content, which are of no clinical significance.• With the use of higher power output techniques, with the presence of florid echoes within the hydrocele, the swirling particles give rise to a ‘snow storm’ appearance.
Testicular sarcoid• Sarcoidosis is a multi- system disorder characterized by non- caseating epitheloid granulomas. The diagnosis is often one of exclusion as many other conditions have similar histology; much reliance is placed on the associated clinical findings and radiographic appearances.
Acute scrotum in children with Henoch-Schonlein purpura• The cause of the acute scrotum in the context of HSAPS is known to be vasculitis and not torsion .• Complications involving the male genital system are unusual.• They include oedema and haematoma of the scrotal wall and spermatic cord, testicular haemorrhage and subcapsular testicular haematoma, epidydimitis, orchitis and penile swelling. The signs often mimic conditions that require surgical intervention, especially torsion of the spermatic cord.
Role of color doppler• The decision to treat expectantly should be supported by high resolution colour Doppler sonography confirming increased testicular blood flow in support of the diagnosis of vasculitis.