Ultrasound of scrotum and testes

Ultrasound examination (ultrasound) of the scrotum gives the clinician significant, and sometimes determining diagnostic information. With the introduction of color Doppler technology it became possible to investigate the vascularization and perfusion of the scrotum organs, which facilitated the diagnosis of torsion of the spermatic cord, inflammatory scrotal diseases, scrotal injury and varicocele.

Blood supply of the testis and appendage is carried out mainly due to testicular arteries originating from the aorta, below the level of the renal arteries. Blood vessels also involve the arteries of the vas deferens and the cremasteric artery that anastomose with the testicular artery. The artery of the vas deferens is a branch of the hypogastric artery, and the cremasteric artery is the lower epigastric artery. The shells of the testicle receive blood supply from the nonparenchymal branches of the testicular and cremasteric arteries.

Venous outflow is carried out from the clustered plexus to the paired testicular veins. The left testicular vein flows into the left renal vein, and the right - into the inferior vena cava at the level of 1-2 lumbar vertebrae. In addition to the clustiform plexus, there is also a plexus of the vas deferens and the cremasteric plexus. All three plexuses are united through communication veins. The outflow from the plexus of the vas deferens and the cremasteric plexus can be carried out directly into the system of the external iliac vein or through the deep lower epigastric vein.

Ultrasound examination begins with the evaluation of the parenchymal blood flow of the testicle and epididymis. To do this, the regimes of the DCS, EHD, and directional EHD are used. Compare the symmetry of the degree of vascularization of both testicles and appendages. The mode of three-dimensional angiography allows the most complete representation of the vascular pattern of the testicle. It is more difficult to visualize the arteries of the epididymis. For this, the EHD mode is used. Artery appendage is divided into 2 branches: anterior, blood supplying the head of the appendage and the posterior bearing. An increasing prevalence of obliterating diseases of the abdominal aorta and peripheral arteries, in part due to the demographic shift, which determines a significant increase in the number of elderly and senile patients suffering from widespread forms of vascular disease ( atherosclerosis, hypertension ) and simultaneously severe concomitant diseases, on the one hand, and achieved over the past decade I the successes of reconstructive vascular surgery, providing the possibility of introducing effective methods of restorative surgical treatment into practice, on the other, determine the need to improve noninvasive diagnostics of peripheral vascular lesions in order to select patients and to determine on the basis of forecasting strictly delineated indications for this or that kind of treatment.

Indications for the procedure

1. Swelling of the scrotum.
2. Injury.
3. Inflammation.
4. Pain.
5. Undescended testis (with palpable formation in the inguinal region of boys and adolescents).
6. Hemospermia.
7. Infertility.

[1], [2], [3], [4], [5]

Preparation

Preparation is not required.

Patient's position

• The patient should lie on his back. Lift the penis to the stomach and cover with a towel. Apply an optional gel on the scrotum.

[6]

Sensor selection

•  If possible, use a 7.5 MHz sector sensor, especially for children, or use a 5 MHz sensor.

Technique of the ultrasound of scrotum and testes

The ultrasound of the scrotum organs starts in the position of the patient on the back with an ultrasonic sensor with a frequency of at least 7 megacycles. If it is necessary to visualize the enlarged veins of the lobar plexus, the study is also performed in the patient standing position.

Due to low blood flow velocities in normal testicular tissue, one should not try to detect low-frequency shifts. The testicle and appendage should be considered in longitudinal and transverse section. Form, size and echogenicity must be compared with the opposite side. In a normal parenchyma, a homogeneous picture of the internal echoes is determined. The parenchyma is surrounded by an echogenic capsule (the belly coat). The color regime should show the same perfusion of both testicles. A typical Doppler spectrum from the testicle artery and the intra-artery arteries shows a two-phase blood flow with an antegrade diastolic component, as a sign of low peripheral resistance. The spectra from the supra-artery arteries between the superficial inguinal ring and the testicle do not contain this diastolic component. The spectra from the cremaster and outgoing arteries reflect the vascular pool with high peripheral resistance.

Sometimes it is difficult to detect arterial influx in boys in the prepubertal period due to a small testicle volume and very low blood flow velocities. With ultrasound dopplerography of the normal appendage, very low blood flow is determined, so perfusion is assessed when comparing the two sides.

Normal performance

Normally, the testicle on the echogram is an echopositive oval formation with clear, even contours and a homogeneous heterogeneous structure. Its volume depends on the age and is normally 10-25 cm ² in an adult . A small amount of fluid is always detected around the testicle in the form of a thin layer of anehogenous contents up to 0.5 cm. The head of its epididymis is visualized above the upper pole of the testicle, and the body and tail along the posterior surface and the lower pole. The head of the appendage is a rounded formation up to 1.5 cm in diameter. The body has a thickness of no more than 0.5 cm. Above the epididymis, the seminal cord is visible.

1. The average testicle length in adults is 5 cm.
2. The average thickness of the testicle is 3 cm.
3. The average transverse diameter is 2 cm.
4. The vertical diameter is 2.5 cm.

The testicle is located at the lower edge of the testicle and is more echogenic than the testicle. Two testicles are separated in the scrotum by a hyperechoic septum. A small amount of fluid is often detected in the cavity of the scrotum.

[7], [8], [9]

Pathology of the scrotum on ultrasound

One-sided increase

One-sided increase can occur with:

1. The hydrocele. The liquid in the scrotum surrounds the testicle in the form of an anechoic zone of varying thickness and location. If a liquid appears as a result of inflammation or trauma, it can be used to determine a suspension that gives an internal echostructure during ultrasound examination. It is also necessary to carefully examine the testicle to exclude a hidden malignant tumor.
2. Trauma and torsion of the testicle.
3. Hernia.
4. Varikotsele.
5. Egg formation, i.e. Swelling or inflammation. Most testicular tumors are malignant. Tumors can be hypoechoic or hyperechoic, and the testicle can be of a normal size or enlarged. We need to compare two testicles, since the tumor can replace the entire normal tissue of the testicle, while the tumor is detected only by the difference in the echogenicity of the two testicles. Sometimes the testes have the same echogenicity, but with slight compression, small tumors can be detected that are not visualized by normal scanning. It is difficult to differentiate the tumor or inflammatory changes.

Hypoplasia or monochromism

If the testicle is not detected in the scrotum during ultrasound examination, then it is not there. If the formation is determined by clinical examination in the inguinal canal, ultrasound examination will help to determine the position and size of the formation, however, it is often difficult to differentiate testicular tissue and an enlarged lymph node. If palpation formation in the inguinal canal is not determined, then the ultrasound examination does not make sense.

Egg attachment

In the epididymis can be found inflammation or cysts.

1. Epididymitis. With ultrasound, an enlarged and hypoechoic appendage on the side of the lesion is detected. If there is concomitant orchitis, the testicle will also be relatively hypoechoic. With chronic epididymitis, both hypo- and hyperechoic structural changes can be detected.
2. Cysts of the epididymis. Cysts can be single and multiple, they are associated with the epididymis. Eggs are not changed. Cysts of the epididymis must be differentiated from more elongated structures with varicocele.

[10], [11], [12], [13]

Acute scrotum syndrome

The main diseases that need to be suspected in acute pain in the scrotum are testicular torsion and epididymitis. It is important to quickly diagnose, as a twisted testicle undergoes irreversible changes within 4-6 hours. The method of choice in urgent situations is ultrasound dopplerography. 

[14], [15], [16], [17]

Injury

If damaged, the testicle may be enlarged or of normal size. If there is an excessive amount of fluid in the scrotum, the testicle should be thoroughly examined in various planes to exclude its damage. A damaged testicle may have a non-uniform echostructure, especially if there is a hematoma or the formation of an abscess. Blood in the cavity of the scrotum will look like a liquid structure, often heterogeneous due to the presence of clots.

Testicular torsion

It is quite difficult to diagnose a torsion according to ultrasound data, but if the normal blood supply of the testicle stops, in the acute stage, the decrease in the echogenicity of the affected testicle will be determined in comparison with the contralateral testicle. The liquid (hydrocele) can be visualized in the cavity of the scrotum.

The most important ultrasound symptom in the first hours from the onset of torsion is the absence or reduction of perfusion on the side of the lesion in comparison with the opposite side.

The level of hypoperfusion on the affected side depends on the duration and degree of torsion. At a subtotal torsion (less than 360 °), residual perfusion can be detected in the affected testicle. In less severe cases, venous obstruction precedes the arterial obstruction, therefore, arterial spectra can be recorded from the affected testicle when it is impossible to register venous ones. In these cases it is important to suspect a torsion of the testicle, and urgent surgical intervention is recommended in order to avoid hemorrhagic infarction of the tissue. With the continuation of torsion, there is an increase in blood flow in the peri-ovary tissue and the skin of the scrotum, which should not be taken for perfusion of the testicle.

In the B-mode, changes are noted after 6-8 hours from the onset of clinical manifestations. The testicle increases, its parenchyma becomes non-homogeneous. The skin of the scrotum on the affected side thickens, hydrocelial can develop. With spontaneous untwisting, the ischemic interval can be replaced by a compensatory increase in testicular perfusion, in such cases, torsion is difficult to differentiate from epididymo-orchitis. When twisting the epididymis or pendant, there is also a sudden sharp pain in the testicle. With ultrasound, the pendant usually looks more echogenic than the testicle parenchyma or epididymis. With the help of ultrasound dopplerography, it is possible to detect reactive inflammation of adjacent structures of the testicle and epididymis in the form of increased blood flow.

Hernia

The epiploon, mesentery or loops of the intestine, prolapse through the hernial gates into the cavity of the scrotum, usually cause the formation of a small hydrocele. The intestinal loops will be determined by ultrasound examination as a mixed echogenicity of the structure against an anechoic fluid background. If there is dense content in the intestine, hyperechoic zones will also be determined.

In the presence of dilatation of the veins draining the testicle and the epididymis, multiple, convoluted, tubular, reduced echogenicity of the structure along the periphery of the testicle cut will be determined during echography, which is often reduced in comparison with the normal testicle. Varicocele more often takes place on the left side: often varicocele is accompanied by infertility. It is necessary to examine the testicle to exclude the tumor: the varicocele also needs to be differentiated from the spermatocel. The Valsalva test provokes dilatation of the testicle veins.

With an increase in the fluid content in the shells, edema develops in the testicles (hydrocele), the diagnostic accuracy of which is closer to 100% with ultrasound.

Tumor tumors account for about 2% of all neoplasms found in men. As a rule, they are malignant. With small tumors, the testicle is not enlarged, in it only a small area is noted, somewhat different in acoustic characteristics from the rest of the parenchyma. With large tumors the testicle increases: note the unevenness of its contour. The internal structure of the testicle becomes non-uniform. In general, testicular tumors are characterized by a heterogeneous structure of predominantly reduced echogenicity. With echodopplerography, the pathological increase in blood flow in inhomogeneous areas is determined. The accuracy of diagnosis of testicular tumors is 84.6%. Echography also allows to detect metastases of testicular cancer in regional lymph nodes (pelvic, para-aortic, paracaval). When the ureter is compressed, enlarged lymph nodes are observed dilatation of the cup-and-pelvis system.

Focal calcifications are defined as hyperechoic areas with posterior acoustic shading, whereas intratumoral necrosis looks hypoechoic. Ultrasound Doppler ultrasound is an additional technique in the diagnosis of testicular tumors, since the presence of local hyperperfusion due to the development of the pathological vascular network confirms the suspicion of the tumor, at the same time its absence does not exclude the tumor process.

Echography allows to diagnose a scrotal hernia, which also manifests by an increase in the scrotum. In this case, scans in the enlarged scrotum determine a number of amorphous echostructures. Sometimes with gaseous contents, characteristic of the intestine.

Ultrasound helps in the diagnosis of inflammatory processes in the testis and its appendage, with cysts, varicocele, trauma to the scrotum organs; allows to detect the testicle with cryptorchidism. 

Varicocele

The study is carried out in the position of the patient lying on his back and standing. In the latter case, an increased hydrostatic pressure is created, expanding the modified venous structures, which facilitates their visualization. With ultrasound in the B-mode, the varicocele is defined as the enlarged veins of the pear-shaped plexus like wormlike anechogenous structures. With an increase in intra-abdominal pressure with a Valsalva test, it is possible to determine the reverse blood flow in the vein of the testicle and the veins of the pear-shaped plexus, which is manifested by inversion of color in the color regime and a change in direction with respect to the base of the spectrum. Extended altered veins persist during treatment, but ultrasound dopplerography does not detect blood flow even during the Valsalva trial.

Expanded venous plexuses are located outside the testicle, but a large varicocele can also affect the intra-venous veins. Differential diagnosis of idiopathic varicocele from symptomatic is based on the ultrasound of the abdominal cavity with the search for the formation of the kidneys and mediastinum.

Epididymitis

In images in the B-mode with epididymitis, an increase in the appendage is determined with a heterogeneous picture of the internal echoes. When the inflammation passes to the testicle (epididymo-orchitis), the parotergic structures also become non-homogeneous. With ultrasound dopplerography, a significant increase in the perfusion of the affected areas is revealed in comparison with the opposite side.

The Doppler spectrum on the affected side also undergoes a characteristic change. Normally, only a small diastolic blood flow is detected in the appendage. In the inflammatory process, the vascular resistance in the epididymis decreases, which leads to a significant increase in diastolic blood flow. Compared with the unaffected side, the resistance index is lower.

Since there are individual differences in resistance indices, the results should be compared with the opposite side, rather than with standard values. With the development of complications (abscess, hemorrhagic infarction), inflammation is difficult to distinguish from traumatic changes or tumors.

[18], [19], [20], [21]

Critical Assessment

An experienced specialist (who has conducted more than 500 ultrasound dopplerography of the renal arteries), examining the patient on an empty stomach, can identify up to 90% of all renal arteries. This figure takes into account all the terminal arteries of the kidneys, but their visualization is a weak point of ultrasound dopplerography. The artery of the end of the kidney, leaving at a low level from the iliac artery, is almost always invisible.

Using direct and indirect criteria, renal artery stenosis is diagnosed with sensitivity and specificity of 85-90%. If renal artery stenosis is diagnosed with duplex scanning or is suspected clinically, digital subtraction angiography should be performed. The value of the resistance index less than 0.80 in the non-stenotic opposite kidney is considered a favorable prognostic sign. In such cases, there is a hope that the treatment of stenosis will improve kidney function and stabilize the pressure.

Control methods, except for digital subtraction angiography, especially after percutaneous intraluminal angioplasty, are ultrasonic dopplerography and MP angiography. However, the latter's capabilities are limited in the presence of a vascular clip or stent, since they give the signal voids in a magnetic field. In these cases, the MRA can only provide indirect information about restenosis based on the different time of contrast of both kidneys. In some cases, ultrasound Doppler ultrasography is superior to angiography. In addition to the ability to measure the volume of blood flow, you can determine the cause of stenosis, for example, compression by hematoma. If the volume of blood flow is known, the hemodynamic significance of stenosis can be determined with better quality than with angiography. In these cases, ultrasound dopplerography can be used to assess moderate to high stenosis, with good blood flow characteristics. Prospective and randomized studies have shown that regular ultrasound dopplerography with 6-month intervals with preventive dilatation of more than 50% of stenoses leads to a significant reduction in the number of occlusion of the stent and the cost of treatment.

In patients with impaired erection, ultrasound dopplerography exceeds traditional Doppler ultrasound, since an evaluation of the morphology of the penis and a quantitative determination of the blood flow velocity are possible. Ultrasound dopplerography can accurately diagnose arterial dysfunction, but the diagnosis of venous insufficiency is difficult due to the lack of normal values for the final diastolic rate and resistance index. If there is a suspected venous outflow, as a cause of erectile dysfunction, ultrasound should be supplemented with cavernosometry and cavernosography.

There are disputes on the etiology of erectile dysfunction and treatment methods. Most patients have a good response to intra-esophageal autoinjection therapy or oral drug use.

Due to the non-invasiveness and simplicity of the procedure, ultrasonic dopplerography replaces the radionuclide method in the differential diagnosis of acute scrotal syndrome and is considered a method of choice. However, ultrasonic dopplerography does not always yield equivalent data. Ultrasonic dopplerography exceeds B-mode with a testicle injury and in the diagnosis of varicocele. To diagnose tumors and determine the location of an undescended testicle, traditional ultrasound or MRI should be performed.

[22], [23], [24], [25], [26], [27]