Scrotal and testicular ultrasound

Ultrasound examination (US) of the scrotum provides the clinician with essential and sometimes decisive diagnostic information. With the introduction of color Doppler technologies, it became possible to examine the vascularization and perfusion of the scrotal organs, which facilitated the diagnosis of spermatic cord torsion, inflammatory diseases of the scrotum, scrotal trauma, and varicocele.

The blood supply to the testicle and epididymis is provided primarily by the testicular arteries, which originate from the aorta below the level of the renal arteries. The arteries of the vas deferens and the cremasteric artery, which anastomose with the testicular artery, also participate in the blood supply. The artery of the vas deferens is a branch of the hypogastric artery, and the cremasteric artery is a branch of the inferior epigastric artery. The testicular membranes receive their blood supply from nonparenchymatous branches of the testicular and cremasteric arteries.

Venous outflow is carried out from the pampiniform plexus into the paired testicular veins. The left testicular vein flows into the left renal vein, and the right one into the inferior vena cava at the level of the 1st or 2nd lumbar vertebrae. In addition to the pampiniform plexus, there is also a plexus of the vas deferens and a cremasteric plexus. All three plexuses are connected to each other by means of communicating veins. Outflow from the plexuses 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 inferior epigastric vein.

Ultrasound examination begins with an assessment of the parenchymatous blood flow of the testicle and appendage. For this, the modes of color Doppler scanning, EDC, and directed EDC are used. The symmetry of the degree of vascularization of both testicles and appendages is compared. The three-dimensional angiography mode allows for the most complete presentation of the vascular pattern of the testicle. It is more difficult to visualize the arteries of the appendage. For this, the EDC mode is used. The artery of the appendage is divided into 2 branches: the anterior, which supplies blood to the head of the appendage, and the posterior, which carries the Increasing prevalence of obliterating diseases of the abdominal aorta and peripheral arteries, partly due to the demographic shift, which determines a significant increase in the number of elderly and senile patients suffering from common forms of vascular disease ( atherosclerosis, hypertension ) and at the same time severe concomitant diseases, on the one hand, and the successes achieved in reconstructive vascular surgery over the past decades, which provide the possibility of introducing effective methods of restorative surgical treatment into practice, on the other, determine the need to improve non-invasive diagnostics of peripheral vascular lesions in order to select patients and determine, based on prognosis, strictly defined indications for a particular type of treatment.

Indications for the procedure

1. Swelling of the scrotum.
2. Trauma.
3. Inflammation.
4. Pain.
5. Undescended testicle (with a palpable mass in the groin area of boys and adolescents).
6. Hematospermia.
7. Infertility.

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Preparation

No preparation required.

Patient position

• The patient should lie on his back. Raise the penis to the abdomen and cover with a towel. Apply the gel randomly to the scrotum.

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Selecting a sensor

• Use a 7.5 MHz sector probe if possible, especially for children, or use a 5 MHz probe.

Technique Scrotal and testicular ultrasound

Ultrasound of the scrotum organs begins with the patient lying on his back using an ultrasound sensor with a frequency of at least 7 MPa. If it is necessary to visualize the dilated veins of the pampiniform plexus, the examination is also performed with the patient standing.

Because of the low blood flow velocities in normal testicular tissue, no attempt should be made to detect low-frequency shifts. The testicle and epididymis should be viewed in longitudinal and transverse sections. The shape, size, and echogenicity should be compared with the opposite side. A homogeneous pattern of internal echoes is observed in normal parenchyma. The parenchyma is surrounded by an echogenic capsule (tunica albuginea). The color mode should show equal perfusion of both testicles. A typical Doppler spectrum from the testicular artery and intratesticular arteries shows biphasic flow with an antegrade diastolic component, a sign of low peripheral resistance. Spectra from the supratecicular arteries between the superficial inguinal ring and the testicle do not contain this diastolic component. Spectra from the cremasteric and efferent arteries reflect a vascular bed with high peripheral resistance.

It is sometimes difficult to detect arterial inflow in prepubertal boys due to the small testicular volume and very low blood flow velocities. Doppler ultrasound of a normal epididymis shows very low blood flow, so perfusion is assessed by comparing the two sides.

Normal performance

Normally, the testicle on the echogram is an echo-positive oval-shaped formation with clear, even contours and a homogeneous heterogeneous structure. Its volume depends on age and is normally 10-25 cm ² in an adult. A small amount of fluid in the form of a thin layer of anechoic content up to 0.5 cm is always determined around the testicle. The head of its appendage is visualized above the upper pole of the testicle, and the body and tail are along the posterior surface and at 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. The spermatic cord is visible above the appendage.

1. The average length of a testicle in adults is 5 cm.
2. The average thickness of a testicle is 3 cm.
3. Average transverse diameter 2 cm.
4. Vertical diameter 2.5 cm.

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

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Scrotum pathology on ultrasound

Unilateral increase

Unilateral enlargement may occur with:

1. Hydrocele. Fluid in the scrotum surrounds the testicle in the form of an anechoic zone of varying thickness and location. If the fluid appears as a result of inflammation or injury, then a suspension may be detected in it, giving an internal echostructure during ultrasound examination. It is also necessary to carefully examine the testicle to exclude a hidden malignant tumor.
2. Testicular trauma and torsion.
3. Hernia.
4. Varicocele.
5. Testicular masses, i.e. tumor or inflammation. Most testicular tumors are malignant. Tumors may be hypoechoic or hyperechoic, and the testicle may be normal in size or enlarged. The two testicles must be compared, as the tumor may replace all normal testicular tissue, and the tumor is only detected by the difference in echogenicity of the two testicles. Sometimes the testicles have the same echogenicity, but with slight compression, small tumors may be detected that are not visualized with a normal scan. It is difficult to differentiate between a tumor and inflammatory changes.

Hypoplasia or monorchism

If the ultrasound examination does not detect the testicle in the scrotum, then it is not there. If a formation is detected in the inguinal canal during clinical examination, then the ultrasound examination will help determine the position and size of the formation, but it is often difficult to differentiate between testicular tissue and an enlarged lymph node. If the formation in the inguinal canal is not detected during palpation, then there is no point in performing an ultrasound examination.

Epididymis

Inflammation or cysts may be found in the epididymis.

1. Epididymitis. Ultrasound examination reveals an enlarged and hypoechoic epididymis on the affected side. If there is concomitant orchitis, the testicle will also be relatively hypoechoic. In chronic epididymitis, both hypo- and hyperechoic structural changes may be detected.
2. Cysts of the epididymis. Cysts can be single or multiple, they are associated with the epididymis. The testicles are not changed. Cysts of the epididymis must be differentiated from more elongated structures in varicocele.

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Acute scrotum syndrome

The main diseases to suspect in acute scrotal pain are testicular torsion and epididymitis. It is important to make a quick diagnosis, as the torsed testicle undergoes irreversible changes within 4-6 hours. The method of choice in emergency situations is Doppler ultrasound.

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Injury

If damaged, the testicle may be enlarged or of normal size. If there is excess fluid in the scrotum, the testicle must be carefully examined in various planes to rule out damage. A damaged testicle may have a non-uniform echostructure, especially if there is a hematoma or an abscess is forming. Blood in the scrotal cavity will appear as a fluid structure, often non-uniform due to the presence of clots.

Testicular torsion

It is quite difficult to diagnose torsion based on ultrasound data, but if normal blood supply to the testicle is interrupted, a decrease in the echogenicity of the affected testicle compared to the contralateral testicle will be determined in the acute stage. Fluid (hydrocele) may be visualized in the scrotal cavity.

The most important ultrasound symptom in the first hours after the onset of torsion is the absence or decrease in perfusion on the affected side compared to the opposite side.

The degree of hypoperfusion on the affected side depends on the duration and extent of torsion. In subtotal torsion (less than 360°), residual perfusion may be detected in the affected testicle. In less severe cases, venous obstruction precedes arterial obstruction, so arterial spectra can be recorded from the affected testicle when venous spectra cannot be recorded. In these cases, it is important to suspect testicular torsion, and urgent surgical intervention is recommended to avoid hemorrhagic tissue infarction. As torsion continues, increased blood flow is noted in the peritesticular tissue and scrotal skin, which should not be mistaken for testicular perfusion.

In B-mode, changes are noted 6-8 hours after the onset of clinical manifestations. The testicle enlarges, its parenchyma becomes inhomogeneous. The skin of the scrotum on the affected side thickens, hydrocele may develop. With spontaneous untwisting, the ischemic interval may be replaced by a compensatory increase in testicular perfusion; in such cases, torsion is difficult to differentiate from epididymo-orchitis. With torsion of the appendage or appendage, sudden acute pain in the testicle also occurs. On ultrasound, the appendage usually looks more echogenic than the parenchyma of the testicle or appendage. Using ultrasound Dopplerography, it is possible to detect reactive inflammation of adjacent structures of the testicle and appendage in the form of increased blood flow.

Hernia

Omentum, mesentery or intestinal loops prolapsing through the hernial orifice into the scrotal cavity usually cause the formation of a small hydrocele. Intestinal loops will be determined by ultrasound examination as a mixed echogenicity structure against the background of anechoic fluid. 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 epididymis, echography will reveal multiple, tortuous, tubular, low-echo structures along the periphery of the testicle section, which is often reduced in size compared to a normal testicle. Varicocele is more common on the left side: varicocele is often accompanied by infertility. It is necessary to examine the testicle to exclude a tumor: varicocele must also be differentiated from spermatocele. The Valsalva maneuver provokes dilatation of the testicular veins.

With an increase in the fluid content in the membranes, hydrocele of the testicular membranes develops, the diagnostic accuracy of which with ultrasound approaches 100%.

Testicular tumors account for about 2% of all neoplasms found in men. As a rule, they are malignant. In small tumors, the testicle is not enlarged, only a small area is noted in it, slightly different in acoustic characteristics from the rest of the parenchyma. In large tumors, the testicle enlarges: unevenness of its contour is noted. The internal structure of the testicle becomes heterogeneous. Basically, testicular tumors are characterized by a heterogeneous structure, predominantly with reduced echogenicity. Echo-Dopplerography determines pathological increase in blood flow in heterogeneous areas. The accuracy of testicular tumor diagnosis is 84.6%. Echography also allows detecting metastases of testicular cancer in regional lymph nodes (pelvic, paraaortic, paracaval). When the ureter is compressed by enlarged lymph nodes, dilation of the renal pelvis and calyces is observed.

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

Echography allows diagnosing scrotal hernia, which also manifests itself as an enlarged scrotum. At the same time, scanograms in the enlarged scrotum reveal many amorphous echostructures, sometimes with gaseous contents, typical of the intestine.

Ultrasound helps in diagnosing inflammatory processes in the testicle and its appendage, cysts, varicocele, injuries to the scrotum organs; it allows detecting the testicle in cryptorchidism.

Varicocele

The examination is performed with the patient lying on his back and standing. In the latter case, increased hydrostatic pressure is created, expanding the altered venous structures, which facilitates their visualization. In B-mode ultrasound, varicocele is determined as dilated veins of the piriform plexus, similar to vermiform anechoic structures. With an increase in intra-abdominal pressure during the Valsalva maneuver, reverse blood flow can be detected in the testicular vein and veins of the piriform plexus, which is manifested by color inversion in the color mode and a change in direction relative to the base of the spectrum. Dilated altered veins are preserved during treatment, but with ultrasound Dopplerography, blood flow is not detected even during the Valsalva maneuver.

The dilated venous plexuses are located outside the testicle, but a large varicocele can also affect the intratesticular veins. Differential diagnosis of idiopathic varicocele from symptomatic varicocele is based on ultrasound examination of the abdominal cavity with a search for renal and mediastinal formations.

Epididymitis

B-mode images of epididymitis show an enlarged appendage with a heterogeneous pattern of internal echoes. When the inflammation spreads to the testicle (epididymo-orchitis), the peritesticular structures also become non-homogeneous. Doppler ultrasound reveals a significant increase in perfusion of the affected areas compared to the opposite side.

The Doppler spectrum on the affected side also undergoes characteristic changes. Normally, only a small diastolic blood flow is determined in the appendage. During the inflammatory process, vascular resistance in the appendage decreases, which leads to a significant increase in diastolic blood flow. Compared to 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, not with standard values. When complications develop (abscess, hemorrhagic infarction), inflammation is difficult to distinguish from traumatic changes or tumors.

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Critical assessment

An experienced specialist (having performed more than 500 ultrasound Doppler sonographies of the renal arteries), examining a patient on an empty stomach, can identify up to 90% of all renal arteries. This figure includes all the terminal arteries of the kidneys, but their visualization is a weak point of ultrasound Doppler sonography. The artery of the end of the kidney, which branches off at a low level from the iliac artery, is almost always not visible.

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

Other methods of control, in addition to digital subtraction angiography, especially after percutaneous endoluminal angioplasty, are Doppler ultrasound and MRA. However, the capabilities of the latter are limited in the presence of a vascular clip or stent, since they produce signal voids in the magnetic field. In these cases, MRA can only provide indirect information about restenosis based on different contrast times of both kidneys. In some cases, Doppler ultrasound is superior to angiography. In addition to the ability to measure blood flow volume, it is possible to determine the cause of stenosis, for example, compression by a hematoma. If the blood flow volume is known, the hemodynamic significance of the stenosis can be determined with better quality than with angiography. In these cases, Doppler ultrasound can be used to evaluate moderate to severe stenoses with good blood flow characteristics. Prospective and randomized studies have shown that regular Doppler ultrasound at 6-month intervals with prophylactic dilation of more than 50% of stenoses leads to a significant reduction in the incidence of stent occlusion and treatment costs.

In patients with erectile dysfunction, Doppler ultrasound is superior to traditional Doppler ultrasound because it can evaluate penile morphology and quantify blood flow velocity. Doppler ultrasound allows for an accurate diagnosis of arterial dysfunction, but diagnosing venous insufficiency is difficult due to the lack of normal values for end-diastolic velocity and resistance index. If venous outflow is suspected as the cause of erectile dysfunction, ultrasound should be supplemented with cavernosometry and cavernosography.

There is some debate about the etiology of erectile dysfunction and treatment methods. Most patients respond well to intracavernous autoinjection therapy or oral medications.

Due to the non-invasiveness and simplicity of the technique, ultrasound Dopplerography replaces the radionuclide method in the differential diagnosis of acute scrotum syndrome and is considered the method of choice. However, ultrasound Dopplerography does not always provide equivalent data. Ultrasound Dopplerography is superior to B-mode in testicular trauma and in the diagnosis of varicocele. Traditional ultrasound or MRI should be used to diagnose tumors and determine the location of the undescended testicle.

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