Scrotal Imaging

The scrotum is a sac hanging outside the body that contains parts of the male reproductive system. The scrotum’s main function is to support testicles Testicles The testicles, also known as the testes or the male gonads, are a pair of egg-shaped glands suspended within the scrotum. The testicles have multiple layers: an outer tunica vaginalis, an intermediate tunica albuginea, and an innermost tunica vasculosa. The testicles are composed of testicular lobules and seminiferous tubules. Testicles outside the body so that spermatogenesis can be completed under optimal conditions. The scrotum can be affected by various pathologic conditions, and imaging is a valuable tool in reaching the appropriate diagnosis. The most important imaging method is ultrasonography +/– Doppler mode because scrotal structures are superficial with no intervening gas. MRI is useful when ultrasound is indeterminate.

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Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

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Ultrasonography

Overview

Ultrasonography is often the best imaging method for the scrotum.

  • Doppler mode: 
    • Useful for assessing vasculature for altered blood flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure 
    • Minimizes radiation to preserve gametes
    • Particularly useful in diagnosis of testicular torsion Testicular torsion Testicular torsion is the sudden rotation of the testicle, specifically the spermatic cord, around its axis in the inguinal canal or below. The acute rotation results in compromised blood flow to and from the testicle, which puts the testicle at risk for necrosis. Testicular Torsion
  • Indications for scrotal ultrasonography: 
    • Mass 
    • Hydrocele Hydrocele Accumulation of serous fluid between the layers of membrane (tunica vaginalis) covering the testis in the scrotum. Varicocele, Hydrocele, and Spermatocele
    • Testicular torsion
    • Infertility Infertility Infertility is the inability to conceive in the context of regular intercourse. The most common causes of infertility in women are related to ovulatory dysfunction or tubal obstruction, whereas, in men, abnormal sperm is a common cause. Infertility
    • Scrotal or inguinal hernia Inguinal hernia An abdominal hernia with an external bulge in the groin region. It can be classified by the location of herniation. Indirect inguinal hernias occur through the internal inguinal ring. Direct inguinal hernias occur through defects in the abdominal wall (transversalis fascia) in hesselbach's triangle. The former type is commonly seen in children and young adults; the latter in adults. Inguinal Canal and Hernias
    • Orchitis Orchitis Epididymitis and orchitis are characterized by acute inflammation of the epididymis and the testicle, respectively, due to viral or bacterial infections. Patients typically present with gradually worsening testicular pain and scrotal swelling along with systemic symptoms such as fever, depending on severity. Epididymitis and Orchitis
    • Epididymitis Epididymitis Epididymitis and orchitis are characterized by acute inflammation of the epididymis and the testicle, respectively, due to viral or bacterial infections. Patients typically present with gradually worsening testicular pain and scrotal swelling along with systemic symptoms such as fever, depending on severity. Epididymitis and Orchitis
    • Varicocele Varicocele A condition characterized by the dilated tortuous veins of the spermatic cord with a marked left-sided predominance. Adverse effect on male fertility occurs when varicocele leads to an increased scrotal (and testicular) temperature and reduced testicular volume. Varicocele, Hydrocele, and Spermatocele

Normal scrotal ultrasonography

  • Homogeneous echotexture
  • Epididymis can be seen with the head at the superior pole of the testicle, extending to the tail at the inferior pole.
  • Doppler mode:
    • Color images show arterial and venous flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure to testicle.
    • Spectral images demonstrate: 
      • Arterial waveform: demonstrates peaks and downslopes
      • Venous waveform: nearly equal heights

Epididymitis Epididymitis Epididymitis and orchitis are characterized by acute inflammation of the epididymis and the testicle, respectively, due to viral or bacterial infections. Patients typically present with gradually worsening testicular pain and scrotal swelling along with systemic symptoms such as fever, depending on severity. Epididymitis and Orchitis and orchitis

Ultrasound findings include:

  • Enlarged epididymis
  • Increased blood flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure to the epididymis: focal or diffuse
  • Decreased echogenicity of the epididymis: focal or diffuse
  • Hydrocele Hydrocele Accumulation of serous fluid between the layers of membrane (tunica vaginalis) covering the testis in the scrotum. Varicocele, Hydrocele, and Spermatocele and scrotal wall thickening are common.

Hydrocele Hydrocele Accumulation of serous fluid between the layers of membrane (tunica vaginalis) covering the testis in the scrotum. Varicocele, Hydrocele, and Spermatocele

Ultrasound findings include:

  • Presence of fluid around the testicle:
    • Presence of internal echoes: most likely acquired hydrocele
    • No internal echoes (simple): most likely congenital
  • Increase in size with straining (e.g., forced expiration against a closed glottis)

Varicocele Varicocele A condition characterized by the dilated tortuous veins of the spermatic cord with a marked left-sided predominance. Adverse effect on male fertility occurs when varicocele leads to an increased scrotal (and testicular) temperature and reduced testicular volume. Varicocele, Hydrocele, and Spermatocele

Ultrasound findings include:

  • Veins (e.g., pampiniform plexus) with a diameter > 2 mm
  • Best seen when comparing Valsalva images to resting images: reversal in blood flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure with this maneuver

Testicular torsion

Ultrasound findings:

  • Normal ultrasound does not exclude torsion: consider repeat ultrasound within 4 hours if there is continued suspicion of torsion.
  • Enlarged hypoechoic testicle in comparison to the normal testicle
  • Spermatic cord twisting 
  • No color or spectral flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure on Doppler evaluation: loss of venous → arterial flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure
  • A testicle that is diffusely hypoechoic and small is a sign of infarction.

Testicular carcinoma

Ultrasound findings include:

  • Abnormal echogenicity
  • Mass with increased blood flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure

MRI

Normal scrotal MRI

Table: Normal scrotal MRI
Structure T1-weighted T2-weighted With contrast
Testicle (homogeneous oval structure) Hypointense to isointense Hyperintense Enhance
Epididymis Isointense Hypointense Enhance
Tunica albuginea Hypointense Hypointense Not applicable

Testicular cancer Testicular cancer Testicular cancer is the most common solid malignancy affecting men 15-35 years of age. Most of the testicular cancers are of the germ cell tumor type, and they can be classified as seminomas and nonseminomas. The most common presentation of testicular cancer is a painless testicular mass. Testicular Cancer

MRI findings include:

  • Heterogeneous testicular mass
  • Irregular borders
  • Contrast enhancement
Transverse t1-weighted image depicts a multilobular left scrotal mass

Transverse T1-weighted image depicts a multilobular left scrotal mass (short arrow), located in the paratesticular space.
The lesion had similar signal intensity when compared with the normal testicular parenchyma (asterisk).
Left hydrocele (long arrow)

Image: “Transverse T1-weighted image” by Tsili AC, Argyropoulou MI MI MI is ischemia and death of an area of myocardial tissue due to insufficient blood flow and oxygenation, usually from thrombus formation on a ruptured atherosclerotic plaque in the epicardial arteries. Clinical presentation is most commonly with chest pain, but women and patients with diabetes may have atypical symptoms. Myocardial Infarction, Giannakis D, Sofikitis N, Tsampoulas K. License: CC BY 2.0

Clinical Relevance

  • Testicular torsion: medical emergency in which the spermatic cord, along with the spermatic artery inside it, twists, cutting off the blood supply. If left untreated, torsion results in testicular infarction, necrosis, and subsequent infertility. Presentation is with sudden severe unilateral scrotal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain, swelling, nausea, and vomiting. On physical examination, the testis is usually very tender to touch and swollen, with no pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain relief on scrotal elevation. The cremasteric reflex is absent. Color Doppler may show decreased blood flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure to the testicle, and this is usually enough to perform surgery in which detorsion is done.
  • Epididymitis Epididymitis Epididymitis and orchitis are characterized by acute inflammation of the epididymis and the testicle, respectively, due to viral or bacterial infections. Patients typically present with gradually worsening testicular pain and scrotal swelling along with systemic symptoms such as fever, depending on severity. Epididymitis and Orchitis and orchitis: 2 conditions that are characterized by the acute inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of the epididymis or the testis caused by viral or bacterial infection. Viral orchitis is more common in prepubertal boys and young adolescents, whereas bacterial infections are more commonly seen in older adolescents. Individuals usually present with acute scrotal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain, swelling, dysuria, urinary frequency, and urgency. Ultrasound can show scrotal wall thickening, and Doppler ultrasound will demonstrate increased blood flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure. Antibiotic treatment of orchitis and epididymitis is indicated when the cause is suspected to be bacterial in origin.
  • Varicocele Varicocele A condition characterized by the dilated tortuous veins of the spermatic cord with a marked left-sided predominance. Adverse effect on male fertility occurs when varicocele leads to an increased scrotal (and testicular) temperature and reduced testicular volume. Varicocele, Hydrocele, and Spermatocele: dilatation of the pampiniform venous plexus that is connected to the internal spermatic vein. Varicoceles are associated with impaired testicular hormonal function and infertility. Most men with varicoceles present with infertility issues, but some may have scrotal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain and heaviness. Ultrasonography of the scrotum usually shows a tubular lesion that increases in size when the individual performs the Valsalva maneuver. When varicoceles are symptomatic or associated with infertility and abnormal seminal fluid analysis, the treatment is surgical correction.

References

  1. Wittenberg, A.F., Tobias, T., Rzeszotarski, M., Minotti, A.J. (2006). Sonography of the acute scrotum: the four T’s of testicular imaging. Curr Probl Diagn Radiol 35:12–21. https://pubmed.ncbi.nlm.nih.gov/16399236/
  2. Andipa, E., Liberopoulos, K., Asvestis, C. (2004). Magnetic resonance imaging and ultrasound evaluation of penile and testicular masses. World J Urol 22:382–391. https://pubmed.ncbi.nlm.nih.gov/15300391/
  3. Watanabe, Y. (2002). Scrotal imaging. Curr Opin Urol 12:149–152. https://pubmed.ncbi.nlm.nih.gov/11859263/

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