Testicular Ultrasound Made Easy: Step-By-Step Guide

Point of care testicular ultrasound is underutilized in the screening of patients with acute scrotal complaints. Instead, many providers rely on “classic” physical exam findings that have been shown to lack the sensitivity to rule out catastrophes such as testicular torsion (Schmitz 2009, Edwards 2025).

Instead, point of care ultrasound (POCUS) can be used as a reliable and practical screening tool to assess patients with acute scrotal complaints (Blaivas 2001, Blaivas 2000, Friedman 2019, Nene 2021, Stringer 2021) 

In this article we will cover basic anatomy, a step-by-step POCUS protocol, and specific pathology. We will not cover topics such as inguinal hernias, testicular masses, basic or advanced doppler explanations, indepth pathophysiology, or indepth treatment algorithms.

Testicular Ultrasound Indications 

• Pain
• Swelling
• Trauma
• Skin changes

Testicular Ultrasound Contraindications

• Patient refusal

Patient Preparation

• Place the patient supine in a frog leg position (knees bent, feet close together, hips externally rotated).
• Place a folded towel under the scrotum for support and comfort.
• Place another towel over the penis to remove it from your scanning region.

Machine Preparation

• Transducer: Linear probe
• Preset: Testicular (or soft tissue)
• Color/power doppler settings as below to increase the amount of blood flow visualized while subsequently decreasing the amount of artifact
  • Wall filter: low (i.e. < 100 Khz)
  • Pulse repetition frequency: low (i.e. 1-2 Hz)
  • Gain output: high (i.e. 70-90%)

Anatomy and Some Normal Findings

External Scrotal Anatomy

• From superficial to deep
  • Skin
  • Dartos muscle
    • Layer of smooth muscle that raises and lower the scrotum for temperature regulation
  • Fascia
  • Cremasteric muscle
    • Layer of striated and smooth muscle that raises and lower the scrotum for temperature regulation
• Normal ultrasound findings
  • Echogenicity: hyperechoic
  • Thickness: 2-8 mm depending on muscle contraction

Internal Scrotal Anatomy

• Tunica vaginalis
  • Membranous tissue layer composed of a visceral and parietal layer that protects the testes and allows for movement of the testes. It attaches to the posterolateral aspect of the testicle.
  • Abnormal tunica vaginalis attachment is responsible for the “bell clapper” deformity predisposing patients to testicular torsion.
  • Hydroceles collect between the potential space between the parietal and visceral layers of the tunica vaginalis.
• Tunica albuginea
  • Fibrous capsule deep to the tunica vaginalis that surrounds each testicle and the corpora cavernosa of the penis. This capsule eventually folds posteriorly into the testicle to form the mediastinum testis.
  • It functions to protect the testicle parenchyma and maintain the integrity/shape of the testicle.
  • Damage to this layer is responsible for testicular rupture.

• Testicle
  • The testicular parenchyma is composed of seminiferous tubules. These converge to a portion of the testicle called the mediastinum testes (linear band of connective tissue in the posterior aspect of the testicle) to reach another portion of the testicle called the rete testes. Finally the rete testis drain to the epididymal head
• Epididymis
  • Composed of a head, body, and tail.
  • The direction of flow is from the head to the tail. The tail then drains to the vas deferens which enters the spermatic cord to exit the scrotum.
  • The head is located superior to the testicle and is the easiest portion to visualize with ultrasound.
  • The body and tail are located posterior to the testicle. They are typically not visualized unless pathology (i.e. epididymitis) is present.
• Spermatic cord
  • Located superior to the testicle.
  • Contains the following:
    • Vasculature: testicular artery and pampiniform venous plexus
    • Vas deferens, lymphatics, nerves

• Appendix teste
  • A remnant of the mullerian duct that is attached to the testicle.
  • Normal findings:
    • Echogenicity: homogenous (similar to the testicle)
    • Length: 5 mm
    • Difficult to visualize unless a hydrocele is present

• Appendix epididymis
  • A remnant of embryonic tissue attached to the epididymal head similar to the appendix testis.
  • Normal findings:
    • Similar to appendix teste

Basic views

Long axis

Indicator up

Short axis

Indicator to the right

Buddy

Indicator to the right.

The probe is placed at the inferior portion of the scrotum to visualize both testicles side by side.

Complete Protocol and Additional Normal Findings

Always begin the examination (steps 1 to 6) with the unaffected testicle in order to set a “baseline” for measurements and doppler settings. These steps can be performed in any order, below is the order we propose to avoid missed steps.

Step 1: Long axis b-mode

• Complete fan through for a qualitative assessment of the testicle and epididymis for:
  • The normal homogenous parenchymal echogenicity similar to the liver or thyroid
  • Abnormalities such as heterogenous portions, cysts, calcifications
  • You may also visualize the
    • Mediastinum teste as a hyperechoic band along the posterior aspect of the testicle
    • Rete teste as a hypoechoic region adjacent to the mediastinum teste

• Measure the testicle length and height
  • Normal adult measurements
    • Length: 4-5 cm
    • Height: 2-3 cm

• Measure the epididymal head length and width.
  • Normal length: 10-12 mm
  • Normal width: 5-12 mm

• Evaluate the spermatic cord in long axis from the posterior-superior testicle for
  • Its normal appearance of multiple hypoechoic linear structures
  • Abnormalities such as varicoceles or the whirlpool sign

Step 2: Short axis b-mode

• Measure testicular width at its central portion
  • Normal adult measurements:
    • Width: 2-3 cm
  • Normal pediatric measurements:
    • Age dependent

• Evaluate the spermatic from the posterior-superior testicle to the inguinal canal for:
  • Normal hypoechoic cystic appearance
  • Normal width in the inguinal canal of 4 mm
  • Abnormalities such as varicoceles and the whirlpool sign

Step 3: Long axis testicular color/power doppler

• Qualitative assessment of blood flow for:
  • The normal even distribution of doppler signals throughout the parenchyma without regions of absent or increased flow
  • Abnormalities such as lack of, decreased, or increased doppler signals
• When performing this step on the unaffected side, adjust the doppler parameters as noted in the “machine preparation” section to increase flow visualized and decrease artifacts. This will be the “baseline” by which you compare the affect side to.

Step 4: Long axis testicular pulse-wave doppler

• Place the pulse wave doppler gate over the regions of color doppler flow in step 3.
• Confirm arterial flow and venous flow in multiple regions to ensure that pathology such as partial torsion or segmental testicular infarction is not occurring.
• Calculate the arterial resistive index for each of the captured arterial doppler waveforms.
• Normal pulse wave doppler findings:
  • Low resistance, monophasic arterial pattern
  • Arterial resistive index: 0.5-0.7
  • Venous flow with minimal pulsatility

Step 5: Long axis epididymis color/power doppler

• Qualitative assessment of blood flow for:
  • Normal doppler signals in multiple regions
  • Abnormalities such as lack of, decreased, or increased doppler signals
• As in step 3, the doppler settings used on the unaffected side will be the “baseline” by which you compare the affected side.

Step 6: Spermatic cord color doppler

• Confirm testicular arterial and venous plexus blood flow.
• Assess the venous diameter
• Normal venous diameter: 0.5-1.5 mm

Step 7: Repeat

• Repeat steps 1-6 on the affected side

Step 8: Buddy view

• Directly compare the echogenicity, width, and color/power doppler signals

Torsion Rule-in Protocol

This incomplete protocol can be used to quickly confirm testicular torsion prior to performing manual detorsion. As in the above protocol, perform steps 1 and 2 on the unaffected first.

Step 1: Testicle

• Measure testicular length, height, and width.
• Qualitatively assess blood flow with color/power doppler.
• Use pulse-wave doppler to confirm arterial and venous flow in multiple regions.

Step 2: Spermatic cord

• Check for the whirlpool sign
• Qualitatively assess blood flow with color/power doppler

Normal Variants

Testicular microlithiasis

• Multiple small calcifications throughout the testicle secondary to hydroxyapatite in the lumen of the seminiferous tubules.
• Appear as hyperechoic non-shadowing foci throughout the testicle.

Scrotal pearls

• Extratesticular calcifications secondary to prior inflammation, prior infection, or prior trauma.

Transmediastinal artery

• A linear artery through the mediastinum testis to the testicular capsule.
• This variant can be present in about 50% of people.

Tunica albuginea cyst

• Cysts that are usually simple, anechoic, and unilocular.

Testicular epidermoid cysts

• Well circumscribed, avascular, intratesticular cysts containing keratin. These usually have alternating hyperechoic and hypoechoic rings that form an “onion ring” pattern.

Striated testes

• Multiple hypoechoic linear bands that run perpendicular to the long axis of the testicle. 
• In younger patient’s this can be due to trauma, inflammation, ischemia, or cancer.
• In older patients with an otherwise normal ultrasound and reassuring examination, this is likely an incidental finding caused by interstitial fibrosis.

Tubular ectasia of the rete testes

• Multiple small avascular cysts or channels around the region of the mediastinum testes. 
• Likely caused by prior epididymal obstruction or inflammation.

Epididymal cyst

• Anechoic, avascular cysts that can occur anywhere along the epididymis

Pathology

Hydrocele

• A common cause of scrotal enlargement. 
• Pathophysiology
  • Fluid collects between the parietal and visceral layers of the tunica vaginalis.
  • The most common cause is a persistent process vaginalis connecting the scrotal sac to the peritoneum. Secondary causes include infection (i.e. orchitis), trauma (hematocele), torsion, cancer, radiation.
• Ultrasound findings
  • Simple hydrocele usually appears anechoic without internal debris.
  • Complex hydrocele is more echogenic with internal debris with septations. 
• Treatment
  • Based on the etiology

Epididymitis

• This is the most common cause of testicular pain in adults. 
• Pathophysiology
  • Inflammation of the epididymis secondary to retrograde spread of bacteria from the bladder and/or prostate. 
  • Common bacterial culprits include E. coli, gonorrhea, chlamydia. 
  • The epididymal head is the most commonly affected location.
• Ultrasound findings
  • Hypoechoic and enlarged epididymis. 
  • Reactive hydrocele
  • Increased blood flow via color/power doppler
  • Decreased resistive index via pulse wave doppler
  • Abscess or necrosis will appear as an avascular hypoechoic or isoechoic region surrounded by inflamed epididymal tissue.
• Treatment
  • Antibiotics

Orchitis

• Pathophysiology:
  • Inflammation of the testicular parenchyma that usually occurs in conjunction with epididymitis (epididymo-orchitis). Therefore, the common bacterial causes are the same as epididymitis.
  • Isolated orchitis is rare and usually viral (i.e. mumps)
• Ultrasound findings
  • Hypoechoic and enlarged testicle.
  • Reactive hydrocele
  • Increased blood flow via color/power doppler
    • Can be regional early in the course
    • Diffuse later in the course
  • Decreased resistive index via pulse wave doppler
  • Abscess or necrosis will appear as an avascular hypoechoic or isoechoic region surrounded by hyperemic testicular parenchyma.
  • Scrotal wall thickening
• False positive ultrasound findings:
  • Cancer can mimic the diffuse hyperemia seen with orchitis. You may differentiate between the two via history and physical examination. 
  • Recent testicular detorsion can also mimic the diffuse hyperemia. You may differentiate between the two by repeating an ultrasound in 15 minutes. If the diffuse hyperemia is secondary to recent detorsion, then it will be improved on repeat ultrasound. 
• Treatment
  • Etiology dependent
  • Antibiotics

Testicular torsion

• Pathophysiology:
  • Twisting of the spermatic cord resulting in ischemia of the testicle.
  • The order of events occurs as below:
    • Spermatic cord torsion → Venous obstruction → Arterial obstruction → Venous/arterial thrombosis → Testicular necrosis.
      • As venous flow is the first to be affected, confirmation of venous flow via pulse-wave doppler is mandatory to rule out torsion.
  • More common on the left due to long spermatic cord
  • Most common underlying cause: Bellclapper deformity
    • Tunica vaginalis completely encircles the testicle, spermatic cord, and epididymis. 
    • Usually a bilateral defect
• Other historical risk factors
  • History of undescended testicle
  • Post traumatic torsion due to forceful cremasteric muscle contraction.
• The importance of prompt recognition and treatment is related to the testicular salvage rates at specific time points.
  • Salvage rates
    • 97% at < 6 hours
    • 79% at 7-12 hours
    • 61% at 13-18 hours
    • 42% at 19-24 hours
    • 24% at 25-48 hours
    • 7% at > 48 hours

• Ultrasound findings
  • Hypoechoic and enlarged testicle in acute torsion.
  • Hyperechoic and shrunken testicle in chronic torsion.
  • Absent or diminished venous blood flow via power/pulse-wave doppler.
  • Absent or diminished arterial blood flow via power/pulse-wave doppler.
  • Increased testicular artery resistive index via pulse wave doppler
  • Whirlpool sign of the spermatic cord.
    • This is a visualization of the portion of the spermatic cord that is twisted.
    • Be wary, this can be misinterpreted as an enlarged epididymis in epididymitis. Differentiate the two by:
      • Finding the epididymal head
      • Assessing color/power doppler (epididymitis will have increased blood flow, while a twisted spermatic cord will have decreased blood flow).
  • Scrotal wall thickening
• Treatment
  • Manual detorsion
    • Open the book
    • Close the book
  • Surgery
    • Orchiopexy
    • Orchiectomy

Torsion of the appendix testis

• Pathophysiology:
  • Twisting of the appendix testis at its attachment to the testicle with subsequent ischemia.
• Unlike testicular torsion, this is not a urologic emergency, but can be associated with significant pain.
• Detached portions of the appendix testes post torsion can become scrotal pearls.
• Ultrasound findings:
  • Hypoechoic
  • Enlarged
  • Lack of or minimal blood flow to the appendix testes
  • Normal or increased blood flow to the testicle and epididymis
  • Reactive hydrocele
• Treatment
  • Supportive care (i.e. NSAIDs)

Trauma

Testicular rupture

• Pathophysiology
  • Disruption of the tunica albuginea resulting in distortion of the testicular parenchyma.
  • Typically caused by blunt force trauma. 
• US findings
  • Abnormal testicular shape
  • Abnormal testicular echogenicity which can be indicative of regions of hemorrhage or necrosis.
  • Hematocele
• Treatment
  • Emergent urology consultation for surgery.

Testicular fracture

• Pathophysiology
  • Disruption of the testicular parenchyma.
  • Typically caused by blunt force trauma.
  • Can be associated with a concomitant testicular rupture.
• Ultrasound findings
  • Hypoechoic band through the testicular parenchyma.
  • Possible hematocele and other findings as in the testicular rupture section above.
• Treatment
  • In conjunction with urology consultation usually supportive care if blood flow is preserved, fracture is minor, and tunica albuginea is intact.
  • Otherwise emergent urology consultation for surgery.

Hematocele

• Pathophysiology
  • Hemorrhage into the potential space between the parietal and visceral layers of the tunica vaginalis. 
  • Common causes include trauma, testicular torsion, and tumors.
• Ultrasound findings
  • Acutely, will see hypoechoic fluid surrounding the testicle. 
  • Over time, this fluid will become more echogenic and larger echogenic foci of hematomas can be seen.

Testicular dislocation

• Pathophysiology
  • Dislocation of the testicle from its normal position in the scrotum.
  • Typically caused by blunt force trauma.
  • The dislocated testicle most commonly located in the external inguinal ring.
• Ultrasound findings
  • Empty scrotum
  • Abnormal testicular location
  • Findings associated with other injuries (i.e. rupture, fracture)
• Treatment
  • Closed reduction in consultation with urology if there is no associated testicular torsion.
  • Otherwise urology consultation for surgery.

Varicocele

• Pathophysiology
  • Abnormal dilation of veins in the pampiniform venous plexus.
  • Most commonly occurs on the left side as this spermatic vein drains into the left renal vein.
  • Two types
    • Primary varicocele due to incompetent valves of the internal spermatic vein. 
    • Secondary varicocele due to pathology such as:
      • Increased external pressure (I.e. hydronephrosis, cirrhosis, masses)
      • IVC thrombosis
      • Nutcracker phenomenon during which the left renal vein is compressed between the superior mesenteric vein and aorta.
• Indications to search for alternative causes of a varicocele (i.e. cancer):
  • Right sided
  • Noncompressible
  • New onset at > 40 y/o
• Ultrasound findings
  • Multiple hypoechoic, serpiginous, tubular structures located superior and lateral to the testicle. 
  • Enlarged pampiniform venous plexus diameter (> 2 mm) which increases in size during a valsalva maneuver.
  • Color/Power doppler
    • More phasic venous blood flow pattern
    • Increased flow with valsalva maneuver
    • Reversal of flow with valsalva maneuver