Scrotal / Testicular Ultrasound

Scrotal ultrasound with colour Doppler is the first-line imaging test for the acute and non-acute scrotum. It reliably differentiates surgical emergencies such as testicular torsion from inflammatory conditions, characterises palpable masses as intra- or extratesticular, and evaluates varicoceles, hydroceles and trauma. Grey-scale defines anatomy and echotexture while colour and spectral Doppler assess perfusion, which is the pivotal finding in the painful scrotum.

Indications

Acute scrotal pain or swelling with suspected testicular torsion
Suspected epididymitis or epididymo-orchitis
Palpable scrotal or testicular mass, including staging of suspected tumour
Scrotal trauma with suspected rupture or haematoma
Varicocele assessment in infertility or scrotal ache
Undescended or non-palpable testis and follow-up of hydrocele or spermatocele

Contraindications & Cautions

No absolute contraindications; ultrasound is non-ionising and safe
Do not delay urological consultation for suspected torsion to obtain imaging when clinical suspicion is high
Severe pain may limit transducer contact; use copious warm gel and gentle technique
Large hydrocele or gross oedema can degrade evaluation of the underlying testis

Patient Preparation

No fasting or bladder preparation required
Warm room and warm gel to reduce cremasteric contraction and patient discomfort
Supine position with the penis retracted onto the lower abdomen and covered
Support the scrotum on a rolled towel between the thighs
Explain that upright positioning and Valsalva may be needed for varicocele evaluation

Technique & Parameters

High-frequency linear array (9-18 MHz); a lower-frequency probe for very large or oedematous scrotum
Systematic grey-scale survey of each testis and epididymis in longitudinal and transverse planes
Obligatory transverse split-screen image comparing both testes for size, echogenicity and vascularity
Colour Doppler optimised for slow flow: low PRF (scale), low wall filter, small colour box, high colour gain
Spectral Doppler to confirm intratesticular arterial and venous waveforms and document symmetric flow
Valsalva manoeuvre and upright imaging to demonstrate pampiniform venous reflux for varicocele

Systematic Review

Compare testicular size and echotexture side to side (normal homogeneous mid-level echoes)
Confirm symmetric intratesticular colour and spectral flow in both testes
Assess epididymal head, body and tail for size, echogenicity and hyperaemia
Evaluate the tunica vaginalis for hydrocele, pyocele or haematocele and for the tunica albuginea integrity
Interrogate the spermatic cord for the whirlpool sign and pampiniform plexus for varicocele/reflux
Characterise any focal lesion as intratesticular (malignant until proven otherwise) versus extratesticular (usually benign)

Key Findings & Significance

Torsion: absent or markedly reduced intratesticular colour flow, enlarged hypoechoic testis, spermatic cord whirlpool sign
Epididymo-orchitis: enlarged hyperaemic epididymis/testis with increased Doppler flow and reactive hydrocele
Intratesticular solid mass with vascularity suggests germ cell tumour; microlithiasis may coexist
Varicocele: serpiginous veins >2-3 mm that enlarge or reflux on Valsalva/standing
Rupture: disrupted tunica albuginea, heterogeneous testis with contour irregularity and haematocele
Extratesticular cystic lesions (spermatocele, epididymal cyst) and simple hydrocele are benign

Differential Considerations

Acute painful scrotum: torsion vs epididymo-orchitis vs torsion of a testicular appendage vs incarcerated hernia
Absent flow mimics: technical (low PRF not set) vs true torsion vs previously infarcted testis
Intratesticular mass: seminoma, non-seminomatous germ cell tumour, lymphoma, infarct, focal orchitis, sarcoid
Extratesticular mass: adenomatoid tumour, spermatocele, epididymal cyst, chronic epididymitis
Scrotal fluid: simple hydrocele vs pyocele vs haematocele

Pearls & Pitfalls

Optimise Doppler for slow flow before calling torsion; document flow in the asymptomatic side as an internal control
Partial or intermittent torsion may show preserved or increased flow; the whirlpool sign is more specific
Any solid intratesticular lesion is malignant until proven otherwise and warrants tumour markers and urology referral
Reactive hydrocele and skin thickening are common but non-specific in inflammation
Testicular microlithiasis alone does not mandate biopsy but warrants attention to associated masses and risk factors

Structured Report

State transducer, comparison and whether Doppler was optimised for slow flow
Report testicular volumes/dimensions, echotexture and symmetry of colour/spectral flow
Describe epididymis, tunica, hydrocele and any varicocele with vein calibre and reflux response
Characterise focal lesions by location, size, echotexture and vascularity
Give an impression addressing the clinical question (e.g. torsion vs inflammation) and recommend urgent urology referral when indicated

References

AIUM Practice Parameter for the Performance of Scrotal Ultrasound Examinations
ACR-AIUM-SPR-SRU Practice Parameter for the Performance of Scrotal Ultrasound
Dogra VS et al. Sonography of the Scrotum. Radiology 2003;227:18-36
Society of Radiologists in Ultrasound Consensus on Testicular Microlithiasis and Incidentalomas

Educational clinical decision support only. Protocols vary by institution and equipment; always confirm with a qualified radiologist and local guidelines before clinical use.

Scrotal / Testicular Ultrasound

📋 Indications

⛔ Contraindications & Cautions

🧑‍⚕️ Patient Preparation

⚙️ Technique & Parameters

🔎 Systematic Review

🩻 Key Findings & Significance

🧠 Differential Considerations

💡 Pearls & Pitfalls

📝 Structured Report

📚 References