Scrotum / testis with Doppler — Reference values

Scrotum / testis with Doppler — Reference values: Minimum protocol, Transducer and Doppler, Testis — adult volume by ellipsoid, Volume in varicocele — Lambert formula.

Scrotal ultrasound should always answer three questions: is there a vascular/infectious emergency, is there an intra- or extratesticular mass, and is there varicocele/reflux affecting volume or fertility. In acute pain, comparative intratesticular Doppler and active search for a twisted cord are central parts of the exam.

Measurements and reference values

Measurement	Usual value	Note
Minimum protocol	bilateral + comparative + Doppler when indicated	Measure both testes in three axes; assess epididymides, tunics, fluid, scrotal wall, spermatic cord and inguinal canal if pain, mass, hernia or varicocele are suspected.Source: AIUM-ACR-SPR-SRU scrotal ultrasound 2025
Transducer and Doppler	linear ≥12 MHz; Doppler optimized for low flow	Adjust scale, wall filter and gain to detect slow intratesticular flow; always compare with the contralateral side in acute pain.Source: AIUM-ACR-SPR-SRU scrotal ultrasound 2025
Testis — adult volume by ellipsoid	length × width × height × 0.52 mL	Ranges vary by population. Use green for 15-25 mL, yellow for 10-14.9 mL or contextual >25 mL, red for <10 mL in adults/postpubertal patients when technique is reliable.usual adult range: 15–25 mLlow-normal / borderline: 10–14,9 mLreduced: <10 mLSource: EAA ultrasound study / andrology reference studies
Volume in varicocele — Lambert formula	length × width × height × 0.71 mL	ESUR-SPIWG prefers Lambert for varicocele assessment and recommends reporting which formula was used.Source: ESUR-SPIWG varicocele recommendations
Testicular asymmetry	<20 %	A difference ≥20% is an important yellow zone in adolescents/varicocele; it affects follow-up and clinical decision-making.Source: EAU Paediatric Urology / ESUR-SPIWG
Epididymis — head	≤12 mm	An enlarged, hypoechoic and hypervascular head supports epididymitis when painful; isolated enlargement may be cyst/spermatocele.Source: EAA ultrasound study / scrotal imaging reviews
Varicocele — largest vein standing with Valsalva	≥3 mm	ESUR considers 3 mm or more diagnostic when measured standing during Valsalva, especially with Doppler reflux.usual: <2 mmborderline: 2–2,9 mmvaricocele: ≥3 mm + refluxoSource: ESUR-SPIWG varicocele recommendations
Varicocele — reflux duration	>2 s	The essential parameter is spectral-Doppler reflux duration; ESUR suggests >2 s standing during Valsalva.no pathologic reflux: <1 sgray zone: 1–2 spathologic: >2 sSource: ESUR-SPIWG varicocele recommendations
Isolated testicular microlithiasis	no routine follow-up	Without a solid mass and risk factors, AUA/ESUR do not recommend routine workup or serial ultrasound.Source: AUA testicular cancer guideline / ESUR microlithiasis guideline

Classifications and calculators

Interactive assistant — scrotum, testes and Doppler

Input	How to interpret	Limitation
Functional normality	Volumes in usual range, symmetric intratesticular flow, no mass, no pathologic reflux and no complication signs.	Always depends on clinical indication and bilateral comparison.
Gray zone	Volume 10-14.9 mL, asymmetry ≥20%, vein 2-2.9 mm, reflux 1-2 s, uncomplicated epididymitis, typical extratesticular lesion or microlithiasis with risk.	Requires context, position, Valsalva and selective follow-up.
Abnormal or urgent	Reduced/absent flow, whirlpool sign, solid intratesticular mass, abscess/pyocele, rupture, complicated hernia or recent isolated right varicocele.	Rapid clinical communication may be required.

Use as educational triage. Torsion may retain some residual flow; a solid intratesticular mass should be treated as malignant until proven otherwise.

Source: AIUM-ACR-SPR-SRU 2025 / ACR acute scrotum / AUA testicular cancer / ESUR-SPIWG

Varicocele — ESUR-SPIWG documentation

Item	Report	Color
No varicocele	Veins <2 mm, no pathologic reflux and no relevant asymmetry.	Green
Borderline/subclinical	Vein 2-2.9 mm, short reflux or finding in only one position.	Yellow
Ultrasound varicocele	Largest vein ≥3 mm standing with Valsalva and reflux >2 s on spectral Doppler.	Red: consensus abnormal.
Adolescent or infertility	Measure both testicular volumes and asymmetry; report the formula used.	Yellow if no atrophy; red if marked atrophy.
Isolated right-sided or recent onset	Consider abdominal/renal extension, especially if it does not reduce supine.	Red because secondary causes must not be missed.

Report position, vein level, diameter, Valsalva, reflux duration and whether standing and supine positions were assessed.

Source: ESUR-SPIWG / Royal College of Radiologists audit template / EAU Paediatric Urology

Acute scrotum — Doppler and critical signs

Finding	Interpretation	Reporting action
Absent or reduced intratesticular flow	Torsion or ischemia until proven otherwise.	Urgent communication.
Whirlpool sign in the cord	Direct sign of torsion, including partial/intermittent torsion.	Describe knot location and residual flow.
Epididymal/testicular hyperemia	Favors epididymitis, orchitis or epididymo-orchitis.	Look for abscess, pyocele and infarction.
Abscess, pyocele, necrosis or infarction	Relevant infectious/vascular complication.	Communicate and suggest urologic correlation.
Trauma with tunica rupture	Risk of testicular loss if delayed.	Describe discontinuity, hematoma and Doppler viability.

Source: ACR acute scrotum / AIUM-ACR-SPR-SRU 2025 / BMUS acute epididymo-orchitis complications

Masses, cysts and microlithiasis

Pattern	Interpretation	Comment
Simple intratesticular or tunica cyst	Anechoic, thin wall, posterior enhancement, no solid component and no flow.	Green if all typical criteria are present.
Solid intratesticular mass	Manage as malignant until proven otherwise.	AUA: tumor markers before treatment; Doppler helps, but absent flow does not exclude tumor.
Typical extratesticular lesion	Epididymal cyst, spermatocele, appendage, lipoma or adenomatoid tumor may be benign.	Describe origin and relationship to epididymis, cord and tunics.
Solid extratesticular mass	More often benign than intratesticular, but not automatically benign.	Consider MRI/referral if indeterminate.
Isolated microlithiasis	No mass and no risk factors: no routine follow-up required.	AUA/ESUR guidance.
Microlithiasis with risk factor	Cryptorchidism/orchidopexy, personal/family history of germ-cell tumor, atrophy or infertility.	Individualized follow-up.

Source: AUA testicular cancer guideline / ESUR microlithiasis guideline / ACR palpable scrotal abnormality

Main differentials

Condition	Useful findings	Pitfall
Testicular torsion	Reduced/absent flow, cord whirlpool, high-riding or horizontal testis, reactive edema.	Residual flow may persist in partial torsion.
Torsion of testicular appendage	Small avascular nodule near upper pole, peripheral reactive hyperemia.	May mimic epididymitis.
Epididymitis/orchitis	Enlarged epididymis, hyperemia, reactive hydrocele and skin thickening.	Infarction/abscess makes it red.
Testicular tumor	Solid intratesticular mass, usually hypoechoic and vascular; calcification/scar may indicate burned-out tumor.	Do not routinely biopsy through the scrotum.
Hydrocele, hematocele or pyocele	Simple fluid, internal echoes, septa, debris, clots or gas depending on etiology.	Complex pyocele/hematocele with symptoms changes urgency.
Inguinoscrotal hernia	Fat or bowel content, peristalsis, Valsalva and reducibility.	Nonreducible bowel or ischemia is urgent.

Source: AIUM-ACR-SPR-SRU / ACR acute scrotum / AUA / ESUR

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