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Scrotal ultrasound
In acute scrotal pain Doppler separates torsion (reduced or absent flow, twisting of the spermatic cord) from inflammation (increased flow); a solid intratesticular mass is malignant until proven otherwise, and an extratesticular mass is usually benign.
Why it matters in the exam
Acute pain: testicular torsion — reduced or absent Doppler flow compared with the other side, and a "whirlpool" sign in the spermatic cord; normal flow does not exclude partial or intermittent torsion, and high clinical suspicion leads to surgery without waiting for imaging. Epididymitis — an enlarged epididymis with increased flow, the commonest cause of acute pain in adults. In a prepubertal boy (about 7–12) — torsion of the appendix testis is the commonest cause: a small avascular nodule near the upper pole, with a normal testis. Trauma: testicular rupture is defined as a tear of the tunica albuginea — a discontinuous contour and heterogeneous texture — and is an indication for early surgery (preferably within 72 hours).
Masses: a solid intratesticular mass — cancer until proven otherwise. Seminoma — hypoechoic and homogeneous; non-seminomatous tumours — heterogeneous, with cysts and calcifications. After US — CT of the chest, abdomen and pelvis for staging, and blood markers. Epidermoid cyst — an "onion ring" structure without flow, benign. Outside the testis: epididymal cyst or spermatocele, hydrocele, and adenomatoid tumour — the commonest extratesticular tumour — benign. Microlithiasis (5 or more tiny foci per field): without risk factors — self-examination only; with risk factors (previous tumour, undescended testis, atrophy) — US follow-up.
Varicocele: veins above 3 mm with reversed flow on Valsalva, almost always on the left because the vein drains at a right angle into the renal vein. An isolated right varicocele or one that does not empty when lying down requires a search for a retroperitoneal mass compressing the vein. Undescended testis: most undescended testes are palpable in the inguinal canal; US is not needed before surgical referral, because it does not change management; orchiopexy is recommended at 6–18 months, and the risk of cancer and infertility remains increased.
Key points
- Torsion — absent flow, whirlpool; urgent surgery.
- Epididymitis — increased flow.
- Intratesticular mass — malignant until proven otherwise.
- Tunica albuginea tear — surgery.
- Right varicocele — look for a retroperitoneal mass.
Summary table
| Condition | Doppler | Additional finding | Action |
|---|---|---|---|
| Testicular torsion | Reduced or absent flow | Whirlpool in the cord | Urgent surgery |
| Epididymitis | Increased flow | Enlarged epididymis | Antibiotics |
| Torsion of the appendix testis | Avascular nodule | Boy 7–12, normal testis | Conservative |
| Testicular rupture | Disrupted flow | Tear of the tunica albuginea | Surgery within 72 hours |
| Intratesticular mass | Internal flow | Seminoma homogeneous; non-seminoma heterogeneous | Orchiectomy and staging CT |
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Sources
- ESUR Scrotal and Penile Imaging Working Group: Recommendations on testicular microlithiasis, 2015 — Follow-up
- ACR Appropriateness Criteria: Acute Onset of Scrotal Pain — Without Trauma, Without Antecedent Mass, 2019 — Doppler US
- EAU Guidelines on Testicular Cancer, 2024 — Diagnosis and staging
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.