Acute scrotum and scrotal mass
ACR AC Acute Scrotal Pain (2024); ACR AC Testicular Cancer Staging (2021); EAU/ESPU acute scrotumUltrasound with colour Doppler is definitive for both presentations and should not be delayed or substituted. The crucial vetting point is the one the scan cannot make: clinically convincing torsion goes to theatre, and imaging must never become the reason for delay.
Acute scrotal pain with suspected torsion, or a palpable intrascrotal mass requiring characterisation and, if malignant, staging.
Referenced decision support — confirm against your local protocol.
Decision support, not a directive. Protocols and timings shown are typical published ones — your local protocol takes precedence, and the vetting radiologist decides.
Accept as requested
Scrotal ultrasound with colour Doppler
Ultrasound scrotum with Doppler
What we'd amend, and why
- High-frequency ultrasound resolves the testicular parenchyma directly and colour Doppler shows perfusion in real time, which is why one study answers both the torsion question and the mass question. Comparative imaging of both sides in the same window is what makes asymmetric flow interpretable — absolute flow signal varies with machine settings, the comparison does not. It is immediately available, needs no contrast and no radiation, and there is no cross-sectional alternative that is faster or better.
Nothing needs resolving before this goes ahead. Routine checks below are owned downstream.
How was this decided?
- pathwaystandard — All ages — scrotal assessment
Decision support only. Local protocol takes precedence.
Pathways
Big forks are separate pathways; the first whose conditions match is the one used.
Acute onset within 24 hours — torsion until a surgeon says otherwise
| Role | Study & protocol | Why this answers the question |
|---|---|---|
| First line | Ultrasound scrotum with Doppler Scrotal ultrasound with colour Doppler usually appropriate | The vetting answer here has two halves and only one of them is about the scan. The scan is right: high-frequency ultrasound with colour Doppler and side-to-side comparison is the study, there is no faster or better alternative, and it must be performed now — on the emergency list, with the patient already referred to urology — rather than booked. The second half is the half that saves testes. Where the history and examination are convincing, the patient goes to theatre and imaging must not be interposed; if the only way to obtain the scan is to wait for it, the right answer is to stop asking for the scan. Salvage is around 90% within six hours of onset, roughly half by twelve hours and close to negligible beyond twenty-four, so an hour of waiting is measured in testicular tissue rather than in turnaround time. Two consequences follow from the physiology. Preserved arterial flow does not exclude torsion — incomplete and intermittent torsion both maintain it — so a normal Doppler study in a convincing presentation is not a negative result, and the signs worth hunting are the whirlpool of the twisted cord, an abnormal transverse or high-riding lie and asymmetric parenchymal echotexture. And a presentation beyond twenty-four hours does not close the question either: a missed torsion presents late with a non-viable testis, and what is then being protected is the contralateral side. |
- This arm changes the tempo, not the study and not the protocol. The same scan, booked as an emergency alongside a surgical referral instead of into a list.
- The decision that does not belong to imaging: a clinically convincing torsion goes to theatre whatever the scan shows or however long it would take to obtain. Manual detorsion at the bedside while theatre is prepared is a urological decision, not one that waits for a report.
- Hours since onset is the single most under-recorded fact on these requests and it is the one that sets the salvage clock. If the request does not state it, ask before booking rather than after.
- Age does not soften this. The commonest misdiagnosis of torsion in a boy is epididymo-orchitis, which is uncommon at that age, and a neonate can torse in utero or perinatally.
- The arm is keyed on hours since onset, so an acutely symptomatic mass enters it too. That is harmless — the first study is the same scrotal ultrasound either way — but the staging ladder for a confirmed tumour lives on the default arm, and a lump without acute pain belongs there.
All ages — scrotal assessment
Matches your inputsDefault| Role | Study & protocol | Why this answers the question |
|---|---|---|
| First line | Ultrasound scrotum with Doppler Scrotal ultrasound with colour Doppler usually appropriate | High-frequency ultrasound resolves the testicular parenchyma directly and colour Doppler shows perfusion in real time, which is why one study answers both the torsion question and the mass question. Comparative imaging of both sides in the same window is what makes asymmetric flow interpretable — absolute flow signal varies with machine settings, the comparison does not. It is immediately available, needs no contrast and no radiation, and there is no cross-sectional alternative that is faster or better. |
| Second line | CT Abdomen and Pelvis CT Abdomen and Pelvis — Portal Venous Phase | Staging once a testicular malignancy is established, not before. Coverage must include the retroperitoneum up to the renal hila, because that is where the first-echelon nodes lie; a study cropped for a pelvic question misses them entirely. |
| Second line | CT Chest CT Chest — Contrast-Enhanced (Venous Phase) | Thoracic staging completes the assessment in confirmed germ cell tumour, where pulmonary metastases are common and their presence changes the chemotherapy regimen. |
- Serum tumour markers are drawn before orchidectomy. Imaging does not replace them and the staging scan is interpreted alongside them.
Pitfalls
- Waiting for an ultrasound in a clinically convincing torsion. The scan should never be the reason a testis is lost: salvage is around 90% within six hours and close to negligible beyond twenty-four, so where the scan cannot happen immediately the patient goes to theatre and the scan is abandoned.
- Booking an acute scrotum onto a routine or next-available ultrasound list. This request is an emergency slot with a urology referral attached, and treating it as an outpatient characterisation study is the commonest way the delay actually happens.
- Recording the onset as "acute" or "since yesterday" rather than in hours. The salvage clock is the only number that changes what happens next, and it is the number most often missing.
- Reading preserved flow as excluding torsion — incomplete and intermittent torsion both maintain flow. Report a normal study in a convincing presentation as not excluding torsion, in those words.
- Failing to state whether a lesion is intratesticular or extratesticular, which is the single distinction that drives management.
- Sending a testicular lump for CT before ultrasound. It irradiates a young man, it cannot resolve the tunica, and it answers the one question that decides everything not at all.
- Staging CT cropped at the iliac crests, missing the retroperitoneal nodes at the renal hila that are the expected first site of spread.
- Attributing an acute scrotum in a young boy to epididymo-orchitis, which is uncommon at that age and is a frequent misdiagnosis of torsion.
- Running years of full-dose surveillance CT in a man in his twenties without asking whether a reduced-dose protocol, fewer timepoints or MRI would do. Cumulative dose in this population is a genuine harm and the alternatives are evidence-based, not improvised.
Priors — what to pull first
- Previous scrotal surgery, undescended testis or a contralateral tumour all raise the risk of malignancy and should be sought before the scan.
- In surveillance after orchidectomy, matching the previous CT technique is what makes nodal measurements comparable.
What makes a good request
- Torsion is a clinical and surgical diagnosis. Where the history and examination are convincing, exploration should proceed and imaging should not be interposed; the testicular salvage rate falls steeply with time.
- The salvage clock is the fact that decides everything else, and it is the one most often missing from the request. Salvage is of the order of 90% when the testis is untwisted within six hours of onset, roughly half by twelve hours, and close to negligible beyond twenty-four — so an hour spent waiting for a scan is not a neutral hour. This card forks on hours since onset for that reason: the study and the protocol do not change, the tempo does.
- Preserved arterial flow does not exclude torsion, particularly incomplete or intermittent torsion. A normal Doppler study in a convincing presentation is not a negative result, and it must be reported in those words rather than as a normal study. The more reliable signs are the whirlpool of the twisted spermatic cord, an abnormal transverse or high-riding testicular lie, and asymmetric parenchymal echotexture.
- Surveillance after orchidectomy runs for years in men in their twenties and thirties, and cumulative CT dose is a real consideration here rather than a theoretical one. Reduced-dose CT protocols and, in stage I seminoma, MRI of the abdomen and pelvis are established substitutes, and randomised evidence supports both fewer scans and the MRI substitution in that group. The number of acquisitions should be what the surveillance protocol requires, not what anyone might want.
- Almost all intratesticular solid masses are malignant and almost all extratesticular ones are benign, so the single most consequential observation is whether the lesion is inside the tunica.
- Once a testicular tumour is confirmed, staging is by contrast-enhanced CT of the chest, abdomen and pelvis, with particular attention to the retroperitoneal nodes at the level of the renal hila — the primary lymphatic drainage, which follows the embryological descent rather than the inguinal route.
Scoring this once it is done
The classification and risk tools this question ends in.
How these studies are acquired
Contrast, phases and timing for every study on the pathways above.
Confirm locally
- Timings, contrast volumes and rates above are typical published values. Your department's protocol, scanner and patient population decide the actual numbers.
- Safety thresholds and premedication policy follow local policy where it differs from the cited guidance.
References
- ACR Appropriateness Criteria — Acute Onset of Scrotal Pain Without Trauma, Without Antecedent Mass (2024 update) · ACR Appropriateness Criteria
- ACR Appropriateness Criteria — Newly Diagnosed Palpable Scrotal Abnormality · ACR Appropriateness Criteria
- ACR Appropriateness Criteria — Staging and Surveillance of Testicular Cancer (2021 update) · ACR Appropriateness Criteria
- EAU/ESPU Guidelines on Paediatric Urology — acute scrotum and testicular torsion (imaging must not delay exploration) · Other
- TRISST: MRI versus CT and three versus seven scans for surveillance in stage I seminoma — randomised non-inferiority trial (label-only: no single stable public article URL held here) · Primary literature
Implemented from the cited published sources. Educational and workflow support only; confirm against current guidelines and local policy before clinical use.