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This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
The Bottom Line
- Twisting of spermatic cord → testicular ischaemia → infarction if not corrected. Bimodal peak: neonates and 12–25 years
- Presentation: sudden onset severe unilateral scrotal pain, often waking from sleep. Nausea/vomiting, referred lower abdominal pain
- Clinical diagnosis — do NOT delay for imaging. Absent cremasteric reflex is the single most sensitive sign
- 6-HOUR RULE: testis salvage rate ~100% if explored within 6 hours, drops to <10% after 24 hours
- Treatment: emergency surgical exploration, detorsion, and bilateral orchidopexy (fix both testes). Orchidectomy if non-viable
Overview
Testicular torsion occurs when the spermatic cord twists on its axis, compromising venous and then arterial blood supply to the testis. The commonest type is intravaginal torsion, caused by a "bell-clapper" anomaly (absence of normal posterior attachment of tunica vaginalis to scrotal wall, allowing the testis to rotate freely). This anatomical variant is bilateral in ~80%, which is why bilateral orchidopexy is performed at the time of surgical exploration. Extravaginal torsion occurs in neonates (the tunica vaginalis has not yet fused to the scrotal wall).
Epidemiology
Annual incidence is approximately 1 in 4,000 males under 25 years. Bimodal peaks: neonatal period and 12–18 years (puberty — increased testicular volume). It is the commonest cause of acute scrotal pain in adolescents. Left side is more commonly affected (the left spermatic cord is typically longer). Testis salvage rate is >90% if explored within 6 hours but <10% beyond 24 hours.
Clinical Features
Symptoms
Sudden onset severe unilateral scrotal pain (often wakes patient from sleep)
Pain may radiate to lower abdomen/groin
Nausea and vomiting (common)
No urinary symptoms (no dysuria/frequency — distinguishes from epididymitis)
Previous similar episodes that resolved spontaneously (intermittent torsion)
Signs
Swollen, tender, high-riding testis (retracted upward by shortened spermatic cord)
Abnormal lie (horizontal rather than vertical — "bell-clapper")
Absent cremasteric reflex (most sensitive clinical sign — 99% sensitivity in some studies)
Prehn sign negative (elevating testis does NOT relieve pain — unlike epididymitis where it may)
Scrotal erythema and oedema (develops over hours)
Investigations
First-line
CLINICAL DIAGNOSISTesticular torsion is a clinical diagnosis. If clinical suspicion is high, proceed DIRECTLY to surgical exploration. Do NOT delay for imaging
Second-line
Doppler ultrasoundONLY if diagnosis is genuinely uncertain (e.g. atypical presentation, older patient). Reduced or absent blood flow supports torsion. Normal flow does not exclude intermittent torsion
Specialist
UrinalysisTypically normal in torsion (positive in epididymitis/UTI — helps differentiate)
1
Emergency surgical exploration
- Consent for exploration, possible orchidopexy, possible orchidectomy
- Scrotal exploration via midline raphe or transverse scrotal incision
- Detorsion of spermatic cord — assess testicular viability (colour, capillary refill after warm wrapping)
- Orchidopexy: fix the affected testis with non-absorbable sutures to dartos fascia (3-point fixation). ALWAYS perform bilateral orchidopexy (bell-clapper anomaly is bilateral in ~80%)
- Orchidectomy: if testis is clearly non-viable despite warm compresses — reduces risk of anti-sperm antibodies affecting remaining testis
2
Manual detorsion (temporising only)
- Can attempt in the emergency department while awaiting theatre — "open the book" technique (medial to lateral rotation)
- Success indicated by immediate pain relief and testicular descent
- MUST still proceed to surgical fixation even if detorsion successful — recurrence rate is high without orchidopexy
Complications
- Testicular loss: If not detorsed within 6 hours — ischaemic necrosis requiring orchidectomy
- Subfertility: Loss of one testis reduces total sperm count. Anti-sperm antibodies may affect the contralateral testis
- Recurrence: Without orchidopexy, high recurrence risk
- Testicular atrophy: Partial ischaemia may cause subsequent atrophy even if initially salvaged
UKMLA Exam Tips
- 16-HOUR RULE: >90% salvage at <6 hours. <10% salvage at >24 hours. Time is testis
- 2Absent cremasteric reflex = most sensitive sign (stroke inner thigh → ipsilateral testis should retract. Absent in torsion)
- 3Do NOT delay for ultrasound if clinical suspicion is high — go STRAIGHT to theatre
- 4Bilateral orchidopexy is ALWAYS performed (bell-clapper anomaly is bilateral in ~80%)
- 5Differentiating torsion from epididymitis: torsion = sudden, no urinary symptoms, high-riding testis, absent cremasteric reflex. Epididymitis = gradual, dysuria, positive urinalysis, Prehn sign positive
- 6Neonatal torsion (extravaginal): presents as painless hard scrotal swelling at birth — often non-salvageable
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