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Stem
A 15-year-old boy presents with 3 hours of sudden severe left scrotal pain and vomiting that began at night. The left testis is high-riding with a horizontal lie; the cremasteric reflex is absent on the left and present on the right. Urinalysis is normal. He is afebrile.
Questions
a) Most likely diagnosis and anatomical predisposition. (3 marks)
Left intravaginal testicular torsion.
Bell-clapper deformity: tunica vaginalis completely invests the testis, allowing a horizontal lie and free rotation of the cord within the tunica — the classic adolescent predisposition.
b) Pathophysiological time course and why salvage is time-critical. (3 marks)
Cord twist → venous obstruction first → oedema → arterial compromise → ischaemia/necrosis.
Viability declines sharply after about 6 hours from onset of pain (not from hospital arrival). This underpins the “explore, don’t delay” rule.
c) Immediate management pathway and operative plan for viable vs non-viable testis. (5 marks)
NBM, IV access, analgesia (e.g. morphine titrated), urgent urology, immediate scrotal exploration. Do not delay for Doppler when clinical suspicion is high; imaging is only for equivocal cases if simultaneous with theatre preparation. Manual detorsion (“open the book”) is a temporary bridge only.
Viable: detorsion + warm assessment + ipsilateral orchidopexy + contralateral orchidopexy in the same anaesthetic (bilateral risk).
Non-viable: orchidectomy + contralateral fixation; counsel fertility implications and later prosthesis; histology if indicated.
d) Three differentials with one discriminator each. (4 marks)
- Epididymo-orchitis — more gradual onset, dysuria/pyuria, cremasteric often preserved (unreliable alone).
- Torsion of appendix testis (hydatid of Morgagni) — blue-dot sign, very localised upper pole tenderness, testis itself softer.
- Torsion of undescended testis — empty hemiscrotum with painful inguinal swelling.
If uncertain between torsion and mimic → explore.
Additional teaching points (mark-scoring phrases)
Salvage order-of-magnitude: highest within 6 h of pain onset; falls progressively thereafter — quote ranges carefully, but the principle is “hours matter.”
Cremasteric reflex: stroke ipsilateral inner thigh → testis elevates; absent supports torsion but presence does not exclude it.
Prehn sign (elevation relieves epididymo-orchitis pain) is unreliable — do not use it to rule out torsion.
Consent must include: orchidectomy if non-viable, bilateral fixation, infection, recurrent torsion (rare after proper fixation), fertility discussion, possible prosthesis later.
Neonatal extravaginal torsion: tunica and testis twist together; often presents with hard discoloured scrotum; urgent senior review — salvage rates lower but delay still unjustified.