Testicular torsion is the interruption of blood supply to the testis due to rotation of the spermatic cord around its own axis — one of the urological EMERGENCIES. If diagnosis is not made within 6 hours by imaging, the risk of testicular loss exceeds 90%. Ultrasound is the primary imaging modality; absent or decreased blood flow on color Doppler and whirlpool sign in the spermatic cord are pathognomonic findings. Torsion most commonly occurs between ages 12-18 but can happen at any age. Neonatal torsion is usually extravaginal type. Bell-clapper deformity (tunica vaginalis completely surrounding the testis) is the most important predisposing factor. Intermittent (spontaneous detorsion) forms may create diagnostic difficulty — surgical exploration is recommended in clinical suspicion.
Age Range
0-25
Peak Age
14
Gender
Male predominant
Prevalence
Uncommon
Testicular torsion results from rotation of the spermatic cord around its longitudinal axis, cutting off arterial supply and venous return to the testis. Intravaginal torsion (most common type) occurs within the tunica vaginalis and Bell-clapper deformity (tunica vaginalis surrounding the testis completely instead of mesentery, leaving the testis free like the clapper of a bell) is predisposing. The degree of rotation varies from 180-720 degrees — ischemia is more severe with >360 degrees. Venous return is interrupted first (lower pressure) — creating venous congestion, edema, and hemorrhage. With interruption of arterial flow, complete ischemia begins. The non-distensible tunica albuginea creates a compartment syndrome-like environment — as intratesticular pressure increases, microvascular perfusion further deteriorates. Within 4-6 hours, irreversible ischemic damage begins and seminiferous tubules necrose. On ultrasound, this pathology manifests as whirlpool sign in the spermatic cord (spiral appearance of twisted vascular structures) and decreased/absent arterial and venous flows on Doppler. In late stages, the testis enlarges, becomes heterogeneous, and shows diffusion restriction (cellular edema and necrosis).
Spiral/whirlpool appearance of twisted vascular structures in the spermatic cord — direct US evidence of spermatic cord rotation. Central cross-section view of twisted structures in transverse plane, helical spiral pattern in longitudinal plane. Pathognomonic for torsion.
Absent or decreased arterial and venous blood flow is seen in the affected testis on color and power Doppler — the most critical and sensitive finding for torsion. In early stage (first 1-2 hours), end-diastolic flow is lost (high-resistance pattern); as it progresses, complete avascularity develops. Reactive hypervascularity is seen in the contralateral normal testis (compensatory increased flow). Doppler settings are critical — low PRF (pulse repetition frequency) and low wall filter should be used. Neonatal torsion and intermittent torsion may cause false negatives.
Report Sentence
No blood flow is detected in the affected testis on color Doppler; reactive hypervascularity is present in the contralateral testis. Findings are consistent with EMERGENT testicular torsion and surgical exploration is recommended.
Spiral/twisted appearance of twisted vascular structures in the spermatic cord — whirlpool sign. This finding is the direct visualization of spermatic cord rotation and is pathognomonic for torsion. The torsion point is usually seen at the superior pole of the testis or in the inguinal canal. Spiral structures appear circular on transverse sections and spiral on longitudinal sections. When color Doppler is added, spiral vascular structures create a colored whirlpool pattern.
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Whirlpool sign — twisted vascular structures are seen in the spermatic cord; this finding is pathognomonic for testicular torsion.
Depending on torsion duration, the testis shows progressive findings: in early stage (0-4 hours) testis may appear normal or slightly enlarged, mid-stage (4-6 hours) testis is enlarged and mildly heterogeneous, late stage (>6 hours) testis becomes markedly enlarged, heterogeneous, and hypoechoic (edema, hemorrhage, necrosis). Very late stage (>24 hours) testis appears globally hypoechoic and avascular due to necrosis. Tunica albuginea may be thickened.
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The testis is enlarged with heterogeneous echotexture and no blood flow on Doppler; findings are consistent with late-stage testicular torsion.
MRI is rarely used for emergent torsion evaluation but may be helpful when diagnosis is difficult. The torsed testis shows heterogeneous signal on T2-weighted images — edema areas hyperintense, hemorrhage areas variable signal, necrosis areas low signal. Torsion and edema in the spermatic cord become evident on T2. On post-contrast sequences, the testis does not enhance (avascular ischemic tissue). Restricted diffusion is seen on DWI.
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On MRI, the testis shows heterogeneous T2 signal with no enhancement on post-contrast sequences; findings are consistent with testicular torsion and ischemia.
Restricted diffusion is seen in the torsed testis on DWI — hyperintensity on high b-value images and decreased signal on ADC maps. Diffusion restriction is due to ischemic cellular edema. This finding may be detected before B-mode changes in early stage and may contribute to early diagnosis of torsion.
Report Sentence
Restricted diffusion is observed in the torsed testis on DWI; findings are consistent with ischemic cellular edema.
Radionuclide testicular scintigraphy (Tc-99m) was historically used for torsion diagnosis. Decreased or absent radiotracer uptake is seen in the torsed testis (cold area = photopenic defect), with a surrounding rim of reactive hypervascularity (rim sign). Currently, scintigraphy is rarely used due to widespread availability of US/Doppler, but may be complementary when US diagnosis is uncertain.
Report Sentence
No radiotracer uptake is seen in the affected testis on testicular scintigraphy with surrounding reactive increased activity; findings are consistent with testicular torsion.
Criteria
Spermatic cord rotation within the tunica vaginalis — most common type (90%). Bell-clapper deformity background. Typically adolescent and young adult (12-18 years peak).
Distinct Features
Bell-clapper deformity may also be present in contralateral testis (bilateral fixation defect). Bilateral orchidopexy (fixation of both testes) is performed during surgery. Whirlpool sign is seen within tunica vaginalis.
Criteria
Rotation of the entire spermatic cord outside the tunica vaginalis — seen in neonatal period (prenatal or postnatal). Occurs before fixation by gubernaculum is complete during testicular descent to scrotum.
Distinct Features
Hard, painless, discolored (blue-black) scrotum in neonate. Testis heterogeneous and avascular on US. Salvage rate very low (prenatal torsion usually irreversible). Contralateral orchidopexy recommended.
Criteria
Recurrent spontaneous torsion and detorsion episodes. Testis appears normal between attacks. Typically sudden onset pain attacks — resolving spontaneously within minutes.
Distinct Features
Torsion findings on US during attack, NORMAL US between attacks. Elective orchidopexy recommended to prevent complete torsion risk. History critical — recurrent sudden scrotal pain + spontaneous resolution.
Distinguishing Feature
Orchitis: INCREASED blood flow (hypervascularity), fever, pyuria. Torsion: DECREASED/ABSENT blood flow, no fever typically, sudden onset. This differentiation is LIFE-SAVING — torsion is surgical EMERGENCY.
Distinguishing Feature
Seminoma: PAINLESS hypoechoic solid mass, hypervascular, progressive growth. Torsion: PAINFUL, avascular, sudden onset, whirlpool sign.
Distinguishing Feature
Varicocele: dilated (>3 mm), tubular venous structures in red-line pattern, increases with Valsalva. Torsion: spermatic cord whirlpool sign, avascular testis. Varicocele may be PAINFUL but acute onset not typical.
Distinguishing Feature
Abscess (late stage): avascular central area + peripheral ring hypervascularity. Torsion: entire testis avascular + whirlpool sign. Abscess develops in orchitis setting (fever, pyuria), torsion starts suddenly.
Urgency
emergentManagement
surgicalBiopsy
Not NeededFollow-up
specialist-referralTesticular torsion is an ABSOLUTE SURGICAL EMERGENCY. Testis salvage rate is >90% if detorsion within 6 hours, 50% at 12 hours, <10% at 24 hours. Manual detorsion (open book maneuver) may be attempted under US guidance but surgical exploration is still required. During surgery, the torsed testis is detorsed, viability assessed (orchiectomy if necrotic), and BILATERAL orchidopexy performed (contralateral testis may also have Bell-clapper). Elective orchidopexy is recommended for intermittent torsion.
Testicular torsion is a SURGICAL EMERGENCY. If surgical detorsion is performed within 6 hours, the salvage rate is approximately 100%; after 12 hours it drops to 20%, and after 24 hours to nearly 0%. When US confirms the diagnosis, IMMEDIATE surgical consultation should be requested — surgery should NOT be delayed for US. Because the contralateral testis also carries bell-clapper risk, bilateral orchiopexy is performed. In late presentations, gangrenous testis requires orchiectomy.